Outcomes of aortic valve replacement via partial upper sternotomy versus conventional aortic valve replacement in obese patients

Outcomes of aortic valve replacement via partial upper sternotomy versus conventional aortic... Abstract OBJECTIVES Excellent outcomes after minimally invasive aortic valve replacement (mini-AVR) have been reported. Therefore, mini-AVR has become a popular treatment option in many cardiac surgery centres. However, whether obese patients particularly benefit from mini-AVR remains unclear. The aim of the present study was to evaluate outcomes of AVR performed through partial upper sternotomy compared to AVR through a full sternotomy (full-AVR) in obese patients. METHODS We retrospectively reviewed the medical records of all patients who underwent isolated AVR at our institution, and 217 consecutive obese [body mass index (BMI) >30 kg/m2] patients were identified. Outcomes of the mini-AVR group were compared with the full-AVR group. RESULTS One hundred and twenty-six patients underwent mini-AVR and 91 patients had full-AVR. The mean age and BMI were 69.8 ± 10.4 years and 32.6 ± 3.1 kg/m2 in the mini-AVR group compared to 70.0 ± 10.5 years and 33.1 ± 3.0 kg/m2 in the full-AVR group. Mortality, myocardial infarction, stroke, renal failure and surgical site infections were equivalent. Mini-AVR was associated with decreased ventilation time [6 h (minimum, min 3 h; maximum, max 76 h) vs 8 h (min 3 h; max 340 h); P = 0.004], shorter intensive care unit (ICU) stay [2 days (min 1 day; max 25 days) vs 4 days (min 1 day; max 35 days); P = 0.031] and reduced transfusion requirements (26.5% vs 56.0%; P = 0.004). Total duration of hospital stay as well as postoperative pain levels were comparable. CONCLUSIONS Patient safety was not affected by mini-AVR. Significant benefits in terms of decreased transfusion requirements, ventilator times and ICU times were found in the mini-AVR group. Consequently, mini-AVR, performed through partial upper sternotomy, should also be routinely offered to obese patients. Aortic valve replacement, Obesity, Minimally invasive, Partial upper sternotomy INTRODUCTION In relation to to the development of the Western society, the proportion of obese patients [body mass index (BMI) >30 kg/m2] in cardiac surgery is continuously growing. Obesity was not found to be a risk factor for cardiosurgical mortality [1, 2]. On the contrary, moderately overweight patients seem to show reduced mortality after cardiac surgery, generally referred to as obesity paradoxon [3, 4]. Most recently, Hartrumpf et al. [5] analysed the outcomes of more than 15 000 cardiosurgical patients. The authors were able to confirm this obesity paradox and clearly show that BMI is not an independent predictor of mortality. Nevertheless, the rates of specific complications, such as prolonged mechanical ventilation and hospital treatment, renal failure and deep sternal and superficial wound infections, increase with the degree of obesity and result in delayed functional recovery of the affected patients [6–12]. Since the introduction of minimally invasive valve surgery in the last decade of the 20th century, minimally invasive aortic valve replacement (mini-AVR) has become a well-established treatment option in many institutions [13–16]. The reported results demonstrate that these operations can be performed safely without any increase in the risk of death or other major complications [17–20]. Regarding postoperative ventilation and intensive care unit (ICU) treatment, blood loss, wound infections and pain, however, only marginal benefits have been found for the patients. The outcome data of obese patients undergoing isolated valve surgery (AVR) through a limited access are sparse and 2 contrasting scenarios seem possible. The combination of obesity and small incision could lead to critical exposure of the operative area and in turn result in excessively prolonged operation times and increased conversion rates, which would marginalize the benefits of a minimally invasive approach. Alternatively, obese patients may increasingly benefit from minimized surgical trauma, compared to normal weight patients, because maintaining the integrity of the chest wall may positively influence postoperative weaning from mechanical ventilation and functional recovery as well as reduce the incidence of sternal wound infections in this high-risk population. The aim of the present study was to compare the outcomes of obese patients who underwent mini-AVR through partial upper sternotomy with those who received conventional AVR (full-AVR). METHODS After approval of the local ethics committee was obtained, we retrospectively reviewed the medical records of all adult patients operated at our institution between January 2000 and January 2015 and identified 217 consecutive obese patients who underwent isolated AVR for the first time. Obesity was defined as a BMI >30 kg/m2. Preoperative characteristics, operative data and postoperative outcomes of those patients who had mini-AVR were compared with those who underwent conventional AVR. All patients who underwent AVR through limited access were operated via partial upper sternotomy. From the start of the study period until December 2013, mini-AVR was performed based on the surgeons’ choice. Since January 2013, partial upper sternotomy is the standard approach for all isolated heart valve surgery. Patients scheduled for mini-AVR did not receive any additional preoperative assessment, and the performance of mini-AVR was not restricted to certain staff surgeons. To assess patients’ postoperative pain levels, the demand for daily analgesic medication was investigated. Additionally, patients’ subjective pain sensation was analysed with the help of a pain chart, which is also part of patients’ medical record. The pain chart ranges from 0 to 10 and is completed daily by the patients and the nursing staff. Statistical analysis Continuous variables except for the length of hospital and ICU stay as well as duration of ventilation are expressed as means ± standard deviations and were compared with Student’s t-test or the Mann–Whitney U-test, as appropriate. The length of hospital and ICU stay as well as duration of ventilation are expressed as median with minimum (min) and maximum (max) values. Categorical variables, expressed as percentages, were compared with a χ2 or Fisher’s exact test, as appropriate. Statistical significance was defined as P-value <0.05. Analyses were performed using SPSS 23.0 (SPSS Inc.) software. Surgical technique for minimally invasive aortic valve replacement Partial upper sternotomy was performed in a standardized fashion. The 8 cm midline skin incision started approximately 2 fingers below the sternal notch. Afterwards, the sternum was incised in an L-form manner from the sternal notch down to the left fourth intercostal space. For cardiopulmonary bypass in moderate hypothermia (32°C), the ascending aorta or the proximal aortic arch was cannulated and a 2-stage cannula was placed in the right atrium. The left ventricle was vented through a small cannula placed in the right upper pulmonary vein or the pulmonary artery. The aortic cross-clamp was applied through the incision. Cold blood cardioplegia was administered in an antegrade fashion into the aortic root and the coronary ostia approximately every 20 min. To prevent air embolism, the operative field was continuously flooded with CO2. After closure of the aortotomy and filling of the heart, deairing was achieved by placing the patient in the Trendelenburg position and inflating the lungs. A suction line was placed in the highest point of the closed aorta to remove the remaining air. After insertion of temporary pacing wires and 2 chest tubes, which were placed from a subxiphoidal position, the sternum was closed with 4 sternal wires via the conventional method. RESULTS Patient characteristics Of the 217 consecutive obese patients, 126 patients were operated through an upper ministernotomy (mini-AVR), and 91 patients received conventional AVR (full-AVR). Mean age and BMI of the full AVR-group were 70.0 ± 10.5 years and 33.1 ± 3.0 kg/m2, compared to 69.8 ± 10.4 years and an average BMI of 32.6 ± 3.1 kg/m2 in the mini-AVR group, showing no significant difference between the 2 groups. Analysis of the patients’ comorbidities, which are displayed in Table 1, revealed a similar risk profile of both groups. Operative risk, calculated with the logistic EuroSCORE, was also comparable between the 2 cohorts. Table 1: Preoperative characteristics of the patients in the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479  ACI: arteria carotis interna; AF: atrial fibrillation; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CVD: cerebral vascular disease; EF: ejection fraction; Hb: haemoglobin; HCT: haematocrit; IDDM: insulin dependent diabetes mellitus; NYHA: New York heart association; PVD: peripheral vascular disease; SD: standard deviation. Table 1: Preoperative characteristics of the patients in the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479  ACI: arteria carotis interna; AF: atrial fibrillation; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CVD: cerebral vascular disease; EF: ejection fraction; Hb: haemoglobin; HCT: haematocrit; IDDM: insulin dependent diabetes mellitus; NYHA: New York heart association; PVD: peripheral vascular disease; SD: standard deviation. Operative characteristics The total duration of the surgical procedure as well as the mean cardiopulmonary bypass time did not differ significantly between the surgical approaches (Table 2), but mean cross-clamp time was significantly longer in the mini-AVR group (70.0 ± 19.0 min vs 76.4 ± 18.9 min; P = 0.015). The mean diameter of the implanted aortic valve prostheses was significantly larger in the minimally invasive cohort (22.9 ± 1.9 mm vs 23.4 ± 1.8 mm; P = 0.011). Table 2: Major operative characteristics of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*  * P-values below 0.05 are considered statistically significant. AVR: aortic valve replacement; ECC: extracorporeal circulation; NA: not applicable; SD: standard deviation. Table 2: Major operative characteristics of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*  * P-values below 0.05 are considered statistically significant. AVR: aortic valve replacement; ECC: extracorporeal circulation; NA: not applicable; SD: standard deviation. Postoperative outcomes Detailed postoperative outcomes of the study groups are displayed in Table 3. Re-exploration due to postoperative bleeding was necessary in 2.2% of the patients in the full-AVR group and in 3.2% of the patients undergoing mini-AVR, showing no significant difference. The rates of postoperative myocardial infarction, stroke and renal failure were similar. The frequency of postoperative atrial fibrillation as well as the necessity of a permanent pacemaker implantation was comparable between groups. No significant difference was found regarding the incidence of superficial wound infections (full-AVR 6.6%; mini-AVR 8.7%) and deep sternal wound infections (full-AVR 3.3%; mini-AVR 5.6%) requiring surgical treatment. A significantly shorter duration of postoperative mechanical ventilation [6 h (min 3 h; max 76 h) vs 8 h (min 3 h; max 340 h); P = 0.004] as well as significantly reduced rates of reintubation (0% vs 7.7%; P = 0.002) and tracheotomy (0% vs 4.4%; P = 0.03) for long-term ventilation were observed in the mini-AVR group. Table 3: Detailed postoperative outcomes of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238  * P-values below 0.05 are considered statistically significant. AF: atrial fibrillation; AVR: aortic valve replacement; DSSI: deep surgical site infection requiring revision; ICU: intensive care unit; max: maximum; min: minimum; MI: myocardial infarction; PM: pace maker; SD: standard deviation; SSI: surgical site infection. Table 3: Detailed postoperative outcomes of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238  * P-values below 0.05 are considered statistically significant. AF: atrial fibrillation; AVR: aortic valve replacement; DSSI: deep surgical site infection requiring revision; ICU: intensive care unit; max: maximum; min: minimum; MI: myocardial infarction; PM: pace maker; SD: standard deviation; SSI: surgical site infection. Patients who underwent mini-AVR received significantly less units of packed red blood cells (1.75 ± 2.73 vs 0.88 ± 1.35; P = 0.002), fresh frozen plasma (0.80 ± 1.89; vs 0.21 ± 0.96; P = 0.003) and platelets (0.18 ± 0.50 vs 0.06 ± 0.32; P = 0.049). Accordingly, freedom from any transfusion was significantly higher in the mini-AVR group (44.0% vs 63.5%; P = 0.004). Mean postoperative time span to freedom from any analgesic medication was similar within both groups (full-AVR 5.87 ± 1.88 days, mini-AVR 6.09 ± 1.79 days; P = 0.433). The postoperative daily percentage of patients who experienced freedom from pain or only a minor pain sensation was also comparable between the groups (Fig. 1). Figure 1: View largeDownload slide The percentage of patients reporting a pain level below 3 on a scale with a maximum value of 10. Blue: full-aortic valve replacement; green: mini-aortic valve replacement. Figure 1: View largeDownload slide The percentage of patients reporting a pain level below 3 on a scale with a maximum value of 10. Blue: full-aortic valve replacement; green: mini-aortic valve replacement. Patients undergoing mini-AVR had a significantly shorter ICU stay [2 days (min 1 day; max 25 days) vs 4 days (min 1 day; max 35 days); P = 0.031], but the median duration of hospital stay was similar [full-AVR 11 days (min 2 days; max 51 days), mini-AVR 10 days (min 4 days; max 70 days)]. In-hospital mortality accounted for 0.92% (2 patients) of the overall study population and was not statistically significant different between the 2 groups [full-AVR 1 (1.09%), mini-AVR 1 (0.79%); P = 0.573]. DISCUSSION We analysed the outcomes of obese patients undergoing AVR through partial upper sternotomy, because the outcome data of this patient subgroup undergoing mini-AVR are sparse. The key question is whether the assumed difficulties in the exposure of the surgical field eventually leading to reduced patient safety and extensive operation times are outweighed by the benefits of a minimally invasive access. The present study, which to our knowledge is the most extensive so far, provides answers to this question. Our results showed that in obese patients, AVR through a partial upper sternotomy did not result in longer operative times compared to conventional AVR. Although significant longer cross-clamp times were found in the mini-AVR group, we do not assume that the mean difference of approximately 7 min of ischaemic time is clinically relevant. The conversion rate to full sternotomy was 0.8%. Mortality as well as the incidence of major complications was equivalent between the study cohorts. These data prove that obese patients are also suitable candidates for mini-AVR. The only other study investigating minimally invasive valve replacement in obese patients was published by Santana et al. [21] in 2011. In this study, the authors compared the outcomes of 64 obese patients undergoing aortic or mitral valve replacement through a parasternal incision and 96 obese patients were operated conventionally. In contrast to our findings, they not only observed significantly longer operation times but also a significant reduction in mortality (0% vs 8.3%). The major complication rate was comparable except for a significant decrease in postoperative renal failure (0% vs 6.2%) in the minimally invasive cohort. Meta-analysis investigating the outcomes after mini-AVR versus conventional AVR consistently assessed longer cross-clamp as well as bypass and operation times in patients operated through limited access but with comparable rates of major complications [17–19]. The size of the implanted aortic prostheses is an important issue in surgical AVR in order to avoid patient-prosthesis mismatch, especially in obese patients. An analysis of our data showed that the mean diameter of the implanted prostheses was even significantly larger in the mini-AVR cohort, demonstrating that also in obese patients, limited access does not drive surgeons to unfavourable compromises. In a recent publication, Bakir et al. [22] could show that a minimally invasive approach for AVR does not increase the incidence of a patient-prosthesis mismatch. In the present study, transfusion requirements of blood products were significantly reduced in the mini-AVR group and freedom from any transfusion significantly increased from 44% in the control group to 63% in the mini-AVR group. Similar results were found in the already mentioned study of Santana et al. [21] and in a most recent study conducted by Ghanta et al. [23]. In contrast, the available meta-analyses comparing AVR through limited access with AVR via full sternotomy either failed to find any significant difference or only found marginal benefits in terms of blood loss or frequency of blood transfusion [17–19]. A possible explanation for these conflicting data might be that obese patients were traditionally not found to be suitable for minimally invasive operations and were consequently excluded from surgery through limited access, although these patients may increasingly benefit from minimized surgical incisions due to their increased body volume and a consequently increased potential wound surface. Although the reduced demand of blood products was not related to an immediate clinical benefit, increasing evidence shows that blood transfusion has a negative impact on long-term outcomes after cardiac surgery [23–26]. Therefore, the blood sparing effect of mini-AVR should not be underestimated. One of the main arguments for minimally invasive valve surgery is the preservation of the chest wall integrity and its benefit in terms of shorter duration of ventilation, less pain and faster postoperative mobilization. In the present study, we found significantly shorter ventilation times and significantly decreased rates of reintubation and tracheotomy in the mini-AVR group. A shorter ICU stay could be observed as well, but the total duration of hospital stay was comparable between both groups. Santana et al. reported a significant reduction in reintubation and long-term ventilation for the mini-AVR group, although the average ventilation time was comparable between both cohorts. Regarding the total duration of ICU and hospital stay, they could demonstrate a significant reduction for patients operated on by the minimally invasive methods [21]. These findings go in line with the already cited meta-analyses [17–19], which predominately revealed favourable results for mini-AVR cohorts in terms of duration of mechanical ventilation, ICU and hospital treatment. Regarding the occurrence of postoperative sternum infection or instability, our study failed to show a protective effect of a hemisternotomy in this high-risk cohort, similar to the majority of studies of non-obese collectives that could not provide evidence for a beneficial effect of a limited access [17–21]. This result somehow contradicts our subjective clinical impression, but the pathogenesis for sternal infections seems to be too multifactorial such that a partially intact rib cage is not sufficient to reduce the incidence of this complication. Our analysis of the postoperative analgesic medication demand and pain scores did not reveal a beneficial impact of upper hemisternotomy for patients’ postoperative pain levels. This finding is in contrast to the meta-analysis of Brown et al. [18] but goes in line with the pooled analysis of Lim et al. [19]. The limitation of both meta-analysis is the sparse data regarding this issue, which may explain the contradictory results. The most popular alternative access for minimally invasive AVR is right minithoracotomy (RT). Several studies have shown that RT, compared to conventional sternotomy, has beneficial effects in terms of shorter ventilation times, shorter ICU and hospital stay and reduced blood product consumption [27, 28]. Publications directly comparing RT and ministernotomy are sparse, but a recently published meta-analysis by Balmforth et al. [29] provides an excellent overview of available data, which could not show a clear benefit of RT compared to ministernotomy. For the RT approach, various anatomical exclusion criteria exist, and so, especially in obese patients, it may not be offered on a routine basis. Frequent peripheral cannulation may also pose a problem with regard to groin complications especially in obese patients. Generally, RT is a technically much more demanding procedure compared to ministernotomy, thereby resulting in longer operation times. In our opinion, ministernotomy should be the first choice minimally invasive access, because it can be performed safely, easily and reliably in all patients with results comparable to RT. Limitations In the present study, all disadvantages of a retrospective observational study design apply. Furthermore, the study period is quite long and therefore small changes in the perioperative therapy regimen during the observational period cannot be excluded. Although both study cohorts showed no significant differences in the preoperative risk profile, propensity score matching was not possible, because the inclusion criteria for minimally invasive AVR changed during the study period from the surgeons’ choice to our departments’ standard approach. CONCLUSIONS The present study provides profound data which show that AVR through partial upper sternotomy should also be offered routinely to obese patients. Patient safety is not affected by the limited access, and significant benefits in terms of reduced transfusion requirements, reduced postoperative ventilation times and shorter ICU stay were found. Future prospective randomized trials are required to confirm our data. Funding This study was supported by institutional and departmental funding sources only. Conflict of interest: none declared. REFERENCES 1 Thourani VH, Keeling WB, Kilgo PD, Puskas JD, Lattouf OM, Chen EP et al.   The impact of body mass index on morbidity and short- and long-term mortality in cardiac valvular surgery. J Thorac Cardiovasc Surg  2011; 142: 1052– 61. Google Scholar CrossRef Search ADS PubMed  2 Atalan N, Fazlioğulları O, Kunt AT, Başaran C, Gürer O, Şitilci T et al.   Effect of body mass index on early morbidity and mortality after isolated coronary artery bypass graft surgery. J Cardiothorac Vasc Anesth  2012; 26: 813– 17. Google Scholar CrossRef Search ADS PubMed  3 Takagi H, Umemoto T. 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Is extreme obesity a risk factor for cardiac surgery? An analysis of patients with a BMI > or = 40. Eur J Cardiothorac Surg  2006; 29: 434– 40. Google Scholar CrossRef Search ADS PubMed  8 Tolpin DA, Collard CD, Lee VV, Elayda MA, Pan W. Obesity is associated with increased morbidity after coronary artery bypass graft surgery in patients with renal insufficiency. J Thorac Cardiovasc Surg  2009; 138: 873– 9. Google Scholar CrossRef Search ADS PubMed  9 Prabhakar G, Haan CK, Peterson ED, Coombs LP, Cruzzavala JL, Murray GF. The risks of moderate and extreme obesity for coronary artery bypass grafting outcomes: a study from the society of thoracic surgeons’ database. Ann Thorac Surg  2002; 74: 1125– 30; discussion 1130–1. 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Does a minimally invasive approach increase the incidence of patient-prosthesis mismatch in aortic valve replacement? J Heart Valve Dis  2014; 23: 161– 7. Google Scholar PubMed  23 Ghanta RK, Lapar DJ, Kern JA, Kron IL, Speir AM, Fonner EJr et al.   Minimally invasive aortic valve replacement provides equivalent outcomes at reduced cost compared with conventional aortic valve replacement: a real-world multi-institutional analysis. J Thorac Cardiovasc Surg  2015; 149: 1060– 5. Google Scholar CrossRef Search ADS PubMed  24 Bhaskar B, Dulhunty J, Mullany DV, Fraser JF. Impact of blood product transfusion on short and long-term survival after cardiac surgery: more evidence. Ann Thorac Surg  2012; 94: 460– 7. Google Scholar CrossRef Search ADS PubMed  25 Reeves BC, Murphy GJ. Increased mortality, morbidity, and cost associated with red blood cell transfusion after cardiac surgery. Curr Opin Cardiol  2008; 23: 607– 12. 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Is ministernotomy superior to right anterior minithoracotomy in minimally invasive aortic valve replacement? Interact CardioVasc Thorac Surg  2017; 25: 818– 21. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Interactive CardioVascular and Thoracic Surgery Oxford University Press

Outcomes of aortic valve replacement via partial upper sternotomy versus conventional aortic valve replacement in obese patients

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
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1569-9293
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1569-9285
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10.1093/icvts/ivy083
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Abstract

Abstract OBJECTIVES Excellent outcomes after minimally invasive aortic valve replacement (mini-AVR) have been reported. Therefore, mini-AVR has become a popular treatment option in many cardiac surgery centres. However, whether obese patients particularly benefit from mini-AVR remains unclear. The aim of the present study was to evaluate outcomes of AVR performed through partial upper sternotomy compared to AVR through a full sternotomy (full-AVR) in obese patients. METHODS We retrospectively reviewed the medical records of all patients who underwent isolated AVR at our institution, and 217 consecutive obese [body mass index (BMI) >30 kg/m2] patients were identified. Outcomes of the mini-AVR group were compared with the full-AVR group. RESULTS One hundred and twenty-six patients underwent mini-AVR and 91 patients had full-AVR. The mean age and BMI were 69.8 ± 10.4 years and 32.6 ± 3.1 kg/m2 in the mini-AVR group compared to 70.0 ± 10.5 years and 33.1 ± 3.0 kg/m2 in the full-AVR group. Mortality, myocardial infarction, stroke, renal failure and surgical site infections were equivalent. Mini-AVR was associated with decreased ventilation time [6 h (minimum, min 3 h; maximum, max 76 h) vs 8 h (min 3 h; max 340 h); P = 0.004], shorter intensive care unit (ICU) stay [2 days (min 1 day; max 25 days) vs 4 days (min 1 day; max 35 days); P = 0.031] and reduced transfusion requirements (26.5% vs 56.0%; P = 0.004). Total duration of hospital stay as well as postoperative pain levels were comparable. CONCLUSIONS Patient safety was not affected by mini-AVR. Significant benefits in terms of decreased transfusion requirements, ventilator times and ICU times were found in the mini-AVR group. Consequently, mini-AVR, performed through partial upper sternotomy, should also be routinely offered to obese patients. Aortic valve replacement, Obesity, Minimally invasive, Partial upper sternotomy INTRODUCTION In relation to to the development of the Western society, the proportion of obese patients [body mass index (BMI) >30 kg/m2] in cardiac surgery is continuously growing. Obesity was not found to be a risk factor for cardiosurgical mortality [1, 2]. On the contrary, moderately overweight patients seem to show reduced mortality after cardiac surgery, generally referred to as obesity paradoxon [3, 4]. Most recently, Hartrumpf et al. [5] analysed the outcomes of more than 15 000 cardiosurgical patients. The authors were able to confirm this obesity paradox and clearly show that BMI is not an independent predictor of mortality. Nevertheless, the rates of specific complications, such as prolonged mechanical ventilation and hospital treatment, renal failure and deep sternal and superficial wound infections, increase with the degree of obesity and result in delayed functional recovery of the affected patients [6–12]. Since the introduction of minimally invasive valve surgery in the last decade of the 20th century, minimally invasive aortic valve replacement (mini-AVR) has become a well-established treatment option in many institutions [13–16]. The reported results demonstrate that these operations can be performed safely without any increase in the risk of death or other major complications [17–20]. Regarding postoperative ventilation and intensive care unit (ICU) treatment, blood loss, wound infections and pain, however, only marginal benefits have been found for the patients. The outcome data of obese patients undergoing isolated valve surgery (AVR) through a limited access are sparse and 2 contrasting scenarios seem possible. The combination of obesity and small incision could lead to critical exposure of the operative area and in turn result in excessively prolonged operation times and increased conversion rates, which would marginalize the benefits of a minimally invasive approach. Alternatively, obese patients may increasingly benefit from minimized surgical trauma, compared to normal weight patients, because maintaining the integrity of the chest wall may positively influence postoperative weaning from mechanical ventilation and functional recovery as well as reduce the incidence of sternal wound infections in this high-risk population. The aim of the present study was to compare the outcomes of obese patients who underwent mini-AVR through partial upper sternotomy with those who received conventional AVR (full-AVR). METHODS After approval of the local ethics committee was obtained, we retrospectively reviewed the medical records of all adult patients operated at our institution between January 2000 and January 2015 and identified 217 consecutive obese patients who underwent isolated AVR for the first time. Obesity was defined as a BMI >30 kg/m2. Preoperative characteristics, operative data and postoperative outcomes of those patients who had mini-AVR were compared with those who underwent conventional AVR. All patients who underwent AVR through limited access were operated via partial upper sternotomy. From the start of the study period until December 2013, mini-AVR was performed based on the surgeons’ choice. Since January 2013, partial upper sternotomy is the standard approach for all isolated heart valve surgery. Patients scheduled for mini-AVR did not receive any additional preoperative assessment, and the performance of mini-AVR was not restricted to certain staff surgeons. To assess patients’ postoperative pain levels, the demand for daily analgesic medication was investigated. Additionally, patients’ subjective pain sensation was analysed with the help of a pain chart, which is also part of patients’ medical record. The pain chart ranges from 0 to 10 and is completed daily by the patients and the nursing staff. Statistical analysis Continuous variables except for the length of hospital and ICU stay as well as duration of ventilation are expressed as means ± standard deviations and were compared with Student’s t-test or the Mann–Whitney U-test, as appropriate. The length of hospital and ICU stay as well as duration of ventilation are expressed as median with minimum (min) and maximum (max) values. Categorical variables, expressed as percentages, were compared with a χ2 or Fisher’s exact test, as appropriate. Statistical significance was defined as P-value <0.05. Analyses were performed using SPSS 23.0 (SPSS Inc.) software. Surgical technique for minimally invasive aortic valve replacement Partial upper sternotomy was performed in a standardized fashion. The 8 cm midline skin incision started approximately 2 fingers below the sternal notch. Afterwards, the sternum was incised in an L-form manner from the sternal notch down to the left fourth intercostal space. For cardiopulmonary bypass in moderate hypothermia (32°C), the ascending aorta or the proximal aortic arch was cannulated and a 2-stage cannula was placed in the right atrium. The left ventricle was vented through a small cannula placed in the right upper pulmonary vein or the pulmonary artery. The aortic cross-clamp was applied through the incision. Cold blood cardioplegia was administered in an antegrade fashion into the aortic root and the coronary ostia approximately every 20 min. To prevent air embolism, the operative field was continuously flooded with CO2. After closure of the aortotomy and filling of the heart, deairing was achieved by placing the patient in the Trendelenburg position and inflating the lungs. A suction line was placed in the highest point of the closed aorta to remove the remaining air. After insertion of temporary pacing wires and 2 chest tubes, which were placed from a subxiphoidal position, the sternum was closed with 4 sternal wires via the conventional method. RESULTS Patient characteristics Of the 217 consecutive obese patients, 126 patients were operated through an upper ministernotomy (mini-AVR), and 91 patients received conventional AVR (full-AVR). Mean age and BMI of the full AVR-group were 70.0 ± 10.5 years and 33.1 ± 3.0 kg/m2, compared to 69.8 ± 10.4 years and an average BMI of 32.6 ± 3.1 kg/m2 in the mini-AVR group, showing no significant difference between the 2 groups. Analysis of the patients’ comorbidities, which are displayed in Table 1, revealed a similar risk profile of both groups. Operative risk, calculated with the logistic EuroSCORE, was also comparable between the 2 cohorts. Table 1: Preoperative characteristics of the patients in the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479  ACI: arteria carotis interna; AF: atrial fibrillation; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CVD: cerebral vascular disease; EF: ejection fraction; Hb: haemoglobin; HCT: haematocrit; IDDM: insulin dependent diabetes mellitus; NYHA: New York heart association; PVD: peripheral vascular disease; SD: standard deviation. Table 1: Preoperative characteristics of the patients in the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Age (years), mean ± SD  70.02 ± 10.51  69.79 ± 10.38  0.875  BMI (kg/m2), mean ± SD  33.11 ± 3.04  32.56 ± 3.09  0.240  Male gender, n (%)  51 (56.0)  69 (54.8)  0.851  EF (%), mean ± SD  58.33 ± 10.82  55.16 ± 14.90  0.221  NYHA, mean ± SD  3.0 ± 1.0  3.0 ± 1.0  0.376  Log EuroSCORE, mean ± SD  7.96 ± 7.48  8.58 ± 8.78  0.592  AF, n (%)   Intermittent (%)  0 (0.0)  2 (1.6)  0.227   Permanent (%)  5 (5.5)  7 (5.6)  0.331  PVD (%), n (%)  7 (7.7)  9 (7.1)  0.879  CVD (%), n (%)  13 (14.3)  8 (6.3)  0.051  ACI stenosis >50% (%), n (%)  3 (3.3)  1 (0.8)  0.344  s/p apoplex (%), n (%)  18 (19.8)  22 (17.5)  0.664  Diabetes (IDDM) (%), n (%)  35 (38.5)  36 (28.6)  0.125  Hypertension (%), n (%)  87 (95.6)  106 (84.1)  0.058  Hypercholesterinaemia (%), n (%)  61 (67.0)  75 (59.5)  0.259  History of smoking, n (%)  32 (35.2)  37 (29.4)  0.365  COPD (Gold III) , n (%)  8 (8.8)  12 (9.5)  0.155  Creatinine (mg/dl) (%), mean ± SD  1.22 ± 0.81  1.12 ± 0.77  0.344  Dialysis (%), n (%)  1 (1.1)  2 (1.6)  0.620  Hb (mg/dl), mean ± SD  13.39 ± 1.85  13.71 ± 1.48  0.164  HCT (%), mean ± SD  41.20 ± 3.82  40.50 ± 4.81  0.479  ACI: arteria carotis interna; AF: atrial fibrillation; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CVD: cerebral vascular disease; EF: ejection fraction; Hb: haemoglobin; HCT: haematocrit; IDDM: insulin dependent diabetes mellitus; NYHA: New York heart association; PVD: peripheral vascular disease; SD: standard deviation. Operative characteristics The total duration of the surgical procedure as well as the mean cardiopulmonary bypass time did not differ significantly between the surgical approaches (Table 2), but mean cross-clamp time was significantly longer in the mini-AVR group (70.0 ± 19.0 min vs 76.4 ± 18.9 min; P = 0.015). The mean diameter of the implanted aortic valve prostheses was significantly larger in the minimally invasive cohort (22.9 ± 1.9 mm vs 23.4 ± 1.8 mm; P = 0.011). Table 2: Major operative characteristics of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*  * P-values below 0.05 are considered statistically significant. AVR: aortic valve replacement; ECC: extracorporeal circulation; NA: not applicable; SD: standard deviation. Table 2: Major operative characteristics of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Duration of surgery (min), mean ± SD  198.46 ± 47.21  194.13 ± 37.47  0.453  Cross-clamp time (min), mean ± SD  70.01 ± 18.96  76.43 ± 18.85  0.015*  ECC time (min), mean ± SD  108.52 ± 32.77  107.46 ± 24.02  0.784  Conversion rate (%), n (%)  NA  1 (0.8)  0.875  Diameter of implanted prosthesis (mm), mean ± SD  22.73 ± 1.92  23.39 ± 1.84  0.011*  * P-values below 0.05 are considered statistically significant. AVR: aortic valve replacement; ECC: extracorporeal circulation; NA: not applicable; SD: standard deviation. Postoperative outcomes Detailed postoperative outcomes of the study groups are displayed in Table 3. Re-exploration due to postoperative bleeding was necessary in 2.2% of the patients in the full-AVR group and in 3.2% of the patients undergoing mini-AVR, showing no significant difference. The rates of postoperative myocardial infarction, stroke and renal failure were similar. The frequency of postoperative atrial fibrillation as well as the necessity of a permanent pacemaker implantation was comparable between groups. No significant difference was found regarding the incidence of superficial wound infections (full-AVR 6.6%; mini-AVR 8.7%) and deep sternal wound infections (full-AVR 3.3%; mini-AVR 5.6%) requiring surgical treatment. A significantly shorter duration of postoperative mechanical ventilation [6 h (min 3 h; max 76 h) vs 8 h (min 3 h; max 340 h); P = 0.004] as well as significantly reduced rates of reintubation (0% vs 7.7%; P = 0.002) and tracheotomy (0% vs 4.4%; P = 0.03) for long-term ventilation were observed in the mini-AVR group. Table 3: Detailed postoperative outcomes of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238  * P-values below 0.05 are considered statistically significant. AF: atrial fibrillation; AVR: aortic valve replacement; DSSI: deep surgical site infection requiring revision; ICU: intensive care unit; max: maximum; min: minimum; MI: myocardial infarction; PM: pace maker; SD: standard deviation; SSI: surgical site infection. Table 3: Detailed postoperative outcomes of the 2 study groups   Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238    Full-AVR (n = 91)  Mini-AVR (n = 126)  P-value  Infections   SSI (%), n (%)  6 (6.6)  11 (8.7)  0.563   DSSI (%), n (%)  3 (3.3)  7 (5.6)  0.434  Cardiac   Resternotomy for major bleeding (%), n (%)  4 (2.2)  3 (3.2)  0.504   Cardiac arrest (%), n (%)  5 (5.6)  1 (0.8)  0.084   MI (%), n (%)  1 (1.1)  1 (0.8)  0.818   New AF (%), n (%)  2 (2.2)  4 (3.2)  0.515   PM implantation (%), n (%)  2 (2.2)  2 (1.6)  0.596  Neurological   Stroke (%), n (%)  5 (5.5)  2 (1.6)  0.112   Delir (%), n (%)  31 (34.1)  34 (27.0)  0.261  Pulmonary   Reintubation (%), n (%)  7 (7.7)  0 (7.0)  0.002*   Tracheotomy (%), n (%)  4 (4.4)  0 (0.0)  0.030*   Duration ventilation (h)  8 (min: 3; max: 340)  6 (min: 3; max: 76)  0.004*  Renal   Renal replacement therapy, n (%)  2 (2.4)  2 (1.6)  0.560  Transfusion requirements   Packed red blood cells (units), mean ± SD  1.75 ± 2.73  0.88 ± 1.35  0.002*   Fresh frozen plasma (units), mean ± SD  0.80 ± 1.89  0.21 ± 0.96  0.003*   Platelets (units), mean ± SD  0.18 ± 0.50  0.06 ± 0.32  0.049*   No transfusion (%), n (%)  40 (44.0)  80 (63.5)  0.004*  Length of stay   ICU (days)  4 (min: 1; max: 35)  2 (min: 1; max: 25)  0.031*   Hospital (days)  11 (min: 2; max: 51)  10 (min: 4; max: 70)  0.238  * P-values below 0.05 are considered statistically significant. AF: atrial fibrillation; AVR: aortic valve replacement; DSSI: deep surgical site infection requiring revision; ICU: intensive care unit; max: maximum; min: minimum; MI: myocardial infarction; PM: pace maker; SD: standard deviation; SSI: surgical site infection. Patients who underwent mini-AVR received significantly less units of packed red blood cells (1.75 ± 2.73 vs 0.88 ± 1.35; P = 0.002), fresh frozen plasma (0.80 ± 1.89; vs 0.21 ± 0.96; P = 0.003) and platelets (0.18 ± 0.50 vs 0.06 ± 0.32; P = 0.049). Accordingly, freedom from any transfusion was significantly higher in the mini-AVR group (44.0% vs 63.5%; P = 0.004). Mean postoperative time span to freedom from any analgesic medication was similar within both groups (full-AVR 5.87 ± 1.88 days, mini-AVR 6.09 ± 1.79 days; P = 0.433). The postoperative daily percentage of patients who experienced freedom from pain or only a minor pain sensation was also comparable between the groups (Fig. 1). Figure 1: View largeDownload slide The percentage of patients reporting a pain level below 3 on a scale with a maximum value of 10. Blue: full-aortic valve replacement; green: mini-aortic valve replacement. Figure 1: View largeDownload slide The percentage of patients reporting a pain level below 3 on a scale with a maximum value of 10. Blue: full-aortic valve replacement; green: mini-aortic valve replacement. Patients undergoing mini-AVR had a significantly shorter ICU stay [2 days (min 1 day; max 25 days) vs 4 days (min 1 day; max 35 days); P = 0.031], but the median duration of hospital stay was similar [full-AVR 11 days (min 2 days; max 51 days), mini-AVR 10 days (min 4 days; max 70 days)]. In-hospital mortality accounted for 0.92% (2 patients) of the overall study population and was not statistically significant different between the 2 groups [full-AVR 1 (1.09%), mini-AVR 1 (0.79%); P = 0.573]. DISCUSSION We analysed the outcomes of obese patients undergoing AVR through partial upper sternotomy, because the outcome data of this patient subgroup undergoing mini-AVR are sparse. The key question is whether the assumed difficulties in the exposure of the surgical field eventually leading to reduced patient safety and extensive operation times are outweighed by the benefits of a minimally invasive access. The present study, which to our knowledge is the most extensive so far, provides answers to this question. Our results showed that in obese patients, AVR through a partial upper sternotomy did not result in longer operative times compared to conventional AVR. Although significant longer cross-clamp times were found in the mini-AVR group, we do not assume that the mean difference of approximately 7 min of ischaemic time is clinically relevant. The conversion rate to full sternotomy was 0.8%. Mortality as well as the incidence of major complications was equivalent between the study cohorts. These data prove that obese patients are also suitable candidates for mini-AVR. The only other study investigating minimally invasive valve replacement in obese patients was published by Santana et al. [21] in 2011. In this study, the authors compared the outcomes of 64 obese patients undergoing aortic or mitral valve replacement through a parasternal incision and 96 obese patients were operated conventionally. In contrast to our findings, they not only observed significantly longer operation times but also a significant reduction in mortality (0% vs 8.3%). The major complication rate was comparable except for a significant decrease in postoperative renal failure (0% vs 6.2%) in the minimally invasive cohort. Meta-analysis investigating the outcomes after mini-AVR versus conventional AVR consistently assessed longer cross-clamp as well as bypass and operation times in patients operated through limited access but with comparable rates of major complications [17–19]. The size of the implanted aortic prostheses is an important issue in surgical AVR in order to avoid patient-prosthesis mismatch, especially in obese patients. An analysis of our data showed that the mean diameter of the implanted prostheses was even significantly larger in the mini-AVR cohort, demonstrating that also in obese patients, limited access does not drive surgeons to unfavourable compromises. In a recent publication, Bakir et al. [22] could show that a minimally invasive approach for AVR does not increase the incidence of a patient-prosthesis mismatch. In the present study, transfusion requirements of blood products were significantly reduced in the mini-AVR group and freedom from any transfusion significantly increased from 44% in the control group to 63% in the mini-AVR group. Similar results were found in the already mentioned study of Santana et al. [21] and in a most recent study conducted by Ghanta et al. [23]. In contrast, the available meta-analyses comparing AVR through limited access with AVR via full sternotomy either failed to find any significant difference or only found marginal benefits in terms of blood loss or frequency of blood transfusion [17–19]. A possible explanation for these conflicting data might be that obese patients were traditionally not found to be suitable for minimally invasive operations and were consequently excluded from surgery through limited access, although these patients may increasingly benefit from minimized surgical incisions due to their increased body volume and a consequently increased potential wound surface. Although the reduced demand of blood products was not related to an immediate clinical benefit, increasing evidence shows that blood transfusion has a negative impact on long-term outcomes after cardiac surgery [23–26]. Therefore, the blood sparing effect of mini-AVR should not be underestimated. One of the main arguments for minimally invasive valve surgery is the preservation of the chest wall integrity and its benefit in terms of shorter duration of ventilation, less pain and faster postoperative mobilization. In the present study, we found significantly shorter ventilation times and significantly decreased rates of reintubation and tracheotomy in the mini-AVR group. A shorter ICU stay could be observed as well, but the total duration of hospital stay was comparable between both groups. Santana et al. reported a significant reduction in reintubation and long-term ventilation for the mini-AVR group, although the average ventilation time was comparable between both cohorts. Regarding the total duration of ICU and hospital stay, they could demonstrate a significant reduction for patients operated on by the minimally invasive methods [21]. These findings go in line with the already cited meta-analyses [17–19], which predominately revealed favourable results for mini-AVR cohorts in terms of duration of mechanical ventilation, ICU and hospital treatment. Regarding the occurrence of postoperative sternum infection or instability, our study failed to show a protective effect of a hemisternotomy in this high-risk cohort, similar to the majority of studies of non-obese collectives that could not provide evidence for a beneficial effect of a limited access [17–21]. This result somehow contradicts our subjective clinical impression, but the pathogenesis for sternal infections seems to be too multifactorial such that a partially intact rib cage is not sufficient to reduce the incidence of this complication. Our analysis of the postoperative analgesic medication demand and pain scores did not reveal a beneficial impact of upper hemisternotomy for patients’ postoperative pain levels. This finding is in contrast to the meta-analysis of Brown et al. [18] but goes in line with the pooled analysis of Lim et al. [19]. The limitation of both meta-analysis is the sparse data regarding this issue, which may explain the contradictory results. The most popular alternative access for minimally invasive AVR is right minithoracotomy (RT). Several studies have shown that RT, compared to conventional sternotomy, has beneficial effects in terms of shorter ventilation times, shorter ICU and hospital stay and reduced blood product consumption [27, 28]. Publications directly comparing RT and ministernotomy are sparse, but a recently published meta-analysis by Balmforth et al. [29] provides an excellent overview of available data, which could not show a clear benefit of RT compared to ministernotomy. For the RT approach, various anatomical exclusion criteria exist, and so, especially in obese patients, it may not be offered on a routine basis. Frequent peripheral cannulation may also pose a problem with regard to groin complications especially in obese patients. Generally, RT is a technically much more demanding procedure compared to ministernotomy, thereby resulting in longer operation times. In our opinion, ministernotomy should be the first choice minimally invasive access, because it can be performed safely, easily and reliably in all patients with results comparable to RT. Limitations In the present study, all disadvantages of a retrospective observational study design apply. Furthermore, the study period is quite long and therefore small changes in the perioperative therapy regimen during the observational period cannot be excluded. Although both study cohorts showed no significant differences in the preoperative risk profile, propensity score matching was not possible, because the inclusion criteria for minimally invasive AVR changed during the study period from the surgeons’ choice to our departments’ standard approach. CONCLUSIONS The present study provides profound data which show that AVR through partial upper sternotomy should also be offered routinely to obese patients. Patient safety is not affected by the limited access, and significant benefits in terms of reduced transfusion requirements, reduced postoperative ventilation times and shorter ICU stay were found. Future prospective randomized trials are required to confirm our data. Funding This study was supported by institutional and departmental funding sources only. Conflict of interest: none declared. REFERENCES 1 Thourani VH, Keeling WB, Kilgo PD, Puskas JD, Lattouf OM, Chen EP et al.   The impact of body mass index on morbidity and short- and long-term mortality in cardiac valvular surgery. J Thorac Cardiovasc Surg  2011; 142: 1052– 61. Google Scholar CrossRef Search ADS PubMed  2 Atalan N, Fazlioğulları O, Kunt AT, Başaran C, Gürer O, Şitilci T et al.   Effect of body mass index on early morbidity and mortality after isolated coronary artery bypass graft surgery. J Cardiothorac Vasc Anesth  2012; 26: 813– 17. Google Scholar CrossRef Search ADS PubMed  3 Takagi H, Umemoto T. 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Is ministernotomy superior to right anterior minithoracotomy in minimally invasive aortic valve replacement? Interact CardioVasc Thorac Surg  2017; 25: 818– 21. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

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Interactive CardioVascular and Thoracic SurgeryOxford University Press

Published: Mar 30, 2018

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