TY - JOUR
AU1 - Ram, Eilon
AU2 - Schwammenthal, Ehud
AU3 - Kuperstein, Rafael
AU4 - Jamal, Tamer
AU5 - Nahum, Eyal
AU6 - Sternik, Leonid
AU7 - Raanani, Ehud
AB - Abstract Open in new tabDownload slide Open in new tabDownload slide OBJECTIVES Left ventricular outflow tract obstruction causes symptoms of heart failure in most patients with hypertrophic cardiomyopathy. Resection of the secondary mitral valve (MV) chordae has recently been shown to move the MV apparatus posteriorly, thereby eradicating the outflow gradient. The aim of this study was to evaluate whether secondary chordal resection concomitant to septal myectomy improves outcomes. METHODS Between 2005 and 2020, a total of 165 patients underwent septal myectomy without MV repair or replacement in our Medical Center. Secondary MV chordal resection was performed in 60 patients, and their outcomes were compared with those of the remaining 105 patients who did not undergo chordal resection (controls). Mean age was 61 ± 13 and 58 ± 16 years, respectively (P = 0.205). RESULTS There were no in-hospital deaths throughout the entire cohort. Of those patients who underwent secondary chordal resection, New York Heart Association functional class decreased from 3 (interquartile range 2–3) preoperatively to 1 (interquartile range 1–2) postoperatively (P < 0.001), and resting outflow gradient decreased from 91 ± 39 mmHg to 13 ± 8 mmHg (86% change, P < 0.001). Compared with controls, patients who underwent secondary chordal resection had a significant lower resting outflow gradient at follow-up (14 ± 7 mmHg vs 21 ± 15 mmHg, P = 0.002). The rate of moderate or more than moderate mitral regurgitation at 5 years was 2% in the secondary chordal resection group and 5% in the controls (hazard ratio 1.05, confidence interval 0.11–10.32; P = 0.965). CONCLUSIONS In this observational study, we report that secondary chordal resection concomitant to septal myectomy for left ventricular outflow tract obstruction is safe, relieves heart failure symptoms and reduces left ventricular outflow tract gradient in appropriately selected patients. Hypertrophic obstructive cardiomyopathy, Septal myectomy, Secondary chordal resection INTRODUCTION Hypertrophic obstructive cardiomyopathy (HCM) is a genetic cardiac disease with a prevalence of approximately 0.2% [1]. Dyspnoea is one of the most frequent symptoms of HCM which develops from left ventricular (LV) outflow tract (LVOT) obstruction, diastolic dysfunction with preserved ejection fraction or systolic dysfunction [2]. Chest pain is also a frequent symptom which develops from myocardial ischaemia caused by microvascular dysfunction, increased LV wall stress and LVOT obstruction. Syncope can be induced by several factors such as fatal arrhythmia, LVOT obstruction and abnormal vascular reflexes. HCM patients have an annual sudden cardiac death risk of 1.5% [3]. Septal reduction therapy is a class I indication in patients with LVOT peak gradients of ≥50 mmHg, who are in New York Heart Association (NYHA) functional class II–IV despite maximum tolerated medical therapy [4]. The choice of therapy is based on a systematic assessment of the mitral valve (MV) and septal anatomy that includes deliberate exclusion of other LV outflow tract and MV abnormalities. Surgical septal myectomy for severe, drug-refractory symptoms associated with dynamic LVOT obstruction secondary to HCM, provides substantial and durable symptom relief, and may improve long-term survival [5, 6]. However, post-myectomy residual gradients occur in approximately 2.5% of HCM patients who undergo septal myectomy [7], and those gradients are associated with less favourable outcomes [8]. Secondary chordal resection, in addition to septal myectomy, was first proposed by Ferrazzi et al. [9], who reported excellent outcomes. We aimed to investigate whether secondary chordal resection in addition to septal myectomy would provide a greater reduction in LVOT gradients in HCM patients compared with septal myectomy alone, and to assess whether secondary chordal resection increases the risk of developing mitral regurgitation (MR). MATERIALS AND METHODS Patient population and study design This is a retrospective, single-centre, observational study based on the results of surgical treatment for HCM. The entire cohort represents the results of a single surgeon, who is an expert in HCM surgery and who performs all the septal myectomy surgical procedures in our referral Medical Center. Following the publication of Ferrazzi et al. [9] in 2015, we began performing secondary chordal cutting in all patients who were identified during surgery as having thickened major secondary chords that may have had an additive role in the increased LVOT gradients. Preoperative, operative, and postoperative data were collected from our departmental database, and all clinical and echocardiographic follow-up was carried out via our outpatient clinic, with a regular annual examination. Patients who were lost to ambulatory follow-up were interviewed over the telephone. Medical treatment was continued by the treating cardiologist throughout and following the surgical procedure, with no change in the postoperative medication protocol during the study period. The study was approved by the Institutional Review Board of our Medical Center (Protocol No 4257). Surgical procedure All patients underwent surgery via a median sternotomy. Standard cardiopulmonary bypass was established by cannulation of the ascending aorta and the right atrium for venous return, or by femoral cannulation in reoperation cases. Myocardial protection was achieved by using intermittent antegrade and/or retrograde cold blood cardioplegia, and all patients underwent extensive septal myectomy through an aortotomy incision as previously reported [10]. For chordal resection, after the myectomy was completed, the ventricular aspect of the mitral anterior leaflet was evaluated in order to identify major secondary chordae, which were then selected with a nerve hook. The selection of secondary chordae for resection was based on the thickness of the chords and evaluation by inspection that may have played an additive role in increased LVOT gradients (Supplementary Material, Fig. S1). The distal part of the selected fibrotic secondary chordae was then cut using blade No. 15 from the anterior leaflet, and the proximal part was cut from its connection to the papillary muscle [11] (Figs 1 and 2). Patients were monitored intraoperatively with transoesophageal echocardiography for evaluation of surgical results. Figure 1: Open in new tabDownload slide Secondary mitral valve chordal resection: Following the myectomy, the ventricular aspect of the mitral anterior leaflet was evaluated in order to identify major secondary chordae (A), which were then selected with a nerve hook (B). The distal part of the selected secondary chords was then cut using blade No. 15 from the anterior leaflet (C), and the proximal part was cut from its connection to the papillary muscle (D and E). (F) The view into the left ventricular outflow tract after septal myectomy and secondary chordal resection. Figure 1: Open in new tabDownload slide Secondary mitral valve chordal resection: Following the myectomy, the ventricular aspect of the mitral anterior leaflet was evaluated in order to identify major secondary chordae (A), which were then selected with a nerve hook (B). The distal part of the selected secondary chords was then cut using blade No. 15 from the anterior leaflet (C), and the proximal part was cut from its connection to the papillary muscle (D and E). (F) The view into the left ventricular outflow tract after septal myectomy and secondary chordal resection. Figure 2: Open in new tabDownload slide Effects of secondary chordal resection on the geometry of the left ventricle and mitral valve apparatus in hypertrophic obstructive cardiomyopathy: The aorto-mitral angle is highlighted in yellow and defined as the angle created between the mitral annulus plane and the aortic annulus plane during early systole. (A) Preoperative anatomy with left ventricular outflow tract obstruction. (B) Postoperative anatomy of septal myectomy without chordal resection, demonstrating theoretical mechanism of systolic anterior motion of the mitral valve. (C) Postoperative anatomy of septal myectomy with chordal resection. Figure 2: Open in new tabDownload slide Effects of secondary chordal resection on the geometry of the left ventricle and mitral valve apparatus in hypertrophic obstructive cardiomyopathy: The aorto-mitral angle is highlighted in yellow and defined as the angle created between the mitral annulus plane and the aortic annulus plane during early systole. (A) Preoperative anatomy with left ventricular outflow tract obstruction. (B) Postoperative anatomy of septal myectomy without chordal resection, demonstrating theoretical mechanism of systolic anterior motion of the mitral valve. (C) Postoperative anatomy of septal myectomy with chordal resection. The aorto-mitral angle was obtained from the echocardiography parasternal long-axis view, and defined as the angle created between the mitral annulus plane and the aortic annulus plane when both valves were closed (early systole). The anterior mitral leaflet-annulus ratio (as a surrogate to the coaptation point in the outflow tract) was calculated as the ratio between anterior mitral leaflet projection on annulus plane and annulus length [12] (Fig. 3). Figure 3: Open in new tabDownload slide Preoperative and postoperative echocardiographic images in a parasternal long-axis view during early systole: measurements of the AML to the annulus ratio in a patient with hypertrophic obstructive cardiomyopathy. The AML–annulus ratio is calculated as the ratio between AML projection on the annulus plane (double white arrows) and the annulus length (yellow dashed line). AML: anterior mitral leaflet; LV: left ventricle; PM: papillary muscle. Figure 3: Open in new tabDownload slide Preoperative and postoperative echocardiographic images in a parasternal long-axis view during early systole: measurements of the AML to the annulus ratio in a patient with hypertrophic obstructive cardiomyopathy. The AML–annulus ratio is calculated as the ratio between AML projection on the annulus plane (double white arrows) and the annulus length (yellow dashed line). AML: anterior mitral leaflet; LV: left ventricle; PM: papillary muscle. Statistical analysis Data were presented as mean ± standard deviation if normally distributed, or as median and interquartile ranges for variables without normal distribution. Continuous variables were tested by the Q–Q plot test and with the Shapiro–Wilk test for normal distribution. Categorical variables were presented as frequencies and percentages, and a χ2 test was used for comparison of categorical variables between patients who underwent secondary chordal resection and controls. A Student’s t-test was performed for comparison of normally distributed continuous variables and Mann–Whitney U-test for non-normal distribution. A one-way analysis of variance was used to describe the % change in LVOT gradients, aorto-mitral angle and anterior mitral leaflet-annulus ratio following the procedure. Time procedure interactions were tested with a linear mixed-effect model, with a random intercept accounting for the individual change before procedure. Kaplan–Meier survival analysis was performed to compare long-term mortality and recurrent MR between the 2 groups, with statistical differences tested by the log-rank test. Cox proportional hazard model was constructed to assess risk factors for long-term mortality using a stepwise selection process. Variables that were associated with one of the groups (P < 0.1 in Tables 1 and 2) were included in the model as were pre-specified clinically significant variables. The covariates included in the final model were: age, atrial fibrillation, concomitant procedure, LV end-systolic diameter and LVOT gradients. Table 1: Patient demographics and data . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Age (years), mean ± SD 61 ± 13 58 ± 16 0.205 Gender (males), n (%) 30 (50) 54 (51) 0.988 NYHA functional class, n (%) 0.028  I 0 (0) 5 (5)  II 16 (27) 36 (36)  III 44 (73) 55 (54)  IV 0 (0) 5 (5) Diabetes mellitus, n (%) 9 (15) 19 (18) 0.804 Atrial fibrillation, n (%) 20 (33) 10 (19) 0.061 Ischaemic heart disease, n (%) 1 (2) 6 (6) 0.412 Hypertension, n (%) 24 (41) 59 (57) 0.071 COPD, n (%) 1 (2) 1 (1) 1.000 Dialysis, n (%) 0 (0) 1 (1) 1.000 Obesity, n (%) 19 (32) 31 (29) 0.856 Hyperlipidaemia, n (%) 32 (55) 63 (60) 0.665 Smoking, n (%) 7 (12) 17 (16) 0.602 Previous cardiac operation, n (%) 2 (3) 11 (10) 0.181 EuroSCORE additive, median (IQR) 4 (3–5) 4 (2.4–6) 0.877 EuroSCORE logistic, median (IQR) 2.7 (1.8–3.5) 2.9 (1.7–5.5) 0.647 Concomitant CABG (%), n (%) 7 (12) 13 (12) 1.000 Concomitant MAZE (%), n (%) 5 (8) 9 (9) 1.000 Concomitant TV repair (%), n (%) 0 (0) 1 (1) 1.000 Concomitant aorta replacement (%), n (%) 1 (2) 4 (4) 0.764 . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Age (years), mean ± SD 61 ± 13 58 ± 16 0.205 Gender (males), n (%) 30 (50) 54 (51) 0.988 NYHA functional class, n (%) 0.028  I 0 (0) 5 (5)  II 16 (27) 36 (36)  III 44 (73) 55 (54)  IV 0 (0) 5 (5) Diabetes mellitus, n (%) 9 (15) 19 (18) 0.804 Atrial fibrillation, n (%) 20 (33) 10 (19) 0.061 Ischaemic heart disease, n (%) 1 (2) 6 (6) 0.412 Hypertension, n (%) 24 (41) 59 (57) 0.071 COPD, n (%) 1 (2) 1 (1) 1.000 Dialysis, n (%) 0 (0) 1 (1) 1.000 Obesity, n (%) 19 (32) 31 (29) 0.856 Hyperlipidaemia, n (%) 32 (55) 63 (60) 0.665 Smoking, n (%) 7 (12) 17 (16) 0.602 Previous cardiac operation, n (%) 2 (3) 11 (10) 0.181 EuroSCORE additive, median (IQR) 4 (3–5) 4 (2.4–6) 0.877 EuroSCORE logistic, median (IQR) 2.7 (1.8–3.5) 2.9 (1.7–5.5) 0.647 Concomitant CABG (%), n (%) 7 (12) 13 (12) 1.000 Concomitant MAZE (%), n (%) 5 (8) 9 (9) 1.000 Concomitant TV repair (%), n (%) 0 (0) 1 (1) 1.000 Concomitant aorta replacement (%), n (%) 1 (2) 4 (4) 0.764 CABG: coronary artery bypass grafting; COPD: chronic obstructive pulmonary disease; IQR: interquartile range; NYHA: New York Heart Association; SD: standard deviation; TV: tricuspid valve. Open in new tab Table 1: Patient demographics and data . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Age (years), mean ± SD 61 ± 13 58 ± 16 0.205 Gender (males), n (%) 30 (50) 54 (51) 0.988 NYHA functional class, n (%) 0.028  I 0 (0) 5 (5)  II 16 (27) 36 (36)  III 44 (73) 55 (54)  IV 0 (0) 5 (5) Diabetes mellitus, n (%) 9 (15) 19 (18) 0.804 Atrial fibrillation, n (%) 20 (33) 10 (19) 0.061 Ischaemic heart disease, n (%) 1 (2) 6 (6) 0.412 Hypertension, n (%) 24 (41) 59 (57) 0.071 COPD, n (%) 1 (2) 1 (1) 1.000 Dialysis, n (%) 0 (0) 1 (1) 1.000 Obesity, n (%) 19 (32) 31 (29) 0.856 Hyperlipidaemia, n (%) 32 (55) 63 (60) 0.665 Smoking, n (%) 7 (12) 17 (16) 0.602 Previous cardiac operation, n (%) 2 (3) 11 (10) 0.181 EuroSCORE additive, median (IQR) 4 (3–5) 4 (2.4–6) 0.877 EuroSCORE logistic, median (IQR) 2.7 (1.8–3.5) 2.9 (1.7–5.5) 0.647 Concomitant CABG (%), n (%) 7 (12) 13 (12) 1.000 Concomitant MAZE (%), n (%) 5 (8) 9 (9) 1.000 Concomitant TV repair (%), n (%) 0 (0) 1 (1) 1.000 Concomitant aorta replacement (%), n (%) 1 (2) 4 (4) 0.764 . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Age (years), mean ± SD 61 ± 13 58 ± 16 0.205 Gender (males), n (%) 30 (50) 54 (51) 0.988 NYHA functional class, n (%) 0.028  I 0 (0) 5 (5)  II 16 (27) 36 (36)  III 44 (73) 55 (54)  IV 0 (0) 5 (5) Diabetes mellitus, n (%) 9 (15) 19 (18) 0.804 Atrial fibrillation, n (%) 20 (33) 10 (19) 0.061 Ischaemic heart disease, n (%) 1 (2) 6 (6) 0.412 Hypertension, n (%) 24 (41) 59 (57) 0.071 COPD, n (%) 1 (2) 1 (1) 1.000 Dialysis, n (%) 0 (0) 1 (1) 1.000 Obesity, n (%) 19 (32) 31 (29) 0.856 Hyperlipidaemia, n (%) 32 (55) 63 (60) 0.665 Smoking, n (%) 7 (12) 17 (16) 0.602 Previous cardiac operation, n (%) 2 (3) 11 (10) 0.181 EuroSCORE additive, median (IQR) 4 (3–5) 4 (2.4–6) 0.877 EuroSCORE logistic, median (IQR) 2.7 (1.8–3.5) 2.9 (1.7–5.5) 0.647 Concomitant CABG (%), n (%) 7 (12) 13 (12) 1.000 Concomitant MAZE (%), n (%) 5 (8) 9 (9) 1.000 Concomitant TV repair (%), n (%) 0 (0) 1 (1) 1.000 Concomitant aorta replacement (%), n (%) 1 (2) 4 (4) 0.764 CABG: coronary artery bypass grafting; COPD: chronic obstructive pulmonary disease; IQR: interquartile range; NYHA: New York Heart Association; SD: standard deviation; TV: tricuspid valve. Open in new tab Table 2: Preoperative echocardiographic data . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Ejection fraction (%), median (IQR) 65 (61–70) 65 (60–70) 0.185 LVEDD (cm), mean ± SD 4.5 ± 0.5 4.6 ± 0.6 0.211 LVESD (cm), mean ± SD 2.7 ± 0.4 2.6 ± 0.5 0.247 Systolic PAP, median (IQR) 35 (30–43) 38 (33–47) 0.152 Left atrial area (cm2), mean ± SD 27 ± 7.4 26.8 ± 6.8 0.863 Mitral regurgitation (%), n (%) 0.006  Up to mild 27 (47) 73 (69)  Moderate 16 (28) 23 (22)  Severe 14 (25) 9 (9) LVOT gradient (mmHg), mean ± SD 91 ± 39 66 ± 34 <0.001 Septum thickness (mm), mean ± SD 24.8 ± 6.3 29.3 ± 6.1 <0.001 AML-annulus ratio, mean ± SD 0.75 ± 0.12 0.78 ± 0.12 0.120 Coaptation height (cm), mean ± SD 2.9 ± 0.8 3 ± 0.8 0.741 Aorto-mitral angle (°), mean ± SD 79 ± 6 84 ± 11 0.014 . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Ejection fraction (%), median (IQR) 65 (61–70) 65 (60–70) 0.185 LVEDD (cm), mean ± SD 4.5 ± 0.5 4.6 ± 0.6 0.211 LVESD (cm), mean ± SD 2.7 ± 0.4 2.6 ± 0.5 0.247 Systolic PAP, median (IQR) 35 (30–43) 38 (33–47) 0.152 Left atrial area (cm2), mean ± SD 27 ± 7.4 26.8 ± 6.8 0.863 Mitral regurgitation (%), n (%) 0.006  Up to mild 27 (47) 73 (69)  Moderate 16 (28) 23 (22)  Severe 14 (25) 9 (9) LVOT gradient (mmHg), mean ± SD 91 ± 39 66 ± 34 <0.001 Septum thickness (mm), mean ± SD 24.8 ± 6.3 29.3 ± 6.1 <0.001 AML-annulus ratio, mean ± SD 0.75 ± 0.12 0.78 ± 0.12 0.120 Coaptation height (cm), mean ± SD 2.9 ± 0.8 3 ± 0.8 0.741 Aorto-mitral angle (°), mean ± SD 79 ± 6 84 ± 11 0.014 AML: anterior mitral leaflet; IQR: interquartile range; LVEDD: left ventricular end-diastolic diameter; LVESD: left ventricular end-systolic diameter; LVOT: left ventricular outflow tract; PAP: pulmonary artery pressure; SD: standard deviation. Open in new tab Table 2: Preoperative echocardiographic data . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Ejection fraction (%), median (IQR) 65 (61–70) 65 (60–70) 0.185 LVEDD (cm), mean ± SD 4.5 ± 0.5 4.6 ± 0.6 0.211 LVESD (cm), mean ± SD 2.7 ± 0.4 2.6 ± 0.5 0.247 Systolic PAP, median (IQR) 35 (30–43) 38 (33–47) 0.152 Left atrial area (cm2), mean ± SD 27 ± 7.4 26.8 ± 6.8 0.863 Mitral regurgitation (%), n (%) 0.006  Up to mild 27 (47) 73 (69)  Moderate 16 (28) 23 (22)  Severe 14 (25) 9 (9) LVOT gradient (mmHg), mean ± SD 91 ± 39 66 ± 34 <0.001 Septum thickness (mm), mean ± SD 24.8 ± 6.3 29.3 ± 6.1 <0.001 AML-annulus ratio, mean ± SD 0.75 ± 0.12 0.78 ± 0.12 0.120 Coaptation height (cm), mean ± SD 2.9 ± 0.8 3 ± 0.8 0.741 Aorto-mitral angle (°), mean ± SD 79 ± 6 84 ± 11 0.014 . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . Ejection fraction (%), median (IQR) 65 (61–70) 65 (60–70) 0.185 LVEDD (cm), mean ± SD 4.5 ± 0.5 4.6 ± 0.6 0.211 LVESD (cm), mean ± SD 2.7 ± 0.4 2.6 ± 0.5 0.247 Systolic PAP, median (IQR) 35 (30–43) 38 (33–47) 0.152 Left atrial area (cm2), mean ± SD 27 ± 7.4 26.8 ± 6.8 0.863 Mitral regurgitation (%), n (%) 0.006  Up to mild 27 (47) 73 (69)  Moderate 16 (28) 23 (22)  Severe 14 (25) 9 (9) LVOT gradient (mmHg), mean ± SD 91 ± 39 66 ± 34 <0.001 Septum thickness (mm), mean ± SD 24.8 ± 6.3 29.3 ± 6.1 <0.001 AML-annulus ratio, mean ± SD 0.75 ± 0.12 0.78 ± 0.12 0.120 Coaptation height (cm), mean ± SD 2.9 ± 0.8 3 ± 0.8 0.741 Aorto-mitral angle (°), mean ± SD 79 ± 6 84 ± 11 0.014 AML: anterior mitral leaflet; IQR: interquartile range; LVEDD: left ventricular end-diastolic diameter; LVESD: left ventricular end-systolic diameter; LVOT: left ventricular outflow tract; PAP: pulmonary artery pressure; SD: standard deviation. Open in new tab Statistical significance was assumed when the null hypothesis could be rejected at P < 0.05. All P-values were the results of 2-sided tests, and the statistical analyses were conducted using R (version 3.5.1). The investigators who initiated the study had full access to and analysed all the data, and wrote the manuscript. All authors vouch for the data and the analysis. RESULTS From February 2005 to August 2020, a total of 244 consecutive patients with HCM in our Department underwent septal myectomy surgery, while patients who underwent concomitant MV repair or replacement surgery (N = 61) or aortic valve replacement (N = 18) were excluded. Ultimately, 165 patients were included in the study: 60 (36%) patients underwent secondary chordal resection concomitant to the myectomy, and 105 (64%) patients underwent extended septal myectomy without secondary chordal intervention (controls). The overall mean age was 59 ± 15 years and 84 patients (51%) were male. Most patients were symptomatic prior to surgery (n = 156, 97%) with a median NYHA functional class of 3 (interquartile range 2–3). Patients who underwent secondary chordal resection had more atrial fibrillation prior to surgery (P = 0.061). All other baseline characteristics were similar between patients who underwent secondary chordal resection and controls (Table 1). The median ejection fraction was 65% (60–70%), and none had right ventricular dysfunction. Preoperative LVOT gradients were higher in the chordal resection group (P < 0.001), the degree of MR was higher (P = 0.006) and the thickness of the septum was smaller (P < 0.001) compared to the control group. No differences were recorded in other echocardiographic characteristics such as ejection fraction, ventricular volumes and pulmonary artery pressure (Table 2). Patients who underwent secondary chordal resection demonstrated shorter procedural times: cardiopulmonary bypass [52 (42–65) vs 69 (48–101) min, P = 0.009] and cross-clamp [33 (29–54) vs 45 (31–77) min, P = 0.077] compared to patients who underwent extended septal myectomy without secondary chordal cutting. Early clinical outcomes There were no in-hospital deaths throughout the entire patient cohort, and no differences between the chordal resection and control groups regarding early complications, which included cardiac failure, stroke, surgical re-exploration due to bleeding or tamponade, permanent pacemaker implantation, acute kidney injury, atrial fibrillation, post-pericardiotomy syndrome, ventilation time, intensive care unit stay and hospital stay (Table 3). In total, 11 (6.7%) patients throughout the entire series required permanent pacemaker implantation due to a high degree of atrioventricular block; of them, 5 (45%) had a pre-existing right branch bundle block. Table 3: Early outcomes . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . 30-day mortality, n (%) 0 (0) 0 (0) 1.000 Cardiac failure, n (%) 0 (0) 0 (0) 1.000 Stroke, n (%) 0 (0) 0 (0) 1.000 Re-exploration, n (%) 2 (3) 5 (5) 0.971 Pacemaker implantation, n (%) 5 (8) 6 (6) 0.724 Acute kidney injury, n (%) 0 (0) 2 (2) 0.737 Atrial fibrillation, n (%) 20 (34) 28 (27) 0.425 Post-pericardiotomy syndrome, n (%) 7 (12) 7 (7) 0.394 Ventilation time (h), median (IQR) 6 (4–8) 6.5 (3–10) 0.397 ICU stay (days), median (IQR) 0.83 (0.47–1.03) 0.96 (0.83–1.21) 0.046 Hospital stay (days), median (IQR) 6 (5–7.5) 5 (4–7) 0.107 . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . 30-day mortality, n (%) 0 (0) 0 (0) 1.000 Cardiac failure, n (%) 0 (0) 0 (0) 1.000 Stroke, n (%) 0 (0) 0 (0) 1.000 Re-exploration, n (%) 2 (3) 5 (5) 0.971 Pacemaker implantation, n (%) 5 (8) 6 (6) 0.724 Acute kidney injury, n (%) 0 (0) 2 (2) 0.737 Atrial fibrillation, n (%) 20 (34) 28 (27) 0.425 Post-pericardiotomy syndrome, n (%) 7 (12) 7 (7) 0.394 Ventilation time (h), median (IQR) 6 (4–8) 6.5 (3–10) 0.397 ICU stay (days), median (IQR) 0.83 (0.47–1.03) 0.96 (0.83–1.21) 0.046 Hospital stay (days), median (IQR) 6 (5–7.5) 5 (4–7) 0.107 ICU: intensive care unit; IQR: interquartile range. Open in new tab Table 3: Early outcomes . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . 30-day mortality, n (%) 0 (0) 0 (0) 1.000 Cardiac failure, n (%) 0 (0) 0 (0) 1.000 Stroke, n (%) 0 (0) 0 (0) 1.000 Re-exploration, n (%) 2 (3) 5 (5) 0.971 Pacemaker implantation, n (%) 5 (8) 6 (6) 0.724 Acute kidney injury, n (%) 0 (0) 2 (2) 0.737 Atrial fibrillation, n (%) 20 (34) 28 (27) 0.425 Post-pericardiotomy syndrome, n (%) 7 (12) 7 (7) 0.394 Ventilation time (h), median (IQR) 6 (4–8) 6.5 (3–10) 0.397 ICU stay (days), median (IQR) 0.83 (0.47–1.03) 0.96 (0.83–1.21) 0.046 Hospital stay (days), median (IQR) 6 (5–7.5) 5 (4–7) 0.107 . Secondary chordal resection (N = 60) (%) . Conventional septal myectomy (N = 105) (%) . P-value . 30-day mortality, n (%) 0 (0) 0 (0) 1.000 Cardiac failure, n (%) 0 (0) 0 (0) 1.000 Stroke, n (%) 0 (0) 0 (0) 1.000 Re-exploration, n (%) 2 (3) 5 (5) 0.971 Pacemaker implantation, n (%) 5 (8) 6 (6) 0.724 Acute kidney injury, n (%) 0 (0) 2 (2) 0.737 Atrial fibrillation, n (%) 20 (34) 28 (27) 0.425 Post-pericardiotomy syndrome, n (%) 7 (12) 7 (7) 0.394 Ventilation time (h), median (IQR) 6 (4–8) 6.5 (3–10) 0.397 ICU stay (days), median (IQR) 0.83 (0.47–1.03) 0.96 (0.83–1.21) 0.046 Hospital stay (days), median (IQR) 6 (5–7.5) 5 (4–7) 0.107 ICU: intensive care unit; IQR: interquartile range. Open in new tab Echocardiography before discharge The postoperative septal thickness was 13 ± 2.9 mm in the chordal resection group and 14.4 ± 3.4 mm in the control group (P = 0.015). Of those patients who underwent secondary chordal resection, the resting outflow gradient decreased from 91 ± 39 mmHg to 13 ± 8 mmHg (an 86% change, P < 0.001) on the echocardiograph before discharge. Compared with controls, patients who underwent secondary chordal resection had significantly lower outflow gradients following surgery (13 ± 8 mmHg vs 19 ± 17 mmHg, respectively, P = 0.024). Furthermore, the aorto-mitral angle increased following surgery in the chordal resection group from 79 ± 6° to 101 ± 8° (a 28% change, P < 0.001), while it did not change significantly among the controls from 84 ± 11° to 81 ± 12° (a 3% change, P = 0.093). In addition, the anterior mitral leaflet to annulus ratio did not change in either group following surgery (Table 4). Table 4: Preoperative and postoperative echocardiographic measurements in patients who underwent secondary chordal resection, concomitant to septal myectomy, and in patients who underwent septal myectomy without secondary chordal resection . Secondary chordal resection . Conventional septal myectomy . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Septal thickness (mm) 24.8 ± 6.3 13 ± 2.9 <0.001 29.3 ± 6.1 14.4 ± 3.4 <0.001 LVOT gradient (mmHg) 91 ± 39 13 ± 8 <0.001 66 ± 34 19 ± 17 <0.001 Aorto-mitral angle (°) 78.7 ± 6.5 101.5 ± 7.6 <0.001 83.8 ± 11.4 80.7 ± 12.1 0.093 AML-annulus ratio 0.75 ± 0.12 0.79 ± 0.11 0.294 0.78 ± 0.12 0.76 ± 0.14 0.150 Systolic PAP (mmHg) 38.4 ± 12.9 34.5 ± 11.1 0.320 40.7 ± 11 40.1 ± 13.1 0.820 . Secondary chordal resection . Conventional septal myectomy . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Septal thickness (mm) 24.8 ± 6.3 13 ± 2.9 <0.001 29.3 ± 6.1 14.4 ± 3.4 <0.001 LVOT gradient (mmHg) 91 ± 39 13 ± 8 <0.001 66 ± 34 19 ± 17 <0.001 Aorto-mitral angle (°) 78.7 ± 6.5 101.5 ± 7.6 <0.001 83.8 ± 11.4 80.7 ± 12.1 0.093 AML-annulus ratio 0.75 ± 0.12 0.79 ± 0.11 0.294 0.78 ± 0.12 0.76 ± 0.14 0.150 Systolic PAP (mmHg) 38.4 ± 12.9 34.5 ± 11.1 0.320 40.7 ± 11 40.1 ± 13.1 0.820 AML: anterior mitral leaflet; LVOT: left ventricular outflow tract; PAP: pulmonary artery pressure; SD: standard deviation. Open in new tab Table 4: Preoperative and postoperative echocardiographic measurements in patients who underwent secondary chordal resection, concomitant to septal myectomy, and in patients who underwent septal myectomy without secondary chordal resection . Secondary chordal resection . Conventional septal myectomy . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Septal thickness (mm) 24.8 ± 6.3 13 ± 2.9 <0.001 29.3 ± 6.1 14.4 ± 3.4 <0.001 LVOT gradient (mmHg) 91 ± 39 13 ± 8 <0.001 66 ± 34 19 ± 17 <0.001 Aorto-mitral angle (°) 78.7 ± 6.5 101.5 ± 7.6 <0.001 83.8 ± 11.4 80.7 ± 12.1 0.093 AML-annulus ratio 0.75 ± 0.12 0.79 ± 0.11 0.294 0.78 ± 0.12 0.76 ± 0.14 0.150 Systolic PAP (mmHg) 38.4 ± 12.9 34.5 ± 11.1 0.320 40.7 ± 11 40.1 ± 13.1 0.820 . Secondary chordal resection . Conventional septal myectomy . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Preoperative, mean ± SD . Postoperative, mean ± SD . P-value . Septal thickness (mm) 24.8 ± 6.3 13 ± 2.9 <0.001 29.3 ± 6.1 14.4 ± 3.4 <0.001 LVOT gradient (mmHg) 91 ± 39 13 ± 8 <0.001 66 ± 34 19 ± 17 <0.001 Aorto-mitral angle (°) 78.7 ± 6.5 101.5 ± 7.6 <0.001 83.8 ± 11.4 80.7 ± 12.1 0.093 AML-annulus ratio 0.75 ± 0.12 0.79 ± 0.11 0.294 0.78 ± 0.12 0.76 ± 0.14 0.150 Systolic PAP (mmHg) 38.4 ± 12.9 34.5 ± 11.1 0.320 40.7 ± 11 40.1 ± 13.1 0.820 AML: anterior mitral leaflet; LVOT: left ventricular outflow tract; PAP: pulmonary artery pressure; SD: standard deviation. Open in new tab Late outcomes Median follow-up was 32 (11–73) months and was completed by 97.6% (161/165) of the patients. The overall survival rate was 98.8% at 1 year (chordal resection: 100%, controls: 98.1%; log-rank P = 0.288) and 95.8% at 5 years of follow-up (chordal resection: 98.3%, controls: 94.3%; log-rank P = 0.801). Multivariable analysis demonstrated that the only independent predictor for late mortality was older age (6.1% increased hazard for mortality per 1-year increment in age; P = 0.039). None of the patients who underwent secondary chordal resection required reoperation, while reoperation was performed on 1 patient from the control group during follow-up (NS). This patient suffered from severe diastolic dysfunction with NYHA functional class IV, and underwent heart transplantation 25 months after conventional septal myectomy. At the latest follow-up, 91% of the patients who underwent secondary chordal resection were in NYHA functional class I or II, while in the control group, 79% had NYHA functional class I or II (P = 0.225). Compared with controls, late echocardiography revealed that patients who underwent secondary chordal resection had significantly lower resting outflow gradients at follow-up (14 ± 7 mmHg vs 21 ± 15 mmHg, P = 0.002). Furthermore, 5-year moderate or more than moderate MR was seen in 5% of patients with myectomy alone, and in 2% in patients with myectomy and secondary chord resection [hazard ratio (HR) 1.05, confidence interval (CI) 0.11–10.32; P = 0.965] (Fig. 4). At follow-up, both groups demonstrated preserved left ventricular systolic function [ejection fraction of 60% (60–65%) vs 60% (58–65%), P = 0.225]. Figure 4: Open in new tabDownload slide Kaplan–Meier curves for moderate or more than moderate MR by chordal resection. MR: mitral regurgitation. Figure 4: Open in new tabDownload slide Kaplan–Meier curves for moderate or more than moderate MR by chordal resection. MR: mitral regurgitation. Video 1: Septal myectomy and secondary chordal resection in a hypertrophic obstructive cardiomyopathy patient. Video 1: Septal myectomy and secondary chordal resection in a hypertrophic obstructive cardiomyopathy patient. Close Sub-analysis: from 2015 onwards We performed an additional analysis from the time we began to implement the use of secondary chordal resection. During this period, we identified 28 patients who underwent septal myectomy without chordal cutting. While there were similar preoperative LVOT gradients (91 ± 39 vs 79 ± 35 mmHg, P = 0.191), the postoperative LVOT gradients (13 ± 8 vs 23 ± 22 mmHg, P = 0.004) and follow-up LVOT gradients (14 ± 7 vs 29 ± 20 mmHg, P < 0.001) were lower in the secondary chordal resection compared with controls. Moderate or more than moderate MR was seen less in the secondary chordal resection group (2.1% vs 16.7%; HR 0.32, CI 0.18–0.57; P < 0.001) (Supplementary Material, Table S1). DISCUSSION This study presents our preliminary experience with secondary chordal resection concomitant to septal myectomy in patients with HCM (Video 1). We have shown that (i) performing secondary chordal resection concomitant to septal myectomy is safe, and provides good early and late clinical outcomes with low morbidity; (ii) secondary chordal resection may provide a greater reduction in the resting outflow gradient compared to conventional myectomy in appropriately selected patients; (iii) secondary chordal resection concomitant to septal myectomy changes the anatomy of the left ventricle and the relationship between the left-sided valves to a further extent than septal myectomy without chordal resection; and (iv) secondary chordal resection is not associated with higher rates of postoperative residual MR or the development of MR during follow-up. The mitral subvalvular apparatus consists of the papillary muscles, primary chordae and secondary chordae. The primary chordae (‘marginal’), inserted on the leaflet-free edges of the MV leaflet, perform a dual role by enhancing both LV systolic pump function and by maintaining valvular competence; they prevent flail and regurgitation by opposing the valve-closing forces during systole [13]. The secondary chordae, which are larger and fewer in number, inserted on the ventricular surface of the anterior leaflet belly at the junction of the rough and smooth zones, help to preserve ventricular shape and function during ejection by maintaining elliptical ventricle geometry and by enhancing regional wall thickening [14]. However, the secondary chordae of HCM patients often appear thickened and retracted, thus contributing to the movement of the MV apparatus towards the interventricular septum and to the development of systolic anterior motion (SAM), resulting in increased LVOT gradients [15]. Other common reasons for residual gradients are inadequate septectomy at the midventricular level and anomalous papillary muscles, chords and trabeculae [16]. We have shown that cutting the secondary chords concomitant to septal myectomy in HCM patients increases the aorto-mitral angle, thereby abducting the anterior mitral leaflet from the LVOT during systole. A narrow aorto-mitral angle facilitates SAM by positioning the anterior leaflet close to the outflow tract. In their study, Varghese et al. [17] showed that a too small angle (<110°) is an independent predictor for SAM that results in obstruction of the LVOT and recurrent MR. Secondary chordae resection concomitant to septal myectomy was first described by Ferrazzi et al. [9]. Their novel operative approach was performed on a subset of HCM patients with mild septal thickness (17 ± 1 mm), and as a result, these patients underwent only a shallow myectomy. By cutting the secondary chordae, they demonstrated movement of the MV coaptation point away from the LVOT to a more posterior position, and thus were able to eradicate the LVOT obstruction and prevent SAM. The rationale behind the use of this technique, also performed in patients who undergo conventional myectomy, is that the MV subvalvular apparatus contributes substantially to LVOT obstruction in all patients with HCM, thereby theoretically justifying surgical correction in addition to an extended myectomy. Ferrazzi et al. [9] describe their secondary chordae resection mechanism, which contributes towards reduced gradients and relieves heart failure symptoms, as being similar to the results described in our study patients. We believe that chordal resection adjunct to septal myectomy is probably most important in cases of HCM with moderate or less than moderate septal hypertrophy, while it may also be effective even in patients with more severe hypertrophy. Based on the evidence that this adjunct is not related to negative outcomes, we decided to perform this procedure in cases where there are significant secondary chords. As the MV leaflets of HCM patients are abnormally long [18], anterior mitral leaflet plication (based on leaflet morphology) concomitant to septal myectomy is advocated by some surgeons in selected patients in order to reduce the risk of SAM with LVOT obstruction [19, 20]. Theoretically, anterior leaflet plication would seem to have the opposite effect of chordal cutting. However, while we observed sporadic cases of intraoperative SAM immediately off-pump, that all subsided with volume loading, we did not encounter a single case of SAM with secondary chordal resection during follow-up. This could be explained by the assumption that the position of the leaflet coaptation plane is determined by the balance of forces acting on the anterior and posterior leaflet in systole. As force equals pressure times area (a larger sail generates more power with the same wind velocity), and pressure is evenly distributed in the LV cavity, the position of the coaptation plane would essentially be determined by the ratio of the anterior to the posterior leaflet size or, more precisely, by the ratio of the anterior and posterior leaflet area available for coaptation. By resecting the secondary chords, the anterior leaflet area available for coaptation is increased, which in turn increases its force in a posterior direction, shifting the coaptation plane posteriorly, pushing it away from the septum, potentially resulting in less SAM (Fig. 2). Secondary chordae play an important role in maintaining LV geometry, and their resection may result in deterioration of global LV systolic performance. Rodriguez et al. [21, 22] raised some serious concerns about this technique during MV repair. However, we have shown in this report that HCM patients who underwent secondary chordae resection presented with preserved ejection fraction at their most recent evaluation, outcomes which were prevented by preserved systolic function and a small LV cavity. Our results demonstrated symptom relief in all patients who underwent secondary chordae resection at the latest follow-up, and eradication of LVOT gradients immediately following surgery and at follow-up. None of the patients who underwent secondary chordae resection required MV repair or replacement during surgery, none developed more than moderate MR at the most recent evaluation, and none required reoperation during follow-up. Avoidance of MV replacement is of great long-term benefit for any patient [23]. We reported a 6.7% rate of permanent pacemaker implantation that also included our learning curve. The pacemaker rate in our series was slightly higher than that described by others, such as Hodges et al. [24] from the Cleveland Clinic who reported a 4.2% incidence of pacemaker implantation, and Vanderlaan et al. [25] who reported a pacemaker implantation rate of 5.3%. However, our results are lower than those published by others such as Obadia et al. [26] who reported a 9% rate in their series. Furthermore, data from the US Nationwide Inpatient Database showed a pacemaker implantation rate of 8.9–13.8%, depending on the number of myectomies performed per year [27]. We reported that procedural time was shorter in the chordae resection group. The longer procedural time in the control group may be explained by the fact that these patients had undergone more previous cardiac operations (10.5% vs 3%, P = 0.181) that can affect operative time. All reoperations in our medical centre include a connection to the cardiopulmonary bypass by femoral access prior to resternotomy. Another explanation may be related to the fact that the control group included earlier experience of septal myectomy surgery (our learning curve) and with time, the procedure becomes more routine and thus shorter time consuming. Our learning curve did not include the secondary chordal resection group. With the emergence of novel technologies, such as computed tomography modelling, it will be possible to plan techniques in advance of surgery in HCM patients who are candidates for septal myectomy [28, 29]. These numerical models will be able to provide information regarding various geometries of the ventricle and MV that would be unforeseeable during the actual surgery. Patient-specific strategies by reconstruction of the ventricle and MV apparatus may be beneficial in planning the surgery. Limitations There are several limitations to this study. While patients were followed up prospectively, the nature of the study was retrospective. Performing secondary chordal resection began in 2015 in patients with thickened major secondary chords which may have played an additive role in their increased LVOT gradients. Prior to that period, all patients underwent septal myectomy only, regardless of the thickness of their secondary chords. This may have led to a selection bias between the 2 eras. Furthermore, our learning curve did not include the secondary chordal resection group, a fact that may have biased our results. Although the majority of patients included in the study underwent isolated septal myectomy (with or without secondary chordae resection), some underwent concomitant procedures, thus making the cohort less homogenous. Potential instructive information regarding the cause of death during follow-up was lacking. The clinical follow-up was longer than the echocardiographic follow-up (with interobserver variance), which may have represented a problem regarding the correlation between follow-up echocardiography and clinical status. Although multivariable models were used in order to overcome possible confounders, residual confounders may not have been included in the models. No primary analysis was defined and some tests were conducted without adjustment for multiple testing. Analyses were exploratory in nature; therefore, 95% CIs were not adjusted for multiple comparisons and inferences drawn from them may not be reproducible. CONCLUSIONS Secondary MV chordae resection through the transaortic approach concomitant to septal myectomy for LVOT obstruction is safe, does not increase the risk of developing late MR, helps to relieve heart failure symptoms, and reduce the LVOT gradient in appropriately selected patients with HCM. This procedure, as opposed to conventional septal myectomy, may reduce the number of patients with residual high gradients in need of MV replacement surgery. A larger study is required in order to make recommendations regarding the future routine use of this approach. SUPPLEMENTARY MATERIAL Supplementary material is available at EJCTS online. Conflict of interest: none declared. Author contributions Eilon Ram: Conceptualization; Formal analysis; Investigation; Methodology; Writing—original draft. Ehud Schwammenthal: Conceptualization; Investigation; Methodology; Writing—review & editing. Rafael Kuperstein: Conceptualization; Data curation; Investigation; Methodology. Tamer Jamal: Data curation; Investigation; Methodology. Eyal Nahum: Conceptualization; Data curation; Investigation. Leonid Sternik: Conceptualization; Investigation; Project administration; Supervision. Ehud Raanani: Conceptualization; Data curation; Investigation; Methodology; Project administration; Supervision; Validation; Writing—review & editing. Reviewer information Reviewer information European Journal of Cardio-Thoracic Surgery thanks Michael Scharfschwerdt and the other, anonymous reviewer(s) for their contribution to the peer review process of this article. REFERENCES 1 Maron BJ , Mathenge R, Casey SA, Poliac LC, Longe TF. Clinical profile of hypertrophic cardiomyopathy identified de novo in rural communities . J Am Coll Cardiol 1999 ; 33 : 1590 – 5 . Google Scholar Crossref Search ADS PubMed WorldCat 2 Melacini P , Basso C, Angelini A, Calore C, Bobbo F, Tokajuk B et al. Clinicopathological profiles of progressive heart failure in hypertrophic cardiomyopathy . Eur Heart J 2010 ; 31 : 2111 – 23 . Google Scholar Crossref Search ADS PubMed WorldCat 3 Rigopoulos AG , Ali M, Abate E, Matiakis M, Melnyk H, Mavrogeni S et al. 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EuroIntervention 2016 ; 11 : 1428 – 31 . Google Scholar Crossref Search ADS PubMed WorldCat ABBREVIATIONS ABBREVIATIONS CI Confidence interval HCM Hypertrophic obstructive cardiomyopathy HR Hazard ratio LV Left ventricular LVOT Left ventricular outflow tract MR Mitral regurgitation MV Mitral valve NYHA New York Heart Association SAM Systolic anterior motion © The Author(s) 2021. 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/open_access/funder_policies/chorus/standard_publication_model)
TI - Secondary chordal resection with septal myectomy for treatment of symptomatic obstructive hypertrophic cardiomyopathy
JF - European Journal of Cardio-Thoracic Surgery
DO - 10.1093/ejcts/ezab116
DA - 2021-03-06
UR - https://www.deepdyve.com/lp/oxford-university-press/secondary-chordal-resection-with-septal-myectomy-for-treatment-of-m71tLdpZCb
SP - 1
EP - 1
VL - Advance Article
IS - 
DP - DeepDyve
ER -