TY - JOUR
AU1 - Holubkov,, Richard
AU2 - Zenati,, Marco
AU3 - J. Akin,, Jodi
AU4 - Erb,, Lyndall
AU5 - Courcoulas,, Anita
AB - Abstract Objective: The CardioThoracic Systems (CTS) registry of minimally invasive direct coronary artery bypass (MIDCAB) was established to examine baseline characteristics of patients undergoing this surgical procedure, document details of the procedures including grafting techniques and post-operative complication rates, and assess post-operative graft patency. Methods: A total of 508 consecutive patients who had MIDCAB using CTS instrumentation between April 1996 and March 1997 at 35 international centers were analyzed. Results: The mean age of patients, 27% of whom were women, was 63 years. Eight percent had previous coronary artery bypass surgery. While nearly all patients had significant stenoses in the left anterior descending artery, 23% had disease in two vessels and 9% in three vessels. Almost all procedures used the left internal mammary artery, with 7% employing multiple or sequential grafts. The entire surgical procedure lasted on average 135 min (median 2 h), with a mean time of 14 min to perform anastomosis. Surgical approaches, including anastomosis technique and method used to maintain bloodless field, varied widely across clinical centers. In-hospital complication rates were relatively low, with 0.6% mortality (0% perioperative), 1.2% conversion to sternotomy with cardiopulmonary bypass, 1.4% conversion to sternotomy without bypass, and 5.5% redo or reintervention. In total, 92% of patients were free from all of these events at hospital discharge; women showed a strong trend toward increased risk for major in-hospital events compared with men. Rib fracture was the most common complication, reported in 12% of patients. Post-operative angiography, performed in 83 patients at an average 2.2 days post-procedure, found full patency in 78 (94%). Conclusions: The CTS registry data indicates that in the great majority of patients, MIDCAB using CTS instrumentation was performed safely and with acute success. Comparative studies, most importantly clinical trials, are needed to determine the types of patients who benefit most from this procedure, as well as its longer-term outcome. Bypass surgery, Minimally invasive, Registry Coronary artery revascularization using coronary artery bypass grafting (CABG), first introduced in 1968 [11], has been demonstrated to prolong life and improve symptomatic status. Follow-up of patients receiving CABG has shown that patients with surgical procedures employing the left internal mammary artery (LIMA) have superior long-term survival compared with patients treated with saphenous vein grafts [19]. LIMA grafting to the left anterior descending (LAD) artery has been shown to be particularly effective. Compared with percutaneous approaches to coronary revascularization, the relative disadvantages of CABG performed with cardiopulmonary bypass and full sternotomy include potentially higher early mortality and morbidity, including potential adverse cerebral outcomes related to cardiopulmonary bypass [17, 23], higher cost of the procedure, and longer hospital stay [15]. As documented by the NHLBI Registries, clinical and angiographic indications for percutaneous transluminal coronary angioplasty (PTCA) since its inception in 1977 [14]have expanded over time [10]. Moreover, newly developed transcatheter approaches, most notably intracoronary stenting, have further widened the patient population eligible for this less invasive percutaneous treatment. However, rates of re-stenosis following transcatheter intervention remain substantial, although intracoronary stenting may lead to somewhat reduced rates of angiographic re-stenosis in highly selected lesions [12]. There has been substantial clinical interest in overcoming these various limitations of CABG by developing a surgical approach that provides the long-term patency benefits of bypass using the IMA and eliminates the need for cardiopulmonary bypass, while reducing procedure cost and length of hospital stay. The recent development of minimally invasive approaches to surgery began with several reports documenting the safety of bypass grafting via median sternotomy without cardiopulmonary bypass (CPB) [3, 6, 21]. Beating-heart bypass has recently been combined with the use of left thoracotomy [18]to perform an anastomosis of the LIMA to the LAD artery which is termed minimally invasive direct coronary artery bypass, or MIDCAB [8, 24]. There are several approaches presently used for MIDCAB, including harvesting of the LIMA using thoracoscopy [1, 4]or under direct vision [24]. Despite promising reports of high success and low acute event rates of the MIDCAB approach [8], as well as decreased cost and length of stay [26], several serious concerns remain about this technique. These include possible compromise of the quality of the anastomosis performed on the beating heart, and the various evolving approaches to MIDCAB, any of which requires comprehensive training [20, 25]. Various types of surgical instrumentation have been developed to facilitate MIDCAB, including retractors to gain exposure for harvest of the LIMA and devices to stabilize the beating heart during anastomosis [25]. In 1996, CardioThoracic Systems, Inc. (Cupertino, CA, USA) established a registry of patients undergoing MIDCAB with their instrumentation [5]to document the in-hospital safety and efficacy of the procedure. Institutions worldwide have enthusiastically participated in this research study. This report examines the experience of patients entered into the registry database as of May, 1997. We examine the baseline clinical and angiographic profiles of the patients, and the characteristics, outcomes, and early angiographic patency following the MIDCAB procedures. 1 Materials and methods 1.1 Data sources Clinical centers enrolled consecutive patients undergoing MIDCAB procedures employing instrumentation from CardioThoracic Systems. Standardized data collection forms were completed for each patient and submitted to CTS. As of May, 1997, these forms were available for 436 consecutively enrolled patients at 35 clinical centers. Data for an additional 72 patients from one large-volume center (University of Chieti, Italy) were electronically transferred from the institution's database to CTS. Therefore, information on a total of 508 patients is analyzed in this report. 1.2 Statistical methods All percentages reflect a denominator of the number of patients with available data for a particular attribute or outcome. Instances where the amount of missing data is substantial are pointed out in the text. Comparisons of event rates between subgroups were performed using the chi-squared test or Fisher's exact test when the expected number of events was small. Multivariate analysis of baseline factors associated with in-hospital outcomes was performed using stepwise logistic regression [16]. All P-values reported are two-sided. 2 Results 2.1 Baseline patient characteristics Table 1 shows the baseline presentation of the 508 registry patients. Age was nearly symmetrically distributed about the mean of 63 years; 8% of patients were aged 80 years or over. Approximately one-third of patients had myocardial infarction prior to their MIDCAB hospitalization, and 9% had history of congestive heart failure. Hypertension and diabetes were relatively prevalent risk factors in this population. Previous coronary intervention was reported by 37% of patients with available data, with 31% having previous catheter-based interventions and 8% prior coronary artery bypass grafting. Table 1 Open in new tabDownload slide Baseline characteristics of registry patients Table 1 Open in new tabDownload slide Baseline characteristics of registry patients Table 2 displays baseline pre-operative angiography findings. Of the 378 patients with a calculated or estimated left ventricular ejection fraction (LVEF), 37% had LVEF less than 50%, with 4% of patients having an LVEF of less than 30%. Detailed angiographic data, available on 454 patients, found significant disease (defined as a stenosis of 50% or greater) in the left anterior descending artery in 98% of patients, the left circumflex in 17%, and the right coronary artery in 26%. 2% of patients had significant stenosis in the left main artery. Significant stenoses were present in two vessels in 23% of patients and in all three vessels in 9%. The mean number of significant lesions per patient was 1.6, and the mean number of total occlusions (100% diameter stenosis) was 0.4. Table 2 Open in new tabDownload slide Pre-operative angiography of registry patients with available information Table 2 Open in new tabDownload slide Pre-operative angiography of registry patients with available information 2.2 Characteristics of the MIDCAB procedures The great majority of procedures (93% of the 423 with detailed grafting information available) involved LIMA conduits anastomosed to the LAD artery. In 5% of procedures, the LIMA was anastomosed to the second diagonal branch. A small proportion of procedures used the RIMA anastomosed to RCA (1.9%) or the gastroepiploic artery (0.4%) as conduits. Saphenous vein grafts were used as conduits in 6% of procedures. Multiple grafts or sequential grafts were used in 7% of MIDCAB procedures: 5% of procedures had multiple anastomoses in the LAD artery only, while 2% involved anastomoses in multiple vessels. So-called 'hybrid' procedures, involving catheter-based revascularization of additional lesions during the same hospitalization, were reported in 1.3% of 378 patients with available information. Including these hybrid procedures, multiple-vessel revascularization was reported in 12% of the 97 patients with angiographically documented multivessel coronary disease and complete graft/procedure information. Technical details of the MIDCAB procedures are shown in the top portion of Table 3. The mean incision length was 10 cm, and the average length of the harvested IMA was 12 cm. At the time of anastomosis, the mean heart rate was 66 beats/min; this rate ranged between 45 and 100 beats/min in 99% of procedures. Table 3 Open in new tabDownload slide Technical details of MIDCAB procedures Table 3 Open in new tabDownload slide Technical details of MIDCAB procedures The approaches used for maintaining a bloodless field, available for 423 patients, varied widely by clinical center. The majority of procedures used snares (61%) or blower/sucker (63%), while 33% reported use of occluder. Other site-specific approaches included bulldog clamps, urethral catheters, and external compression using the CTS stabilizer. The anastomosis suture technique, for which limited information is available, also varied by clinical center. Continuous/running suture was used most frequently (61% of the 360 procedures with available data), with less frequent use of the approach of separate incisions in the heel and toe of the anastomosis (36%) and interrupted stitches (3%). The times required to perform various components of the MIDCAB procedures are shown in the second part of Table 3. The IMA harvest time was on average 35 min with a median of 30 min. Target vessel occlusion time was on average 20 min, with a mean time of 14 min to perform anastomosis. The entire operation, from skin to skin, lasted on average 135 min, with a median time of 2 h. 2.3 Major in-hospital events In-hospital rates of major events for the registry cohort of 508 patients are shown in the top of Table 4. The three in-hospital deaths (0.6%) occurred in 3 males, aged 76, 78, and 81 years. (None occurred during the MIDCAB procedure.) Of the 13 patients (2.6%) who converted to sternotomy, six also required cardiopulmonary bypass, while seven had sternotomy performed without bypass due to anatomic concerns (reasons listed included small or inaccessible IMA, as well as intramyocardial placement or calcification of the LAD artery.) Redo or reintervention was reported in 28 patients (5.5%); of 21 patients with detailed information available, nine had reoperation for bleeding, seven had surgical revision of the anastomosis, and five had percutaneous intervention for blockages at the site of anastomosis. Of the 508 registry patients, 41 (8.1%) had one or more major events (death, conversion to sternotomy, or need for reintervention) in-hospital. A comparison of early versus late procedures at each institution did not find any trend towards a 'learning curve' in terms of major event rates. Table 4 Open in new tabDownload slide Major in-hospital events and complications Table 4 Open in new tabDownload slide Major in-hospital events and complications We performed multivariate logistic regression analysis to identify baseline factors associated with major events. This analysis, which considered the factors shown in Table 1 along with extent of angiographic disease, found female gender (odds ratio for a major event in women versus men=1.85, P=0.07) to be the only baseline factor strongly associated with major in-hospital events. No other baseline factors examined, clinical or angiographic, showed significant association with this outcome. It should be noted that this analysis reflects risk for the composite endpoint of any major event rather than its components. Women, whose major event rate was 11.9% versus 6.8% in men, were at increased risk for conversion to sternotomy (4.4% vs. 1.9%) and reintervention (7.4% vs. 4.9%), but no women died compared with 0.8% of men. Patients with diabetes mellitus had a significantly higher rate of conversion to sternotomy (6.6% vs. 1.7% for non-diabetics, P=0.02), but overall major event rates were not significantly higher for diabetics compared to non-diabetics (12.1% vs. 7.1%, P=0.11). 2.4 Complications Rates of procedural complications, which were available on a subgroup of 436 registry patients, are shown in the second part of Table 4. Rib fracture was the most commonly reported complication, occurring in 11.5% of procedures. While pericarditis was reported in 8.3% of procedures, the majority of cases were reported at one center, indicating potential differences in interpretation of this event. 2.5 Post-operative angiographic patency A subgroup of 83 patients had post-procedural angiography of the anastomosis site(s) which showed unequivocal findings according to qualitative assessment. The mean time of this angiographic assessment was 2.2 days post-procedure, ranging from immediately post-operatively to 21 days after surgery. Information about whether angiography was routine or due to symptoms was not available. Of these 83 patients, 78 (94%) had full patency of the anastomosis. 3 Discussion Our analysis of the CTS registry patients found relatively low major event rates in this population of patients, some of whom had relatively high risk profiles in terms of pre-existing clinical conditions and severity of coronary disease. MIDCAB was performed without in-hospital mortality, conversion to sternotomy, or reintervention in 92% of patients. Rib fracture was the most commonly reported complication across clinical centers. The limited number of patients with post-operative angiography showed a high rate of anastomosis patency. The registry major event rates are comparable to other recently reported series; it should be pointed out that some of the patients in these series are also in the CTS registry, and hence these reports are not completely independent. Calafiore et al. [8]reported a series of 155 patients, with a mean age of 61 years, 50% of whom had lesions in multiple vessels. In-hospital mortality was 0.6% (one event), with redo or reintervention in 6.4% of patients. In this series, three patients (1.9%) had reintervention (two redo via sternotomy, one PTCA) because of angina due to angiographically documented stenosis at the anastomosis. At a mean 5.6 months of follow-up, 92% were alive, free of cardiac events, and asymptomatic. The trend of increased major in-hospital event rates in women observed in the registry is in concordance with a number of studies of women treated with CABG using sternotomy and cardiopulmonary bypass, although these studies have also tended to find higher in-hospital mortality in females [22]. Buffolo et al. [7]reported post-operative angiographic analysis on 39 patients receiving MIDCAB (LIMA to the LAD or diagonal artery) without cardiopulmonary bypass from September 1995 to August 1996. Routine post-operative angiography found patency in 33 patients (84.5%), while six had stenosis or occlusion necessitating reoperation via median sternotomy, which was uniformly performed without complications. These 39 patients represented relatively complete angiography from a series of 45. While this MIDCAB approach is primarily used to bypass disease in the LAD artery, there have been recent developments in the so-called 'hybrid revascularization' approach, where LIMA bypass of LAD lesions via MIDCAB is combined with angioplasty of lesions in other vessels during the same hospitalization [2, 9, 13]. This combined approach has the potential to offer many patients needing multiple-vessel revascularization a less costly, less invasive treatment with the demonstrated advantage of a LIMA–LAD bypass [19]. A randomized trial of bypass surgery versus 'hybrid revascularization' in patients suitable for both approaches is currently in the startup phase at the University of Pittsburgh Medical Center. The limitations of our analysis are common to voluntary multicenter registries of a rapidly emerging and evolving approach. Since the inclusion criterion for this registry was treatment with CTS instrumentation, patients for whom MIDCAB was intended, but who converted to sternotomy prior to introduction of CTS equipment, were not uniformly entered across centers. Also, since this registry is restricted to in-hospital outcome, with no information on post-discharge status, it is possible that some late post-hospital reinterventions were not captured. The analyses of untoward events should be viewed with these limitations in mind. While information was nearly complete for registry patients with respect to key baseline characteristics, there was substantial missing information for angiography as well as details of the procedures. Post-operative angiography was very limited, with variability between centers in the indications for post-operative catheterization, and the true anastomosis patency could therefore be different than the reported figure. Finally, while all cases used CTS instrumentation, there was variability in surgical technique between centers as well as between surgeons, and examination of the learning curve in this series is difficult due to many institutions in this series having entered a very small number of patients at the time of analysis. These limitations, considered together with the very encouraging findings of the registry, offer guidance for the ongoing evaluation of the safety and efficacy of MIDCAB. Multicenter studies with rigorous entry criteria, data monitoring, mandatory post-operative angiography and post-hospital follow-up of all patients can provide highly reliable assessment of anastomosis patency. These studies may be prospective observational series or randomized clinical trials. The observational design has the advantage of entering a wide spectrum of patients undergoing MIDCAB and the capability to document learning curves and evolution of the procedure. While comparison of techniques in rigorously conducted observational studies is informative, only randomized trials can rigorously demonstrate the equivalency or superiority of MIDCAB to other coronary revascularization approaches in terms of anastomosis patency and benefit to the patient. Such trials should have inclusion criteria as wide-ranging as possible, in order to maximize their generalizability, and should be limited to clinical centers and surgeons having documented expertise with all approaches to be compared. In summary, our analysis of the first 508 patients in the CTS registry indicates that this procedure may be performed on a variety of patients, including those with extensive clinical and angiographic risk profiles, with relatively low rates of major events. Angiography on a limited number of these patients suggests that early anastomosis patency is high. The ongoing enrollment of consecutive patients in this registry will document the continued evolution of this MIDCAB approach. Appendix A Clinical centers contributing patients to the CTS registry (and participating individuals) Benetti Foundation, Rosario, Argentina (Federico J. Benetti, MD); Bereich Medizin Charité, Berlin, Germany (Prof. Dr. Wolfgang Konertz); Columbia Los Robles Regional Medical Center, Thousand Oaks, CA (Mohammad A. Gharavi, MD); Columbia Hospital at Medical City, Dallas TX (David O. Moore, MD; Michael Mack, MD); Columbia Medical Center, Phoenix, AZ (Joseph Auteri, MD); Columbia Mercy Medical Center, Canton, OH (Tony Cryssos, MD); Columbia Ocala Regional Medical Center, Ocala, FL (Michael Carmichael, MD); Columbia Regional Medical Center of Southwest Florida, Fort Myers, FL (Michael P. Metke, MD); Pitt County Memorial Hospital, East Carolina University, Greenville, NC (Joseph Elbeery, MD); Emory University Hospital, Atlanta, GA (Joseph Craver, MD); Encino-Tarzana Medical Center, Encino, CA (Mohammad A. Gharavi, MD); Good Samaritan Hospital, San Jose, CA (Robert D. Wuerflein, MD); Indiana University Medical Center, Indianapolis, IN (Yousef Mahomed, MD); Jewish Hospital Healthcare, Louisville, KY (Paul A. Spence, MD); Lenox Hill Hospital, New York, NY (Valavanur A. Subramanian, MD); Makati Heart/Makati Medical Center, Makati City, Philippines (J. Barril, MD; George Garcia, MD); Medizinische Hochschule Hannover, Hannover, Germany (Jochen Cremer, MD); Memorial Medical Center, Long Beach, CA (Dan Bethencourt, MD); Mercy General Hospital, Sacramento, CA (Robert H. Allen, MD; Allen S. Morris, MD; Frank N. Slachman, MD); Montreal General Hospital, Montreal, Canada (Hani Af Shennib, MD); Mustaffa Kamel Hospital, Alexandria, Egypt (George Garcia, MD); Palm Beach Gardens Medical Center, Palm Beach Gardens, FL (Richard Faro, MD; Joseph Motta, MD); Phoenix Memorial Hospital, Phoenix, AZ (Jay Hessel, MD); St. Charles Medical Center, Bend, OR (Robert R. Lazzara, MD); St. Joseph's Hospital and Health Center, Syracuse, NY (Mehdi Marvasti, MD); St. Joseph's Hospital, Tampa, FL (Dennis Pupello, MD); St. Vincent's Hospital, Indianapolis, IN (Robert G. Matheny, MD; David A. Heimansohn, MD; Keith B. Allen, MD); Tulane University Medical Center, New Orleans, LA (Bruce Toporoff, MD); University Chieti, Italy (Antonio M. Calafiore, MD; Gabrielle DiGiammarco, MD; Giovanni Teodori, MD); University Dresden, Germany (Hermann Reichenspurner, MD, PhD); University Hospital Groningen, Netherlands (Jan G. Grandjean, MD; Piet W. Boonstra, MD, PhD); University Innsbruck, Austria (O. 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TI - MIDCAB characteristics and results: the CardioThoracic Systems (CTS) registry
JF - European Journal of Cardio-Thoracic Surgery
DO - 10.1016/S1010-7940(98)00100-6
DA - 1998-10-01
UR - https://www.deepdyve.com/lp/oxford-university-press/midcab-characteristics-and-results-the-cardiothoracic-systems-cts-D1fAVfJ4Aj
SP - S25
EP - S30
VL - 14
IS - Supplement_1
DP - DeepDyve
ER -