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J Thorac Cardiovasc Surg 2003;125:779-781
© 2003 The American Association for Thoracic Surgery
Editorials |
From the Bristol Heart Institute, University of Bristol, Bristol, United Kingdom.
Received for publication June 30, 2002. Revisions requested July 1, 2002; revisions received July 30, 2002. Accepted for publication Aug 6, 2002. Address for reprints: Gianni D. Angelini, MD, Professor of Cardiac Surgery, Bristol Heart Institute, Bristol Royal Infirmary, Bristol BS2 8HW, United Kingdom (E-mail: R.Ascione{at}bristol.ac.uk).
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The evidence |
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1 but rather disappointing in other cases, such as the advent of transmyocardial laser revascularization. 2
With OPCAB, the surgical scientific community has tended to turn its thumb down, continually demanding evidence. Actually, this has been fortunate, because many off-pump centers have been prompted to design studies of good quality, producing a number of prospective randomized trials, case-matched reports, and observational reports. The best of them, as determined by study design, size of the surgical population, and quality of the statistical analysis used, are discussed here. Beating Heart Against Cardioplegic Arrest Study (BHACAS) 1 and 2 were two single-center randomized trials carried out on a total population of 401 patients undergoing elective operations (200 of which were performed off pump). 3 Completeness of revascularization was similar between the two groups, and in-hospital mortality did not differ (1% for on pump vs 0% for off pump). Benefits associated with OPCAB included significant reductions in chest infection, inotropic requirement, incidence of arrhythmias, total chest tube drainage and consequent transfusion requirement, intubation time, intensive care, hospital stay, and costs. The outcome of a multicenter randomized trial in a cohort of 281 patients (142 undergoing operations off pump) was reported by Van Dijk and coworkers 4 and showed no differences in terms of in-hospital mortality and morbidity. The patients undergoing off-pump surgery, however, had a shorter ventilation time, were discharged 1 day earlier, and had a reduction of 41% in release of creatine isoenzyme MB relative to the on-pump patients.
Although the results of prospective randomized studies are rightly considered the criterion standard, they are not powered to detect differences in more than few chosen end points. Moreover, their findings cannot be uncritically extended to an entire surgical population if there are restricted exclusionary criteria. For these reasons very large retrospective studies, supported by sophisticated statistical analysis might be equally helpful. A recent study from Magee and colleagues 5 in a cohort of 8449 patients (1983 patients with operations performed off pump) used propensity score analysis to demonstrate that elimination of cardiopulmonary bypass improves early survival in patients undergoing multivessel coronary artery bypass grafting. Similarly, Cleveland and coworkers, 6 in a multicenter retrospective risk-adjusted analysis of 118,140 coronary artery bypass grafting procedures without concomitant surgery drawn from the National Adult Cardiac Surgery Database of The Society of Thoracic Surgeons (11,717 of which were OPCAB), showed significant benefits associated with OPCAB. These included decreases in operative mortality (from 2.9% to 2.3%) and major complications such as deep sternal infection, bleeding, renal failure, and prolonged ventilation (from 14.1% to 10.6%). Similar results were reported by Calafiore and associates. 7 However, a major limitation of this kind of study is the potential for bias related to differences in patient selection, surgical technique, and, not least, surgical skill.
Comparisons assessing inflammatory and coagulation activation and subsystem organ dysfunction also deserve mention. Several studies have reported a significant attenuation of inflammatory activation 8,9 and coagulation impairment 3,5,7,10 with OPCAB relative to conventional surgery. The lower release of troponin I during OPCAB 4,11 suggests limited myocardial injury, a possible explanation for the reduced incidence of postoperative arrhythmias and inotropic support among these patients. 3,12 A protective effect of OPCAB on renal function is suggested both by biochemical evaluation in patients undergoing elective operations 13 and by the analysis of major clinical outcomes among patients at higher risk for postoperative renal dysfunction either from diabetes 6 or from preoperative non-dialysis-dependent renal insufficiency. 14 A word of caution is needed regarding the efficacy of OPCAB in preventing neuropsychologic dysfunction. Although a lower release of S100 protein was recorded soon after off-pump coronary surgery, the results regarding early and late cognitive dysfunction are controversial in the sense that they have been either better or similar when compared with conventional surgery. 15,16 There are many more studies in the literature on OPCAB, and several on patients at higher risk who might benefit the most from this procedure. The vast majority of these studies report benefits associated with OPCAB, whereas the remnant minority suggest that OPCAB is as good as conventional surgery in terms of mortality and morbidity. 17-19
One of the major criticisms of OPCAB is the performance of suboptimal anastomoses, with the potential for poor long-term results. The late clinical outcomes of the two BHACAS trials (29.3 ± 7.4 and 15.7 ± 5.5 months for BHACAS 1 and 2 respectively) showed no differences between groups in terms of late mortality, cardiac-related events, and need for further coronary revascularization procedure. 3 These results are similar to those reported by van Dijk and coworkers 4 at 1 month of follow-up and are supported by angiographic evidence reported by others. 7,20,21 Considering that conventional coronary surgery has benefited from 30 years of surgical technical evolution, the results of developed OPCAB are quite encouraging in light of its relatively short life. Perhaps before the BHACAS data OPCAB without stabilization devices and intracoronary shunts suggested somewhat poorer long-term outcome. 22
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The implications of the evidence |
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6,7,18,21,23,24
Thousands of OPCAB procedures each year are already being performed as consequence of the possibility of reducing morbidity, but this may also have a welcome economic spin-off. The calculation of the in-hospital costs of the first BHACAS trial showed a saving of about 25% per patient. 22 However, the enthusiasm for OPCAB has not been uniform within developed countries, as judged by the amount of literature produced. The adoption of OPCAB in the United Kingdom (for example) has rightly or wrongly been slower than France, German, Italy, or the United States, and this could be due to different approaches of these countries to a recognized teaching program.
The evidence supporting OPCAB deserves for the scientific community to call for a forum and make specific recommendations. If it is agreed that the evidence is against OPCAB, then those performing such procedures should stop because they are affecting the quality of care of thousands of patients worldwide. If, on the other hand, it is agreed that the evidence for benefit of OPCAB is conclusive, then the implications are of a different order. Implementation of OPCAB could improve the quality of care for many patients operated on each year with conventional techniques. This predicts the need for a recognized teaching program that addresses genuine concerns about OPCAB, the organization of dedicated audit systems of OPCAB, and, not least, consideration of the ethical issue of those research projects designed to randomly assign patients to both techniques purely for study purposes.
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  A. Sedrakyan, A. W. Wu, A. Parashar, E. B. Bass, and T. Treasure Off-Pump Surgery Is Associated With Reduced Occurrence of Stroke and Other Morbidity as Compared With Traditional Coronary Artery Bypass Grafting: A Meta-Analysis of Systematically Reviewed Trials * Supplemental Appendix I Stroke, November 1, 2006; 37(11): 2759 - 2769. [Full Text] [PDF]
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 M. C. Guida, G. Pecora, A. Bacalao, G. Munoz, P. Mendoza, and L. Rodriguez Multivessel Revascularization on the Beating Heart by Anterolateral Left Thoracotomy Ann. Thorac. Surg., June 1, 2006; 81(6): 2142 - 2146. [Abstract] [Full Text] [PDF]
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 D. N. Wijeysundera, W. S. Beattie, G. Djaiani, V. Rao, M. A. Borger, K. Karkouti, and R. J. Cusimano Off-Pump Coronary Artery Surgery for Reducing Mortality and Morbidity: Meta-Analysis of Randomized and Observational Studies J. Am. Coll. Cardiol., September 6, 2005; 46(5): 872 - 882. [Abstract] [Full Text] [PDF]
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 T. D.L. Keenan, Y. Abu-Omar, and D. P. Taggart Bypassing the Pump: Changing Practices in Coronary Artery Surgery Chest, July 1, 2005; 128(1): 363 - 369. [Abstract] [Full Text] [PDF]
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