Invited commentary

Abstract

Surgical revascularization for ischemic cardiomyopathy remains a controversial topic. Patient selection clearly is a major issue. In fact the STICH Trial funded by the NHLBI has been developed to give us better information on this topic. Dr Al-Ruzzeh and colleagues started with the hypothesis that off-pump revascularization was clearly superior to on-pump revascularization in patients with ischemic cardiomyopathy. The univariate analysis demonstrated that the off-pump group actually did better. More thorough statistical analysis demonstrated that in fact, the presence of cardiopulmonary by-pass was not a significant factor. The major finding that the author’s noted was preoperative VT or VF was in fact a harbinger of a poor outcome. The author’s are to be congratulated for their thorough statistical analysis in this difficult group of patients. The other question is why such a high mortality in the on-pump group? This mortality is 14%, which is certainly higher than most reported series. Our most recent publication in this group of patients has an operative mortality for less than 4% in patients undergoing on-pump bypass for ischemic cardiomyopathy [1Cope JT, Kaza AK, et al. A cost comparison of heart transplantation versus alternative operations for cardiomyopathy. Ann Thorac Surg 2001;72:1298–305Google Scholar]. The question therefore is why did this group do so poorly? Since VT/VF was a marker for poor outcome one would wonder if the mortality didn’t relate to arrhythmia deaths. In fact the majority of both the on-pump and off-pump group’s deaths were due to heart failure. Myocardial infarction also did not seem to be prevalent in either group of patients, suggesting against acute graft closure. I believe the answer is clear based on the author’s own data. Only approximately 50% in both on-pump and off-pump group of patients had angina preoperatively. Viability studies were not done by these authors in the belief that this was not necessary and could potentially exclude some patients who would benefit from having bypass surgery. I believe this is a serious error. The fact of the matter is that there was very significant mortality rate in both groups of patients and the majority of the deaths relate to heart failure. This seems to speak against patients getting much improvement in ejection fraction. This also suggests some of these patients did not have viable myocardium that could have been predicted by preoperative viability studies. We and others have suggested that ischemic cardiomyopathy can be treated with coronary revascularization if two conditions are met. There must be some viable myocardium that will be revascularized, and there should be good targets for the revascularization. We believe the absence of either of these conditions will markedly increase the mortality and have demonstrated this previously [2Langenburg SE, Buchanan SA, Sabik JF III. Predicting survival after coronary revascularization for ischemic cardiomyopathy. Ann Thorac Surg 1995;60:1193–7Google Scholar]. These authors have touched on this in that preoperative VT/VF may predict less viable myocardium. It is probably important to return to the issue of on-pump versus off-pump for this group of patients. What do we know about off-pump revascularization? Puskas and colleagues demonstrated in an excellent randomized study that off-pump surgery provided complete revascularization, was safe, with a patency equivalent to on-pump surgery. He was able to demonstrate no survival advantage in stable patients undergoing coronary bypass. He was able to demonstrate reduced blood utilization in off-pump surgery [3Hart JC, Puskas JD, et al. Off-pump coronary revascularization: current state of the art. Sem Thorac Cardiovasc Surg 2002;14:70–81Google Scholar]. It would be exciting if off pump surgery provided a survival advantage in patients undergoing coronary bypass for ischemic cardiomyopathy. Unfortunately, the present does not demonstrate that. It will take a well-designed randomized study to prove that off-pump by-pass is superior to on-pump in patients with limited ventricular reserve.