Letter by Pocar et al Regarding Article, “Percutaneous Treatment With Drug-Eluting Stent Implantation Versus Bypass Surgery for Unprotected Left Main Stenosis: A Single-Center Experience”
To the Editor:
We commend Chieffo et al1 for the very interesting results obtained with implantation of drug-eluting stents for unprotected left main stenosis. However, statistical significance was reached only for composite end points despite a different antiplatelet regimen, and the somewhat optimistic conclusions sound unconvincing to a surgical audience.2
Only 42 of 107 patients (39%) undergoing stenting had 3-vessel disease, which describes a selected population when compared with surgical series with left main disease. Conversely, the authors state that the “approach selected appeared suitable to guarantee complete revascularization,” (p 2542) but only 18 of 42 patients (43%) and 68 of 98 patients (69%) in the interventional and surgical cohorts, respectively, had additional right coronary stenoses treated during the index procedure. This seems logical (although unspecified) for staged percutaneous approaches but is surprising from a surgical standpoint, given that it demonstrates incomplete revascularization in nearly one-third of the cases of 3-vessel disease. Furthermore, the number of bypass grafts per patient is not specified. Incomplete revascularization is a well-known risk factor for suboptimal results, possibly including occluded right coronary arteries with prior inferior wall infarction.3
The observations above might correlate with the incidence of perioperative myocardial infarction (creatine kinase-MB isoenzyme ≥40 ng/mL) in surgically treated patients, which appears exceedingly high (overall, 26%; on-pump operations, 34%), especially in view of the relatively low prevalence of unstable angina (22%). Myocardial protective techniques are not described and may imply important variables, including specific protocols for energy-depleted hearts and retrograde cardioplegia. In this respect, creatine kinase-MB levels ≥25 ng/mL correlate with 30-day mortality rates and postoperative left ventricular dysfunction.4 Similarly, perioperative myocardial injury during off-pump revascularization often relates to early graft dysfunction and predicts 1-year adverse cardiac outcome.5
Although end points include stroke or major cerebrovascular events, no data are shown regarding prior events, screening for carotid disease, or carotid revascularization during the follow-up period. This further reduces the strength of composite end points comprising cerebrovascular complications. Furthermore, patients with left main disease show a higher prevalence of critical carotid stenosis and should thus be more aggressively investigated, especially those who are older or who have multiple higher-risk factors.
Finally, stating that “[I]t might, however, be fair to point out that routine angiographic follow-up was part of this initial protocol to detect early left main stent restenosis” (p 2545) in patients treated with stenting, the authors1 implicitly exclude the occurrence of angiographically driven repeat revascularization in surgically treated patients, pointing out another limitation inherent to the retrospective nature of their study.
Chieffo A, Morici N, Maisano F, Cosgrave J, Montorfano M, Airoldi F, Carlino M, Michev I, Melzi G, Sangiorgi G, Alfieri O, Colombo A. Percutaneous treatment with drug-eluting stent implantation versus bypass surgery for unprotected left main stenosis: a single-center experience. Circulation. 2006; 113: 2542–2547.
Gaudino M, Alessandrini F, Glieca F, Luciani N, Cellini C, Pragliola C, Morelli M, Girola F, Possati G. Effect of surgical revascularization of a right coronary artery tributary of an infarcted nonischemic territory on the outcome of patients with three-vessel disease: a prospective randomized trial. J Thorac Cardiovasc Surg. 2004; 127: 435–439.