Response to Letters Regarding Article, “Percutaneous Treatment With Drug-Eluting Stent Implantation Versus Bypass Surgery for Unprotected Left Main Stenosis: A Single-Center Experience”
In the letter by Brocco et al, the authors focused on the correspondence between clinical relevance and statistical significance. The decision to emphasize study results as clinically relevant but not statistically significance is quite controversial in relatively small retrospective studies with exploratory purposes such as our study.1 In our opinion, a pragmatic “win criterion” for these kinds of studies would be the simultaneous achievement of both clinical and statistical significance. We do not believe that not mentioning as clinically relevant a non–statistically significant difference can substantially bias the readers’ conclusions any more than emphasizing as noteworthy a difference that is potentially coincidence.
In the letter by Pocar et al, different issues are raised. The authors pointed out the problem of the incomplete revascularization (IR), which is frequently evoked as a limitation of percutaneous transluminal coronary angioplasty as compared with bypass surgery.2 Although the survival benefit of complete revascularization after bypass surgery is well documented, the importance of opening all stenotic or occluded vessels is still debated for percutaneous transluminal coronary angioplasty, and a strategy of “ischemic-driven revascularization” is often the standard of care for cardiologists.2,3 However, the benefit is still controversial in terms of in-hospital and long-term outcomes of surgical grafting of a dominant graftable right coronary artery (RCA) tributary of an infarcted nonischemic territory in patients with 3-vessel disease.4 In our study,1 RCA disease was also present in 98 patients (69%) in the coronary artery bypass grafting (CABG) group versus 42 (40%) in the percutaneous coronary intervention (PCI) group. For a cardiologist, the presence of disease in the nonrevascularized RCA is not always an accurate measure of IR. Among the 43 patients with RCA disease not revascularized, 11 had a hypoplastic RCA or distal-segment disease with a small area of distribution. In 20 patients, chronic total occlusion in the RCA was present with a documentation of prior myocardial infarction. Moreover, 4 patients in the CABG group received only a left internal mammary artery graft to the left anterior descending artery because of anatomic or clinical conditions. We did not detect a significant difference in the rate of IR between the PCI and CABG groups (in the total population, 14.9% in PCI versus 21.8% in CABG, P=0.19; and in 3-vessel disease, 38% in PCI versus 27.5% in CABG, P=0.23). Because of the differences in baseline characteristics between the 2 groups, we prefer not to speculate on this finding. It is well known that IR after CABG occurs in 6% to 21% of the cases, mostly depending on clinical and lesion baseline characteristics, as well as the type of the intervention performed (off pump > on pump).2,5 In our experience, patients with IR were more frequently older and had lower ejection fraction, diabetes mellitus, and higher EuroScore. We did not detect any correlation between IR and the occurrence of postprocedure myocardial infarction. In accordance with the current literature, the occurrence of IR was associated with worse outcome and a lower survival rate at 1 year. It is still unclear whether the worse outcome depends on the IR or the worse baseline clinical lesion characteristics of this group of patients. As recently suggested by Dr Teirstein,3 the increased risk of death after revascularization in patients with low ejection fraction or with severe comorbidities is unlikely to be caused by IR, and it is hard to imagine a statistical technique capable of adjusting for that degree of risk.
Regarding cerebrovascular events, the presence of prior cerebrovascular events and/or prior carotid revascularization are included in the EuroScore calculation that we reported in our article. Moreover, the population has also been stratified according to the EuroScore, and, consequently, we have taken into account in the analysis this variable.
Concerning the angiographic follow-up (mandatory according to current guidelines only for PCI, not for surgical revascularization of unprotected left main coronary artery), this is a bias that we have in our practice that most probably reflects what is the common standard of care. As also discussed in our article, we cannot exclude that fact that because CABG patients have no such routine follow-up, the parallel ability to detect asymptomatic graft closure or restenosis may be underestimated with the current standard of care.
Chieffo A, Morici N, Maisano F, Bonizzoni E, 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.
Hannan EL, Racz M, Holmes DR, King SB III, Walford G, Ambrose JA, Sharma S, Katz S, Clark LT, Jones RH. Impact of completeness of percutaneous coronary intervention revascularization on long-term outcomes in the stent era. Circulation. 2006; 113: 2406–2412.
Teirstein PS. The dueling hazards of incomplete revascularization and incomplete data. Circulation. 2006; 113: 2380–2382.
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.