BMS vs LIMA for Proximal LAD Lesions: 10-Year Follow-up of the SIMS Trial

Abstract & Commentary

By Andrew J. Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco. Dr. Boyle reports on financial relationships relevant to this field of study.

Source: Goy JJ, et al. 10-year follow-up of a prospective randomized trial comparing bare-metal stenting with internal mammary artery grafting for proximal, isolated de novo left anterior coronary artery stenosis the SIMA (Stenting versus Internal Mammary Artery grafting) trial. J Am Coll Cardiol. 2008;52:815-817.

Coronary artery stenoses involving the proximal left anterior descending coronary artery (LAD) have caused significant concern for clinicians over the years. If these lesions give rise to a myocardial infarction, this is often termed the "widow maker" because of the large area of myocardium subtended by the LAD and the high mortality associated with proximal LAD occlusion. Coronary stenting provides a less invasive alternative to coronary artery bypass graft (CABG) surgery. However, proximal LAD stenting with bare-metal stents (BMS) has a high rate of in-stent restenosis (ISR). The SIMS trial was a randomized, controlled study designed to compare CABG using left internal mammary artery (LIMA) grafts with stenting using BMS in patients with isolated de novo lesions in the proximal LAD.

Goy et al enrolled 121 patients at six European sites and randomized them to stenting or CABG for proximal LAD stenosis. The baseline data and two-year outcomes have been reported previously. Follow-up data at 10 years was available in 119 patients. The primary composite endpoint was all-cause mortality, myocardial infarction (MI), and repeat revascularization; the secondary endpoint was angina. After 10 years of follow-up, the primary endpoint was reached more often in the stent group than the CABG group (42% vs 17%, p < 0.0001), which was driven by an increased rate of revascularization (29% vs 5%, p < 0.0001). The rates of death (8% vs 7%, p = 0.4) and MI (5% vs 5%, p = NS) did not differ between stent and CABG groups, respectively. Most patients in both groups were free of angina (93%) or had mild angina (7%). Goy et al concluded that the only difference between stenting and LIMA grafting for proximal LAD disease is the need for repeat revascularization.

Commentary

This study confirms the excellent long-term efficacy and safety of CABG with LIMA graft for isolated proximal LAD disease. In addition, it confirms the long-term safety and efficacy of stenting for proximal LAD disease, albeit with a higher rate of revascularization than CABG. It is noteworthy that only 28% of patients initially received statin therapy, whereas, at study's end, 89% of patients were receiving statins, with no difference between groups. This reflects the changing practice pattern for secondary prevention over the past 10 years. After 10 years, 94% of stented patients and 96% of CABG patients were receiving anti-platelet therapy, but Goy et al provide no details regarding whether this was aspirin alone or dual anti-platelet therapy. This study is limited by small numbers and by including a very specific homogeneous group of patients. However, when looking at the absolute numbers of events, it is unlikely that even with doubling or tripling of the number of patients that there would be a discernable difference in death or MI. Notable strengths of this study are the randomized nature of its design and the excellent rate of 10-year follow-up (98% of patients).

The stents used in this study were first generation bare-metal stents, and technology has evolved significantly since then. It is enticing to speculate that with drug-eluting stents, better medical therapies and optimization of anti-platelet therapies, that event rates could be further reduced, both in the patients receiving stents and those having CABG, but this remains to be prospectively evaluated.