Impact of diabetes on outcome following isolated minimally invasive bypass grafting of the left anterior descending artery

Abstract

Background: The outcome in patients treated by conventional coronary artery bypass grafting (CABG) for coronary artery disease is negatively influenced by the presence of diabetes. The relative effect of diabetes in patients undergoing isolated minimally invasive revascularization of the left anterior descending artery (LAD) using the internal thoracic artery (ITA) has as yet not specifically been looked at. Thus, this study sought to evaluate the impact of diabetes on mid-term outcome following minimally invasive coronary artery bypass grafting (MIDCAB).

Methods: From 1996 to 1999, 411 patients received a MIDCAB procedure at our institution and were now followed up. In this study population there were 63 diabetic patients (15.3%) and 348 nondiabetic patients (84.7%). Isolated proximal stenoses or an occlusion of the LAD were present in 262 patients (63.7%), whereas 149 (36.3%) had multi-vessel disease (MVD) at the time of the MIDCAB procedure. The clinical outcome was evaluated by questionnaires sent to the patients and their physicians.

Results: The mean follow-up was 29.4 +/- 11.1 months. The incidence of myocardial infarction was significantly higher in diabetics as compared to nondiabetics (9.5% vs 3.2%, p = 0.034). Diabetics and nondiabetics had similar rates of subsequent revascularization procedures during follow-up. Cumulative total survival of diabetic and nondiabetic patients was not statistically different. The 3-year cardiac mortality was however significantly higher in diabetic than in nondiabetic patients if MVD was initially present (Kaplan-Meier estimate: 10.7% vs 2.5%, relative risk [RR] = 5.5, p = 0.017 by log-rank test). The 3-year cardiac mortality in diabetic and nondiabetic patients with isolated disease of the LAD (single vessel disease [SVD]) was not significantly different. After adjustment of baseline characteristics by Cox regression analysis the 3-year risk of cardiac death was significantly higher in the diabetic group (RR = 1.82, CI 95%:1.2 to 3.3, p = 0.045).

Conclusions: The results support diabetes to be an independent risk factor for outcome in patients with MVD undergoing a MIDCAB procedure in analogy to those undergoing CABG procedures. Diabetics with isolated disease of the LAD, however, benefit out of proportion from this treatment modality.