Influence of diabetes mellitus on long-term survival in systematic off-pump coronary artery bypass surgery.

BACKGROUND: Diabetic patients generally present a more diffuse and calcified coronary artery disease than nondiabetic patients that can affect long-term outcome especially if an off-pump coronary artery bybass graft (OPCABG) technique is used. The aim of this study was to compare long-term results of OPCABG surgery for diabetic and nondiabetic patients.
METHODS: This is a retrospective analysis of prospectively gathered data over a 10-year period of 1,000 consecutive and systematic OPCABG patients operated on between September 1996 and April 2004. Average follow-up period was 66 +/- 28 months and was 97% complete. Overall survival as well as occurrence of major adverse cardiac events in diabetic and nondiabetic patients were specifically studied.
RESULTS: In all, 278 diabetic patients and 722 nondiabetic patients were treated. There was no difference in 30-day mortality between the two groups (p = 0.70). Diabetic patients had more postoperative acute renal insufficiency (p = 0.01) and infections (sepsis; p = 0.002), and deep sternal infections (p = 0.04) Ten-year survival (p = 0.006) and survival free of major adverse cardiac events (p = 0.02) was decreased in the diabetic group. Age (hazard ratio [HR] = 1.06), peripheral vascular disease (HR = 1.72), carotid disease (HR = 1.53), congestive heart failure (HR = 1.51), incomplete revascularization (HR = 2.37), chronic renal insufficiency (HR = 1.93), left ventricular ejection fraction (HR = 0.13), and a lesser use of multiple internal thoracic artery grafts (HR = 0.67), but not diabetes mellitus (p = 0.13) were significant determinants of long-term mortality. Similarly, peripheral vascular disease (HR = 1.92), chronic renal insufficiency (HR = 2.36), emergent operation (HR = 1.71), chronic obstructive pulmonary disease (HR = 1.76), previous percutaneous coronary intervention (HR = 1.66), left ventricular ejection fraction (HR = 0.26), ischemic mitral regurgitation (HR = 1.83), and a lesser use of multiple internal thoracic artery grafts (HR = 0.72) were determinants of decreased survival free of major adverse cardiac events but not diabetes (p = 0.2). Breaking down the major adverse cardiac events, diabetes was found an independent predictive factor of recurrent myocardial infarction (HR = 1.85) and a borderline cause of readmission for congestive heart failure (p = 0.06). Need for new revascularization was comparable for both population (p = 0.37).
CONCLUSIONS: In our series of OPCABG surgery patients, diabetic patients had a comparative operative mortality and perioperative myocardial infarction rate as nondiabetic patients. However, they had an increased prevalence of postoperative acute renal insufficiency and infections. They also had a worse outcome than nondiabetic patients, but that was mainly due to a higher prevalence of preoperative comorbidities and a lesser use of multiple internal thoracic artery grafts. However, diabetes itself was a potential risk factor for long-term occurrence of myocardial infarction and congestive heart failure.