Effect of preoperative hemoglobin A1c levels on long-term outcomes for diabetic patients after off-pump coronary artery bypass grafting

Summary

Background

Diabetes mellitus is an independent risk factor for cardiovascular events after coronary artery bypass grafting (CABG), and hemoglobin A1c (HbA1c) is the most convenient marker for monitoring glycemic control among diabetic patients. However, few studies have reported the impact of baseline HbA1c levels on outcomes for diabetic patients after CABG. This study therefore aimed to investigate whether preoperative HbA1c levels in diabetic patients are predictive of long-term outcomes after off-pump CABG (OPCAB).

Methods and results

Of 893 patients undergoing primary isolated OPCAB at Juntendo University Hospital from July 2002 to December 2007, subjects comprised 306 diabetic patients <80 years old. We divided these patients into 3 groups according to the preoperative HbA1c levels. No significant differences in baseline characteristics, angiographic findings, or operative parameters were apparent among the 3 groups. No operative or in-hospital mortality occurred. All-cause mortality and cardiac mortality rates were 6.2% (19 cases) and 1.3% (4 cases), respectively. Kaplan–Meier's survival showed no significant differences in all-cause or cardiac mortality (log-rank test, p = 0.26, p = 0.17, respectively). Multivariate analysis by Cox's proportional hazards model also demonstrated that no covariates predicted mortality except for age.

Conclusions

Preoperative HbA1c levels might not predict long-term outcomes for diabetic patients undergoing OPCAB. Careful evaluation for diabetes should be needed in preoperative management of CABG.