Long-term outcome in men and women after CABG; Results from the IMAGINE trial

Background: The aim of this study is to determine sex differences in long-term outcome after coronary artery bypass grafting (CABG). Methods: The international randomized controlled IMAGINE study included 2553 consecutive patients with a left ventricular ejection fraction of >40% who underwent isolated CABG. Median follow-up was 32 months (IQR 17-42 months). The composite endpoint comprised of death, myocardial infarction (MI), cerebrovascular event, angina, revascularization and congestive heart failure. Cox regression analysis was used to examine sex differences in outcome post-CABG. Results: Of the 2553 patients, 2229 were men and 324 (13%) were women. Women were older and more often reported diabetes and hypertension. Smoking and impaired renal function were more prevalent in men. Women experienced a higher event rate during follow-up (composite endpoint 18% vs 12%; P = 0.007). Cox regression showed an increased risk of the composite endpoint in women after adjustment for age (HR 1.48 (95% CI: 1.11-1.97)) which was non-significant after additional adjustment for other confounders (HR 1.26 (95% CI: 0.92-1.72)). Conclusion: Women have a worse long-term outcome after CABG than men in univariate analysis. However, after adjusting for potential confounders female sex became a non-significant predictor for prognosis, possibly due to the small sample size of women. Definite answers regarding sex-differences in long-term outcome after CABG should come from future pooling of studies comprising a larger number of women.