Objective: Coronary artery bypass grafting (CABG) is associated with significant cerebral morbidity, usually manifested as cognitive decline or stroke. The underlying mechanism leading to cognitive decline is still unclear. Presence of coronary collateral arteries, which may reflect an overall better cardiovascular condition, recently appeared to relate to a better cardiac outcome after CABG. In this study, we investigated the hypothesis that presence of coronary collaterals is associated with less cognitive decline after coronary artery bypass grafting.
Methods: Data from 281 patients undergoing first-time coronary artery bypass grafting were used. Presence of coronary collaterals was determined on the preoperative angiogram. Cognitive function was evaluated before the operation, at 3 and 12 months and 5 years thereafter by standardised neuropsychological assessment. Cognitive decline in individuals was determined by calculating the reliable change score, a cognitive change score corrected for natural testing variability and practice effects.
Results: Cognitive decline was found in 19 (8%) patients at 3 months, in 31 (12%) patients at 12 months and in 82 (34%) at 5 years follow-up. Presence of coronary collaterals was independently associated with a better cognitive outcome at both 3 months (odds ratio (OR) 0.30; 95% confidence interval (CI) 0.09-0.95; p=0.04) and 12 months (OR 0.42; 95% CI 0.18-0.97; p=0.04) after coronary artery bypass grafting. At 5 years, the OR was 0.57 (95% CI 0.31-1.05; p=0.07).
Conclusions: In patients undergoing first-time coronary artery bypass grafting, presence of coronary collaterals is associated with a decreased risk of cognitive decline at both 3 and 12 months of follow-up. This trend persists at 5-year follow-up. Preoperative differences in the cardiac vascular condition may therefore predict cognitive outcome in patients undergoing coronary artery bypass grafting.