OBESITY IS ASSOCIATED WITH INCREASED RATES OF REVASCULARIZATION IN CORONARY ARTERY BYPASS GRAFTING PATIENTS: A LARGE COHORT STUDY

While excess mass has been demonstrated to be associated with improved survival in subjects with coronary artery disease (CAD), other potential outcomes have not been widely considered. The objective of this analysis was to assess the relationship between obesity and repeat revascularization in subjects who have undergone coronary artery bypass grafting (CABG). The Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) database was used to obtain information. All subjects who underwent CABG between 1995 and 2010 and had a recorded body mass index (BMI) were included in this study. On the basis of BMI, subjects were classified as normal weight (18.5-24.9kg/m2), overweight (25-29.9kg/m2), obese class I (30-34.9kg/m2), obese class II (35-39.9kg/m2), or obese class III (≥40 kg/m2). The outcome of interest was time to repeat revascularization: the first percutaneous coronary intervention (PCI) or CABG after the index CABG. Cox proportional hazard models were used to determine the association between obesity and freedom from repeat revascularization. Normal weight subjects were the referent group. The models were then adjusted for age, sex and all clinical risk factors. There were a total of 13416 subjects included in this study, 23% of whom were of normal weight (n=3082). The more obese subjects were younger, less likely to be male, and suffered from a greater burden of cardiometabolic illnesses (trends across weight categories all p<0.0001). The median follow-up time was 6.3 (IQR, 3.8, 8.9) years; there were 1029 who subjects who had repeat revascularization. In unadjusted models BMI was associated with increased revascularization (overweight Hazard Ratio (HR), 1.22, 95%CI 1.03, 1.45; Obese Class I 1.22, 95%CI 1.01, 1.48; Obese Class II/III 1.60, 95%CI 1.28, 2.00). This association persisted following adjustment in overweight (HR 1.20, 95%CI 1.01, 1.42) and obese class II/III subjects (HR 1.41, 95% CI 1.12, 1.77). Despite an obesity paradox conferring greater survival on obese subjects with CAD, we found that obesity is associated with an increased risk of revascularization. This may represent the higher comorbidity burden present in obese subjects, and elevated residual risk. This finding is novel, and highlights the need to pay particular attention to managing residual risk in obese subjects with CAD.