Obesity: a non-independent risk factor for mortality in chronic coronary syndrome submitted to medical therapy, percutaneous coronary intervention or coronary artery by-pass grafting. The MASS trial

Abstract

Background: Epidemiological studies suggest that obesity may confer protection in some common disease settings such as heart failure, atrial fibrillation, sudden death, acute coronary syndrome, and chronic coronary artery disease (ChCAD). However, previous published ChCAD results are based in registry data, and overweight and mild/moderate obesity were more likely to undergo revascularization procedures despite having lower risk coronary anatomy. Objective: To test the hypothesis whether body mass index (BMI) and other risk factors are independent risk factors for total mortality in patients with ChCAD that were randomized to optimized medical therapy (OMT), OMT associated with percutaneous coronary intervention (PCI), or OMT associated with coronary artery by-pass grafting (CABG) in the prospective randomized MASS trial. Methods: From 547 patients with ChCAD 177 were randomized to OMT, 156 to OMT + PCI (95 with non-drug-eluting stent, 61 with drug-eluting stent), and 214 to OMT + CABG. The mean studied follow-up was 1997+868 days. The OMT followed the current guideline orientation. The following risk factors: history of hypertension; current smoking; serum levels of cholesterol, LDL-cholesterol, HDL-cholesterol, triglyceride, fasting glucose, HbA(1c); waist circumference; BMI in kg/m2 (BMI < 24.9; 24.9 < BMI < 29.9; 29.9 < BMI < 34.9; BMI > 34.9); age; sex; and the procedure (OMT or OMT+PCI or OMT + CABG) were tested in univariate and multivariate analysis as independent predictor of total mortality. Results: It was observed statisticaly: no differences in 6 years survival between OMT (81%), OMT+PCI (85%), and OMT+CABG (85%); no differences in survival according the BMI in the total group; no differences according the BMI in OMT+PCI and OMT+CABG groups except tendency (p=0.057) in OMT for higher survival for 24.9< BMI<29.9 and lower survival for BMI >34.9. On univariate analysis systemic hypertension (p=.002), smoking (p=0.02), and age (p=0.00) were associated with mortality in ChCAD. In multivariate analysis only history of systemic hypertension and current smoking were determinants of mortality during the follow-up. Conclusion: BMI and other accepted risk factors for CAD were not identified as independent risk factors for mortality after OMT, OMT+PCI, and OMT+CABG except hypertension, and current smoking. Obesity paradox was not identified. Independently of other risk factors and percutaneous or surgical procedures, the acknowledge of hypertension and current smoking importance is essential in ChCAD management under OMT.