Prognostic impact of body mass index in patients undergoing coronary artery bypass surgery

Background: Obesity has numerous adverse effects on general, and especially, cardiovascular health. Plasma adiponectin, an adipokine, is inversely related to adipose tissue mass, and also the prognosis of heart failure and coronary artery disease (CAD). Coronary artery bypass grafting (CABG) surgery is usually the treatment of choice for patients with complex CAD. Objective: To investigate the impact of body mass index (BMI) and the associated biomarkers on clinical outcomes after CABG. Methods: Patients with CAD who underwent CABG by a single cardiac surgeon team were prospectively enrolled and followed for up to 5 years after CABG. Results: Among the 234 consecutive patients (aged 70.4±10.5 years, BMI 24.68±3.27 kg/m², 84.6% men), there were 76 mortalities during follow-up. BMI was negatively correlated with adiponectin (r=-0.203, p=0.003), high-sensitivity C-reactive protein (hsCRP; r=-0.176, p=0.009), and N-terminal pro-brain natriuretic peptide (NT-proBNP; r=-0.271, p<0.001). Patients of normal weight (BMI <25 kg/m²) had a decreased event free survival when compared with overweight or obese patients (BMI ≥25 kg/m²). After accounting for age, sex, manifest acute coronary syndrome, glomerular filtration rate, and left ventricular ejection fraction, BMI remained correlated with cardiovascular mortality in the study population. (HR and 95% CI per 1 kg/m ²: 0.912 (0.833 to 0.998)). However, adiponectin, hsCRP, and NT-proBNP would abolish the prognostic impact of BMI. In addition, risk-stratified subgroup analysis showed that adiponectin, hsCRP and NT-proBNP predicted mortality in patients with normal weight, rather than in overweight or obese patients. Conclusions: BMI was inversely associated with the prognosis of CABG. Such association may be linked to the baseline mechanisms related to metabolic disorder (adiponectin) and systemic inflammation (hsCRP). Future pathophysiological validation is indicated.