Impact of body mass index on surgical coronary revascularization for ischaemic heart failure: insights from STICHES

Aims: Patients with obesity and ischaemic heart failure may counter-intuitively have better outcomes compared with patients with normal body weight due to an ‘obesity paradox’. This study sought to determine if body mass index (BMI) impacts the treatment effects or safety outcomes of the treatment of ischaemic heart failure with coronary artery bypass grafting (CABG). Methods and results: We obtained and reviewed the Surgical Treatment of Ischaemic Heart Failure (STICHES) data for 1212 patients. We categorized obesity by the World Health Organization (WHO) classes to define baseline characteristics and test for treatment interactions for the primary and secondary STICHES outcomes by treatment groups. While CABG decreased the risk of death, there was no evidence of treatment interaction by BMI per 5 kg/m² (P = 0.83) or WHO obesity class. For the overall cohort, there was no interaction by WHO obesity class for the cumulative incidence of death in either the medical therapy or CABG plus medical therapy (P-interaction = 0.90). There was a non-significant trend for higher BMI and a lower risk of death [hazard ratio 0.92, 95% confidence interval (CI) 0.85–1.00, P = 0.051]. Increasing body size (per 5 kg/m²) was associated with return to the operating room (odds ratio 2.48, 95% CI 1.45–4.26, P < 0.001) and infectious mediastinitis (odds ratio 2.09, 95% CI 1.10–3.97, P = 0.024) at 30 days but not other 30 day safety outcomes. Conclusions: The benefit of CABG vs. medical therapy for ischaemic heart failure was consistent regardless of BMI or WHO obesity class for death or secondary clinical outcomes. However, higher BMI was associated with some short-term post-CABG complications.