Sleep apnoea (SA) is prevalent and independently associated with adverse cardiovascular events after percutaneous coronary intervention. Patients with complex and high-risk features are often referred for coronary artery bypass grafting surgery (CABG) and it remains unknown if SA is a risk marker. We evaluated the association between SA and major adverse cardiac and cerebrovascular events (MACCE) in patients undergoing non-urgent CABG.

This was a prospective cohort study conducted between November 2013 and December 2018. Patients from 3 public hospitals referred to a tertiary cardiac centre for non-urgent CABG were recruited for an overnight sleep study prior to CABG. The mean follow-up duration was 2.1 years. 

Among the 1007 patients who completed the study, SA (defined as apnoea-hypopnoea index ≥15 events per hour) was diagnosed in 513 patients (50.9%). Most of the patients underwent on-pump CABG (96.7%) and received a left internal mammary artery graft (95.2%). MACCE, a composite of cardiovascular mortality, non-fatal myocardial infarction, non-fatal stroke and unplanned revascularisation, occurred in 123 patients (12.2%). The crude incidence of MACCE was higher in the SA than the non-SA group (15.0% versus 9.5%, p=0.003). Likewise, the crude incidence of all-cause mortality (7.2% versus 4.3%, p=0.028), sudden cardiac death (3.9% versus 1.6%, p=0.028) and heart failure hospitalisations (10.9% versus 5.3%, p=0.001) was higher in the SA than the non-SA group. Multivariate Cox regression analysis demonstrated that SA was predictive of MACCE with an adjusted hazard ratio of 1.54 (95% confidence interval, 1.06-2.22; p=0.023), after adjusting for the effects of age, gender, body mass index, left ventricular ejection fraction, hypertension and chronic kidney disease. 

Sleep apnoea is independently associated with increased MACCE in patients undergoing CABG. Further evaluation regarding the efficacy of treatment of sleep apnoea in patients undergoing CABG surgery is warranted.