Sleep apnoea is associated with long-term cardiovascular outcomes in patients undergoing coronary artery bypass grafting

Abstract Background Sleep apnoea is highly prevalent in patients undergoing coronary artery bypass grafting (CABG), and is associated with poorer peri-operative outcomes. However, whether sleep apnoea is associated with long-term cardiovascular outcomes remain unknown. Purpose We aimed to examine the relationship between sleep apnoea and long-term major adverse cardiac and cerebrovascular events (MACCE) in patients undergoing non-urgent CABG. MACCE was a composite endpoint that comprised cardiovascular mortality, non-fatal myocardial infarction, no-fatal stroke, and unplanned revascularisation. Methods This was a prospective cohort study with five years follow-up. Between 2013 and 2018, a total of 1007 patients referred to a tertiary cardiac centre for non-emergent CABG were recruited. All the participants underwent an overnight sleep study using an FDA-approved portable diagnostic device. Sleep apnoea was diagnosed when the apnoea-hypopnoea index was ≥15 events per hour. The clinical team involved in patient care was independent of the research project and blinded to the sleep study results. Results The sleep apnoea (n=513 patients, 50.9%) and non-sleep apnoea groups did not differ in terms of surgical complexity, based on the number of bypass grafts and the estimated blood loss. Fourteen patients died, including nine in the sleep apnoea and five in the non-sleep apnoea group. At an average follow-up of 4.8 years, the overall cohort had 221 patients (21.8%) experienced the four-component MACCE. This included 59 cardiovascular deaths (5.9%), 85 non-fatal myocardial infarctions (8.4%) , 90 non-fatal strokes (8.9%), and 71 unplanned revascularizations (7.1%). Compared with the non-sleep apnoea group, the sleep apnoea group experienced a higher crude incidence of MACCE (estimated 5-year incidence, 24.6% vs 17.2%, p=0.011). For the individual components, the incidence of cardiovascular death (6.6% vs 4.1%, p=0.071), non-fatal myocardial infarction (9.2% vs 7.7%, p=0.02), and non-fatal stroke (9.6% vs 8.3%, p=0.41) was higher in the sleep apnoea than the non-sleep apnoea group. The incidence of unplanned revascularizations was similar between the two groups (7.0% vs 7.1%, p=0.96). The Kaplan-Meier survival curve is shown in Figure 1. In the Cox regression analysis, sleep apnoea was associated with a higher incidence of MACCE (unadjusted Hazard Ratio [HR]=1.41, 95% Confidence Interval [CI]: 1.08 - 1.85, p=0.011). After adjustment for the effects of age, gender, body mass index, left ventricular ejection fraction, diabetes mellitus, hypertension, chronic kidney disease, and excessive daytime sleepiness, sleep apnoea was independently associated with MACCE (adjusted HR: 1.32; 95% CI: 1.01-1.73; p=0.041). Conclusion To the best of our knowledge, this is the first report showing that in patients undergoing an non-urgent CABG, sleep apnoea was independently associated with a 30% higher risk of MACCE over a long-term follow-up period.