P108 Obstructive Sleep Apnoea in Acute Coronary Syndrome: An Observational Study

Obstructive sleep apnoea (OSA) is a risk factor for cardiovascular disease. CPAP therapy is the primary treatment for OSA and is known to improve long term cardiovascular health outcomes. Recent neutral findings of randomised clinical trials have created uncertainty about whether effective CPAP therapy can improve cardiovascular health in patients with OSA. We conducted a cross-sectional observational study in patients with acute coronary syndrome (ACS) diagnosed with OSA. We aimed to characterise key surrogate markers of cardiovascular health in this cohort to inform a future intervention study of personalised OSA therapy. 70 patients with ACS (age (IQR):58[52,63]years, BMI:27[24,30]kg/m2) were recruited. A level 2 sleep study was conducted to confirm OSA diagnosis within 6 months after discharge. Carotid femoral pulse wave velocity(cfPWV), pulse wave analysis, endothelial function, heart rate variability, and baroreflex sensitivity were measured. Patients were categorised as no-mild OSA(AHI<15events/h) and moderate-severe OSA(AHI≥15events/h) for analysis. 67% of patients were found to have moderate-severe OSA(AHI≥15events/h) and 40% of patients had severe (AHI≥30events/h). cfPWV was elevated in moderate-severe OSA compared to no-mild OSA (7.4[6.6,8.5] vs. 6.1[4.7,7.1]m/s, p=0.003). This was no longer significant after adjusting for age (p=0.296) and BMI (p=0.053). cfPWV correlated with AHI (rs = 0.35, P=0.0069). Measures of pulse wave analysis, flow mediated dilatation, heart rate variability, and baroreflex sensitivity did not differ between patient groups (data not shown). OSA is highly prevalent in patients with ACS. Arterial stiffness measured by cfPWV appears to show best promise as an outcome measure for a future intervention trial of personalised OSA therapy.