P080 The effect of long-term CPAP use on sub-clinical echocardiographic markers of cardiovascular disease in patients with moderate–severe OSA

Abstract Background Obstructive sleep apnoea (OSA) has been associated with major adverse cardiac events (MACE) in longitudinal observational studies, however randomised controlled trials (RCTs) have not shown reduction in long-term risk of MACE with CPAP therapy. We, therefore, aimed to better understand the effect of long-term CPAP on sub-clinical changes in cardiac function. We will use propensity score matching techniques on observational data, which mimics RCTs, to provide causal inference about the effect of CPAP. Methods Participants (n = 264) with moderate–severe OSA (AHI ≥ 15 events/hr) at baseline (2006-2010) without major MACE (baseline or follow up) were assessed for sub-clinical cardiac measures between 2019 and 2021. Participants were recruited for follow-up assessment if they had either excellent adherence to CPAP (median nightly use = 7 hours 40 minutes/night, n = 134) or no/minimal use of CPAP (n = 130). Sub-clinical echocardiographic markers of cardiovascular disease at follow-up will be analysed and compared between the two groups matched on a range of cardiovascular and health risk factors using propensity score methods. Echocardiographic markers will include: left atrial volume and area, left ventricular (LV) bidimensional parameters, LV ejection fraction and myocardial performance index, LV diastolic function, LV tissue doppler parameters, right atrial and ventricular parameters, pulmonary hypertension, left and right ventricular strain parameters. Progress to Date Data has been cleaned and tabulated and is awaiting statistical analysis. Intended outcome and impact Determine the impact of excellent vs. no CPAP treatment in moderate–severe OSA, without pre-existing MACE, on sub-clinical echocardiographic markers of cardiovascular disease over 13 years of follow up.