LAUSR

Abstract Funding Acknowledgements Type of funding sources: None. Background Obstructive Sleep Apnea (OSA) is a highly prevalent disorder in developed countries. It is well known that OSA is strongly associated with Atrial Fibrillation (AFib) and sinus pauses, but its impact on ventricular arrhythmias is less clear. Purpose The aim of this study was to evaluate the presence of rhythm disorders in 24h Holter in patients with OSA and their association with different grades of OSA severity. Methods We performed a retrospective single-center cohort study. The study included patients who underwent both a level 3 polysomnography and a 24h Holter test at our hospital center between 1 January 2015 and 31 December 2019 (n=464). We excluded patients without OSA, patients with OSA under current treatment with CPAP/APAP and those who only had 24h Holter test after starting CPAP/APAP. Patients were divided into 3 groups according to the OSA severity in the sleep study test: mild, moderate and severe. The Holter was analyzed for the presence of AFib, number of premature atrial contractions (PACs), presence of runs of PACs, number of premature ventricular contractions (PVCs), presence of non-sustained ventricular tachycardia (NSVT) and the presence of conduction disorders. Premature contractions were considered frequent when greater than 30 per hour. These results were compared in the three groups. Results This cohort included 233 patients: 89 classified into mild, 74 into moderate and 70 into severe OSA form. The baseline characteristics of patients are depicted in table 1. The overall median age was 67 (57-73) years and was similar between the groups. Male gender was more prevalent in the overall sample and statistically more prevalent in the severe OSA group (56.2% in mild vs 75.7% in severe OSA, p=0.08). Regarding cardiovascular risk factors, there was no difference between the groups except for obesity, with higher body mass indexes translating into more OSA severity (p=0.049). Results are shown in table 2. We observed that OSA severity and AFib are associated. AFib was more prevalent in the moderate and severe forms of OSA (13.5% in moderate and 18.6% in severe OSA vs. 6.7% in mild OSA; p=0.041). The prevalence of atrioventricular block and the prevalence of intraventricular block were higher in the moderate group of OSA (p=0.048; p=0.007). There was no association between OSA severity and the burden and complexity of PACs. On the contrary, we found a higher percentage of frequent PVCs in more severe forms of OSA (20.3 and 21.4% in moderate and severe group, p=0.031). Conclusion In the present study the severity of OSA was associated with a higher prevalence of AFIb and conductions disorders as expected. However, it was also associated with higher prevalence of frequent premature ventricular contractions but not with atrial premature contractions. Further studies are needed to confirm these findings and to study the benefit of level 3 polysomnography testing in patients with frequent PVCs. Table 1 Table 2