Abstract 14965: Atrial Conduction During Obstructive Sleep Apnea: Comparison of Stacked Versus Isolated Apnea Episodes

Abstract

Introduction: Obstructive sleep apnea (OSA) is associated with increased rates of atrial fibrillation (AF). Recent randomized data suggest that traditional scoring of OSA needs to evolve to improve cardiovascular outcomes. Traditional scoring of OSA does not fully reflect pathophysiological links between OSA and AF, particularly regarding OSA-induced prolongation of p-wave duration (PWD), which is the most powerful predictor of AF occurrence. Hypothesis: We hypothesized that OSA episodes that closely follow each other (serially stacked apneas, ssOSA) exert greater effect on PWD compared to isolated OSA (iOSA) episodes. Methods: Sleeping patients (adults with mild-moderate OSA and presence of both iOSA and ssOSA, but without other cardiovascular comorbidities) undergoing diagnostic polysomnography were recorded by continuous 8-lead ECG. iOSA was defined as OSA episodes with no other episode within 30 seconds. ssOSA consisted of ≥3 consecutive apneas with inter-OSA intervals <30 seconds. PWD was defined from onset of p-wave in any ECG lead to termination in any lead (measured by digital calipers, averaged over 3 beats from first half of OSA and 3 beats from second half of OSA). Wilcoxon rank-sum test was used. Results: We analyzed 208 OSA episodes (51.0% iOSA, 49.0% ssOSA) which occurred in 12 patients (7 women; age 63.1±11.5 years; apnea hypopnea index 16.8±5.4). PWD was longer during ssOSA compared to iOSA (median 117.7ms vs 109.6ms; p<0.0001). The following variables did not differ between ssOSA and iOSA: PR interval (p=0.3139), RR interval (p=0.7531), peripheral oxygen saturation (p=0.7776). Conclusions: The impact of OSA on atrial conduction delay is exacerbated by the phenomenon of OSA stacking, which seems independent of oxygen desaturation and heart rate. Stacking of OSA episodes may be an underused and cost-efficient variable in evaluating the severity of OSA and the effectiveness of OSA treatments with the ultimate goal of reducing occurrence of AF.