Basrawala, Hussain

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.

Abstract Background Even though obstructive sleep apnea (OSA) is strongly associated with atrial fibrillation (AF), the use of traditional OSA scoring by apnea hypopnea index (AHI) did not result in improved arrhythmia outcomes in recent randomized trials. Longer OSA episodes lead to stronger pro-arrhythmic changes, and whether very long OSA episodes are more prevalent in AF patients remains unknown. Purpose We hypothesized that AF patients with mild-moderate OSA manifest greater percentage of long (>20s), very long (>30s), and extremely long (>40s) OSA episodes, compared to control OSA patients matched to AHI, age and sex. Methods From patients studied with diagnostic polysomnography in our laboratory between 2016 and 2018, we selected 22 patients with mild-moderate untreated OSA of which 11 patients had history of paroxysmal AF and 11 patients did not have any cardiac history. The length, oxygen desaturation, and relationship to neighboring events was manually re-measured in all recorded apnea and hypopnea events. Results In the 22 included patients (age 62.5±9.1 years, AHI 12.8±6.1, 40% female) we recorded 1021 apneas: 508 in the AF group and 513 in the control group. AF patients had longer apneas compared to the patients without AF history (mean length 28.7±11.7s vs. 23.3±9.9s; p<0.0001). The proportion of apneas that were long (>20s), very long (>30s), and extremely long (>40s) was greater in the AF group as compared to the control (p=0.0039, p=0.0215, p=0.0104, respectively; see figure). The acute oxygen saturation drops (>2%) during apneas were comparable between the AF group and control groups (p=0.13), but the long (>20s) apneas were prone to greater oxygen desaturations. Length of Apneas Conclusions While traditional scoring of OSA focuses on episodes lasting >10s, our data newly show that longer durations of OSA events are particularly prevalent in AF patients. These results, combined with recent mechanistic studies showing that longer apneas exert greater pro-arrhythmic effect on atrial conduction, suggest that novel scoring of OSA placing more weight on longer apneas should be explored, especially when screening and titrating OSA therapy in patients at risk of AF.