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Considerable night-to-night variability in sleep-disordered breathing raises atrial fibrillation risk

In the VARI-OSA-AF study, long-term sleep-disordered breathing and simultaneous atrial fibrillation monitoring conferred a relationship between night-to-night variability of sleep-disordered breathing and subsequent risk for atrial fibrillation.

The observational cohort study enrolled 72 patients with dual-chamber pacemakers (MicroPort). Researchers exported atrial fibrillation (AF) and respiratory disturbance index (RDI) data from the pacemakers, with the aim to monitor nightly sleep-disordered breathing (SDB) and daily AF burden. The researchers then used the pacemaker-based Sleep Apnea Monitoring algorithm to assess daily SDB. Mean per-patient follow-up was 21 weeks.

In this study, severe SDB was defined as a mean RDI of at least 20 per hour. Thirty-two percent of patients had a mean RDI of at least 20 per hour. Fifty-six percent of patients had a mean RDI of at least 20 per hour for at least 1 week; of those, 73% exhibited paroxysmal weekly SDB patterns. The average RDI among all patients was 17.9 events per hour.

“Long-term SDB and simultaneous AF monitoring showed, for the first time, that in individual patients, the nights with the highest SDB severity conferred a more than 2.3-fold increased risk of having at least 1 hour of AF the same day vs. nights with the lowest SDB severity. By contrast, there was no increased risk of AF in the 24 hours before the nights with the highest SDB severity,” Dominik Linz, MD, PhD, with the Center for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia, and colleagues wrote in JACC: Clinical Electrophysiology.

Among the individual patients, the nights when patients had the highest RDI conferred a 1.7-fold increased risk for having at least 5 minutes of AF the same day, 2.3-fold increased risk for at least 1 hour of AF and a 10.2-fold increased risk for at least 12 hours compared with the nights when patients had the lowest RDI (P < .001 for all), according to the results.

The researchers reported significant variation in RDI from night to night; the absolute standard deviation was 6.3 events per hour, according to the results.

In other findings, the researchers reported that cumulative AF on any single day of the patients’ follow-up of longer than 5 minutes was observed in 44%, longer than 1 hour in 40% and longer than 12 hours in 15%.

It is estimated that the prevalence of moderate to severe SDB in patients with AF ranges from 21% to 72%, according to background information. The presence of SDB is associated with a number of consequences in this population, including reduced efficacy of catheter-based and pharmacologic antiarrhythmic therapies, the researchers wrote. Technologies in implanted pacemakers — as evaluated in the current study — may provide valuable data on SDB.

“Long-term SDB monitoring demonstrates considerable night-to-night variability in SDB severity, which cannot be detected by one single overnight sleep study. Herein, we provide evidence for a dynamic substrate for AF, where SDB severity on a specific night directly relates to AF risk during the same day,” the researchers wrote. “Instead of the current practice of establishing a categorical diagnosis of SDB from a single overnight sleep study, SDB burden, determined as the proportion of nights with higher RDI, may be a better metric to assess the extent of dynamic SDB-related cardiovascular responses such as daily AF risk and cardiovascular outcomes.” – by Katie Kalvaitis

Disclosures: Linz reports he is on advisory boards of LivaNova/MicroPort and Medtronic, received lecture and/or consultant fees from LivaNova/MicroPort, Medtronic and ResMed, and received funding from Medtronic, ResMed and Sanofi. Please see the study for all other authors’ relevant financial disclosures.