Practice Update: Cardiology

CONFERENCE COVERAGE

ATS 2017

12

Sleep apneamay increase risk of atrial fibrillation Obstructive sleep apnea may raise the risk of developing atrial fibrillation, reports a retrospective clinical cohort study. T etyana Kendzerska, MD, PhD, of the University of Ottawa Canada, explained that obstructive sleep

apnea is characterized by repetitive epi- sodes of shallow or paused breathing during sleep that lead to a drop in blood oxygen level and disrupted sleep. “There is strong biologic plausibility that obstructive sleep apnea may increase the risk of developing atrial fibrillation through a number of mechanisms,” she said. “Evidence is emerging from ani- mals and smaller studies in humans that obstructive sleep apnea may increase the risk of developing atrial fibrillation through oxidative stress, increased sympathetic activity, metabolic abnormalities, endothe- lial dysfunction, and cardiac stretch from intrathoracic pressure swings.”

needed to confirm this finding and under- stand the potential mechanisms.” Drs Kendzerska and Leung did not include hypertension in their primary analysis. “Hypertension may be the causal path- way between obstructive sleep apnea and atrial fibrillation, so including it might have diminished the association between obstructive sleep apnea and atrial fibrilla- tion,” Dr Kendzerska said. She added, “In our secondary analysis, however, we did control for hypertension, and the association between oxygen desaturation and atrial fibrillation remained significant, suggesting that obstructive sleep apnea can cause atrial fibrillation directly without the intermediate step of developing hypertension.” Limitations of the study included not hav- ing data on adherence to continuous positive air pressure for obstructive sleep and whether or not a participant’s hyper- tension was being treated. Drs Leung and Kendzerska are analyzing data connect- ing obstructive sleep apnea to emergency department visits for atrial fibrillation. Dr Kendzerska concluded that this large clinical cohort with suspected obstructive sleep apnea free of arrhythmias at baseline, sleep time spent with oxygen desaturation <90% was a significant independent pre- dictor of incident hospitalization for atrial fibrillation over the next 10 years. The findings support a causal relationship between obstructive sleep apnea, chronic nocturnal hypoxemia, and new-onset atrial fibrillation.

Other studies have shown that women with sleep apnea are at higher risk of cardiovascular consequences, including mortality. Greater endothelial dysfunction, higher propensity to develop pulmonary and systemic hypertension, and impaired heart rate responses to autonomic challenges in women with obstructive sleep apnea may explain these findings...

Participants hospitalized for atrial fibrillation in follow-up were more likely to be older, male, current or ex-smokers, and suffered a higher level of comorbidities, and more severe obstructive sleep apnea as meas- ured by apnea-hypopnea index or degree of nocturnal oxygen desaturation. In univariate analyses, apnea-hypopnea index >30 vs ≤30 events per hour and ≥10 vs <10 minutes of sleep time spent with oxygen desaturation <90% were significant predic- tors of hospitalization for atrial fibrillation: HR 1.92, 95% CI 1.41–2.62 and HR 2.81, 95% CI2.07–3.81, respectively. After controlling for known risk factors, sleep time spent with oxygen hazard ratio 1.64, 95% confidence interval 1.18–2.28. This associationwas signifi- cantly stronger inwomen thanmen (P = 0.02). Dr Leung said, “Other studies have shown that women with sleep apnea are at higher risk of cardiovascular consequences, includ- ingmortality. Greater endothelial dysfunction, higher propensity to develop pulmonary and systemic hypertension, and impaired heart rate responses to autonomic challenges in women with obstructive sleep apnea may explain these findings, but further studies are

Dr Kendzerska and Richard S. Leung, MD, PhD, of the University of Toronto, reviewed the records of 8256 adults (aver- age age 47 years) referred with suspected obstructive sleep apnea, but free of phy- sician-diagnosed heart rate abnormalities, including atrial fibrillation at baseline. Par- ticipants were followed for up to 13 years. During that time, 173 developed atrial fibril- lation that resulted in hospitalization. They controlled for known risk factors such as age, sex, smoking status, alcohol dependency/intoxication, prior congestive heart failure, chronic obstructive pulmonary disease, and pulmonary embolism/infarc- tion. Cox regression analysis was used to investigate the longitudinal association between obstructive sleep apnea and hos- pitalization for atrial fibrillation. A total of 8256 subjects were analyzed. Median age was 47 years, 62% were men, the median apnea-hypopnea index was 15 events per hour, and 28% were apnea-hypopnea index >30. Over a median follow-up duration of 10 (interquartile range 7–13 years), 173 participants (2.1%) were hospitalized for atrial fibrillation.

PracticeUpdate Editorial Team

PRACTICEUPDATE CARDIOLOGY