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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.”
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.
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
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.
PracticeUpdate Editorial Team
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...
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