Best prediction for atrial fibrillation?

New research suggests that sleep-related hypoxia is a better predictor of atrial fibrillation (AF) risk than the commonly used apnea and dyspnea (AHI).

“Our findings suggest that it is important to consider hypoxia more when performing a polysomnogram and attempting to classify cardiovascular risk,” said co-author Katherine Heinzinger of the Cleveland Clinic, Ohio. Medscape Medical News.

“There have been multiple studies showing that a high AHI level, which indicates acute sleep apnea, is associated with atrial fibrillation. But pathologically, it makes sense that hypoxia or gas exchange problems as a result of sleep apnea would affect the heart system. and blood vessels,” Heinzinger said.

The results were presented at SLEEP 2022, the 36th annual meeting of the sleep-related professional societies.

Notable motives?

Drawing on data from sleep studies conducted at the Cleveland Clinic, researchers tested the hypothesis that disturbed breathing during sleep and, in particular, sleep-related hypoxia are associated with the development of atrial fibrillation after accounting for confounding factors.

Of the 42,057 patients without atrial fibrillation at baseline, 1947 (4.6%) developed atrial fibrillation over the following 5 years.

In a multivariate model, for every 10 units increase in the percentage of sleep time with oxygen saturation less than 90% (T90), ICD increased by 6% (hazard ratio). [HR], 1.06; 95% CI, 1.04-1.08).

Patients with the highest T90 (11.6%) had a 28% greater risk of developing atrial fibrillation than the reference patients with T90 lower than 0.1% (HR, 1.28; 95% CI, 1.11–1.47).

For every 10 units of reduction in minimum oxygen saturation (SaO2), the risk of developing atrial fibrillation was increased by 9% (heart rate, 1.09; 95% confidence interval, 1.03–1.15); And for every 10 units decreased in mean SaO2, the risk of developing atrial fibrillation was increased by 30% (HR, 1.3; 95% CI, 1.18–1.42).

In contrast, for every 10-unit increase in AHI, the risk of developing atrial fibrillation increased by only 2% (HR, 1.02; 95% CI, 1.00–1.03).

Heinzinger said that the fact that the results were similar on all three measures of hypoxia, T90, minimum and mean SaO2, shows “significant internal consistency.”

Although the AHI also showed a positive association with atrial fibrillation, the magnitude of this association was much smaller than the magnitude of the association between measures of hypoxia and atrial fibrillation.

The findings suggest that sleep-related hypoxia is the “prominent driver” in the development of atrial fibrillation, Heinsinger said.

“We believe the mechanisms underlying hypoxia and atrial fibrillation are related to autonomic dysfunction; i.e. elevated sympathetic activity and oxidative stress on tissues at the cellular level that cause changes in the cardiac substrate, such as fibrosis, which then lead to arrhythmias,” she added. atrial “.

‘compelling’ Observation

Comment on the results for Medscape Medical NewsMarcus, MD, University of California, San Francisco, notes that although obstructive sleep apnea is now “a well-established risk factor for developing atrial fibrillation, we still don’t understand how or why this happens.”

Marcus, who was not involved in the research, said the finding in this new study that severe hypoxia contributes to atrial fibrillation risk is “particularly compelling” given that AHI in the same group showed a much less significant association with atrial fibrillation in the future.

However, he noted, since this was an observational study, “we need to exercise caution before inferring causal relationships.”

For example, there is now evidence that the same sleep disturbance (eg insomnia), independent of obstructive sleep apnea, can predict the development of atrial fibrillation.

“Therefore, while this study provides valuable new insights that require future evaluations, it is possible that hypoxia is only a sign or secondary phenomenon of some other causal process,” he added.

The study was funded by The Cleveland Clinic Neurological Institute Experimental Grant for Outcomes Research and Education and the Transformative Research Resource Development Award in Neuroscience. Heinzinger and Marcus did not report any relevant financial relationships.

SLEEP 2022: The 36th Annual Meeting of the Professional Societies Affiliated with Sleep. Abstract 0745. Submitted on 8 June 2022.

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