A Better Predictor of Atrial Fibrillation?

Sleep-related hypoxemia is a better indicator of atrial fibrillation (AF) risk than the commonly used apnea-hypopnea index (AHI), new research suggests.

“Our findings suggest the importance of looking more at hypoxia when doing a sleep study and trying to layer. cardiovascular risk“co-investigator Catherine Heinzinger, DO, of the Cleveland Clinic, Ohio, said Medscape Medical News.

“There have been numerous studies showing that higher AHI, indicating more severe sleep apnea, is associated with atrial fibrillation. But pathologically, it makes much more sense that it would be hypoxia or the gas exchange issues that result from sleep apnea. This would affect cardiovascular system, “Heinzinger said.

The findings were presented at SLEEP 2022, the 36th annual meeting of the Associated Professional Sleep Societies.

Outstanding Driver?

Using data from sleep studies conducted at the Cleveland Clinic, the researchers tested the hypothesis that sleep disorder and, in particular, sleep-related hypoxemia are associated with the development of AF after accounting for confounding factors.

Among 42,057 patients without AF at baseline, 1947 (4.6%) developed AF over the next 5 years.

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

Patients with the highest T90 (11.6%) had a 28% higher risk for incidental AF compared with referral patients with a T90 of less than 0.1% (HR, 1.28; 95% CI, 1.11–1.47).

For every 10-first decrease in minimum oxygen saturation (SaO2), the risk for AF increased by 9% (HR, 1.09; 95% CI, 1.03-1.15); and for every 10-first decrease in average SaO2, the risk for AF increased by 30% (HR, 1.3; 95% CI, 1.18-1.42).

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

The fact that the results were similar across all three hypoxemic measures, T90 and minimum and medium SaO2, shows “great internal consistency,” Heinzinger said.

Although AHI also showed a positive relationship with AF, the size of that association was significantly smaller than the size of the association between the hypoxic measures and AF, she noted.

The findings suggest that sleep-related hypoxemia is the “eminent driver” in the development of AF, Heinzinger said.

“We believe that the mechanisms behind hypoxemia and atrial fibrillation are related to autonomic dysfunction; that is, increased sympathetic activity and oxidative stress on tissues at the cellular level that cause changes in the heart substrate, such as fibrosis, which then leads to arrhythmia. atrial fibrillation, “she added.

‘Convincing’ I observe

Commenting on the findings for Medscape Medical NewsGregory M. Marcus, MD, University of California, San Francisco, noted this however obstructive sleep apnea is now “a well-established risk factor for the development of atrial fibrillation, we still do not understand how or why this happens.”

The finding in this new study that more severe hypoxemia contributes to risk for AF is “particularly compelling” because the AHI in the same cohort showed a much less significant relationship with future AF, said Marcus, who was not involved with the research. .

However, he noted that because this was an observational study, “we need to be careful before concluding causal relationships.”

For example, there is now evidence that sleep disruption itself (as with insomnia), even independent of obstructive sleep apnea, can predict the development of AF, Marcus said.

“Therefore, while this study provides valuable new insights that guarantee future assessments, perhaps hypoxemia is simply a sign or epiphenomenon of some other causal process,” he added.

The study was funded by the Cleveland Clinic Neurological Institute Center for Outcomes Research & Education Pilot Grant and the Neuroscience Transformation Research Development Award. Heinzinger and Marcus reported no related financial relationships.

SLEEP 2022: the 36th Annual Meeting of the Associated Professional Sleep Societies. Summary 0745. To be presented June 8, 2022.

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