Researchers have linked severe obstructive sleep apnea to increased risk of subclinical myocardial injury - an early sign of heart damage. This is according to a study published in the American Journal of Respiratory and Critical Care Medicine.
According to the researchers from Brigham and Women's Hospital in Boston, previous studies have shown obstructive sleep apnea (OSA) - interrupted breathing during sleep - to be linked with increased prevalence of cardiovascular disease.
But they note that this is the first study to independently link OSA severity to early heart damage that could potentially cause heart disease and failure.
To reach their findings, the research team analyzed 1,645 participants who were middle aged and older from the Atherosclerosis Risk in Communities and the Sleep Health Study. All participants were free of heart disease and heart failure at the baseline of the study.
While at home, the participants underwent one overnight polysomnography - a test that monitors a person's sleep patterns. Using a respiratory disturbance index, the researchers categorized the patients' severity of OSA as none, mild, moderate or severe.
Participants also had blood samples taken, and they were followed-up for a median of 21.4 years. During this time, there were 222 deaths, 212 patients experienced coronary heart disease events, and 122 participants experienced heart failure.
OSA linked to increased hs-TnT levels
According to the researchers, both coronary heart disease and heart failure can be predicted by increased levels of high sensitivity troponin T (hs-TnT).
Results of the study revealed that each OSA group showed significantly increased hs-TnT levels, with the highest levels linked to the group with severe OSA.
Dr. Amil M. Shah, of Brigham and Women's Hospital and study author, explains:
"Although OSA is associated with increased cardiovascular risk, a causal association has been hard to establish because of the association of OSA with other risk factors.
In our study, we were able to demonstrate that greater OSA severity is independently associated with higher hs-TnT levels, suggesting a role for subclinical myocardial injury in the relationship between OSA and heart failure."
Monitoring of hs-TnT levels in OSA patients 'beneficial'
Although the study authors note that their findings are limited by the small number of study participants, they say their findings suggest that monitoring hs-TnT levels in patients with OSA and using this as a marker would be beneficial.
"Our results suggest a relationship between subclinical myocardial injury and the increased cardiovascular risk seen in patients with OSA," Dr. Shah adds.
"Monitoring of hs-TnT levels in these patients may have prognostic value, particularly in patients with severe OSA."
Medical News Today recently reported on a study suggesting that continuous positive airway pressure (CPAP) therapy - used to treat sleep apnea - could help patients appear more alert and youthful.