Not only will treating sleep apnea improve sleep, it may also resolve future heart failure by reversing structural and functional heart impairments associated with the sleep disorder, according to a new study.

Researchers discovered that moderate to severe obstructive sleep apnea patients had significantly larger left ventricles and worse filling and emptying parameters, effects similar to hypertension, compared to people without the sleep condition.

Dr. Gregory Lip of the University of Birmingham, England, and his team found that some of the heart changes associated with sleep disorder included increased mass, thickening of the heart wall and reduced pumping ability.

However, after six months of continuous positive airway pressure treatment, heart irregularities seen in sleep apnea patients improved or returned to “near-normal measurements,” the scientists reported in study published in the journal Circulation: Heart Failure.

"This may imply that obstructive sleep apnea could be crucial in development of left ventricular diastolic dysfunction, which may lead to heart failure and increased mortality if left untreated," Lip and his team concluded.

The study compared 40 patients with moderate to severe obstructive sleep apnea to 40 people with high blood pressure and 40 healthy people. 

Using 2D and 3D echocardiograms and Doppler imaging of heart muscle tissue, before and after 26 weeks of sleep apnea treatment, researchers found that before treatment the abnormal heart structure and function changes seen in sleep apnea patients resembled typical changed associated with people with chronic high blood pressure, even though sleep patients only had moderately elevated blood pressure.

While previous studies have suggested that obstructive sleep apnea contributes to the worsening of structural and performance changes in the left ventricle and can lead to heart failure, the latest study, which had better defined and controlled patient groups and used more advanced echocardiograms and Doppler imaging, confirmed past findings.

Researchers noted that there were some limitations to the study and that apnea patients typically have a higher body mass index, and a larger randomized trial should clarify the findings. 

Experts estimate that more than 18 million Americans have some form of sleep apnea, according to estimates from The National Sleep Foundation.

"Obstructive sleep apnea patients may have cardiac abnormalities that often are undetected, but will improve with continuous positive airway pressure," Lip said in a statement released on Tuesday. "Patients also need to understand that obstructive sleep apnea is not a benign disorder, but that their risk of heart problems can be easily treated with continuous positive airway pressure."

Researchers recommend doctors to ask patients or partners of patients with hypertension and those with abnormal echocardiograms about snoring and other signs of sleep apnea.