Premature ventricular contractions are common in the significant proportion of patients with coronary heart disease who also have sleep apnea, according to a presentation at the annual meeting of the American Heart Association.

Researchers evaluated 134 patients with coronary heart disease who had not been diagnosed with a sleep disorder. Among patients who had ventricular premature contractions, more than 40 percent also had severe sleep apnea.

“The real worry is that benign arrhythmia can be a harbinger of a much more serious ? and lethal ? heart rhythm disorder,” said principal investigator Raj Bhalodia, MD, of Saint Louis University School of Medicine. “While most people with the mild version of arrhythmia will be just fine, in some people, it’s possible it can worsen during the night and lead to sudden death.”

The researchers found that sleep apnea seemed to exacerbate premature ventricular contractions, especially during the dream stage, or rapid eye movement (REM) stage, of sleep.

“There’s less oxygen being pumped through the body in REM than in other stages of sleep, and this can bring on arrhythmia,” Bhalodia said. “The brain is less alert, which is why people don’t simply wake up to solve the problem.”

Bhalodia was interested in studying the link between the two disorders because previous research showed that people with sleep apnea who died suddenly from arrhythmia tended to die more during sleep ? unlike other heart disease patients whose sudden deaths tend to happen the most often in the few hours after waking up.