Sleep Apnea May Trigger Nighttime Heart Problems

Heart attacks most often occur during the daytime, generally between 6 a.m. and noon. A nighttime heart attack, when the heart should be at rest, means that something unusual has happened, according to Dr. Virend Somers. Dr. Somers, a cardiologist from the Mayo Clinic. is the lead author of a report in the July 29 issue of the Journal of the American College of Cardiology. The study links the nighttime heart attacks with the breathing disorder obstructive sleep apnea.

The link is not fully established, but it seems logical, said Dr. Somers, after he and colleagues have been working for a decade to show that sleep apnea is to blame for nighttime heart attacks and strokes. Their studies looked at the most common form, obstructive sleep apnea, in which the tube carrying air to the lungs collapses periodically, blocking the flow. According to Somers, "About 10 years ago, we showed that obstructive sleep apnea has a powerful effect on the sympathetic nervous system causing an acute increase in adrenaline flow, high blood pressure and lack of oxygen."

Another study showed that sudden death at night is more common for people with sleep apnea. One of the most common causes of sudden death is a heart attack, and in this study, Somers and his colleagues studied the breathing patterns of 92 people admitted to hospital after heart attacks. The vast majority of those who suffered night time heart attacks had undiagnosed sleep apnea. "So, perhaps sleep apnea is acting as a trigger for night-time heart attacks." Somers said. This study is not considered a conclusive study because it was not critically controlled, following people with sleep apnea for years to determine their risk of nighttime heart attacks.

Dr. Allan Pack, director of the sleep center at the University of Pennsylvania, said that several studies have shown a link between sleep apnea and cardiac problems. The largest, done several years ago, followed thousands of individuals, and "It showed that people with sleep apnea who refused treatment had a three- to fourfold increased risk of cardiac events." The new study adds "a relative difference in the time of cardiac events." Pack said, "If someone has a heart attack in the night, you would strongly suspect sleep apnea."

Sleep apnea is characterized by pauses in breathing during sleep, with the episodes occurring repeatedly. The individual with sleep apnea frequently is not aware of any breathing difficulty. The bed partner of the individual will be interrupted by the agitation of the person as they struggle for breath, as well as the fact that most sufferers snore heavily. Symptoms may be present for years without diagnoses. During the time the sufferer may come to regard daytime sleepiness and fatigue as normal conditions unrelated to sleep problems.

If sleep apnea is diagnosed use of a Continuous Positive Air Pressure (CPAP) device keeps airways open by pushing air into the lungs through a face mask. The device is somewhat cumbersome, but it can reduce the risk of future cardiac events. Behavioral interventions, losing weight, stop smoking, avoiding alcohol, and sleeping on your side may also be beneficial to those with sleep apnea.