Heart-stopping sex is rare, but when it occurs it usually happens to a man, says one of the first large studies to examine sudden cardiac arrest during or just after sex.
Sex is linked to about 1 in 100 sudden cardiac arrests in men and 1 in 1,000 in women, according to the study presented Sunday at a scientific meeting of the American Heart Association and published in the "Journal of the American College of Cardiology."
"The findings are reassuring," for people with heart disease concerned that sex might be dangerous, said senior author Sumeet Chugh, a cardiologist at Cedars-Sinai Heart Institute in Los Angeles. "Now we can tell them the risk is very low."
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Sudden cardiac arrest occurs when an electrical malfunction causes the heart to stop beating. Most victims die. The medical condition is different from a heart attack, in which blood flow to the heart is cut off. People who have suffered heart attacks or have other heart problems are at increased risk of cardiac arrest.
The new study looked at 4,557 sudden cardiac arrests over several years in Portland, Oregon, and found just 34 happened during sexual intercourse or in the hour afterward. Men suffered two-thirds of all sudden cardiac arrests but at a much higher rate when linked to sex — 32 out of the 34 cases.
"If you ask me why that is, I just don't know," Chugh said. It's possible, he said, that men have more underlying risks or that some took risky medications or supplements that did not show up in the study.
The same disproportionate risk among men was found in earlier studies, including some reviewed in a report published in 2012. That report suggested additional risk factors for men who died during sex: "The majority (75 percent) were having extramarital sexual activity, in most cases with a younger partner in an unfamiliar setting and/or after excessive food and alcohol consumption."
Another finding from the new study: Just one-third of people who collapsed during or after sexual intercourse received CPR "despite the fact that you are usually guaranteed a bystander," in such cases, Chugh said.
CPR, ideally paired with use of an automated external defibrillator and an immediate call to 9-1-1, can significantly increase survival odds, he said. Just 12 percent of patients in the study survived.
The American Heart Association says sex is safe for most people with stabilized heart disease, but patients should talk to their doctors about individual risks. Heart attack survivors and others can reduce risks related to sexual exertion by engaging in regular physical activity, it adds.