Despite what you may have seen on TV, a new study says it's rare for sexual intercourse to trigger sudden cardiac arrest. If it does happen though, you're better off if your partner knows CPR.

While sudden cardiac arrest results in more than 300,000 deaths each year in the United States, fewer than 1% were linked with sexual activity. In fact, only 1 in 100 men and 1 in 1,000 women experience sudden cardiac arrest during sexual activity, according to data published in the Journal of the American College of Cardiology and presented at the American Heart Association Scientific Sessions.

Researchers led by Dr. Sumeet Chugh, associate director of the Cedars-Sinai Heart Institute, analyzed data from the community-based Oregon Sudden Unexpected Death Study. More than 4,500 cases were examined as part of the study, and only 34 cases occurred during or within an hour of engaging in sex. All reported cases were based on emergency medical service reports containing detailed information regarding the cause of the cardiac arrest.

"People will ask their doctors if sex increases their risk of sudden death, and we've never had the answer before because there never was a study," says Dr. Chugh, the study's senior author. "Over the years, we've had a fair bit of data on physical activity and how it's related to sudden cardiac arrest, but no one had looked specifically at sexual activity. The risk is very small."

Sudden cardiac arrest occurs when an electrical impulse goes awry and the heart suddenly stops beating, halting blood flow to the brain and other vital organs. It usually causes death if not treated within minutes.

Patients who experienced sudden cardiac arrest linked to sexual activity had higher rates of ventricular fibrillation—a serious cardiac rhythm disturbance—and tachycardia, a higher-than-normal heart rate. The majority of cases were men with a previous history of heart disease.

Though all of these medical emergencies were witnessed by another person, a surprisingly small number of the patients received CPR. CPR can keep the blood circulating—and the victim alive—until first responders arrive to take over. It's a life-saving skill worth learning.

"Even though sudden cardiac arrest during sexual activity was witnessed by a partner, bystander CPR was performed only in one-third of the cases," Dr. Chugh says. "This highlights the importance of continued efforts to educate the public on the importance of CPR, no matter the circumstance."