The chances of experiencing sudden cardiac arrest (SCA) after sex are slim, but in those rare cases mortality rates are high, reports a study presented this week at the American Heart Association’s Scientific Sessions symposium.

Despite what’s portrayed on television and in movies, SCA triggered by sexual activity is an uncommon plot twist in the real world, senior study author Sumeet Chugh, MD, said in a release from the American College of Cardiology. Previous studies have confirmed sex can trigger non-fatal cardiac events like heart attacks, but Chugh and colleagues designed their study to determine whether or not sexual activity is a risk factor for SCA in particular, since the condition accounts for 350,000 deaths in the U.S. each year.

Chugh and co-authors used the Oregon Sudden Unexpected Death Study to identify 4,557 SCAs in Portland between 2002 and 2015. Details of each case were laid out in the database, which collects specific information for each patient based on emergency medical service reports. The researchers only included cases in which patients were 18 years old or up.

Of the total cohort who suffered SCAs in the 13-year study period, the authors found just 0.7 percent of the pool—34 patients—experienced SCAs related to sex. The patients who did were more likely to be male, middle-aged, black and have a history of cardiovascular disease, according to the ACC. Most were taking heart medication at the time.

What was perhaps most shocking to the researchers, though, was the lack of bystander support in these cases. Despite another partner being present in all sex-linked SCAs, just one-third of those patients received immediate CPR. According to the study, the low bystander CPR rate accounted for less than 20 percent of patients who survived to hospital discharge.

“Even though SCA during sexual activity was witnessed by a partner, bystander CPR was performed in only one-third of the cases,” Chugh said in the release. “These findings highlight the importance of continued efforts to educate the public on the importance of bystander CPR for SCA, irrespective of the circumstance.”

Chugh et al. presented their findings at the Scientific Sessions conference Sunday in Anaheim, California, and their paper was simultaneously published in the Journal of the American College of Cardiology.