Sex is a “recognised trigger” for sudden cardiac arrest (SCA), which causes 300,000 deaths a year in the United States, but the overall rates are low, the report in the Journal of the American College of Cardiology says.

The doctors behind the paper stressed the importance of public education on CPR “irrespective of circumstance”, after their analysis found just one third of these cases saw resuscitation attempted despite their partner being present.

Researchers from the Cedars-Sinai Medical Centre Heart Institute analysed the cause of 4,525 detailed records of fatal cardiac arrest, and found just 34 (0.7 per cent) were as a result of sex.

The data, recorded from paramedic notes as part of a long-running study on sudden unexpected deaths found more than half of these happened (55 per cent) during sex, while the rest occurred within 15 minutes.

Men made up the vast majority of the sex-triggered deaths, 32 out of 34, and this means in men, one per cent of all sudden heart attack deaths was sex related, compared with 0.1 per cent in women.

It also found that sudden fatal heart attacks among people with a pre-existing heart condition were not significantly more likely to be triggered by sex.

The letter said: “The absolute risk of sex-SCA appears to be extremely low, even among subjects with clinical heart disease that have a prevalence of 7 per cent to 10 per cent in the community”.

But it can’t give a more detailed risk analysis on how likely sex is to trigger a heart attack compared with resting or other activity without knowing how frequently these people were having sex.

There is another lesson though; survival rates after a heart attack are much higher where chest compressions and CPR are started while waiting for an ambulance.

And while all the sex-triggered deaths had a partner present, CPR was only started in a third (32 per cent) of cases.

This was slightly higher than the 27 per cent of non-sex triggered heart attacks, the difference was not statistically significant and those individuals might have died alone.

Dr Sumeet Chugh, senior study author and associate director of the Cedars-Sinai Heart Institute said: “Even though SCA during sexual activity was witnessed by a partner, bystander CPR was performed in only one-third of the cases.

“These findings highlight the importance of continued efforts to educate the public on the importance of bystander CPR for SCA, irrespective of the circumstance.”

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