Over 650 people admitted to hospital with their first heart attack between 1993 and 1994 took part in the study. Over three quarters were men. Half were aged between 45 and 60. And around three quarters were married.
They were interviewed shortly after recovery about any symptoms and the circumstances, including sexual activity, during the four days leading up to their heart attack. They were also asked general questions about the frequency and timing of sex. Physical fitness was assessed by the frequency and intensity of regular exercise.
Most of the interviewees were sexually active. Of all those interviewed, almost four out of 10 had had premonitory symptoms, but none had had sex in the four hours before the heart attack. Of the remainder, just five had had sex two hours before their attack.
The researchers calculated that those having sex were twice as likely to have a heart attack an hour later as those who had not had sex. And those who took little or no exercise were four times as likely to have a heart attack an hour later. Alarming as this might sound, the researchers say that the absolute risk per hour is very low, added to which the frequency of sex tended to be low. They therefore conclude that sex once a week poses only minimal risk, and that doctors should encourage heart patients not to abstain from sex for fear of triggering a heart attack.
[Sexual activity as a trigger of myocardial infarction. A case-crossover analysis in the Stockholm Heart Epidemiology Programme (SHEEP) 2001;86:387-90]
Journal
Heart