Having sex with someone who isn't your significant other could literally break your heart, according to British scientists.

Researchers at St. Thomas's Hospital in London say people having affairs or one-night stands are more prone to heart attacks than people in long-term relationships, reports BBC News Online. Their study found that 75 percent of cases of death during sexual activity involved extra-marital intercourse.

And the risk of death during sex rose even further when there was a significant difference in age between the partners, the researchers found.

The good news is that only 1 percent of all heart attacks are triggered by sexual activity, the BBC report notes.