A heart attack trigger is a factor, which explains why a heart attack occurs on a particular day or time. It is the final straw that triggers the attack and is distinct from the underlying cause, which may be a combination of smoking, poor diet, lack of exercise or being overweight.

According to the new ranking of these triggers, cocaine use increases the risk 23-fold, and a cup of coffee raises it 50 per cent. Some triggers lead to a big increase in risk – limited exposure reduces it. As relatively few people take cocaine, despite the high risk to individual users, the drug triggers less than 1 per cent of all heart attacks.

Coffee is widely drunk, so despite the relatively low risk to coffee drinkers, the beverage triggers one in 20 heart attacks. More than 2 per cent of heart attacks occur during or after sex (the exertion which triggers it). Professor David Spiegel halter at Cambridge University noted that if everyone stopped having sex, heart attacks could be reduced, but that is unlikely to be a popular public health message.