Triggering a heart attack

Headlines such as “Shopkeeper dies while chasing thieves” and the ever increasing volume of letters from solicitors to cardiologists testify to the fact that the press and public are convinced that heart attacks are triggered by events. For bereaved relatives, sadness and grief may turn to loneliness and bitterness, and increasingly today to a desire to blame something or someone. The sympathetic solicitor in his office in the hospital foyer lends a willing ear and seeks expert advice. Employers and insurers also want an answer to the question of what triggers a heart attack. The suspicion that vigorous physical effort might provoke myocardial infarction was raised some 60 years ago.1 Emotional distress has likewise been incriminated.2 More recent studies have corroborated these findings. The MILIS (Multicenter Investigation of Limitation of Infarct Size) investigators, for example, found that antecedent physical activity was present in 14.1% of 849 cases and emotional upset in 18.4%.3 One American4 and one German study,5 using the novel epidemiological method known as case crossover, have suggested respectively a sixfold and twofold increase in risk of myocardial infarction in the hour after heavy physical exertion such as slow jogging, shovelling snow, swimming, pushing a lawnmower, or heavy gardening. The German study suggested further that there was an increased risk in the hours after waking or emotional upset.5 The suspicion that ventricular fibrillation and sudden cardiac death also occur more often than would be expected by chance during vigorous physical effort enjoys support from exercise testing laboratories and elsewhere.6 Only one small and rather overlooked …