Meta-analysis of possible external triggers of acute myocardial infarction

Background: Although it is well known that the acute myocardial infarction can be triggered by events such as physical activity, emotional stress, sexual activity or eating, the observed frequencies of these events preceding the onset of myocardial infarction vary between published reports. Methods: A meta-analysis of 17 seldom population-based studies that included data on frequency of external triggers or onsets during sleep was performed. In each analysis, the data were combined only from the studies reporting on a particular trigger. Results: Of the 10 519 patients, heavy physical activity was recorded before the onset of myocardial infarction in 6.1%, whereas mild-to-moderate physical activity was recorded in 28.6% of 7517 patients. Eating preceded the onset in 8.2% of 4785 patients, various kinds of emotional stress in 6.8% of 2565 (particularly anger in 2.1% of 2283), meteorologic stress in 3.7% of 3371, and sexual activity in 1.1% of 3406 patients. Out of 11 778 patients, 20.7% had infarction onset during sleep. Triggers in general (OR=1.45, 95%CI=1.21–1.76; p<0.0001), heavy physical activity (OR=6.21, 95%CI=3.77–10.23; p<0.0001) and eating (OR=1.70, 95%CI=1.14–2.53; p=0.0008) were more likely to precede the infarction onset in men while women were more likely to report emotional stress (OR=0.66, 95%CI=0.50–0.86; p=0.002). Conclusions: The present meta-analysis defines the occurrence of possible external triggers before the onset of myocardial infarction in general population, but their actual contribution to the very onset is somewhat less frequent. Future investigation should identify other eventual triggers unrecognized as yet, asses the risk of triggering myocardial infarction among patients with defined levels of ischemic heart disease or plaque vulnerability, and further elucidate the pathophysiologic mechanisms of gender differences and beneficial effect of habitual physical activity.