Acute myocardial infarction triggered by physical exertion: a systematic review and meta-analysis.

AIMS: While regular physical activity has clear benefits to cardiovascular health, physical exertion can trigger acute myocardial infarction (AMI). We aimed to estimate how many AMIs may be attributed to bouts of physical exertion, and to explore possible modifiers of this association. METHODS: MEDLINE, ISI Web of Science, and Scopus databases were searched for case-crossover studies reporting the relative risk (RR) of exertion-related AMI and exposure prevalence in the control periods. We used random-effects model to pool the RR estimates, and mixed-effects model and random-effects meta-regression for subgroup analyses, and estimated the population attributable fraction (PAF) at population level and in different subgroups. The study met the Preferred Reporting Items for Systematic Reviews and Meta-Analyses requirements. RESULTS: Twelve studies including 19 891 AMI patients met the criteria for inclusion. There was a strong overall association between episodic physical exertion and AMI (RR=3.46; 95% confidence interval [CI], 3.16-3.78). The total PAF was 10.6% (95% CI, 9.44-11.83). For each additional year of age, the RR of exertion-related AMI increased by approximately 3%, but the PAF decreased by 2%. For each additional time of habitual activity per week the RR of exertion-related AMI decreased by approximately 43%. The impact was greater among those engaged in physical exertion one to three times a week (≥20% of cases), and among those who did not take compared to those who took ß-blocker (p=0.049). CONCLUSIONS: Every tenth AMI may be assigned to physical exertion. The impact was more pronounced among younger patients, those exposed to exertion one to three times a week, and those not-taking ß-blockers.