In the INTERHEART study, researchers explored the triggering association of acute physical activity and anger or emotional upset with a myocardial infarction (AMI) to quantify the importance of these potential triggers in a large, international population.

INTERHEART was a case-control study of first AMI completed in 262 centers across 52 countries. In this analysis, they included only cases of AMI and used a case-crossover approach to estimate odds ratios for AMI occurring within 1 hour of triggers.

Trained study staff performed a standardized physical examination on participants and administered a structured questionnaire. Participants with AMI (cases) were asked the questions, “Were you engaged in heavy physical exertion?” and “Were you angry or emotionally upset?” in the 1 hour before the onset of symptoms and during the same hour on the previous day.

Control participants were asked, “During the last 24 hours, were you engaged in heavy physical exertion?” and “During the last 24 hours, were you angry or emotionally upset?”

Data were also collected on age, ethnicity, diet, physical activity, tobacco use, education, employment, psychosocial factors, and cardiovascular risk factors. Anthropometric measurements (height, weight, waist, and hip circumference) were measured in a standardized manner.

Medical history (diabetes mellitus, hypertension, angina, stroke, other vascular disease, and depression) and baseline medications were self-reported. Smoking was categorized as never smoking, former smoking, or current smoking. Obesity was defined as body mass index of ≥30 kg/m2.

Countries were grouped into 10 geographical regions: Western Europe, Central and Eastern Europe, Middle East and Egypt, Africa, South Asia, China and Hong Kong, Southeast Asia and Japan, Australia and New Zealand, South America and Mexico, and North America.

Physical activity was categorized as mainly sedentary, mild exercise, or moderate/strenuous activity. Stress was categorized as none or some periods of stress versus several periods or permanent stress. Education was categorized as none, 1 to 8 years, 9 to 12 years, trade school, or college/university.

Of 12,461 cases of AMI, 13.6% (n=1650) engaged in physical activity and 14.4% (n=1752) were angry or emotionally upset in the case period (1 hour before symptom onset).

Physical activity in the case period was associated with increased odds of AMI (odds ratio, 2.31; 99% confidence interval [CI], 1.96–2.72) with a population-attributable risk of 7.7%.

Anger or emotional upset in the case period was associated with increased odds of AMI (odds ratio, 2.44; 99% CI, 2.06–2.89) with a population-attributable risk of 8.5% (99% CI, 7.0–9.6).

There was no effect on modification by geographical region, prior cardiovascular disease, cardiovascular risk factor burden, cardiovascular prevention medications, or time of day or day of onset of AMI. Both physical activity and anger or emotional upset in the case period were associated with a further increase in the odds of AMI.

From the results, it was reported that physical exertion and anger or emotional upset are common in the 1 hour before the onset of symptoms of AMI and that either exposure may act as an external trigger for AMI in all age groups. We report no differences by geographical region, previous cardiovascular disease, cardiovascular prevention medications, cardiovascular risk factors, and INTERHEART risk score.

Circulation. http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.116.023142/-/DC1 and http://dx.doi.org/10.1161/CIRCULATIONAHA.116.023142. 2016;134:1059-1067