Exercise, diet and dental work as precipitants of myocardial infarctions: A case-crossover study

Purpose: Although chronic risk factors for myocardial infarction (MI) are well established, acute risk factors such as physical exercise (EX), fast food (FF) and dental work (DW) as triggers for MI events are less clearly defined. This study's aim was to explore the potential association of these precipitants in the 8 weeks (wk) prior to presentation to hospital for an MI. Methods: The Precipitants study utilised a case-crossover design enrolling 351 patients presenting with either ST-elevation or high risk NSTEMI. The design allowed patient's to function as their own control, enabling assessment of these acute triggers. Standardised patient questionnaires within 72 hours of onset of MI symptoms were completed by trained research nurses (2). Definitions included: EX, exercise resulting in deep breathing, panting and sweating; FF, fried chicken, pizza or hamburger purchased from a registered fast food company; and DW, involving local anaesthesia. Data were collected prior to the onset of MI; FF and EX data at 4 hourly intervals for 48 hours (hrs), then 24 hourly until 96 hrs and DW at weekly intervals over an 8 wk period. Results: Amongst 351 MI patients, we found positive associations with; FF ingested between 0 and 24 hrs compared to 72–96 hrs (OR = 5.67, p = 0.003, CI: 1.6–30.2), EX 0–4 hrs compared to 24–28 hrs (OR = 2.2, p = 0.001, CI: 1.3–3.5), and DW 0–7 wks compared to 7–8 wks (OR = 26, p < 0.001, CI: 4.3–1066). Conclusion: Amongst patients who have had an MI in this population, the acute risk factors of moderate-vigorous exercise, fast food, and dental work appear to precipitate the clinical event of an MI.