Triggering myocardial infarction by infection: A case-crossover study

Background: Chronic risk factors for myocardial infarction, MI are well described. There is increasing evidence suggesting that infection is associated with an increased risk of MI. We explored the relationship between infection (INF), with and without antibiotic use (AB) over an 8-week period prior to presentation to hospital for a MI. Method: We examined patients presenting with ST-elevation MI or high risk non-ST-elevation MI using a case-crossover design. With this design, the patients function as their own control, enabling the assessment of temporal factors. Patients were interviewed, in hospital, by trained research nurses (2) within 72 h of onset of MI symptoms, via a standardized questionnaire. INF was defined as a temperature >38 °C or skin or respiratory tract infection. Information about AB to treat INF was also elicited and confirmed by GP contact. Results: Amongst 351 MI patients, we found an increased risk associated with INF 0–7 days compared to 7–8 weeks (OR = 7.5, p = 0.002, CI: 1.7–67.6) and AB 0–7 days compared to 7–8 weeks (OR = 3.5, p = 0.03, CI: 1.1–14.6). Conclusion: In this population, infection, with or without antibiotic use appears to precipitate an MI event. The results from this study support previous study findings that infection is a potential inflammatory trigger of MI. Further studies are required to explore the role that infective agents play in the triggering of MI.