Association between Influenza-like illness and acute myocardial infarction patients: A case-control study

Seasonal Influenza can cause cardiovascular complications. Therefore, this study aimed to investigate recent influenza-like illnesses (ILI) in acute myocardial infarction (AMI) patients compared to other hospitalized patients as the control group during the cold season in the north of Iran. This retrospective case-control study included 300 patients (150 AMI patients and 150 controls) aged ≥ 50 years hospitalized for acute myocardial infarction (AMI) or other conditions between September 22, 2019, and March 15, 2020. Patients in each group were frequency-matched for gender and age range. The primary exposure was a recent ILI (fever ≥ 37.8°C, cough, and sore throat) in the past month. The patients’ mean age was 64.42 ± 9.47 years, with a range of 50-94 years. Forty-five (15%) patients had diseases that met the ILI criteria. The AMI group patients significantly reported more ILI than controls (adjusted OR: 3.04, 95% CI: 1.02 to 9.09, p < 0.001). On the other hand, patients who received the influenza vaccine were significantly less likely to have an acute myocardial infarction than those who did not receive the vaccine (adjusted OR: 0.02, 95% CI: 0.001 to 0.38, p = 0.006). In conclusion, the present study demonstrates that ILI can significantly increase the risk of AMI. Also, it was confirmed that Influenza vaccination could significantly reduce the risk of AMI.