One of the late-breaking trials presented during the virtual European Society of Cardiology (ESC) Congress 2021 held in late August was the IAMI trial, which was simultaneously published in Circulation. The Influenza Vaccination After Myocardial Infarction (IAMI) study was an investigator-initiated, randomized, double-blind trial to compare inactivated influenza vaccine with saline placebo administered shortly after myocardial infarction (MI) (99.7% of patients) or high-risk stable coronary heart disease (0.3%). The primary endpoint was the composite of all-cause death, MI, or stent thrombosis at 12 months.
Due to the Covid-19 pandemic, the data safety and monitoring board decided to halt the trial prematurely after only 2571 participants were randomized at 30 centers across eight countries; 1290 were assigned to influenza vaccine and 1281 to placebo. Over the 12-month follow-up, the primary outcome occurred in 67 participants (5.3%) assigned influenza vaccine and 91 participants (7.2%) assigned placebo (hazard ratio, 0.72; 95% confidence interval, 0.52 to 0.99; P=0.040). Rates of all-cause death were 2.9% and 4.9% (hazard ratio, 0.59; 0.39 to 0.89; P=0.010), of cardiovascular death 2.7% and 4.5%, (hazard ratio, 0.59; 0.39 to 0.90; P=0.014), and of MI 2.0% and 2.4% (hazard ratio, 0.86; 0.50 to 1.46, P=0.57) in the influenza vaccine and placebo groups, respectively.
Despite the reduced statistical power, these findings suggest that the vaccine against seasonal influenza, available in any given year, may be one of the better in-hospital secondary-prevention measures. As of today, influenza vaccination boasts a class I, level of evidence B recommendation in the current guidelines. Nevertheless, these guidelines are frequently not followed.
Reference: https://www.ahajournals.org/doi/abs/10.1161/CIRCULATIONAHA.121.057042
