Influenza Vaccination for Cardiovascular Prevention: Further Insights from the IAMI Trial and an Updated Meta-analysis

PURPOSE OF REVIEW: Influenza infection is a significant, well-established cause of cardiovascular disease (CVD) and CV mortality. Influenza vaccination has been shown to reduce major adverse cardiovascular events (MACE) and CV mortality. Therefore, major society guidelines have given a strong recommendation for its use in patients with established CVD or high risk for CVD. Nevertheless, influenza vaccination remains underutilized. Historically, influenza vaccination is administered to stable outpatients. Until recently, the safety and efficacy of influenza vaccination among patients with acute myocardial infarction (MI) had not been established. RECENT FINDINGS: The recently published Influenza Vaccination after Myocardial Infarction (IAMI) trial showed that influenza vaccination within 72 h of hospitalization for MI led to a significant 28% reduction in MACE and a 41% reduction in CV mortality, without any excess in serious adverse events. Additionally, we newly performed an updated meta-analysis of randomized clinical trials (RCTs) including IAMI and the recent Influenza Vaccine to Prevent Adverse Vascular Events (IVVE) trial. In pooled analysis of 8 RCTs with a total of 14,420 patients, influenza vaccine, as compared with control/placebo, was associated with significantly lower risk of MACE at follow-up [RR 0.75 (95%CI 0.57–0.97), I(2) 56%]. SUMMARY: The recent IAMI trial showed that influenza vaccination in patients with recent MI is safe and efficacious at reducing CV morbidity and mortality. Our updated meta-analysis confirms a 25% reduction in MACE. The influenza vaccine should be strongly encouraged in all patients with CVD and incorporated as an essential facet of post-MI care and secondary CVD prevention.