Acute myocardial infarction and influenza: a meta-analysis of case–control studies

Abstract

ObjectiveAcute myocardial infarction (AMI) is the leading cause of death and disability globally. There is increasing evidence from observational studies that influenza infection is associated with AMI. In patients with known coronary disease, influenza vaccination is associated with a lower risk of cardiovascular events. However, the effect of influenza vaccination on incident AMI across the entire population is less well established.MethodThe purpose of our systematic review of case–control studies is twofold: (1) to estimate the association between influenza infection and AMI and (2) to estimate the association between influenza vaccination and AMI. Cases included those conducted with first-time AMI or any AMI cases. Studies were appraised for quality and meta-analyses using random effects models for the influenza exposures of infection, and vaccination were conducted.Results16 studies (8 on influenza vaccination, 10 on influenza infection and AMI) met the eligibility criteria, and were included in the review and meta-analysis. Recent influenza infection, influenza-like illness or respiratory tract infection was significantly more likely in AMI cases, with a pooled OR 2.01 (95% CI 1.47 to 2.76). Influenza vaccination was significantly associated with AMI, with a pooled OR of 0.71 (95% CI 0.56 to 0.91), equating to an estimated vaccine effectiveness of 29% (95% CI 9% to 44%) against AMI.ConclusionsOur meta-analysis of case–control studies found a significant association between recent respiratory infection and AMI. The estimated vaccine effectiveness against AMI was comparable with the efficacy of currently accepted therapies for secondary prevention of AMI from clinical trial data. A large-scale randomised controlled trial is needed to provide robust evidence of the protective effect of influenza vaccination on AMI, including as primary prevention.

If There were a Vaccine Against Acute Myocardial infarction, Would You Use it?

“…A number of studies show that influenza is associated with AMI [4][5][6][7]. In a meta-analysis of available case-control studies, we showed that influenza infection doubles the risk of AMI [4].…”

“…There is, in fact a large body of evidence from both randomized controlled clinical trial (RCT) and observational studies which suggest that influenza vaccine protects against AMI [4]. We were the first to calculate vaccine effectiveness against AMI and found that influenza vaccine effectiveness was 45% against AMI [5].…”

“…In a meta-analysis of available case-control studies, we showed that influenza infection doubles the risk of AMI [4]. In a prospective study, we tested patients admitted with AMI for influenza and found that almost 10% of AMI patients had undiagnosed, unrecognized influenza infection as an antecedent event [5].…”

“…We were the first to calculate vaccine effectiveness against AMI and found that influenza vaccine effectiveness was 45% against AMI [5]. The pooled vaccine effectiveness against AMI calculated from all available studies is 29% [4]. From observational studies, it is estimated that influenza vaccine could provide vaccine effectiveness of 15-45% against MI [3,11].…”

Influenza Vaccination for Secondary Prevention of Cardiovascular Events: A Systematic Review

“…8 and the highest risk is among those with established CVD. 9 The mechanism by which influenza increases the risk of CV events is unclear, but may be related to triggering of rupture of vulnerable atherosclerotic plaques.…”