Influenza vaccination: a one-shot deal to reduce cardiovascular events.

Abstract

This editorial refers to ‘Influenza vaccination and risk of hospitalization in patients with heart failure: a self-controlled case series study’, by H. Mohseni et al. doi: 10.1093/eurheartj/ehw411. Influenza contributes to significant morbidity and mortality across the globe every year. The estimated number of hospitalizations attributable to influenza infection are grossly underestimated among patients with cardiovascular (CV) disease, in whom a severe upper respiratory infection can initiate a cascade of physiological events that ultimately lead to acute worsening or exacerbation of underlying heart disease. Patients with heart failure in particular are at a high risk for influenza-related complications,1 including hospitalizations, which occur more frequently during the winter months, often in conjunction with influenza infection.2 A number of mechanisms support a causal association between influenza infection and CV events ( Figure 1 ). Influenza infection can result in increased metabolic demand, adrenergic surge, endothelial dysfunction, hypercoagulability, and hypoxia.3 Systemic immune stimulation and inflammation in the setting of influenza infection can trigger acute plaque rupture. Influenza predisposes patients to develop other infections such as pneumonia, which may itself be associated with increased CV risk due to prolonged elevation in cytokine levels and a procoagulant state.4–6 Moreover, influenza is known to cause myocardial depression directly,7 possibly mediated through increases in proinflammatory cytokines,8,9 and histological evidence of myocardial injury, myocarditis, and myocyte necrosis has been demonstrated from patients following influenza-related deaths.10 Figure 1 Influenza infection increases the risk for acute cardiovascular events (myocardial infarction and heart failure exacerbations) through several mechanisms involving pro-inflammatory mediators, neurohormonal activation, and activation of the coagulation cascade. Influenza vaccination has been accepted as an effective, well-established strategy to reduce influenza-related illness, and this potential benefit in high-risk …