The link between influenza and myocardial infarction: vaccination protects.

The association between influenza and cardiovascular disease has been known since the influenza pandemics of the early years of the last century. This association is more consistent and more lasting in the case of particularly severe infections. Several pathogens, including influenza viruses, can modulate the inflammatory response and influence the biology of atherosclerotic plaque to rupture it and cause a Type 1 myocardial infarction. Clinically relevant viral infections can also exacerbate pre-existing cardiovascular disease and contribute to the development of a Type 2 myocardial infarction through an increase in the metabolic demands of the myocardial tissue for fever and tachycardia and the possible induction of hypoxaemia. Evidence of a relevant protective efficacy of influenza vaccination provides further robust and convincing support for a causal link between influenza and myocardial infarction. Consistent cardiovascular protection linked to influenza vaccination has also been demonstrated in patients with recent myocardial infarction to suggest the possibility that this procedure may become an integral part of in-hospital management of acute coronary syndromes. Despite the solidity of these evidences, acknowledged by the guidelines that recommend influenza vaccination in patients at increased cardiovascular risk, still today an unacceptably high proportion of patients at high cardiovascular risk do not receive flu vaccination. Despite some potential limitations of the current flu vaccination, its advantages in terms of reducing cardiovascular events and related mortality are still such as to justify its wide use, especially, but not limited to, in patients with high cardiovascular risk.