Influenza and coronary artery disease: exploring a clinical association with myocardial infarction and analyzing the utility of vaccination in prevention of myocardial infarction.

Both coronary artery disease and influenza outbreaks contribute significantly to worldwide morbidity and mortality. An increasing number of epidemiologic studies have concluded that a temporal association exists between acute viral illnesses and myocardial infarction. Viral illnesses such as influenza can cause or exacerbate coronary atherosclerosis by activating inflammatory pathways. Data from a large case-controlled trial and two randomized controlled trials suggest that influenza vaccination in patients with coronary artery disease may lead to a decrease in incidence, morbidity, and mortality from acute myocardial infarction. A meta-analysis of the two randomized controlled trials for cardiovascular death demonstrated a pooled relative risk of 0.39 (95% confidence interval, 0.20-0.77) for patients who received the influenza vaccine compared with placebo.