[Secondary prevention of coronary artery disease. Flu vaccinations and new evidence of the role of infection in acute coronary syndromes]

Abstract

Recent reports have detected an increase in the number of patients with acute coronary syndromes during the flu season. More recently, case-control studies of patients with prior infarction have shown that flu vaccination significantly reduces the risk of myocardial necrosis and strokes. The World Health Organization recommended flu vaccination for the Southern Hemisphere in the winter of 2001. We evaluated the preventive impact of flu vaccination on subsequent ischemic events in myocardial infarction patients and in subjects undergoing scheduled percutaneous coronary angioplasty. In the first study we included 200 myocardial infarction patients admitted in the first 72 hours and 100 patients scheduled for angioplasty/stent (PCI) without unstable coronary artery disease, prior bypass surgery, angioplasty or tissue necrosis, were included in a prospective, multicenter registry, during the winter season. Infarction patients received standard therapy, and then were randomly allocated in a single-blind manner as a unique intramuscular Influenza vaccination or as controls. Similarly, PCI patients were allocated to either vaccination or control. The first primary outcome -cardiovascular death- occurred within 6 months in 2% of the patients in the vaccinnated group vs 8% of controls (RR: 0.25; 95% CI, 0.07-0.86; p = 0.01). The triple composite end point occurred in 11% of the patients in the vaccinnated group vs 23% of controls (p = 0.009) at 6 months. Although our study is the first to demonstrate lower rates of cardiovascular ischemic events in patients vaccinated against Influenza during the flu season, the modification of flu vaccination recommendations in patients admitted for cardiovascular events merits further study before being considered.