Influenza Vaccination as Prevention Therapy for Stable Coronary Artery Disease and Acute Coronary Syndrome: A Meta-Analysis of Randomized Trials.

BACKGROUND:Influenza can cause a significant burden on patients with coronary artery disease. This meta-analysis assessed the effectiveness of influenza vaccination in patients with acute coronary syndrome and stable coronary artery disease. METHODS:We searched the Cochrane Controlled Register of Trials (CENTRAL), Embase, MEDLINE, www. CLINICALTRIALS:gov, and the World Health Organization International Clinical Trials Registry Platform from inception to September 2021. Estimates were summarized using the Mantel-Haenzel method and a random-effects model. To assess heterogeneity the I² statistic was used. RESULTS:Five randomized trials, comprising 4187 patients, were included, 2 of which included patients with acute coronary syndrome and 3 that included patients with stable coronary artery disease and acute coronary syndrome. Influenza vaccination significantly reduced the risk for all-cause mortality (relative risk [RR] = 0.56; 95% confidence interval [CI], 0.38-0.84), cardiovascular mortality (RR = 0.54; 95% CI, 0.37-0.80), major acute cardiovascular events (RR = 0.66; 95% CI, 0.49-0.88), and acute coronary syndrome (RR = 0.63; 95% CI, 0.44-0.89). On subgroup analysis, influenza vaccination remained effective for these outcomes in acute coronary syndrome but did not meet statistical significance in coronary artery disease. Furthermore, influenza vaccination did not reduce the risk for revascularization (RR = 0.89; 95% CI, 0.54-1.45), stroke or transient ischemic attack (RR = 0.85; 95% CI, 0.31-2.32), or heart failure hospitalization (RR = 0.91; 95% CI, 0.21-4.00). CONCLUSIONS:Influenza vaccine is a cheap and effective intervention to reduce the risk for all-cause mortality, cardiovascular mortality, major acute cardiovascular events, and acute coronary syndrome among coronary artery disease patients, especially in those with acute coronary syndrome.