Influenza Vaccination Reduces Cardiovascular Events in Patients With Acute Coronary Syndrome

Study Questions:

Does influenza vaccination reduce the risk of acute coronary syndrome (ACS)?


This was a prospective randomized study of 439 patients who had been admitted with ACS within 8 weeks of study enrollment. Patients were randomized to receive inactivated influenza vaccination or no treatment. All patients were treated with standard cardiovascular therapies according to their primary cardiologists. Exclusion criteria included age under 50 years, significant renal or liver disease, hemoglobin <10 g/dl, cancer, a life expectancy less than 1 year, or a contraindication to influenza vaccination. Follow-up occurred for 1 year after vaccination. The primary outcome of interest was the occurrence of major adverse cardiac events (MACE) including death, hospitalization for ACS, hospitalization for heart failure, and stroke. Secondary endpoints included cardiovascular death at 12 months.


At entry, 159 patients had experienced an ST-segment elevation myocardial infarction (STEMI), 206 a non-STEMI, and 74 unstable angina. A total of 221 patients were randomized to receive the influenza vaccine, and 218 patients were randomized to the control group. Patients who received the influenza vaccine were less likely to experience MACE during the follow-up, as compared to the control group (9.5% vs. 19.3%; unadjusted hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.57-0.86; p = 0.004). After adjustment for potential confounders including age, sex, serum creatinine, angiotensin-converting enzyme inhibitors, and coronary revascularization, the risk of MACE was lower in the vaccination group compared to the control group (HR, 0.67; 95% CI, 0.51-0.86). There were no significant differences between the two groups for cardiovascular death or hospitalization for heart failure.


The authors concluded that influenza vaccination reduced MACE among patients after ACS.


This study highlights the importance of routine vaccination. Too often cardiac patients are not advised to receive the influenza vaccination; clinicians can increase rates of vaccination by incorporating this into routine assessments at every visit.

Clinical Topics: Acute Coronary Syndromes, Heart Failure and Cardiomyopathies, Prevention, Acute Heart Failure

Keywords: Myocardial Infarction, Influenza, Human, Acute Coronary Syndrome, Follow-Up Studies, Hemoglobins, Influenza Vaccines, Life Expectancy, Heart Failure, Vaccination, Hospitalization

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