Flu vaccination in acute coronary syndromes and planned percutaneous coronary interventions (FLUVACS) Study

We have previously reported a significant benefit of vaccination against flu on the incidence of a single and composite end-point of death, myocardial infarction or recurrent ischaemia in patients with myocardial necrosis and planned percutaneous coronary interventions. To determine whether the observed benefits of vaccination against flu were maintained beyond the winter season a 1-year follow-up was conducted.

During the winter season, we enrolled prospectively 200 myocardial infarction patients admitted in the first 72 h, and 101 planned angioplasty/stent patients (PCI) without unstable coronary artery disease, prior by-pass surgery, angioplasty or tissue necrosis. Only four patients failed to meet the inclusion criteria. Participants were randomly allocated to receive flu vaccination or remain unvaccinated on top of standard medication (control group). The study was conducted in hospitalized patients with the aim to test the potential beneficial effect of flu vaccination in a secondary prevention scenario. Under intention to treat analysis the incidence of the primary end-point cardiovascular death at 1 year was significantly lower among patients receiving vaccination, 6% as compared with controls, 17% (relative risk with vaccine as compared with controls, 0.34; 95% confidence interval (CI), 0.17 to 0.71; P=0.002). The triple composite end-point occurred in 22% of the patients in the vaccine group vs 37% in controls, hazard ratio 0.59, 95% CI 0.4 to 0.86) P=0.004. The beneficial effect was mainly detected in acute myocardial infarction patients (four events in the active arm vs 21 in the control group, P=0.0002 [95% CI 0.19, 0.07-0.53]), and Cox regression analyses revealed that there was a greater benefit with flu vaccination in patients at high risk according with the TIMI score, and those with non-ST-segment deviation myocardial infarction (95% CI: 0.13 [0.03-0.52])

Influenza vaccination may reduce the risk of death and ischaemic events in patients suffering from infarction and post-angioplasty during flu season. This effect was significantly evident at 1-year follow-up. Larger confirmatory studies are needed to evaluate the real impact on flu vaccination on outcome after acute coronary syndromes.