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RCT-IVVE trial: Do HF patients benefit from annual flu shots?

Presented by
Prof. Mark Loeb, McMaster University, Canada
ACC 2022
Phase 4, RCT-IVVE
Major cardiovascular events were not significantly reduced in patients with heart failure (HF) who received an annual influenza vaccine compared with those who had not received an annual flu shot. Although the primary endpoint of the IVVE trial was not met, the authors argued that other findings of the trial suggest that administrating an annual influenza vaccine in this population offers clinical benefits.

The phase 4 RCT-IVVE trial (NCT02762851) randomised 5,129 patients with HF from Asia, Africa, and the Middle East to receive an annual influenza vaccine or a placebo shot [1]. The first primary endpoint of the study was a composite of cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke. The second primary endpoint added HF hospitalisation to the composite outcome of the first primary outcome. After 3 years, the first primary outcome had occurred in 691 patients, whereas the second primary outcome was reported in 1,470 cases. Prof. Mark Loeb (McMaster University, Canada) presented the results after 3 years.

Based on an all-year-round analysis, the first primary endpoint was not met: no significant difference in the composite of cardiovascular events was observed between patients who received an annual flu shot (14.8%) and those who received a placebo (16.0%; HR 0.93; P=0.30). Similarly, the second primary outcome (primary endpoint + HF hospitalisation) did not display significant differences between the experimental arm (20.3%) and the placebo arm (22.1%; P=0.13). Notably, during the flu season, fewer cardiovascular events were observed in the vaccine arm (7.7%) than in the placebo arm (9.4%; HR 0.82; 95% CI 0.68–0.99). Moreover, pneumonia rates and hospitalisation rates were 42% and 15% lower in patients who received an annual influenza vaccine compared with those who did not.

"Although our prespecified endpoints were not significant, our data suggest that there is a clinical benefit to getting a flu shot, given the clear reduction in pneumonia, moderate reduction in hospitalisation and reduction in vascular events and deaths during periods of peak influenza,” concluded Prof. Loeb. “Further trials and large-scale observational studies are needed to clarify the benefits of influenza vaccination in patients with HF or other cardiovascular diseases.”

    1. Loeb M, et al. Randomized controlled trial of influenza vaccine in patients with heart failure to reduce adverse vascular events (IVVE). Abstract 406–08, ACC 2022, 2–4 April, Washington DC, USA.


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