Influenza vaccination should be part of standard hospital care after a myocardial infarction

Influenza vaccination reduces the risk of death from all causes, myocardial infarction or stent thrombosis at 12 months in hospitalized patients with myocardial infarction or high-risk coronary heart disease, according to recent research presented during a Hot Line session today at the ESC 2021 Congress.

During influenza epidemics, more people die of cardiovascular causes than during non-epidemic periods. Observational studies have suggested a protective effect of influenza vaccination on cardiovascular events, and single-center randomized trials have supported these findings. Flu vaccination is recommended for patients with heart disease, but not part of standard hospital care following acute myocardial infarction.

The IAMI trial was the largest randomized trial to date to assess whether influenza vaccination improves outcomes after myocardial infarction or percutaneous coronary intervention in high-risk patients with coronary artery disease. The trial was conducted in 30 hospitals in eight countries (Sweden, Denmark, Norway, Latvia, United Kingdom, Czech Republic, Bangladesh and Australia) during four influenza seasons from October 2016 to February 2020.

Participants were randomized in a 1: 1 ratio to receive either the influenza vaccine or a placebo within 72 hours of an invasive coronary intervention or hospitalization. The primary endpoint was a composite endpoint of death from all causes, myocardial infarction or stent thrombosis at 12 months. A hierarchical testing strategy was used for the primary secondary outcomes of all-cause death, cardiovascular death, myocardial infarction, and stent thrombosis.

The trial was terminated prematurely on April 7, 2020 by the Data Safety and Oversight Committee due to the COVID-19 pandemic after the recruitment of 2,571 patients (58% of target). The average age of the participants was 60 years and 18% were women.

The primary composite endpoint occurred in 67 patients (5.3%) in the vaccine group and 91 (7.2%) in the placebo group (hazard ratio [HR] 0.72; 95% confidence interval [CI] 0.52-0.99; p = 0.040). Regarding the secondary endpoints, deaths from all causes occurred in 37 patients (2.9%) in the vaccine group and 61 (4.9%) in the placebo group (HR 0.59; 95% CI 0.39-0.89, p = 0.010). The cardiovascular death rates were 2.7% and 4.5%, respectively (HR 0.59; 95% CI 0.39-0.90, p = 0.014). There was no difference between the groups in the rate of myocardial infarction, which occurred in 25 (2.0%) and 29 (2.4%) patients in the vaccine and placebo groups, respectively (HR 0.86; 95% CI 0.50-1.46; p = 0.57).

Serious adverse events were rare and of similar type and incidence in the two groups. injection site reactions such as pain, redness, swelling and hardening have been reported much more often in patients assigned to influenza vaccine.

The IAMI trial found that in patients with myocardial infarction or high-risk coronary artery disease, early influenza vaccination resulted in a lower risk of all-cause death, myocardial infarction, or 12-stroke stent thrombosis. months compared to placebo. Our results suggest that influenza vaccination should be considered as part of hospital treatment after myocardial infarction. “

Ole Fröbert, Principal Investigator, Professor, University of Örebro, Sweden