Flu shot yields mixed findings in HF, with some seasonal CV benefit
Click Here to Manage Email Alerts
WASHINGTON — People with HF who received an annual influenza vaccine had a reduction in major CV events during peak influenza season and lower rates of hospitalization and pneumonia on a year-round basis, according to the IVVE study.
IVVE was a randomized controlled trial of an influenza vaccine to prevent adverse CV events in 5,000 participants with HF who received a vaccine or placebo over three influenza seasons. The global trial, which was conducted in 10 countries across Africa, Asia and the Middle East, did not meet its co-primary endpoints, which were focused on major adverse CV events on a year-round basis, but showed benefit in some secondary endpoints, including a 16% reduction in risk for all hospitalizations and 42% reduction in risk for pneumonia.
However, taken together, “it speaks to the importance of vaccinating patients with HF against influenza,” Mark Loeb, MD, the Michael G. DeGroote chair in infectious diseases at McMaster University, Ontario, Canada, said during a late-breaking clinical trial presentation at the American College of Cardiology Scientific Session.
This is the first randomized controlled trial to assess the benefits of the influenza vaccine in people with HF, according to an ACC press release.
The pragmatic, double-blind, randomized trial included 5,129 adults (mean age, 57 years; 51% women) with HF in 10 countries where influenza vaccines are not common. Most participants had NYHA class II or III HF. Thirty-one percent had severe left ventricular dysfunction (LV ejection fraction 30%) and 22% had preserved EF (> 50%).
Those enrolled previously received an influenza vaccine not more than once in the previous 3 years. Participants were randomly assigned to receive an influenza vaccine (0.5 ml intramuscular dose of inactivated vaccine; Vaxigrip) or placebo (0.5 ml saline) annually for up to 3 years; they were also allowed to get the vaccine outside of the trial, but Loeb said only a fraction did. Researchers then tracked outcomes for a median of 3 years.
Outcomes at 3 years in those who received a vaccine compared with placebo were as follows:
- First primary outcome – CV death, nonfatal MI or nonfatal stroke: 14.8% vs. 16%; HR = 0.93 (95% CI, 0.81-1.07); P = .3
- Second primary outcome – CV death, nonfatal MI, nonfatal stroke or HF hospitalization: 20.3% vs. 22.1%; HR = 0.91 (95% CI, 0.81-1.03); P = .13
- All-cause mortality: 16.7% vs. 18.4%; HR = 0.9 (95% CI, 0.79-1.03); P = .13
- CV mortality: 13% vs. 14.6%; HR = 0.89 (95% CI, 0.77-1.04); P = .13
- All hospitalizations: 15.1% vs. 17.6%; HR = 0.84 (95% CI, 0.74-0.97); P = .01
- HF hospitalizations: 9.4% vs. 10.7%; HR = 0.88 (95% CI, 0.74-1.05); P = .15
- Pneumonia: 2.4% vs. 4%; HR = 0.58 (95% CI, 0.42-0.8); P = .0006
“There was no significant difference in the primary outcomes between participants assigned to influenza vaccine vs. placebo. Secondary outcomes of pneumonia and hospitalization were reduced in the influenza vaccine group,” Loeb said.
When the researchers evaluated events that occurred during peak influenza season compared with non-peak periods, they found a significant reduction in the first primary outcome (7.7% vs. 9.4%; HR = 0.82; 95% CI, 0.68-0.99), all deaths (8.4% vs. 10.6%; HR = 0.79; 95% CI, 0.66-0.95), CV deaths (6.7% vs. 8.7%; HR = 0.77; 95% CI, 0.63-0.94) and pneumonia (1.1% vs. 2.1%; HR = 0.51; 95% CI, 0.32-0.81) in the influenza vaccine group compared with placebo.
Loeb said many of the effects found during peak flu circulation disappeared outside of it.
Perspective
Back to Top
Edward T.A. Fry, MD, FACC, FSCAI
This was a well-conducted study that had hard endpoints. What we know from being vaccinated against the flu is that we feel better and we can go to work or continue on with our daily lives, and those factors were not captured. That is an area where there may have been benefit that was not seen.
The study was conducted in low-to-middle-income countries, where maybe the threshold to be admitted to the hospital was purely subjective. Perhaps that bar was higher than in higher-income countries. Nonetheless, hospitalization was reduced, which indicates there was probably a significant relative benefit for the individual.
The benefits mostly seemed to happen during the flu season, which was intuitive. This was a particularly interesting study related to vaccine interest, a major topic right now.
Collapse
Loeb M, et al. Joint American College of Cardiology/New England Journal of Medicine Late-Breaking Clinical Trials. Presented at: American College of Cardiology Scientific Session; April 2-4, 2022; Washington, D.C. (hybrid meeting).
Read more about
Click Here to Manage Email Alerts