Regular flu shots may be life-saving for patients with heart failure
Getting vaccinated against influenza can improve survival of patients with heart failure (HF), with earlier and more frequent vaccination being associated with a greater protection against deaths from cardiovascular (CV) events or any cause, a large Danish nationwide cohort study shows.
“Influenza infection is a serious event for patients with HF … Patients with HF have decreased circulatory reserve,” explained the researchers. “Hence, patients with HF may fail to meet the increased metabolic demand of infection, and this may possibly result in decompensation or exacerbation of HF symptoms.”
After a median follow-up of 3.7 years on 134,048 adults with HF (mean age 73.3 years, 55.9 percent male), 58 percent of participants died of all causes and 36 percent died of CV causes. [Circulation 2019;139:575-586]
Patients who had ≥1 influenza vaccination during the follow-up period were 18 percent less likely to die of any cause or CV causes (adjusted hazard ratio [HR], 0.82; p<0.001 for both) than those who were not vaccinated, after adjusting for comorbidities, medications, education level, and household income.
Of note, patients who had annual vaccination after HF diagnosis had significantly lower risk of both all-cause and CV mortality than those without vaccination (p<0.001 for both). Specifically, the more frequent the vaccination, the greater the risk reductions were for all-cause (HRs, 0.89, 0.82, 0.72 for one, 1–3, and >3 vaccinations, respectively) and CV mortality (HRs, 0.89, 0.80, 0.71, respectively; p-trend<0.001 for both).
Also, vaccination earlier in the year (September and October) was associated with greater reductions in the risk of all-cause and CV deaths compared with vaccination later in the year (November and December; p-trend<0.001).
“Vaccination early in the season may be more efficient for preventing influenza infection because the patient is allowed less time during the season to contract influenza before vaccination,” the researchers suggested. “Thus, it may be beneficial to administer the vaccine as early in the season as possible.”
“If multiple episodes of infection are prevented by multiple vaccinations, it is possible that the patient is spared unnecessary disease progression caused by multiple influenza infections, and this may explain in part why [more frequent] vaccinations was associated with greater reductions in mortality,” they added.
Giving HF the best shot
Although the study only included patients who were newly diagnosed with HF, lead author Dr Daniel Modin from the University of Copenhagen in Denmark believed that the protective benefits of influenza vaccination are likely to extend to any patients with HF.
“Routine vaccination is inexpensive, side effects are few to none, and the potential benefits are large,” commented Drs Adam DeVore and Ankeet Bhatt from Duke University School of Medicine in Durham, North Carolina and Brigham and Women’s Hospital in Boston, Massachusetts, US, respectively in a commentary. [Circulation 2019;139:587-589]
“[These findings,] in conjunction with preceding observational analyses, make a strong case for annual, early, well-matched influenza vaccination in patients with HF to improve all-cause and CV mortality,” they added. “Despite these potential advantages, most contemporary cohort studies have shown that vaccination rates remain disappointingly low in this high-risk population.”
“I hope that our study can assist in making physicians and cardiologists who care for patients with HF aware of how important influenza vaccination is for their patients,” said Modin, who suggested that influenza vaccination be considered as a potential treatment strategy in HF comparable to medications.
“Emphasizing this in future HF guidelines would encourage vaccination of patients with HF and likely improve patient survival,” he said.