Getting an annual flu shot can save heart failure patients' lives, according to new research in the American Heart Association's journal Circulation.

Flu season usually begins in the fall and runs through the spring, with cases often peaking during the winter months. Annual flu vaccination is regarded as a safe, low-cost way to reduce flu-related deaths and complications and is routinely recommended for patients with histories of heart disease and stroke. However, little is known about the possible impact a simple flu shot may have on the survival of heart failure patients.

Influenza can be very serious or even fatal for patients with heart failure because heart failure patients are often older than 65, have compromised circulation and other health complications, and infection may exacerbate heart failure symptoms. Moreover, heart failure is expected to increase over the next decade as the population ages, highlighting a greater need to provide better care for these patients.

In this study, researchers analyzed data on 134,048 patients with newly diagnosed heart failure over a 12-year period. Flu vaccination rates ranged from 16 percent in 2003 to 52 percent in 2015 with a peak of 54 percent in 2009. Among the researchers' findings:

Flu vaccination was associated with an 18 percent reduced risk of premature death, even after accounting for other factors such as medications, other health conditions, income and education.

Annual flu vaccination following a heart failure diagnosis was associated with a 19 percent reduction in both all-cause and cardiovascular death when compared with no vaccination.

Flu vaccination frequency mattered; getting a flu shot less than once per year but more than not at all was associated with a 13 percent reduced risk of all-cause death and an 8 percent reduced risk of cardiovascular death.

Timing mattered; there was a greater reduction in cardiovascular and all-cause death when vaccination occurred earlier in the flu season during September and October versus in November and December.

Lead study author Daniel Modin, an investigator from the University of Copenhagen in Denmark, said that while this research only looked at patients with newly-diagnosed heart failure, the protection from a flu shot likely benefits any patient with heart failure.

"Recent studies have indicated that the influenza vaccination coverage of patients with heart failure is inadequate," said Modin. "I hope that our study can assist in making physicians and cardiologists who care for patients with heart failure aware of how important influenza vaccination is for their patients. Influenza vaccination may be regarded as a standard treatment in heart failure similar to medications."