High Rates of Acute Cardiovascular Events Among Hospitalized Patients With Influenza

The rate of acute cardiovascular events was found to be high in adults hospitalized with influenza.

The rate of acute cardiovascular events was found to be high in adults hospitalized with influenza, according to a study published in the Annals of Internal Medicine.

In this cross-sectional study, the data of 80,261 adult patients (median age, 69 years) from the large, multicenter FluSurv-NET network were examined. Patients had been hospitalized in 17 US states with laboratory-confirmed influenza during the 2010 to 2011 and 2017 to 2018 flu seasons. Discharge codes were used to identify acute cardiovascular (CV) events. Exposure variables also assessed in the analysis included age, tobacco use, chronic conditions, influenza vaccination, influenza antiviral medication, and influenza type or subtype.

Of patients included in the analysis, 11.7% had an acute CV event, with acute heart failure (6.2%) and acute ischemic heart disease (5.7%) being the most common events, and hypertensive crisis (1.0%), cardiogenic shock (0.3%), acute myocarditis (0.1%), acute pericarditis (0.05%), and cardiac tamponade (0.02%) observed at lower rates. Patients with acute CV events had a median length of hospital stay of 5 days, which was longer in those with cardiogenic shock (9 days), 38.9% of whom died during hospitalization.

Factors significantly associated with acute heart failure included: older age (50-64 years: adjusted risk ratio [aRR], 1.40; 95% CI, 1.22-1.61; 65-74 years: aRR, 1.58; 95% CI, 1.36-1.84; 75-84 years: aRR, 1.88; 95% CI, 1.62-2.18; ≥85 years: aRR, 2.32; 95% CI, 2.00-2.70), extreme obesity (aRR, 1.19; 95% CI, 1.06-1.33), current tobacco use (aRR, 1.17; 95% CI, 1.07-1.28), atrial fibrillation (aRR, 1.40; 95% CI, 1.30-1.52), chronic heart failure or cardiomyopathy (aRR, 8.33; 95% CI, 7.60-9.12), coronary artery disease (aRR, 1.18; 95% CI, 1.10-1.27), diabetes mellitus (aRR, 1.09; 95% CI, 1.01-1.17), and chronic renal disease (aRR, 1.22; 95% CI, 1.14-1.32).

In addition, factors associated with a higher risk for acute ischemic heart disease included older age (50-64 years: aRR, 2.04; 95% CI, 1.72-2.43; 65-74 years: aRR, 2.93; 95% CI, 2.44-3.51; 75-84 years: aRR, 3.43; 95% CI, 2.85-4.12; ≥85 years: aRR, 4.37; 95% CI, 3.64-5.25), current tobacco use (aRR, 1.33; 95% CI, 1.20-1.48), chronic heart failure or cardiomyopathy (aRR, 2.11; 95% CI, 1.93-2.31), coronary artery disease (aRR, 1.75; 95% CI, 1.61-1.91), diabetes mellitus (aRR, 1.15; 95% CI, 1.06-1.24), and chronic renal disease (aRR, 1.25; 95% CI, 1.15-1.36).

Study limitations include the sole enrollment of hospitalized patients with laboratory-confirmed influenza as well as the lack of available data on some known risk factors for CV events, such as hypertension and hyperlipidemia.

“Increasing rates of influenza vaccination, especially among those with CV risk factors, is essential in preventing infection and potentially attenuating influenza-related CV complications and adverse outcomes,” noted the study authors.


Chow EJ, Rolfes MA, O’Halloran A, et al. Acute cardiovascular events associated with influenza in hospitalized adults: A cross-sectional study. Ann Intern Med. published online August 25, 2020. doi:10.7326/M20-1509