Acute cardiovascular events appear to be key contributors to morbidity and mortality in adult patients hospitalized with influenza.
A population-based study of patients hospitalized with the flu found that 12% experienced an acute cardiovascular event, the most common of which were acute heart failure (aHF) and acute ischemic heart disease (aIHD).
The authors of the study, Eric J. Chow, MD, Centers for Disease Control and Prevention, Atlanta, Georgia, and colleagues, suggested the results support the need for increasing the rates of flu vaccination. The study was published in the Annals of Internal Medicine.
According to Chow and colleagues, while respiratory disease has been recognized as “the hallmark” of influenza virus infection, cardiovascular events should be recognized as an important potential complication of the infection, as well.
However, there have been few population-based studies estimating the frequency of acute cardiovascular events associated with influenza. This study by Chow and colleagues was designed to examine acute cardiovascular events among adults hospitalized with laboratory-confirmed influenza, as well as the risk factors associated with aHF and aIHD in those patients.
For this study, the authors used data from FluSurv-NET, a large, multicenter, U.S. network sponsored by the CDC that conducts population-based surveillance of hospitalizations associated with laboratory-confirmed influenza. The study sample included 80,261 patients (median age 69 years) hospitalized with influenza during the flu seasons of 2010 through 2018.
Chow and colleagues determined that 11.7% of these patients experienced an acute cardiovascular event during their hospitalization for influenza. These outcomes included:
- Acute heart failure (6.2%).
- Acute ischemic heart disease (5.7%).
- Hypertensive crisis (1.0%)
- Cardiogenic shock (0.3%).
- Acute myocarditis (0.1%).
- Acute pericarditis (0.1%).
- Cardiac tamponade (0.03%).
Of patients who experienced an acute cardiovascular event, 53.5% had aHF and 49.3% had aIHD. Almost all of these patients were age 65 or older. Compared to patients under the age of 50, older patients had an increased risk for both aHF (50 to 64 years: adjusted risk ratio [aRR], 1.40 [95% CI, 1.22-1.61]; 65 to 74 years: aRR, 1.58 [CI, 1.36-1.84]; 75 to 84 years: aRR, 1.88 [CI, 1.62 to 2.18]; and ≥85 years: aRR, 2.32 [CI, 2.00 to 2.70]) and aIHD (50 to 64 years: aRR, 2.04 [CI, 1.72 to 2.43]; 65 to 74 years: aRR, 2.93 [CI, 2.44 to 3.51]; 75 to 84 years: aRR, 3.43 [CI, 2.85-4.12]; and ≥85 years: aRR, 4.37 [CI, 3.64-5.25]).
Of fatal cases, 1 in 4 had an associated acute cardiovascular event.
Tobacco use, as well as underlying cardiovascular disease, diabetes, and renal disease were significantly associated with higher risk for aHF and aIHD. For example, the unadjusted weighted prevalence of acute cardiovascular events was greater in patients with underlying conditions, with 20.6% of those having chronic cardiovascular disease, 19.3% with chronic renal disease, and 14.8% with diabetes having an acute cardiovascular event.
Chow and colleagues also found that women (aRR, 0.87 [CI, 0.80-0.93]) and obese patients (aRR, 0.84 [CI, 0.77-0.93]) had a lower risk for aIHD, while patients who were vaccinated against influenza at least 2 weeks before hospitalization compared with unvaccinated patients had lower risks for both aHF and aIHD, as did patients who received early antiviral treatment.
“Especially among patients with risk factors for acute cardiovascular events, practitioners may play an essential role in mitigating the burden of cardiovascular disease by maintaining high rates of annual influenza vaccination and providing early antiviral treatment to patients with suspected or confirmed influenza,” the authors suggested.
“Increasing rates of influenza vaccination, especially among those with cardiovascular risk factors, is essential in preventing infection and potentially attenuating influenza-related cardiovascular complications and adverse outcomes,” they concluded.
In an editorial accompanying the study, Chandini Raina MacIntyre, PhD, University of New South Wales, Sydney, New South Wales, Australia, noted that it is possible that influenza is substantially underdiagnosed, with studies suggesting that influenza-related hospitalizations may be undetected by a factor of 5 in adults over the age of 65. Which means, MacIntyre wrote, the “rate of simultaneous influenza and acute cardiovascular disease may be even greater than suggested by this research.”
MacIntyre went on to argue that patients with influenza should be assessed for cardiovascular health and vaccination status, while those presenting with acute cardiovascular events during the flu season should be assessed for influenza.
Most importantly, MacIntyre pointed out that despite evidence that vaccination can prevent a proportion of acute cardiovascular events, and therefore provide a substantial public health benefit, it “continues to be overlooked.”
“It is time to recognize the significant and preventable cardiovascular morbidity and mortality associated with influenza,” she wrote. “It is time to view influenza vaccination as a routine secondary preventive measure for cardiovascular events.”
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Acute cardiovascular events are key contributors to morbidity and mortality in patients hospitalized with laboratory-confirmed influenza. Twelve percent of these patients experience these events, the most frequent of which are acute heart failure and acute ischemic heart disease.
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Increasing vaccination rates are needed to prevent cardiovascular morbidity and mortality associated with influenza.
Michael Bassett, Contributing Writer, BreakingMED™
MacIntyre reports grants from Sanofi, grants from Seqirus, outside the submitted work.
Cat ID: 914
Topic ID: 74,914,730,914,190,30,653,924
