#19,174
Over the past 15 years we've seen growing evidence that influenza (and other respiratory) infections can raise the risk of heart attacks and strokes, particularly in the acute phase of the illness, with elevated risks that may extend for weeks.
Eurosurveillance: Influenza Vaccination Attenuates Acute Myocardial Infarction and Stroke Risk Following Influenza Infection
JAHA: Viral Infections and Risk of Cardiovascular Disease: Systematic Review and Meta‐Analysis
While the exact mechanism isn't fully understood, it appears that severe respiratory infections - which are often accompanied by hypoxemia, increased inflammation, hypotension, and hypercoagulability - can place enormous stresses on the cardiovascular system.
Adding to the growing evidence of an influenza-cardiovascular risk link, we have a prospective Danish study - published this week in Influenza & Other Respiratory Viruses - which found that > half of 241 hospitalized influenza patients showed evidence of cardiac dysfunction.While this observational study cannot tell us whether influenza inflammation caused these cardiac dysfunctions, it suggests that increased inflammation and degraded cardiac function are often seen in conjunction with hospitalized patients with influenza.
A reminder that respiratory protection (vaccines, masks, good `flu hygiene',etc.) is also very likely heart protection. Follow the link to read the full report.
Inflammation and Cardiac Dysfunction in Hospitalized Patients With Influenza: The FluHeart Study
Kristoffer Grundtvig Skaarup, Filip Soeskov Davidovski, Emil Durukan, Ema Rastoder, Maria Dons, Morten Sengeløv, Bernadette Rasborg … See all authors
First published: 19 May 2026
https://doi.org/10.1111/irv.70266Digital Object Identifier (DOI)
ABSTRACT
Background
Influenza virus infection can lead to acute cardiovascular events, but the relationship between influenza-induced inflammation and cardiac dysfunction remains unclear. This study evaluated whether the severity of inflammation was associated with cardiac impairment, as assessed by echocardiography, in hospitalized patients with influenza.
Methods
In this prospective cohort study conducted in Denmark across three influenza seasons (2021–2022, 2022–2023, and 2023–2024), consecutive hospitalized patients with laboratory-confirmed influenza underwent protocolized echocardiography. Associations between C-reactive protein (CRP) levels and measures of cardiac function were assessed using multivariable models.
Results
Among 241 patients (median age, 73.2 years; IQR, 58.3–82.8; 53% female), 54% had left ventricular (LV) systolic dysfunction (ejection fraction < 50% or global longitudinal strain < 16%), 15% had signs of elevated LV filling pressure (E/e′ ≥ 14), 29% had right ventricular (RV) systolic dysfunction (tricuspid annular plane systolic excursion [TAPSE] < 1.7 cm or RV free wall strain < 20%), and 31% had pulmonary hypertension (RV systolic pressure [RVSP] > 40 mmHg). CRP showed a significant nonlinear association with E/e′, RVSP, and TAPSE. E/e′ and TAPSE worsened with higher CRP up to 100 mg/L, plateauing thereafter, whereas RVSP worsened at CRP levels > 100 mg/L.
Conclusions
Cardiac dysfunction was observed in more than half of all examined hospitalized patients with influenza. Higher levels of inflammation were independently associated with elevated LV filling pressure, pulmonary hypertension, and RV dysfunction, supporting a potential link between influenza infection and cardiac impairment.
(SNIP)
Discussion
In this prospective cohort study of hospitalized patients with laboratory-confirmed influenza infection, we made several key findings.
- First, more than half of all patients exhibited LV or RV dysfunction.
- Second, higher levels of influenza-related acute systemic inflammation, assessed by CRP, were associated with elevated LV filling pressure (E/e′), pulmonary hypertension (RVSP), and impaired RV systolic function (TAPSE).
These associations were independent of age, sex, preexisting cardiac and pulmonary conditions, and time since admission, supporting a potential inflammatory contribution to cardiac dysfunction during influenza infection.
This is the largest echocardiographic study of patients with influenza and the first prospectively conducted study to systematically evaluate cardiac function in patients hospitalized with laboratory-confirmed influenza. Furthermore, prior echocardiographic studies of influenza have not included speckle tracking technology, which enables more sensitive assessment of myocardial function [17]. The present findings extend previous evidence by suggesting that inflammation during acute influenza infection may contribute to cardiac impairment, beyond what would be expected from preexisting cardiac disease alone [18].
Additionally, the observed association between influenza-induced inflammation and cardiac dysfunction may help explain the seasonal increases in hospitalizations for new-onset and preexisting heart failure, as well as cardiovascular mortality, seen during influenza epidemics [4, 19].
(SNIP)
Conclusion
In this cohort of patients hospitalized with laboratory-confirmed influenza, more than half showed signs of either LV or RV dysfunction. Increased levels of influenza-induced inflammation were independently associated with elevated LV filling pressure, pulmonary hypertension, and RV dysfunction, indicating a possible direct connection between influenza infection and cardiac dysfunction.
While I'm well past having to worry about dying tragically young - I'd still like to postpone the inevitable - so I get the flu shot every year, I've stayed current with my COVID vaccines, and have just added the Prevnar 20 pneumonia vaccine to my previous pneumovax protection.
Everyone has to make their own risk-reward calculation, of course. And none of these steps are guaranteed to be 100% effective.
But at my age, I'll take whatever advantage I can get.