Cardiac Events in Adults Hospitalized for Respiratory Syncytial Virus vs COVID-19 or Influenza.

Importance: Respiratory viral infections (RVIs) are associated with elevated cardiovascular risk; however, less is known about cardiac complications after hospitalization for respiratory syncytial virus (RSV) vs other vaccine-preventable RVIs (COVID-19 or influenza). Objective: To compare the risk of acute cardiovascular complications in adults hospitalized for RSV vs COVID-19 or influenza. Design, Setting, and Participants: This population-based cross-sectional study, conducted before RSV vaccination rollout in Singapore, assessed all adults hospitalized for RSV or influenza (January 1, 2017, to June 30, 2024) and all adults hospitalized for COVID-19 during Omicron XBB/JN.1 transmission (January 1, 2023, to June 30, 2024). Exposure: Hospitalization for RSV, influenza (vaccinated or unvaccinated), or COVID-19 (boosted [≥3 vaccine doses] or unboosted [<3 vaccine doses]). Main Outcomes and Measures: Cardiovascular events during RSV, influenza, or COVID-19 hospitalization, defined as any cardiac, cerebrovascular, or thrombotic event, occurring from admission until discharge or death. Odds of any cardiovascular event (RSV vs COVID-19 or RSV vs influenza) and severe RVI (intensive care unit admission) with or without an acute cardiovascular event were estimated using multivariate logistic regression, adjusted for sociodemographic and clinical characteristics. Results: A total of 32 960 RVI hospitalizations (mean [SD] patient age, 66.58 [18.99] years; 17 056 [51.7%] female) were included (2148 for RSV, 14 389 for influenza, and 16 423 for COVID-19). Of the 2148 patients hospitalized for RSV, 234 (10.9%) had an acute cardiovascular event. Higher odds of any acute cardiovascular event (adjusted odds ratio [AOR], 1.31; 95% CI, 1.12-1.54) as well as other individual cardiac events were observed in RSV hospitalizations vs boosted COVID-19 (dysrhythmia: AOR, 1.52; 95% CI, 1.19-1.94; heart failure: AOR, 1.75; 95% CI, 1.30-2.35). Similarly, higher odds of any acute cardiovascular event (AOR, 1.58; 95% CI, 1.24-2.01) as well as dysrhythmias or heart failure were observed in patients hospitalized for RSV vs unboosted COVID-19. Odds of a cardiovascular event were not significantly different in RSV vs influenza, except among contemporaneous hospitalizations after the pandemic (2023-2024), where odds of heart failure (AOR, 2.09; 95% CI, 1.21-3.59) were significantly higher in RSV hospitalizations vs vaccine-breakthrough influenza hospitalizations. Occurrence of a cardiovascular event was associated with greater odds of severe RSV requiring intensive care unit admission (AOR, 2.36; 95% CI, 1.21-4.62). Conclusions and Relevance: In this cross-sectional study, 1 in 10 patients hospitalized for RSV had a concurrent acute cardiovascular event. Odds of cardiac events were significantly higher in RSV vs COVID-19 hospitalizations in both vaccine-boosted and unboosted individuals. In contemporaneous hospitalizations for RSV or influenza after the pandemic (2023-2024), odds of heart failure were significantly higher in RSV hospitalizations vs vaccine-breakthrough influenza hospitalizations. These findings suggest that patients with preexisting cardiovascular risk should consider vaccination against RVIs.