Discussion
The role of immune based process in heart failure development and progression has shown considerable attention lately. In this paper, we analyzed VAERS database to identify the role of vaccines in heart failure. Our results showed that COVID-19 vaccines were associated the most with heart failure (acute or chronic) with ROR of 21, followed by smallpox vaccine (ROR 7.2). Vaccines for Influenza, zoster, hepatitis, and PPV were associated with reduced incidence of heart failure.
The relationship between infection and heart failure is not very well characterized. While a direct cause of infection in heart failure pathogenesis is ill defined, infection is known to precipitates decompensation and mortality in heart failure patients(14). COVID-19 infection has been implicated in heart failure occurrence. For example, in Wahun, China, heart failure was among the most common outcomes after COVID-19 infection(15). Possible mechanisms have been postulated such as infiltration of inflammatory cells, release of cytokines and endothelial injury(16). Influenza infection is associated with enhanced mortality and morbidity in hospitalized heart failure patients(17). Other types of infections are much less studied in the context of heart failure.
Most of the existing vaccine literature focused on the impact of influenza vaccination on cardiovascular health. For instance, influenza vaccination has been shown to be associated with reduced all-cause mortality and from acute myocardial infarction and stroke in hypertension patients(18). Additionally, the same research group and others elegantly showed that annual influenza vaccination was associated with significant decrease of death among heart failure patients(12, 13). Influenza vaccines reduced death and hospitalization from stroke, acute coronary disease and heart failure and in patients with acute coronary disease(19). Despite the protective effect of influenza vaccines in heart failure, much less is known about the effect of other vaccines on heart failure. Our data corroborated with the current literature by showing significant reduction of heart failure exacerbation or incidence in patients who received influenza vaccines compared to other vaccine. Surprisingly, our results showed a significant increase of heart failure incidence or exacerbation in patients who received COVID-19 or smallpox vaccines. While an explanation for this association is not clear, COVID-19 and smallpox vaccines have been shown to increase the risk of myopericarditis, coronary artery disease and arrhythmia (20-23) which may potentially contribute to heart failure development and progression.
While this study showed a novel association between vaccines and heart failure, further studies are warranted to delineate the molecular mechanisms underlying this association. Additionally, using passive surveillance systems such as VAERS suffer from important limitations including reporting bias and inaccuracy of adverse events reports. Due to the publicity of COVID-19 vaccination adverse events, it is possible that many complications have been reported more frequently. It is also important to mention that studies based on VAERS generally conclude association, however, do not prove causality. Due to these limitations, our results should be interpreted with caution until clinical trials have been conducted.
In conclusion, our results here showed that vaccines against Influenza, zoster, hepatitis, and PPV are associated with reduced heart failure incidence and exacerbation. However, heart failure is associated with COVID-19 and smallpox vaccines. This study serves as a good start to investigate further the association between vaccines and heart failure in longitudinal studies.