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.