Association of Acute-Phase IL-6 and SAA with Cardiovascular Events and Mortality Six Years After COVID-19 Infection: An Observational Cohort Study.

Coronavirus disease 2019 (COVID-19) has been associated with an increased long-term cardiovascular risk, potentially mediated by magnitude of the acute inflammatory response inflammation. Interleukin-6 (IL-6) and serum amyloid A (SAA) are key components of the inflammatory cascade and may serve as biomarkers of post-COVID cardiovascular vulnerability. This longitudinal observational study investigated the association between post- COVID-19 infection IL-6 and SAA levels and major cardiovascular events over a six-year follow-up period. A total of 97 individuals with documented prior SARS-CoV-2 infection were included. Circulating IL-6 and SAA concentrations were measured in the acute phase. The composite endpoint included incident arrhythmia, myocardial infarction, and all-cause mortality. Biomarker distributions were right-skewed and were therefore analyzed using non-parametric methods and penalized logistic regression models. During follow-up, 14.4% of participants experienced the composite endpoint. Individuals with adverse outcomes had significantly higher IL-6 and SAA levels compared with event-free participants. IL-6 demonstrated the strongest association with mortality, whereas SAA showed particularly robust associations with the composite endpoint, and with myocardial infarction. Both biomarkers independently predicted long-term adverse events. Circulating IL-6 and SAA concentrations measured during the acute phase of SARS-CoV-2 infection were analyzed in relation to long-term cardiovascular outcomes. These findings support the hypothesis that the magnitude of the acute inflammatory response during SARS-CoV-2 infection may be associated with long-term cardiovascular outcomes and suggest that combined assessment of IL-6 and SAA may have potential utility for hypothesis-generating prognostic signal requiring validation, pending validation in larger studies.