The Heart Under Viral Attack: From Infection and Vaccination to Myocardial Injury

Chronic heart failure remains a major global burden, with respiratory viral infections frequently precipitating hospitalisation and mortality.Viral myocarditis has emerged as a significant contributor to cardiac dysfunction, driven by both direct cytopathic effects and immune-mediated pathways.This review synthesises contemporary experimental and clinical evidence on the molecular mechanisms by which cardiotropic viruses-including Coxsackievirus B, herpesviruses (HHV 6, EBV, CMV), parvovirus B19, influenza viruses and SARS CoV 2damage the myocardium, with particular emphasis on the roles of Toll like receptors, viral proteases and the pro inflammatory cytokines TNF α, IL 6 and IL 1β.These cytokines exert negative inotropic actions, promote cardiomyocyte apoptosis and disrupt extracellular matrix homeostasis, thereby contributing to adverse ventricular remodelling and heart failure progression.The review also examines the veterinary legacy of coronavirus vaccine development, which has been largely overlooked in human cardiology.For over half a century, veterinary medicine has confronted coronaviruses as devastating livestock pathogens, accumulating extensive knowledge of vaccine platforms, viral mutation and immune escape mechanisms that proved instrumental in expediting the creation of mRNA vaccines against COVID 19.Importantly, the review appraises the cardiac safety profile of these vaccines, concluding that the incidence of vaccine associated myocarditis-predominantly observed in young males after the second dose-is substantially lower than the risk of myocarditis following natural SARS CoV 2 infection.Although rare, post vaccination cardiac complications warrant ongoing surveillance and mechanistic research.Overall, this comprehensive overview underscores the convergence of infectious disease, immunology and vaccinology in shaping our understanding of virus related heart disease, while highlighting the translational value of veterinary research.Future investigations should focus on identifying individual susceptibility factors and developing targeted strategies to mitigate both viral and vaccine induced myocardial injury, thereby improving outcomes for patients with or at risk of heart failure.