Cardiovascular Complications Lower in Patients With Post-Vaccine Myocarditis

Cardiovascular events were less severe at 18 months in patients with myocarditis attributed to COVID-19 mRNA vaccination than in patients with myocarditis from other origins, according to study findings published online ahead of print in JAMA.

“However, affected patients, mainly healthy young men, may require medical management up to several months after hospital discharge,” wrote researchers from the EPI-PHARE Scientific Interest Group in Epidemiology of Health Products from the French National Agency for the Safety of Medicines and Health Products and the French National Health Insurance.

The study included all patients aged 12 to 49 years hospitalized for myocarditis in France between December 27, 2020, and June 30, 2022. Among them, 558 were categorized as having post-vaccine myocarditis (within 7 days after COVID-19 mRNA), 298 with post-COVID-19 myocarditis (within 30 days of SARS-CoV-2 infection), and 3779 with conventional myocarditis. Researchers followed patients for 18 months to gauge long-term outcomes.

Patients with post-vaccine myocarditis were younger than other groups, the study found. Average ages were 25.9 years with post-vaccine myocarditis, 31.0 years with post-COVID-19 myocarditis, and 28.3 years with conventional myocarditis. Patients with post-vaccine myocarditis were also more frequently male: 84%, compared with 67% with post-COVID-19 myocarditis and 79% with conventional myocarditis.

Over the 18 months after hospital admission, the standardized incidence of the composite clinical outcome—which included hospital readmission for myopericarditis, other cardiovascular events, and all-cause death—was lower in patients with post-vaccine myocarditis (32 events/558 patients) compared to patients with conventional myocarditis (497 events/3779 patients); researchers reported a weighted hazard ratio of 0.55. Patients with post-COVID-19 myocarditis had a similar standardized incidence as the conventional myocarditis group: 36 events among 298 patients, for a weighted hazard ratio of 1.04, according to the study.

“The standardized frequency of medical procedures and drugs prescribed in patients with post-vaccine myocarditis or post-COVID-19 myocarditis followed a similar trend in the 18 months following hospital discharge to that of patients with conventional myocarditis,” researchers reported.

Reference
Semenzato L, Le Vu S, Botton J, et al. Long-term prognosis of patients with myocarditis attributed to COVID-19 mRNA vaccination, SARS-CoV-2 infection, or conventional etiologies. JAMA. Published online August 26, 2024. doi:10.1001/jama.2024.16380