Fewer complications at 18 months seen with post-COVID-19 vaccination myocarditis

Patients with post-COVID-19 mRNA vaccination myocarditis show a lower frequency of cardiovascular complications than those with conventional myocarditis or post-COVID-19 myocarditis at 18 months, according to a study published online Aug. 26 in the Journal of the American Medical Association.

Laura Semenzato, from the French National Agency for the Safety of Medicines and Health Products and French National Health Insurance, and colleagues examined the prognosis and management of post-COVID-19 mRNA vaccination myocarditis compared to other types of myocarditis during 18 months of follow-up. The analysis included 4,635 individuals who were hospitalized for myocarditis, including 558 with postvaccine myocarditis, 298 with post-COVID-19 myocarditis, and 3,779 with conventional myocarditis.

The researchers found that patients with postvaccine myocarditis were younger than those with post-COVID-19 and conventional myocarditis (mean age, 25.9, 31.0, and 28.3 years, respectively) and were more frequently men (84, 67, and 79%, respectively). There was a lower standardized incidence of the composite clinical outcome (hospital readmission for myopericarditis, other cardiovascular events, and all-cause death) for patients with postvaccine myocarditis than those with conventional myocarditis (weighted hazard ratio, 0.55; 95% confidence interval, 0.36 to 0.86).

Individuals with post-COVID-19 myocarditis had similar outcomes to conventional myocarditis (weighted hazard ratio, 1.04; 95% confidence interval, 0.70 to 1.52). Postvaccine myocarditis and post-COVID-19 myocarditis showed a similar trend for frequency of medical procedures and drugs prescribed posthospital discharge to that of patients with conventional myocarditis.

"Affected patients, mainly healthy young men, may require medical disease management for up to several months after hospital discharge," the authors write.

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