Myocarditis relapse and COVID19 infection or vaccination: a single-center experience

Abstract

Abstract Background Myocarditis has rarely been associated with COVID19 infection and it emerged as a possible rare side effect after vaccination with messenger RNA (mRNA) vaccines. Myocarditis may have an unfavorable outcome and may relapse, particularly in females with immune-mediated/autoimmune features and a predisposing immunogenetic background. Purpose We aimed to assess the prevalence of myocarditis relapse during CoVid19 outbreak and following the onset of the vaccination campaign in a cohort of patients with history of clinically suspected or biopsy proven myocarditis. Methods We included consecutive, randomly selected patients with history of clinically suspected or biopsy proven myocarditis (defined in keeping with the World Health Organization and the European Society of Cardiology (ESC) criteria) coming for a regular follow-up visit to the Cardioimmunology outpatient clinic of a tertiary referral center from September-1-2021 to January-31-2022. History of CoVid19 infection and vaccination status were investigated, and patients underwent clinical, laboratory and echocardiographic check-up (Table1), as per usual practice during planned outpatient follow-up visits. As patients were selected based on already planned follow-up outpatient schedule, to rule out selection bias between the study cohort (n=240) and the remaining patients from our outpatient registry (n=714) we compared clinical, laboratory and imaging features (at baseline and at follow-up) of the two groups. Results Out of 240 patients (25% of the 954-outpatient registry cohort) receiving a scheduled follow-up visit, 43 (18%) developed CoVid19 infection, all before vaccination, with mild symptoms; no patient required hospitalization, none developed myocarditis relapse (based upon symptoms, troponin, new ECG or morpho-functional abnormalities at cardiac imaging) during or following CoVid19 infection. Of the 240 patients, 180 (75%) received vaccination, all but 33 with mRNA vaccines; none developed myocarditis relapse, neither early (within 3 weeks from first or second dose) nor later. No differences were found when comparing clinical and diagnostic features between the last follow-up prior to CoVid19 outbreak and the last follow-up by far. There was also no difference in terms of clinical-diagnostic features at baseline and at follow-up between the study cohort (n=240) and the remaining outpatient registry (n=714). Conclusions In our randomly selected cohort of patients with history of clinically suspected or biopsy proven myocarditis, both CoVid19 infection and vaccination were uneventful. These data do not support a clinically relevant role of COVID19 infection or mRNA vaccination in triggering myocarditis relapses in patients with prior known myocarditis and reinforce the indication to vaccination also in this patients’ subset, in keeping with a recent ESC consensus document.