Title : Clinical and cardiac imaging follow-up of the patients with COVID-19 vaccine-associated myocarditis: A systematic review and meta-analysis
Myocarditis has emerged as a serious adverse event after the COVID-19 vaccination. Our review study summarized the findings of Cardiac MRI and clinical follow-up of the patients with COVID-19 vaccine-associated myocarditis. We systematically searched MEDLINE, Embase, and Scopus databases up to 21 Oct 2022. We included studies performing initial and follow-up cardiac MRIs for patients with COVID-19 vaccine-associated myocarditis. Case reports, as a single series of cases, were combined with the case series using random effect models according to study heterogeneity. Twenty-one case reports/series (n = 109 patients) met our eligibility criteria. At the time of follow-up, myocarditis symptoms were resolved in all patients, but an abnormal Electrocardiography (ECG) and elevated troponin level were detected in 21% (9/43) and 4% (3/71) of them, respectively. Median imaging follow-up times varied from 3 to 6.3 months. On follow-up Cardiac MRI, the persistence of Late Gadolinium Enhancement (LGE) was observed in 74% (95% confidence interval (CI): 66 to 82%), but its extension declined compared to the baseline in almost all patients. Persistent LGE was accompanied by myocardial edema (LGE + and raised T2) in six patients and it was consistent with myocardial fibrosis (LGE without edema) in remained cases (n=67). Mean changes (95% CI) of cardiac MRI left ventricular ejection fraction (LVEF) (%) was +2.96 (+1.78 to +4.14) from baseline. In terms of adverse cardiac events, non-sustained ventricular tachycardia was experienced by two patients during follow-up. In conclusion, although most patients likely experience rapid clinical improvement, cardiac MRI abnormalities, mainly LGE, may persist in a notable proportion of them beyond the acute phase. Three patients had persistently elevated troponin levels that raised concerns about possible ongoing or recurrent myocarditis. Longer follow-up (at least one year from diagnosis) may be required to have a better vision of COVID-19 vaccine related myocarditis prognosis.