Myocarditis post-SARS-CoV-2 vaccination: a systematic review

Variable clinical criteria taken by medical professionals across the world for myocarditis following coronavirus disease 2019 (COVID-19) vaccination along with wide variation in treatment necessitates understanding and reviewing the same. A systematic review was conducted to elucidate the clinical findings, laboratory parameters, treatment and outcomes of individuals with myocarditis after COVID-19 vaccination after registering with PROSPERO. Electronic databases including MEDLINE, EMBASE, PubMed, LitCovid, Scopus, ScienceDirect, Cochrane Library, Google Scholar and Web of Science were searched. A total of 85 articles encompassing 2184 patients were analysed. It was a predominantly male (73.4%) and young population (mean age: 25.5 ± 14.2 years) with most having taken an mRNA-based vaccine (99.4%). The mean duration from vaccination to symptom onset was 4.01 ± 6.99 days. Chest pain (90.1%), dyspnoea (25.7%) and fever (11.9%) were the most common symptoms. Only 2.3% had comorbidities. CRP was elevated in 83.3% and cardiac troponin in 97.6% patients. An abnormal ECG was reported in 979/1313 (74.6%) patients with ST-segment elevation being most common (34.9%). Echocardiographic data were available for 1243 patients (56.9%), of whom 288 (23.2%) had reduced left ventricular ejection fraction. Non-steroidal antiinflammatory drugs (76.5%), steroids (14.1%) followed by colchicine (7.3%) were used for treatment. Only 6 patients died among 1317 of whom data were available. Myocarditis following COVID-19 vaccination is often mild, seen more commonly in young healthy males and is followed by rapid recovery with conservative treatment. The emergence of this adverse event calls for harmonizing case definitions and definite treatment guidelines, which require wider research.