Myocarditis a Significant Postacute Complication of COVID-19 Infection

Myocarditis is a cardiovascular complication of a COVID-19 infection that has been reported at approximately 1 year following the index infection, according to the results of a systematic review and meta-analysis published in the Canadian Journal of Cardiology. 

Recognizing that information regarding the risk for myocarditis during the postacute phase of COVID-19 is scarce, researchers sought to evaluate the risk for incident myocarditis among survivors of COVID-19 within 1 year from the index date of infection via a systematic review and meta-analysis of the available data. They obtained data on all studies published at any time through September 1, 2022, in which the long-term risk for myocarditis among COVID-19 survivors had been reported.

Four studies were included in the meta-analysis, with a total of 20,875,843 patients. Among them, 1,245,167 had a confirmed diagnosis of COVID-19 infection. Overall, 59.1% of the participants were men. The mean patient age was 56.1 years. The patient cohorts comprised mainly middle-aged individuals. The mean length of follow-up in the study was 9.5 months.

Results of the study showed that myocarditis was reported in 0.21 of 1000 patients who survived a COVID-19 infection (95% CI, 0.13-0.42). In contrast, acute myocarditis was reported in 0.09 of 1000 control subjects (95% CI, 0.07-0.12). According to the Newcastle-Ottawa quality assessment scale, all of the studies evaluated were of moderate to high quality.

Per pooled analysis, patients who had recovered from a COVID-19 infection had a significantly increased risk for incident myocarditis (hazard ratio, 5.16; 95% CI, 3.87-6.89; P <.0001) within 1 year from the index infection. The results yielded were confirmed by sensitivity analysis.

A limitation of the study is that most of the articles evaluated identified the occurrence of incident myocarditis from large medical record datasets that use ICD-10 codes and the researchers did not perform a clinical follow-up; thus, the possibility that miscoding might have biased the study results cannot be excluded. Further, the potential overestimation of the results because of the presence of competing risks cannot be excluded.

“Myocarditis represents a relatively rare postacute COVID-19 sequelae within 1 year after the index infection,” the study authors wrote. “Physicians must be aware of this potential sequalae allowing its prompt recognition and treatment.”