Incidence of acute myocarditis and pericarditis during the coronavirus disease 2019 pandemic: comparison with the prepandemic period.

BACKGROUND: Myocarditis and pericarditis have been proposed to account for a proportion of cardiac injury during SARS-CoV-2 infection. The impact of COVID-19 the pandemic on the incidence of this acute inflammatory cardiac disease was not systematically evaluated. AIM: To examine the incidence and prevalence of inflammatory heart disorders prior to and during the COVID-19 pandemic. METHODS: We compared the incidence and prevalence of acute inflammatory heart diseases (myocarditis, pericarditis) in the provinces of Pisa, Lucca and Livorno in two time intervals: prior to (PRECOVID, from 1 June 2018 to 31 May 2019) and during the COVID-19 pandemic (COVID, from 1 June 2020 to May 2021). RESULTS: Overall 259 cases of inflammatory heart disease (myocarditis and/or pericarditis) occurred in the areas of interest. The annual incidence was of 11.3 cases per 100 000 inhabitants. Particularly, 138 cases occurred in the pre-COVID, and 121 in the COVID period. The annual incidence of inflammatory heart disease was not significantly different (12.1/100 000 in PRECOVID vs 10.3/100 000 in COVID, P = 0.22). The annual incidence of myocarditis was significantly higher in PRECOVID than in COVID, respectively 8.1/100 000/year vs. 5.9/100 000/year (P = 0.047) consisting of a net reduction of 27% of cases. Particularly the incidence of myocarditis was significantly lower in COVID than in PRECOVID in the class of age 18-24 years. Despite this, myocarditis of the COVID period had more wall motion abnormalities and greater LGE extent. The annual incidence of pericarditis was, instead, not significantly different (4.03/100 000 vs, 4.47/100 000, P = 0.61). CONCLUSION: Despite a possible etiologic role of SARS-CoV-2 and an expectable increased incidence of myocarditis and pericarditis, data of this preliminary study, with a geographically limited sample size, suggest a decrease in acute myocarditis and a stable incidence of pericarditis and of myopericarditis/perimyocarditis.