Prevalence, Characteristics, and Outcomes of COVID-19–Associated Acute Myocarditis
Authors: Ammirati Enrico , Lupi Laura , Palazzini Matteo , Hendren Nicholas S. , Grodin Justin L. , Cannistraci Carlo V. , Schmidt Matthieu , Hekimian Guillaume , Peretto Giovanni , Bochaton Thomas , Hayek Ahmad , Piriou Nicolas , Leonardi Sergio , Guida Stefania , Turco Annalisa , Sala Simone , Uribarri Aitor , Van de Heyning Caroline M. , Mapelli Massimo , Campodonico Jeness , Pedrotti Patrizia , Barrionuevo Sánchez Maria Isabel , Ariza Sole Albert , Marini Marco , Matassini Maria Vittoria , Vourc’h Mickael , Cannatà Antonio , Bromage Daniel I. , Briguglia Daniele , Salamanca Jorge , Diez-Villanueva Pablo , Lehtonen Jukka , Huang Florent , Russel Stéphanie , Soriano Francesco , Turrini Fabrizio , Cipriani Manlio , Bramerio Manuela , Di Pasquale Mattia , Grosu Aurelia , Senni Michele , Farina Davide , Agostoni Piergiuseppe , Rizzo Stefania , De Gaspari Monica , Marzo Francesca , Duran Jason M. , Adler Eric D. , Giannattasio Cristina , Basso Cristina , McDonagh Theresa , Kerneis Mathieu , Combes Alain , Camici Paolo G. , de Lemos James A. , Metra Marco 
Published: April 2022

Background:
Acute myocarditis (AM) is thought to be a rare cardiovascular complication of COVID-19, although minimal data are available beyond case reports. We aim to report the prevalence, baseline characteristics, in-hospital management, and outcomes for patients with COVID-19–associated AM on the basis of a retrospective cohort from 23 hospitals in the United States and Europe.

Methods:
A total of 112 patients with suspected AM from 56 963 hospitalized patients with COVID-19 were evaluated between February 1, 2020, and April 30, 2021. Inclusion criteria were hospitalization for COVID-19 and a diagnosis of AM on the basis of endomyocardial biopsy or increased troponin level plus typical signs of AM on cardiac magnetic resonance imaging. We identified 97 patients with possible AM, and among them, 54 patients with definite/probable AM supported by endomyocardial biopsy in 17 (31.5%) patients or magnetic resonance imaging in 50 (92.6%). We analyzed patient characteristics, treatments, and outcomes among all COVID-19–associated AM.

Results:

AM prevalence among hospitalized patients with COVID-19 was 2.4 per 1000 hospitalizations considering definite/probable and 4.1 per 1000 considering also possible AM. The median age of definite/probable cases was 38 years, and 38.9% were female. On admission, chest pain and dyspnea were the most frequent symptoms (55.5% and 53.7%, respectively). Thirty-one cases (57.4%) occurred in the absence of COVID-19–associated pneumonia. Twenty-one (38.9%) had a fulminant presentation requiring inotropic support or temporary mechanical circulatory support. The composite of in-hospital mortality or temporary mechanical circulatory support occurred in 20.4%. At 120 days, estimated mortality was 6.6%, 15.1% in patients with associated pneumonia versus 0% in patients without pneumonia (
P
=0.044). During hospitalization, left ventricular ejection fraction, assessed by echocardiography, improved from a median of 40% on admission to 55% at discharge (n=47;
P
<0.0001) similarly in patients with or without pneumonia. Corticosteroids were frequently administered (55.5%).

Conclusions:
AM occurrence is estimated between 2.4 and 4.1 out of 1000 patients hospitalized for COVID-19. The majority of AM occurs in the absence of pneumonia and is often complicated by hemodynamic instability. AM is a rare complication in patients hospitalized for COVID-19, with an outcome that differs on the basis of the presence of concomitant pneumonia.