Rationale and design of the French cohort of acute myocarditis diagnosed by cardiac magnetic resonance imaging (MyocarditIRM)

Claire Bouleti, Clement Servoz, Benjamin Alos, Ehmer Carsten, Alexis Jacquier, Julien Ternacle, Jean-Francois Deux, Victoria Tea, Elie Mousseaux ,Rodrigue Garcia, Guillaume Bonnet, Olivier Huttin, Mariama Akodad,
Theodora Bejan-Angoulvant, Benoit Lattuca, Alban Redheuil, Nicolas Glatt, Denis Angoulvant, Phalla Ou

Background: Acute myocarditis usually presents as chest pain with rising troponin and normal coronary
arteries. Despite frequent favourable evolution at the acute phase, it is associated with heart failure and
ventricular rhythm disorders, and is considered the leading cause of sudden cardiac death in young,
apparently healthy, adults. There are no specific recommendations for acute myocarditis diagnosis and
management, only expert consensus, given the lack of large databases.

Aim: The main objective is to describe the contemporary presentation of acute myocarditis, its management and in-hospital outcomes. Secondary objectives are to investigate survival and event-free survival
for up to 10 years of follow-up, the determinants of prognosis, the modalities of treatment and follow-up
and the gaps between expert consensus and real-life management.

Methods: MyocarditIRM is a prospective multicentre cohort that enrolled 803 consecutive patients with
acute myocarditis in 49 participating centres in France between 01 May 2016 and 28 February 2019.
The diagnosis of acute myocarditis was acknowledged by cardiac magnetic resonance, using the Lake
Louise Criteria. Exclusion criteria were age < 18 years, lack of health coverage, contraindication to cardiac
magnetic resonance and refusal to participate. Detailed information was collected prospectively, starting
at admission. Cardiac magnetic resonance imaging (diagnosis and follow-up) is analysed centrally by the
certified core laboratory IHU ICAN. Ten years of follow-up for each patient is ensured by linking with the
French National Health Database, and includes information on death, hospital admissions, major clinical
events and drug consumption.

Conclusion: This prospective cohort with long-term follow-up represents the largest database on acute myocarditis worldwide, and will improve knowledge about its presentation, management and outcomes.