Left and right atrial feature tracking in acute myocarditis: A feasibility study

Area of Science:

• Cardiology
• Medical Imaging
• Biophysics

Background:

• Acute myocarditis can lead to cardiac dysfunction.
• Assessing atrial function is crucial for understanding diastolic dysfunction.
• Cardiac magnetic resonance (CMR) feature tracking (FT) offers novel insights into myocardial mechanics.

Purpose of the Study:

• Evaluate the feasibility and reproducibility of CMR-FT derived strain and strain rate (SR) parameters for the left atrium (LA) and right atrium (RA) in acute myocarditis.
• Assess the potential of these parameters in detecting diastolic dysfunction.
• Investigate the diagnostic value of LA and RA strain parameters in acute myocarditis.

Main Methods:

• Retrospective analysis of CMR cine data from 30 patients with CMR-positive acute myocarditis and 25 healthy controls.
• Longitudinal strain and SR analysis of both atria using dedicated FT software.
• Assessment of intra- and inter-observer reproducibility using Bland-Altman analyses, ICCs, and CVs.

Main Results:

• CMR-FT analysis was feasible in all subjects with good reproducibility for reservoir and conduit function parameters.
• Patients with myocarditis showed impaired LA reservoir and conduit function compared to controls (LA ε_s: 32±17 vs. 46±13, p=0.019).
• Left atrial early diastolic strain rate (LA SR_e) was the best independent predictor of acute myocarditis (AUC 0.80), with 83% sensitivity and 80% specificity at a cut-off of -1.6s^-1.

Conclusions:

• Patients with myocarditis exhibit impaired atrial reservoir and conduit function, potentially indicating ventricular diastolic dysfunction.
• Left atrial SR_e is a powerful discriminator for acute myocarditis diagnosis using CMR.
• Atrial strain analysis demonstrates significant discriminative power in CMR-based diagnosis of acute myocarditis.