Acute myocarditis: prognostic role of speckle tracking echocardiography and comparison with cardiac magnetic resonance features.

To evaluate longitudinal systolic function in patients with myocarditis, its correlation with cardiac magnetic resonance (CMR) features, and its predictive value in functional recovery and arrhythmias onset during follow-up (FU) on optimized medical therapy (OMT). Patients with acute myocarditis, confirmed through CMR criteria, and age- and sex-matched healthy controls were enrolled. Two-dimensional (2D) transthoracic echocardiography, including speckle tracking analysis, was performed at admission and after 6 months of FU. Patients of myocarditis group also underwent 24 h ECG Holter monitoring during FU. 115 patients with myocarditis (mean age 41 ± 17, 70% males) and 70 healthy subjects were enrolled. Global longitudinal strain (GLS) and sub-epicardial strain were markedly lower in the myocarditis group than in controls (mean GLS%: - 14.1 ± 5.1 vs - 23.1 ± 3.6, p < 0.001). A strong positive correlation between total scar burden (TSB) on CMR and baseline LV GLS was found (r = 0.67, p < 0.0001). GLS improved after 6 months of FU in myocarditis on OMT (mean GLS%: - 14.1 ± 5.1 vs - 16.5 ± 4.8, p < 0.01). By bivariate correlation analysis, baseline LVEF, GLS, and TSB were all associated with LVEF at 6 months of FU. Moreover, by multivariable linear regression analysis, these parameters confirmed to be independent predictors of functional recovery at 6 months (LVEF β 0.38, p < 0.01; GLS β - 0.35, p < 0.01; total scar burden β - 0.52, p < 0.0001). Segmental peak systolic strain was significantly different between segments with and without late gadolinium enhancement on CMR (- 13.2 ± 3.1% vs - 18.1 ± 3.5%, p < 0.001). A segmental strain of - 12% identified scar with a sensitivity of 79% and a specificity of 84% (AUC = 0.91; 95% CI 0.73-0.97; p < 0.001). In addition, baseline LV GLS in myocarditis resulted predictive of non-sustained ventricular tachycardias (cut-off value > - 12%; sensitivity84%; specificity74.4%; AUC = 0.75). Parameters of myocardial longitudinal deformation are importantly associated with the presence of a scar on CMR and are predictors of functional outcome and ventricular arrhythmias in patients with acute myocarditis. Their assessment during ultrasound examination should be considered to get more information about the prognosis and risk stratification of this subset of patients.