Myocardial deformation in acute myocarditis with normal left vntricular wall motion. A cardiac magnetic resonance and two-dimensional strain echocardiography study.

Purpose: Focal acute myocarditis is characterized by myocardial damage and normal wall motion of left ventricle (LV). Two-dimensional strain echocardiography (SE) imaging is a new ultrasonography technique which uses standard B-mode images for analysis and quantification of circumferential and longitudinal deformation. Delayed enhancement (DE) cardiac magnetic resonance (CMR) is accurate to identify myocardial damage due to myocarditis. Aim of the study was to correlate circumferential and longitudinal deformation with DE in patients with focal myocarditis. Methods: 10 male patients (31±8 years) with a diagnosis of acute focal myocarditis underwent to SE and to DE-CMR in the same day and in random order. CMR protocol consisted of cine images to evaluate systolic wall thickening (SWT), and DE to determine location of myocardial damage. SE was performed using a commercial US system (MyLab50CV, Esaote Florence). Echocardiographic recordings were done from apical views (4,2 and 3 chambers views) for the evaluation of longitudinal strain, and for short axis views at basal, middle and apical level of LV for the evaluation of circumferential strain. To quantify longitudinal and circumferential strain, the images were analysed offline by "track"LV endocardial borders in an operator driven automatic approach ("XStrain Imaging"). Results: All patients showed DE located in epicardial layer of inferior (N=1 patient), inferolateral (N=3), and anterolateral wall (N=2) and boht anterolateral and inferolateral walls (N=4) suggestive for myocarditis. Longitudinal strain was analysed in 96% (153/160) of the total segments, those with DE (37 segments; -18±4%) had showed a significant lower longitudinal strain (p=0.005) in comparison with segments without DE (116 segments; -22±6%). Circumferential strain was analysed in 64% (102/160) of the total segments; no difference was observed in segments with and without DE (24 segments, -23±5% and 78 segments -23±6%, respectively). SWT was analysed in all 160 segments, no different was found between segments with and without DE. Conclusion: In patients with focal myocarditis, longitudinal strain but not circumferential one is reduced in the segments with DE in presence of normal systolic wall thickening.