(33).
Three-dimensional speckle tracking echocardiography is an advanced echo imaging technique that is postulated to provide a comprehensive assessment of LV function with additional advantaged over 2D imaging(34), i.e. simultaneous speckle tracking in more than one direction allowing for assessment of longitudinal, circumferential and radial strain simultaneously, and requirement for a single apical acquisition, which in turn, may make assessment of LV strain more time efficient and thus more applicable in a busy clinical setting (34).The utility of 3D-LVS has been demonstrated in several pathologies including ischemic heart disease, cardio-oncology, valvular heart disease, left ventricular hypertrophy hence certainly applicable for myocarditis. Furthermore, 3D-LVS has successfully been used to identify subclinical LV dysfunction (35),and shown to be non-inferior to 2D STE in patients with aortic stenosis(36). Of the included studies, one study did demonstrate that patients with acute myocarditis in comparison to controls had lower 3D LV-GLS values. This study also highlighted that there was a good correlation between 2D- and 3D- GLS measurements in this study (r=0.84, p<0.01). These findings are also in keeping with pooled results on 2D LV-GLS from the meta-analysis in our study. Nonetheless, 3D-STE is still currently used primarily in the research settings and not in routine clinical practice given its high image and operator dependency. Some of the disadvantages of 3D STE which may still serve as barriers for application in routine clinical use, include the requirements for a stable regular heart rhythm during image acquisition and analysis, optimal LV images and with good temporal resolution and a high frame rate. Nonetheless, 3D-LVS may still have a useful role in the diagnostic work-up in myocarditis