Different responses of the myocardial contractility by layer following acute pressure unloading in severe aortic...

The present study evaluated change in left ventricle (LV) biomechanics, layer-by-layer, following acute pressure unloading in patients with severe aortic stenosis (AS). In twenty-eight consecutive patients with severe AS who underwent transcatheter aortic valve replacement (TAVR), LV peak global longitudinal and circumferential strains of the endo-, midmyo- and epicardium were evaluated using multilayer speckle tracking echocardiography before, 1 week after, and 1 month after TAVR. Longitudinal and circumferential strains were significantly highest in the endocardium and lowest in the epicardium at baseline. At 1 month following TAVR, longitudinal strain significantly improved in all layers compared with the baseline [endocardium (%) -16.7 ± 3.8 vs. -18.6 ± 3.3, P = 0.01; mid-myocardium -14.4 ± 3.2 vs. -16.2 ± 3.5, P < 0.01; epicardium -12.4 ± 2.8 vs. -13.6 ± 2.6, P = 0.01], whereas LV ejection fraction and circumferential strain remained unchanged. Importantly, only those with LV hypertrophy demonstrated improved longitudinal strain [endocardium (%) -15.7 ± 3.0 vs. -18.7 ± 2.9, P < 0.01; mid-myocardium -13.6 ± 2.7 vs. -16.0 ± 2.5, P < 0.01; epicardium -11.8 ± 2.4 vs. -13.7 ± 2.3, P < 0.01]. The improvement in longitudinal strain was more prominent in the endocardium, which was evident even at an early time point (1 week) after TAVR. Longitudinal strain significantly improved in all three layers following acute pressure unloading, the most prominent of which was observed in the endocardium. Evaluation of multilayer strain may provide new insights into the LV mechanics in the future.