Thirty-four patients with DCM with baseline LV ejection fractions (LVEFs) < 40%and 13 subjects with preserved LVEFs (鈮?0%) were enrolled. After baseline measurements, pneumatic compression of the聽lower extremities (Pcom) was used to increase LV afterload. Subsequently, sublingual nitroglycerin (SL-NG) was administered to modify preload. Conventional echocardiographic parameters, LV end-systolic wall stress, net LV twist angle, and apex-to-base-rotation delay (ABRD) were assessed under each condition.
In patients with DCM, although LV end-systolic wall stress significantly increased under Pcom (196.9 卤 64.9 g/m2 at baseline vs 231.8 卤 78.9 g/m2 under Pcom, P < .017) and decreased after SL-NG application (231.8 卤 78.9 g/m2 under Pcom vs 197.4 卤 67.4 g/m2 after SL-NG, P < .017), net LV twist angle and ABRD showed no significant changes depending on LV loading condition (for LV twist, 7.63 卤 4.47掳 at baseline vs 7.03 卤 4.13掳 under Pcom vs 7.35 卤 4.36掳 after SL-NG, P聽= 0.65; for ABRD, 16.56 卤 13.81%at baseline vs 17.19 卤 14.81%under Pcom vs 15.95 卤 13.27%after SL-NG, P聽= .53). Careful examination of individual patient data revealed that LV twist was load independent when patients had LV twist < 12掳. ABRD was also found to be load independent, but only in patients with LVEFs < 34%. In contrast, LV twist and ABRD were load dependent in patients with preserved LVEFs.
LV twist and its component, ABRD, had relatively load insensitive properties in patients with long-standing DCM and can be used in future clinical trials as load-independent indexes of LV dyssynchrony.