Abstract 2076: Cibenzoline Attenuates Left Ventricular Outflow Tract Obstruction In Patients With Hypertrophic Obstructive Cardiomyopathy - Insights From Changes In Left Ventricular Regional And Temporal Heterogeneity
(Background) We have previously reported that the class Ia antiarrhythmic drug, cibenzoline (CBZ), attenuates the LV outflow tract obstruction and improves LV diastolic function in HOCM patients. However, the effect of CBZ on LV regional (strain) and temporal (LV dyssynchrony) heterogeneity is unknown. The aim of this study was to elucidate the effect of CBZ on LV dyssynchrony and strain in HOCM patients.
(Methods) Eleven patients with HOCM (mean age, 60±16 years) underwent echocardiographic examination including tissue Doppler and speckle tracking imaging using a Vivid 7 Dimension (GE Healthcare) before and after the intravenous administration of CBZ (1.4 mg/kg over 5 min). Using a custom software package (EchoPAC PC: GE Healthcare), we measured baseline radial strain of each septal and free wall segment from the short axis view, and longitudinal strain of each septal and free wall segment from the apical view. An LV systolic dyssynchrony index was defined as the time difference between the peak systolic velocity at the anteroseptal and posterolateral segments (S-P delay).
(Results) After CBZ, a significant reduction in LV pressure gradient (LVPG) (from 86+/−71 to 38+/−54 mm Hg, P<0.01) was achieved combined with increased early diastolic mitral annular velocity (e′) (2.4+/−1.1 to 3.1+/−1.3 ms, P<0.01). Furthermore, radial strain in both septal (30.8+/−13.0 to 22.5+/−14.1 %, P<0.01) and free wall (40.5+/−17.1 to 34.5+/−17.1 %, P<0.05) segments decreased significantly. In contrast, longitudinal strain did not change after CBZ (septal; −7.3+/−5.0 to −7.9+/−5.1 %, free wall; −11.8+/−4.8 to −11.3+/−4.3 %, both P=NS). CBZ significantly shortened S-P delay (82+/−47 ms to 40+/−48 ms, P<0.01). There was a significant correlation between e′ and S-P delay (r=−0.45, P<0.05).
(Conclusion) In HOCM patients, CBZ attenuates radial strain in both septal and free wall segments but not longitudinal strain. The decreased radial strain might decrease systolic anterior movement of the papillary muscle and thus, the mitral valve and its septal contact leading to a reduction in LVPG. Furthermore, CBZ improves diastolic function shown as increase in e′, which might be due to a decrease in LV dyssynchrony.