Abstract 8980: Effective Cardiac Resynchronization Therapy May Normalize Longitudinal Dyssynchrony Evaluated by 3-Dimentional Speckle Tracking Imaging

Abstract

Background: Cardiac resynchronization therapy (CRT) becomes standard therapy for severe heart failure and its indication is now spreading to mild to moderate heart failure. However there remains approximately 30% non-responders and the mechanism of reverse remodeling induced by CRT is still unclear. Thereby we investigated which kind of dyssynchrony parameter, existing during own beat, was improved by CRT-on. Methods: We investigated 43 patients by 3-dimentional speckle tracking imaging (3DSTI) (ARTIDA, TOSHIBA Medical System): 12 CRT responders, defined as left ventricular end-systolic volume reduction >15% at 6 months after CRT, 14 CRT non-responders and age matched 17 healthy normal controls. Radial strain, longitudinal strain and circumferential strain were investigated and we calculated the following 3DSTI parameter: strain delay index (SDI) which was defined as the sum of the difference between peak and end-systolic each parameter across 16 segments. 3DSTI was investigated at >6months after CRT implantation and evaluated during CRT-off as own beat and CRT-on for responders and non-responders and during sinus rhythm for normal controls to estimate CRT effect at chronic phase. Results: During CRT-off, radial and longitudinal SDI were significantly higher in responders than non-responders, but circumferential SDI was not significantly different. After turning CRT-on, radial and longitudinal SDI were improved to lose significant difference, but circumferential SDI showed significant difference. Turning CRT-on, longitudinal SDI of responders had no more significant difference with normal controls (figure). Conclusions: Effective CRT pacing at chronic phase improves radial and longitudinal dyssynchrony, especially longitudinal SDI tend to be normalized. Reverse remodeling after CRT might be induced by improvement of longitudinal dyssynchrony.