IMPACT OF AORTIC PRE-EJECTION DELAY ON ECHOCARDIOGRAPHIC RESPONSE TO CRT IN HEART FAILURE PATIENTS WITH LEFT BUNDLE BRANCH BLOCK Stefania Sacchi, MD, Lisa Innocenti, MD, Alessandro Paoletti Perini, MD, Paola Attanà, MD, Sara Scaramuzzi, MD, Paolo Carrai, MD, Alberto Fanfani, MD, Giuseppe Ricciardi, MD, Paolo Pieragnoli, MD, Luigi Padeletti, MD Dipartimento Cuore e Vasi, Università degli Studi di Firenze, Firenze, Italia Purpose: To investigate the relation between the baseline amplitude of pre-ejection interval and the echocardiographic response to CRT at 6-month follow-up in LBBB patients. Method: By standard echocardiography, baseline ejection fraction (EF), left ventricular volumes (LVEDV, LVESV), pre-ejection period (PEP) and pre-ejection period corrected for heart rate (PEPc) were assessed in 65 LBBB patients undergoing to CRT. At 6 month-follow up LV reverse remodeling was investigated. CRT patients were considered responders when a reduction > 15% of LVESV occurred. Summary: Sixty five consecutive LBBB patients (42 males, mean age 68±9 years, mean EF 27%±6) underwent CRT implantation. At 6-month follow-up 36 (55%) patients resulted responders. At baseline, QRS duration, EF, LVEDV and LVESV were similar between responders and non-responders (p=0.215, p=0.283, p=0.131, p=0.095, respectively). Before CRT implantation, PEP and PEPc were longer in responders than in non-responders (153±27 versus 129±30 ms, p=0.001 and 183±27 versus 158±31 ms, p=0.001). A significant relation was observed between PEP, PEPc and the magnitude of LV reverse remodeling (Spearman's Rho -0.480, p<0.001 and Spearman's Rho -0.485, p<0.001, respectively). Conclusion: In LBBB patients, despite comparable baseline QRS duration, high values of PEP and PEPc correlate well with CRT induced reverse remodeling at 6-month follow-up.