Abstract 20350: Discordant Left Bundle Branch Block is Associated With Left Ventricular Dyssyncrhony at Cardiac Magnetic Resonance Imaging in Patients With Nonischemic Cardiomyopathy

Abstract

LBBB is frequently linked to left ventricular (LV) dyssynchrony and adverse prognosis in HF. LBBB has been defined as concordant (cLBBB) or discordant (dLBBB), when associated in lead I and V5, V6 with a positive or negative T wave respectively. dLBBB has been associated with a worse clinical and prognostic profile in HF patients. We sought to evaluate association between different patterns of LV dV/dT curves at CMR, LBBB morphology, clinical correlates and prognostic role in patients with nonischemic systolic HF. Methods and Results: One hundred and fifteen consecutive patients with LBBB were submitted between 2004 and 2014 to a complete cardiological evaluation, including CMR with analysis of dV/dT curves of LV contraction, and follow-up for cardiac events. We distinguished two different patterns of global and segmental LV systole: a “narrow” pattern (NP) generated by synchronous contraction of wall segments; a “wide” pattern (WP), when delay in contraction between wall segments resulted in a prolungation of systolic peak with a flat or notched morphology. Fourteen patients presenting with normal LV dimensions and function all had cLBBB and NP, while out of 101 patients with HF, those with dLBBB (65%) presented with shorter QRS duration (p < .01) and higher level of NT-proBNP (p < .001). WP was observed more frequent in dLBBB patients (p < .003) as a mark of greater intraventricular dyssynchrony. According to systolic pattern, those with WP had higher levels of NT-proBNP, lower EF and higher LV volumes than those with NP, whereas no significant difference was found in QRS duration. At multivariate analysis only dLBBB (p=.006) and EF (p=.001) were independent predictors of WP. At Kaplan-Meier analysis, the presence of WP was associated with a worse prognosis considering a composite end-point of cardiac death, hospitalization for HF and ICD shock (p<.005). At Cox analysis only presence of WP (p = .029) and level of NT-proBNP (p= .004) were independent predictors. Conclusions: In nonischemic systolic HF patients with LBBB, presence of a WP at CMR dV/dT curves is associated with dLBBB, identifies greater LV dyssynchrony with possible major benefits from resynchronization therapy and is an independent prognosticator.