Abstract 16271: Resolution of Left Bundle Branch Block With Sacubitril/Valsartan in Patients With Heart Failure With Reduced Ejection Fraction

Abstract

Introduction: Sacubitril/valsartan is associated with structural and functional reverse remodeling. It is uncertain if a subset of patients with HFrEF and LBBB treated with sacubitril/valsartan have resolution of LBBB. We aim to assess the effect of sacubitril/valsartan on QRS duration and LVEF in patients with HFrEF and LBBB. Methods: We performed a retrospective study of HFrEF patients treated with Sacubitril/Valsartan from January 2014 to June 2019. Minimum duration of treatment and follow-up was 3 months. Electrocardiographic and echocardiographic parameters were reviewed at four time points. Patients with baseline LBBB were identified. Patients with CRT ≧3 months after sacubitril/valsartan initiation were included and censored following CRT implantation. Results: Among 368 patients that met study criteria, 56 (15%) had baseline LBBB. Mean age was 64 (± 13.5), 53.6% were male and 78.6% had nonischemic cardiomyopathy. During median (IQR) follow-up of 9.1 months (5-18 mo), five (9%) had resolution of LBBB to normal conduction and two (4%) had improvement to non-specific IVCD. Examples of ECGs illustrating LBBB resolution are shown in Figure 1. Time to resolution of LBBB ranged from 1.2-5.7 months. Long term follow-up was only available in one patient with resolution of LBBB lasting at least 25.6 months after initiation of Entresto. The majority (n=4/5, 80%) had nonischemic cardiomyopathy. There was a trend towards greater improvement in LVEF in those with LBBB resolution vs. persistence (23 ± 6% vs. 9 ± 15%, p=0.11) as well as a trend towards greater reduction in LVIDd (-1.2 ± 0.8 cm vs. -0.5 ±0.7 cm, p=0.08). Conclusion: A small subset of patients with LBBB and HFrEF have resolution of LBBB with Sacubitril/Valsartan therapy. This may have important ramifications for timing of CRT implantation and highlights the potential importance of assessing the underlying rhythm in patients that receive a CRT device.