Response to Cardiac Resynchronization Therapy in Cardiomyopathy Patients with Right Bundle Branch Block

Sara Zand; Hakimeh Sadeghian; Ali Kazemisaid; Masoumeh Lotfi-Tokaldany; Arash Jalali; Akram Sardari

doi:10.18502/jthc.v18i2.13320

Sara Zand Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
Hakimeh Sadeghian Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Ali Kazemisaid Department of Electrophysiology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Masoumeh Lotfi-Tokaldany Tehran Heart Center, Cardiovascular Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Arash Jalali Tehran Heart Center, Cardiovascular Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Akram Sardari Department of Cardiology, School of Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.

DOI: https://doi.org/10.18502/jthc.v18i2.13320

Keywords: Cardiac resynchronization therapy; Right bundle branch block; Cardiomyopathies

Abstract

Background: The use of cardiac resynchronization therapy (CRT) in heart failure patients with right bundle branch block (RBBB) is under debate. We present early and late echocardiographic characteristics of a series of heart failure patients with RBBB who underwent CRT.

Methods: In this retrospective descriptive study, 18 patients with RBBB in the surface electrocardiogram underwent CRT between 2005 and 2015. All the patients had the New York Heart Association functional class III/IV, a left ventricular ejection fraction (LVEF) ≤35%, and a QRS duration ≥120 milliseconds. The median follow-up duration was 19 months. The echocardiographic response was based on a ≥5% increase in LVEF.

Results: Within 48 hours after CRT implantation, LVEF increased from 24.58%±7.08% before to 28.46±8.91% after CRT (P=0.005) and to 30.00±9.44% at follow-up (P=0.008). Among the 18 patients, 12 (66.7%) were responders within 48 hours after CRT. The following baseline echocardiographic parameters were higher in the responders than in those without an increased LVEF, although the difference did not reach statistical significance: septal-to-lateral wall delay (48.33±33.53 vs 43.33±38.82 ms), anteroseptal-to-posterior wall delay (41.7±1.75 vs 38.33±18.35 ms), and interventricular mechanical delay (48.50±21.13 vs 31.17±19.93 ms). The mean QRS duration was higher in the responders than in the non-responders (183.58±40.69 vs 169.00±27.36 ms). Death was reported in 3 out of the 18 patients (16.7%) at follow-up. The 3 deceased patients had a higher baseline interventricular mechanical delay than those who survived.

Conclusion: Our results indicated that patients with RBBB might benefit from CRT. Further, patients with higher intra and interventricular dyssynchrony and a wider QRS may show better responses.