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. 2021 Jan-Feb;21(1):14-17.
doi: 10.1016/j.ipej.2020.10.006. Epub 2020 Nov 17.

Cardiac resynchronisation therapy in patients with left bundle branch block with residual conduction

Christian Grebmer  1 , Lena Friedrich  2 , Verena Semmler  2 , Marc Kottmaier  2 , Felix Bourier  2 , Amir Brkic  2 , Patrick Blazek  2 , Severin Weigand  2 , Matthew O' Connor  3 , Isabel Deisenhofer  2 , Gabriele Hessling  2 , Christof Kolb  2 , Carsten Lennerz  2
Affiliations

Cardiac resynchronisation therapy in patients with left bundle branch block with residual conduction

Christian Grebmer et al. Indian Pacing Electrophysiol J. 2021 Jan-Feb.

Abstract

Aim: To evaluate whether left bundle branch block with residual conduction (rLBBB) is associated with worse outcomes after cardiac resynchronisation therapy (CRT).

Methods: All consecutive CRT implants at our institution between 2006 and 2013 were identified from our local device registry. Pre- and post-implant patient specific data were extracted from clinical records.

Results: A total of 690 CRT implants were identified during the study period. Prior to CRT, 52.2% of patients had true left bundle branch block (LBBB), 19.1% a pacing-induced LBBB (pLBBB), 11.2% a rLBBB, 0.8% a right bundle branch block (RBBB), and 16.5% had a nonspecific intraventricular conduction delay (IVCD) electrocardiogram pattern. Mean age at implant was 67.5 years (standard deviation [SD] = 10.6), mean left ventricular ejection fraction (LV EF) was 25.7% (SD = 7.9%), and mean QRS duration was 158.4 ms (SD = 32 ms). After CRT, QRS duration was significantly reduced in the LBBB (p < 0.001), pLBBB (p < 0.001), rLBBB (p < 0.001), RBBB (p = 0.04), and IVCD groups (p = 0.03). LV EF significantly improved in the LBBB (p < 0.001), rLBBB (p = 0.002), and pLBBB (p < 0.001) groups, but the RBBB and IVCD groups showed no improvement. There was no significant difference in mortality between the LBBB and rLBBB groups. LV EF post-CRT, chronic kidney disease, hyperkalaemia, hypernatremia, and age at implant were significant predictors of mortality.

Conclusion: CRT in patients with rLBBB results in improved LV EF and similar mortality rates to CRT patients with complete LBBB. Predictors of mortality post-CRT include post-CRT LV EF, presence of CKD, hyperkalaemia, hypernatremia, and older age at implant.

Keywords: Cardiac resynchronisation therapy; Heart failure; Left bundle branch block; Left bundle branch block with residual conduction.

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Conflict of interest statement

Declaration of competing interest None.

Figures

Fig. 1
Fig. 1
Kaplan-Meier curve comparing mortality between LBBB and rLBBB.
Fig. 2
Fig. 2
Kaplan-Meier curve comparing mortality between LBBB and pLBBB.
Fig. 3
Fig. 3
Kaplan-Meier curve comparing mortality between LBBB and IVCD >120 ms.
See this image and copyright information in PMC

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