Left bundle branch pacing in patients with structural heart disease: personalizing cardiac resynchronization therapy

Abstract

Biventricular pacing remains the cornerstone of cardiac resynchronization therapy (CRT) in patients with heart failure, with well-established benefits. Left bundle branch pacing (LBBP) offers a physiologic alternative by engaging the native conduction system to restore synchrony and has generated significant enthusiasm. However, the growing adoption of LBBP should be tempered by recognition that a one-size-fits-all approach may not address the underlying substrate, particularly in those with intraventricular conduction delay. While a less-than-optimal LBBP implant may be sufficient in bradycardia patients, its adequacy in heart failure patients, who may require more precise consideration of conduction disease, remains uncertain. This review gives a comprehensive framework for integrating LBBP into CRT, including pre-implant, intraprocedural, and post-implant assessment. It also provides practical guidance on when to pursue LBBP alone, when to supplement with a coronary sinus lead, and when to consider conventional biventricular pacing, with an emphasis on a personalized approach to the underlying conduction substrate for maximal therapeutic benefit.

Keywords: Biventricular pacing; Cardiac resynchronization therapy; Conduction system pacing; Heart failure; Intraventricular conduction delay; Left bundle branch block; Left bundle branch pacing.

Graphical Abstract

Figure 1

The 2025 ESC/EHRA consensus guidelines on conduction system pacing favour BiVP over CSP for traditional CRT indications.

Figure 2

Ultra-high-frequency ECG demonstrating activation patterns for (A) IVCD and (B) true LBBB.

Figure 3

Septal scar represented by percentage of LGE preventing successful lead deployment at the left ventricular septum.

Figure 4

Left: Left-sided EP study with demonstration of complete conduction block at the proximal left bundle with QRS activation over the right bundle with retrograde activation of the Purkinje potentials (PPs) from the apex to the base of the left ventricular septum. Right: QRS correction with recruitment of latent PP during non-selective HBP with base to apical activation. Correction of the LBBB during HBP identifies patients who are likely to achieve maximal electrical resynchronization with LBBP.

Figure 5

Intraprocedural high-output pacing at the level of the His corrects the underlying LBBB.

Figure 6

Demonstration of non-selective to selective LBB pacing (transition) in an ischaemic cardiomyopathy patient with a very dilated left ventricle despite the QRS morphology in V1 of only DSP (during NS-LBBP), a phenomenon referred to as ‘functional’ DSP due to slow conduction via the left conduction system. In such a case, a CS lead should be considered because of incomplete resynchronization. (Permissions obtained to reproduce figure.)

Figure 7

(A) Achievement of LBB pacing with reduction in COI coinciding with LBB capture. Although the presence of a terminal R/r in V1 at the left of the screen may have suggested to stop, the COI remained high, and therefore screwing was continued until a reduction in COI was seen. (B) Reduction in COI during screw progression through the septum. Only functional DSP obtained despite progression through the entire septum through to perforation to the left ventricle (as exhibited by loss of capture on the final beat).

Figure 8

Kinking of the sheath can rarely occur during cephalic vein approach. Ultimately switched to axillary vein puncture for improved sheath reach and apposition.

Figure 9

Tricuspid valve angiography with the nine-partition method for fluoroscopic-guided implant.

Figure 10

Available sheaths for conduction system pacing. (A) Boston Scientific sheaths: SSPC1–4: 40 cm working lengths, inner diameter 8Ff SSPC NXT 2.5 and Y working lengths 42 cm, inner diameter 7 Fr, and outer diameter 9 Fr. (B) Abbott sheaths: CPS locator 3D and direct 3D, working length 42 cm, inner diameter 7 Fr, and outer diameter 9 Fr. (C) Abbott CPS locator 3D medium and large extra-long, working length 45 cm, and inner and outer diameters 7 Fr and 9 Fr, respectively. (D) Biotronik Selectra 3D: two lengths (39 and 42 cm) and three curves (40, 55, and 65 mm). Inner diameter 7.3 Fr. (E and F) Medtronic C315His fixed sheath, 43 cm working length and inner and outer diameters 5.4 Fr and 7.0 Fr. C304His deflectable sheath working length 43 cm. Inner and outer diameters 5.7 Fr and 8.4 Fr.

Figure 11

Lead behaviour during penetration of the interventricular septum. Both drill and screwdriver effects can result in perforation.

Figure 12

Different programmed atrio-ventricular delays during left bundle branch pacing in a patient with baseline LBBB, exhibiting fusion with intrinsic right bundle.