His-bundle pacing gains foothold in heart failure with LBBB

Cardiac resynchronization therapy (CRT) with His-bundle pacing led to successful and lasting cardiac resynchronization in almost three-quarters of patients with symptomatic heart failure (HF) and left bundle branch block (LBBB), shows the His-Alternative study presented at EHRA 2021.  

The current gold standard treatment for symptomatic HF patients with LBBB is biventricular pacing (BiV-CRT), but limitations such as challenge in lead placement due to unfavourable cardiac anatomy can lead to suboptimal synchronization of the heart, according to presenting author Dr Michael Vinther from Copenhagen University Hospital –Rigshospitalet in Copenhagen, Denmark.

“In patients with LBBB, previous studies have indicated that pacing distally in the His-bundle can capture the LBBB and provide resynchronization using the natural conduction system,” he pointed out.

Although His-CRT may not necessarily emerge as a substitute for BiV pacing, the current study indicates that His-CRT may be a feasible alternative to BiV-CRT, highlighted Vinther.

In the single-centre study, 50 patients with NYHA class 2-4 HF despite optimal medical therapy, left ventricular (LV) ejection fraction ≤35 percent, and LBBB were randomized to either His-bundle pacing or BiV pacing as first-line CRT strategy. [J Am Coll Cardiol EP 2021;doi:10.1016/j.jacep.2021.04.003]

Almost three-quarters of the patients (72 percent) treated first-line with His-CRT had successful implantation of a His-lead and maintained correction of the LBBB at 6 months. The remaining 28 percent in whom His-bundle pacing was unsuccessful subsequently crossed over to BiV pacing.

In patients assigned to the BiV-CRT group, LV-lead implantation was successful in 96 percent of patients, with the remaining treated with His-bundle pacing. 

Hence, all patients in the study achieved successful resynchronisation with one or the other CRT methods, reported the investigators.

“His-CRT resulting in significant shortening of QRS width and significant improvements in echocardiographic parameters, as well as symptoms and physical capabilities that were comparable to the improvement seen with BiV CRT,” said Vinther. “[The results indicate] that His-pacing correcting LBBB might be a feasible alternative to conventional CRT-pacing in symptomatic HF patients.”

“This, however, came at the expense of higher pacing thresholds,” he pointed out, to which he added, was a recognized, key limitation of His-CRT.

The pacing thresholds for His-CRT to succeed were higher compared with BiV-CRT at implantation (1.8 vs 1.2 V; p<0.01) — a difference which only widened at 6-month follow-up (2.3 vs 1.4 V; p<0.01). The higher pacing thresholds could lead to more frequent need of replacement for pulse generators — which brings potential implications of higher risk of infections with more frequent changeouts.    

“Longer follow-up time is required to evaluate whether this will pose a clinically relevant problem in the future,” said the researchers.

As this is a single-centre study with relatively small sample size, the researchers cautioned against extrapolating the findings to CRT candidates in general. The study included only patients with LBBB defined by the Strauss criteria and those with severe kidney disease were excluded, they pointed out.