His-optimized CRT improves electrical resynchronization in advanced HF patients

His-optimized cardiac resynchronization therapy successfully narrowed QRS duration, improved left ventricular (LV) ejection fraction and heightened functionality in 27 patients with advanced heart failure (HF), according to a study published in Circulation: Arrhythmia and Electrophysiology.

CRT is a critical tool for patients with advanced HF, cardiomyopathy and left bundle branch block (LBBB), first author Pugazhendhi Vijayaraman, MD, and colleagues wrote, and recent work suggests His bundle pacing (HBP) can narrow QRS duration on electrocardiograms, improving clinical outcomes down the line.

“HBP is associated with dramatic QRS narrowing and LV resynchronization comparable to CRT resulting in improved clinical outcomes,” Vijayaraman, of Geisinger Heart Institute in Wilkes-Barre, Pennsylvania, and co-authors wrote. “Further, in patients with advanced cardiomyopathy, LBBB and intraventricular conduction defect may coexist, and resynchronization may be more complete when intervened on at the level of the specialized conduction system by HBP in conjunction with sequential LV pacing in peripheral myocardial areas activated alte.”

The authors hypothesized electrical resynchronization measured by the narrowing of the QRS complex might be accomplished more effectively with HBP followed by sequential LV pacing—a process otherwise known as His-optimized cardiac resynchronization therapy (HOT-CRT).

Vijayaraman et al. attempted permanent HBP in 27 patients, 17 of whom had LBBB, 5 of whom had an intraventricular conduction defect and 5 of whom had right ventricular pacing. All patients were referred for CRT in addition to an LV lead.

In each patient, HBP was followed by LV pacing at a delay equal to a corresponding His-ventricular interval. The researchers measured QRS duration at baseline, as well as during HBP, biventricular pacing and HOT-CRT.

HOT-CRT was successful in 25 of 27 patients, Vijayaraman and co-authors reported. QRS duration at baseline was an average 183 ms, but that narrowed significantly to 162 ms with biventricular pacing, 151 ms during HBP and 120 ms during HOT-CRT. Over a mean follow-up of 14 months, LV ejection fraction also improved, from 24 percent to 38 percent.

“At the time of the device implantation, HOT-CRT resulted in improved electrical resynchronization when compared with conventional biventricular pacing or HBP alone and was felt to be the best clinical option for these patients,” the authors wrote. “The patients reported had advanced, therapy-refractory congestive heart failure (37 percent NYHA class IV), and the baseline QRS was 183 ms, which justified this highly individualized treatment approach.”

Vijayaraman et al. also noted their subjects’ New York Heart Association class improved overall during the study, from 3.3 at baseline to 2.04.  

The team said that while HBP was been proposed recently as an alternative to biventricular pacing to achieve CRT, experts worry about His-Purkinje disease and struggle with a paucity of long-term data proving HBP’s efficacy in patients with LBBB. HOT-CRT, on the other hand, might offer a solution.

“HOT-CRT offers the advantage to use the LV lead in addition to HBP in a potential scenario of progression of conduction disease,” the authors wrote. “HOT-CRT may provide a major advantage in patients with intraventricular conduction defect in whom both biventricular pacing and HBP have not been shown to provide significant clinical benefits.”