His bundle pacing trumps right ventricular approach in single-center study

A His bundle pacing (HBP) strategy was associated with a significant reduction in hospitalizations for heart failure when compared to pacemaker implantation via the right ventricle, according to a study published online May 14 in the Journal of the American College of Cardiology.

According to the authors, right ventricular pacing (RVP) is prone to electrical and mechanical dyssynchrony—when variance in cardiac contraction times contributes to heart failure, atrial fibrillation and mortality.

“Recognition of the deleterious effects of RVP has led to a continued search for alternate pacing sites,” wrote Mohamed Abdelrahman, MD, with Geisinger Heart Institute in Pennsylvania, and colleagues. “Permanent HBP is a physiological alternative to RVP. Depolarization of the ventricles through the His-Purkinje system induces normal synchronous ventricular activation and, therefore, avoids the dyssynchrony induced by RVP.”

Two hospitals affiliated with Geisinger Health System participated in the trial, with one attempting to perform HBP and the other performing RVP. They analyzed 332 consecutive patients scheduled for HBP and 433 who underwent RVP.

After a mean follow-up of about two years, the researchers found:

  • HBP was successful in 304 of 332 patients (92 percent), with 17 of the failures attributed to His-ventricular block. The patients for whom HBP was unsuccessful underwent RVP instead.
  • 25 percent of the patients in the HBP group and 32 percent in the RVP group met the primary outcome of death, heart failure hospitalization or an upgrade to biventricular pacing.
  • The difference was driven primarily by patients with a ventricular pacing burden greater than 20 percent. One-fourth of the HBP patients fitting this description met the composite endpoint versus 36 percent of RVP patients.
  • Heart failure hospitalizations were significantly reduced in HBP (12.4 percent versus 17.6 percent), and there was a trend toward reduced mortality (17.2 percent versus 21.4 percent).

Abdelrahman et al. said a study with more patients and a longer follow-up would likely be necessary to detect a significant mortality difference. Even so, they believe the results point toward a definite advantage with HBP.

“These findings addressed the clinical need to determine the best possible ventricular pacing site in patients requiring permanent pacemakers for bradycardia therapy,” they wrote. “This study supports the concept that HBP can prevent ventricular dyssynchrony by facilitating conduction through the native His-Purkinje system.”

Technical challenges and higher pacing thresholds may have prevented HBP from achieving widespread use so far, the authors noted. The strategy was first defined in 2000 and the researchers believe there is a learning curve of about 20 to 25 implants before an operator can be expected to achieve consistent results.

In this study, HBP took an average of 15 minutes longer than RVP and was associated with an additional three minutes of fluoroscopy duration (10 versus seven minutes). This is despite 85 percent of the implants being performed by operators with at least four years’ experience, although a novice operator implanted the rest of the pacemakers under expert guidance with equal procedural success.

Underscoring the severity of the learning curve, the authors of a related editorial highlighted the marked improvement in the HBP success rate from a previous study at Geisinger. A study from 2011 had an 80 percent procedural success rate, which improved to 92 percent in this trial conducted from 2013 through 2016.

That previous study also highlighted the increased need for lead revisions and battery changes among the HBP group, areas that offer further opportunities for improvement.

Still, Kenneth A. Ellenbogen, MD, and Santosh K. Padala, MD—both with the division of cardiology at Virginia Commonwealth University—said HBP should be the preferred technique, particularly among patients expected to have a high pacing burden.

“The compelling results of this analysis provide clear and unambiguous direction for the superiority of HBP over RVP,” the editorialists wrote. “After decades, it is now clear that HBP, by providing true physiological pacing, can trump RVP in our quest to discover the holy grail of pacing. The study results, however, need to be validated in a multicenter, randomized fashion.”