Conduction system pacing is being heavily researched as an alternative to traditional coronary sinus pacing. There were three late-breaking clinical studies at Heart Rhythm 2023 highlighting the success of left bundle branch area pacing (LBBAP), also known as his-bundle pacing (HBP), as an alternative to the standard of care.
To find out more about this trend in electrophysiology (EP), Cardiovascular Business spoke with Juan C. Diaz, MD, a specialist with Clinica Las Vegas in Medellin, Colombia, who presented the results from the SYNCHRONY Collaborative Group late-breaking trial.[1] The trial compared LBBAP vs. standard biventricular pacing (BiVp) for cardiac resynchronization therapy (CRT).
"Most of LBB pacing has been used for the pacing indication of AV block, and we started using it as a first-line therapy in patients with heart failure and had excellent results with it. We think it is a move forward in the treatment of patients with heart failure," Diaz explained. "The results from our study were excellent. We had a significant 38% decrease in the composite outcome of heart failure, hospitalization and all-cause mortality. And this impact was seen very early on from the beginning of the study."
Heart failure symptoms also decreased, with approximately 80% of patients seeing an improvement of at least one functional NYHA heart failure class, compared to just 66% in the BiVp arm of the study.
"In all the years we have done resychronization therapy, there has not been a move that brought the field forward like bundle branch pacing, so we feel this is a really important thing," Diaz explained.
He also said there is physiological evidence showing it improves overall outcomes and left ventricular ejection fraction (LVEF). Many EPs are moving to this new method of pacing because makes physiological sense, he added, and the trials on His pacing at Heart Rhythm 2023 will likely encourage more operators to start using it.
LBB pacing is easy to perform, more efficient than biventricular pacing
Diaz said LBB pacing is simple to do, which was reflected in the study results. Even with it being a new procedure for the EPs, procedure times and fluoroscopy times were shorter than with the current standard of care.
Procedure times should go down even more, he added, as operators become more familiar with the procedure. One issue is that the tools they used to implant LBB pacing leads are not optimized for the procedure, so if vendors can come up with dedicated tools for this, it could make a big impact.
Diaz said fluoroscopy is used to find anatomical landmarks to start, and electromapping is used to confirm the location of the Bundle of His. This navigation is then used to pinpoint where to screw the lead into the ventricular septum.
"Once you get into the LBB area, you can determine if you are pacing the left bundle or if you are just pacing the left ventricular septum," Diaz said.
Study results from the SYNCHRONY Collaborative Group late-breaking trial
In this prospective multicenter study, patients with ischemic or nonischemic cardiomyopathy underwent first-time CRT system implant with either LBBAP or BiVp between January 2020 and August 2022. The primary efficacy outcome was a composite of heart failure (HF)-related hospitalization and all-cause mortality. The primary safety outcome was the occurrence of acute and long-term procedure-related complications. Secondary outcomes included improvement in New York Heart Association (NYHA) functional class, electrocardiographic, and echocardiographic parameters. The study enrolled 371 patients, and 178 were involved in LBB pacing.
The primary outcome occurred in 31 of 128 LBBAP (24.2%) and 103 of 243 BiVp subjects (42.4%). The superiority of LBBAP was driven by a 39.3% risk reduction in HF-related hospitalizations (22.6% vs. 39.5%) without significant difference in all-cause mortality (5.5% vs. 11.9%). Serious procedure-related complications were infrequent, with no difference in long-term procedure-related complications (LBBAP 9.4% vs. BiVp 15.2%). Subjects receiving LBBAP had significantly shorter procedural (95 [IQR 55] vs. 129 [IQR 58] minutes) and fluoroscopy times (12 [IQR 13.7] vs. 21.7 [IQR 15.7] minutes). LBBAP patients more frequently had improvement ≥1 NYHA class (80.4% vs. 67.9), had shorter paced-QRS duration (123.7±18 vs. 149.3±29.1 msec), and had greater changes in LVEF (8.04±9.9 vs. 3.9±7.9; p<0.01) than patients undergoing BiVp.
Two other late-breaking LBB pacing trials at Heart Rhythm 2023
The HOT-CRT trial found greater improvement in left ventricular ejection fraction with HBP CRT compared to biventricular pacing.
Among the 100 randomized patients, HOT-CRT was successful in 48/50 (96%) patients and BVP-CRT in 41/50 (82%) patients.[2] In this pilot study, HOT-CRT was associated with greater improvement in LVEF compared to BVP (12.4% vs 8% increase) at six months.
"This randomized trial demonstrated a strong rate of success between both LBBP and BVP therapies. When looking at both CRT options, we believe this should be a positive signal for physicians who are recommending His-Purkinje conduction system pacing as a treatment for their patients,” presenter Pugazhendhi Vijayaraman, MD, of the Geisinger Heart Institute in Wilkes-Barre, Pennsylvania, said in an HRS statement. “We hope the results of this trial will give physicians an alternative option for consideration that will ultimately improve clinical outcomes and overall patient care."
The late-breaking results from the International LBBAP Collaborative Study Group also showed the new technique is a promising alternative, and may result in superior resynchronization compared to the traditional biventricular pacing.[3] The 1,778-patient study found paced QRSd (ms) in LBBAP was more narrow than baseline (128±19 vs 161±28) and significantly more narrow compared to BiVp (144±23, p<0.001). LVEF improvement was seen in both groups, but was greater in LBBAP compared to BiVp (41±13 vs 37±12%).
"While previous observational data has shown how LBBAP can improve clinical outcomes for patients with class 1 or 2 indications for CRT, this trial includes one of the largest series of patients to date. Although traditional BVP set a high standard-of-care for patients, these findings add to the growing body of evidence showing LBBAP as a successful CRT option that is being seen more frequently in centers across the globe,” said Vijayaraman, who also presented this study.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: dfornell@innovatehealthcare.com