Next Gen Innovator wins award for paper on His bundle pacing
Cardiology Today Next Gen Innovator Parikshit S. Sharma, MD, MPH, FACC, FHRS, and colleagues won the Joan and Douglas P. Zipes Publication of the Year Award presented in May at the Heart Rhythm Society Annual Scientific Sessions.
According to HRS, the award is intended “to honor the seminal article published in HeartRhythm each year that most contributed to major advances in understanding and/or treating cardiac arrhythmias.”
Sharma and colleagues found that permanent His bundle pacing may be a viable strategy for certain patients with HF with reduced ejection fraction requiring cardiac resynchronization therapy, especially as a rescue strategy for patients who fail biventricular pacing.
As the paper’s first author, Sharma, who is assistant professor of medicine and director of the electrophysiology laboratory at Rush University Medical Center, received an honorarium, complimentary registration to HRS, a stipend to cover travel and accommodation costs at HRS and a plaque. The paper’s corresponding author, Pugazhendhi Vijayaraman, MD, FACC, FHRS, director of cardiac electrophysiology at Geisinger Wyoming Valley Medical Center in Wilkes Barre, Pennsylvania, received a plaque.
In an exclusive interview, Sharma discussed the ideas behind the study and its results and implications with Cardiology Today.
Question: What was the purpose of this study?
Answer: Cardiac resynchronization therapy (CRT) is conventionally performed with biventricular (BiV) pacing, using a lead placed in the right ventricle and a second lead typically on the basal-lateral LV epicardium via coronary sinus venous access. This achieves CRT in patients with HF and a low LVEF. We know that His bundle pacing can correct some of the dissynchrony created by bundle branch blocks by placing a lead at the bundle of His, distal to the site of disease. We have demonstrated in the past that this is feasible in between 80% and 90% of cases.
The purpose of this study was to assess if His bundle pacing is a feasible alternative for CRT, either as a rescue strategy or as an upfront (primary) strategy. We assessed the response of His bundle pacing for CRT in a multicenter cohort from five sites, including Rush University Medical Center, where I practice. This was a retrospective analysis of pooled data looking specifically at patients with HFrEF and an indication for CRT, whether it be bundle branch block, more than a 40% pacing burden with low EF, cardiomyopathy or previous nonresponse to BiV CRT.
Q: What kinds of patients were included?
A: Patients that received cardiac resynchronization with His bundle pacing, which we termed His-CRT, were broken down into two groups per the indication. The first group was those who failed a LV lead implantation, whether it be anatomical challenges to get into the coronary sinus or a suboptimal location of the coronary sinus lead. This group was called rescue His bundle pacing for CRT. The second group comprised of patients in whom His bundle pacing was performed as a primary strategy before attempted coronary sinus lead implantation. This group was called primary His bundle pacing for CRT. The study included a total of 106 patients.
We used our standard protocol to achieve His bundle pacing, which was using the Medtronic lead (SelectSecure SureScan MRI model 3830) and its delivery sheath (C315HIS). In the cohort, 33 patients had the rescue strategy and 73 patients had the primary strategy. A bundle branch block pattern, predominantly left bundle branch block, was prevalent in about 45% of patients. The rest of the patients had complete heart block and a need for significant pacing, underwent atrioventricular nodal ablation or had pacing-induced cardiomyopathy and need for an upgrade.
Q: What were your major findings?
A: What we found in the study was that we were successful in accomplishing His-CRT in 95 of 106 patients, about 90% success. Selective His bundle pacing, in which we selectively captured the His bundle alone, was achieved in about 50% of patients. Selective His bundle pacing among patients with bundle branch block was achieved in 43%. The QRS durations were significantly narrower in the His bundle pacing group across the board, whether one looked at the overall study population or whether among patients with bundle branch block or past ventricular pacing.
There was a significant improvement in LVEF from about 30% on average to 44% with His bundle pacing. Those patients with baseline LVEF < 35% demonstrated a significant improvement, from 25% to 40%, while those with a baseline LVEF between 35% and 50% demonstrated about an 11% increase in LVEF, from 44% to 55%, also a significant improvement.
There was also a significant improvement in NYHA functional class in the overall cohort, the rescue-strategy group and the primary-strategy group.
Eight patients underwent His bundle pacing for nonresponsive CRT. Six were responders at the end of the follow-up period.
In conclusion, His bundle pacing was feasible and safe as a rescue strategy for CRT in those patients that failed LV lead placement or nonresponders to BiV-CRT. It was also feasible and safe as a primary strategy for cardiac resynchronization in patients with indications for CRT. It led to a significant improvement in QRS duration, LVEF and NYHA functional class.
While this was a large-scale multicenter experience, a limitation is that it was retrospective, and these were nonconsecutive patients, which could lead to potential bias. Also, there was no direct comparison made to BiV-CRT in a 1:1 strategy. There is need for large-scale, randomized studies before we recommend His bundle pacing as a primary strategy for cardiac resynchronization.
Q: What do the findings mean for patients going forward?
A: His bundle pacing is definitely a good bailout strategy. If a patient fails a coronary sinus lead placement, often their next-best option becomes surgical LV lead placement. That is more invasive. For those patients, one could try His bundle pacing as a bailout strategy before pocket closure, and this could prevent a re-do procedure. In the bailout population, His bundle pacing is reasonable.
There are other groups where His bundle pacing could potentially be considered as an upfront strategy. These include patients undergoing AV nodal ablation and CRT with an intact distal conduction system and a narrow QRS. In such cases, one can take advantage of His bundle pacing and retain normalized ventricular activation. Another population that might potentially benefit from His-CRT is patients with right bundle branch block. In another study we conducted, we looked at His bundle pacing in patients that need CRT and have right bundle branch block. That population does not respond well to BiV-CRT and might do better with His-CRT. There are definite subgroups that might benefit from it. We need more data before we can make it a primary strategy for any indication for CRT.
Q: How did it feel to win the Zipes award?
A: It was a big surprise. It is truly an honor early in your career to have an opportunity to work together with some of the giants in your field. And it is an honor to advance the field in collaboration with my former mentors such as Dr. Vijayaraman, the senior author on the paper, and Kenneth A. Ellenbogen, MD, FACC, FHRS, the Hermes A. Kontos, MD Professor in Cardiology, Pauley Heart Center’s chairman of the division of cardiology and director of clinical cardiac electrophysiology and pacing at Virginia Commonwealth University and the McGuire VA Medical Center. It was a lot of work to put the paper together. It was an incredible honor to receive the award this early in my career. This motivates me, our fellows and our nurses to do more work that advances our field. We have a lot of nurses who are very enthusiastic and also presented at HRS; one won best abstract in the Allied Professionals category. I am also thankful to Richard G. Trohman, MD, MBA, FHRS, the director of cardiac electrophysiology at Rush. – by Erik Swain
For more information:
Parikshit S. Sharma, MD, MPH, FACC , FHRS , can be reached at email@example.com; Twitter: @psharmadoc.
Disclosure: Sharma reports he consults for Abbott, Biotronik and Medtronic and received speaker honoraria from Medtronic.