High Intensity His Bundle Pacing in Heart Failure Patients With Narrow QRS Outcome Study (HIPPOS)

December 15, 2025 updated by: Grigorios Katsouras, Miulli General Hospital

Cardiac Resynchronization Therapy (CRT) decreases heart failure hospitalizations and mortality and increases left ventricular Ejection Fraction (EF) in patients with dilated cardiomyopathy, left bundle branch block and QRS duration >130msec. His bundle pacing has a similar effect in this category of patients. However, CRT is not beneficial in heart failure (HF) patients with narrow QRS. His-bundle pacing delivers physiological ventricular activation and has been shown to improve acute hemodynamic function in patients with heart failure, a prolonged PR interval, and either a narrow QRS or RBBB through AV delay optimization. We observed an acute hemodynamic effect during application of higher pacing output (3.5 Volts/1 msec) in HF patients with dilated or ischemic cardiomyopathy and narrow QRS independently of the paced QRS duration or AV delay shortening.

This is a single-center, prospective randomized single-blinded study, recruiting a sub-population of patients with heart failure (dilated or ischemic cardiomyopathy, EF<50%, narrow QRS (<110 msec), in optimal medical treatment who have an indication for ICD.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Cardiac Resynchronization Therapy (CRT) decreases heart failure hospitalizations and mortality and increases left ventricular Ejection Fraction (EF) in patients with dilated cardiomyopathy, left bundle branch block and QRS duration >130msec. His bundle pacing has a similar effect in this category of patients. However, CRT is not beneficial in heart failure (HF) patients with narrow QRS. His-bundle pacing delivers physiological ventricular activation and has been shown to improve acute hemodynamic function in patients with heart failure, a prolonged PR interval, and either a narrow QRS or Right Bundle Branch Block (RBBB) through atrioventricular (AV) delay optimization. We observed an acute hemodynamic effect during application of higher pacing output (3.5 Volts/1 msec) in HF patients with dilated or ischemic cardiomyopathy and narrow QRS independently of the paced QRS duration or AV delay shortening.

This is a single-center, prospective randomized single-blinded study, recruiting a sub-population of patients with heart failure (dilated or ischemic cardiomyopathy, EF<50%, narrow QRS (<110 msec), in optimal medical treatment who have an indication for ICD.

All patients will be implanted with a CRT (Cardiac Resynchronization Therapy) defibrillator with one of the leads positioned on the His bundle to obtain direct His-bundle capture. (There will be a 1-month run-in period where the output voltage will be 3.5 Volts/1 or 2V/1msec according to the group so as to obtain stable threshold).

A single-blinded design will then be employed to investigate the effect of His bundle pacing. Patients will be allocated in random order to six-month treatment periods in each of the following two states (1) 3.5 Volts/1 msec pacing output direct His-bundle pacing, AV delay will be programmed in order to obtain a PR interval of 120-140msec; (2)back up only pacing (pacemaker programmed to VVI 30 bpm or AAI(R-DDD(R) 60bpm). Endpoint measurements will be taken at baseline, 1 month run-in period of 3.5 Volts/1 msec or 2V/1msec pacing output and 6 months post randomization. Treating Physicians will be aware of assignment in order to facilitate routine device follow-up. Echocardiographic and electrocardiographic evaluation will be performed in a blinded manner. Treatment allocation will be blinded to the endpoint assessor and the patient.

Patients entering the study will attend for implantation of a CRT pacemaker device with one lead positioned on the His bundle. This will be performed in Miulli General Hospital (and other participating centres) no later than 2 months after the patient's screening visit.

Before the intervention patients will be randomized to either receive active pacing treatment with 3.5 V/1 msec or back up only pacing (pacemaker programmed to VVI 30 bpm or AAI(R)-DDD(R) 60) for 6 months. All patients will be implanted with an Implantable cardioverter defibrillator (ICD) and an ICD lead in the right ventricle (RV) (either RV apex or RV septum). In all patients a pacing lead will be positioned in the right atrium (typically the right atrial appendage). All patients will have a pacemaker lead positioned on the His bundle to obtain direct His-bundle capture.

After implantation of the device there will be a 1-month run-in period that the device will be programmed to deliver His bundle pacing therapy during this period at 3.5 Volts/1msec or 2V/1msec according to the assignment group.

One month after patients are implanted with their device, patients will either receive active pacing treatment with 3.5 V/1 msec or back up only pacing (pacemaker programmed to VVI 30 bpm or AAI(R)-DDD(R) 60bpm) for 6 months. Treatment allocation will be obtained using an Interactive Web Response System (IWRS) programmed with a randomization schedule provided by the trial statistician. Appropriate blocking will be used.

Study Type

Interventional

Enrollment (Estimated)

34

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Italy
    • Bari
      • Acquaviva delle Fonti, Bari, Italy, 70021
        • Recruiting
        • Miulli General Hospital
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 90 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Aged 18 or above
  • Ventricular Ejection Fraction (EF) < 50%; BNP needs to be ≥250ng/L or N Terminal-pro BNP≥600ng/L for patients with EF 36-50% and they should have an ICD indication
  • New York Heart Association (NYHA) class I-IV
  • Narrow QRS duration (≤110ms) on 12 lead ECG

Exclusion Criteria:

  • Other serious medical condition with life expectancy of less than 1 year
  • Lack of capacity to consent
  • Pregnancy
  • Previous aortic valve surgery

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: High intensity His bundle pacing

After implantation of the device there will be a 1-month run-in period that the device will be programmed to deliver His bundle pacing therapy during this period at 3.5V/1msec.

After one month these patients will continue to receive active pacing treatment with 3.5V/1msec.
Device: High Intensity His Bundle pacing
All patients will be implanted with an Implantable cardioverter defibrillator (ICD) and an ICD lead in the right ventricle (either RV apex or RV septum). In all patients a pacing lead will be positioned in the right atrium (typically the right atrial appendage). All patients will have a pacemaker lead positioned on the His bundle to obtain direct His-bundle capture.
Sham Comparator: Back up only ventricular pacing

After implantation of the device there will be a 1-month run-in period that the device will be programmed to deliver His bundle pacing therapy during this period at 2V/1msec.

After one month these patients will receive back up only pacing (pacemaker programmed to VVI 30 bpm or AAI(R)-DDD(R) 50bpm) for 6 months.
Device: High Intensity His Bundle pacing
All patients will be implanted with an Implantable cardioverter defibrillator (ICD) and an ICD lead in the right ventricle (either RV apex or RV septum). In all patients a pacing lead will be positioned in the right atrium (typically the right atrial appendage). All patients will have a pacemaker lead positioned on the His bundle to obtain direct His-bundle capture.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in left ventricular ejection fraction
Time Frame: Baseline pre-intervention, randomisation and 6 months post randomisation
change in left ventricular ejection fraction measured by 2D echo at 6 months compared to baseline
Baseline pre-intervention, randomisation and 6 months post randomisation

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Changes in B-type Natriuretic Peptide (BNP)
Time Frame: Baseline pre-intervention, randomisation and 6 months post randomisation
Measured from blood samples
Baseline pre-intervention, randomisation and 6 months post randomisation
Changes in Quality of Life (QOL) Scores
Time Frame: Baseline pre-intervention,1 and 6 months post randomisation
Change in QOL measured by the Kansas City Cardiomyopathy Questionnaire at 1 and 6 months compared to baseline. Scores are scaled 0-100, where 0 denotes the lowest reportable health status and 100 the highest
Baseline pre-intervention,1 and 6 months post randomisation
Changes in arrhythmia burden
Time Frame: 1 month and 6 months post randomization.
Measured during Pacemaker control
1 month and 6 months post randomization.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Miulli General Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 29, 2023

Primary Completion (Estimated)

February 1, 2026

Study Completion (Estimated)

May 1, 2026

Study Registration Dates

First Submitted

August 4, 2022

First Submitted That Met QC Criteria

August 4, 2022

First Posted (Actual)

August 8, 2022

Study Record Updates

Last Update Posted (Actual)

December 22, 2025

Last Update Submitted That Met QC Criteria

December 15, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • MGH_003

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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