Rate or Rhythm Control in CRT: the RHYTHMIC Study (RHYTHMIC)

70 patients with heart failure, AF and CRT with BiV<95% will be randomised to either AF ablation or AV node ablation. Evaluation at 6 months with echocardiography and clinical assessment.

Study Overview

• Status: Recruiting
• Conditions: Heart Failure; Atrial Fibrillation
• Intervention / Treatment: Procedure: AF catheter ablation; Procedure: AV node ablation

Detailed Description

70 patients with heart failure, AF and CRT with BiV<95% will be recruited from outpatient clinic, pacing clinic or inpatient wards. Patients will be consented and will undergo baseline investigation with a transthoracic 2D echocardiogram, ECG, blood tests, cardiac CT with perfusion imaging, 6 minute walk test (6MWT), cardio-pulmonary exercise test (CPET) and Minnesota Living with Heart Failure Questionnaire. Patients who are successfully screened will be randomized 1:1 to receive AF catheter ablation rhythm control or AV-node ablation rate control.

Ablation Procedure:

Patients will receive either AF catheter ablation or AV-node ablation during the procedure. Patients randomised to AF catheter ablation will receive isolation of all four pulmonary veins and additional lesions, considered indicated by the operator. The procedure will be classified as successful if all four veins are isolated and the patient is in sinus rhythm. Patients may undergo DC-cardioversion under sedation if they remain in atrial fibrillation. AV-node ablation will be performed in line with current standard of care. Patients will also undergo additional research investigations at the time of ablation as follows:

Acute Haemodynamic Study:

All patients will also undergo an acute haemodynamic study with pressure wire assessment of both the right ventricle and the left ventricle at the start and end of the procedure. This involves inserting pressure wires into the RV via a vein in the groin and into the LV via an artery in the wrist or the groin. This will provide novel information on how AF catheter ablation and AV-node ablation affect cardiac contractility.

Invasive Electroanatomical Mapping (Optional):

This is an optional additional procedure that patients may opt into at the time of recruitment. This is performed during the ablation procedure with mapping catheters and software which are CE marked and already in clinical use. Mapping of all four cardiac chambers will be performed. This will be achieved via a vein and an artery in the groin. This will provide novel information on how AF catheter ablation and AV-node ablation affect electrical activation of the atria and ventricles.

Follow-up:

Patients will undergo a 2D transthoracic echocardiogram and ECG 1 week post ablation. Patients will then be followed up at 6 months with 2D transthoracic echocardiogram, ECG, clinical review, CPET, 6MWT, Minnesota Living with Heart Failure Questionnaire and pacing check.

Patients in the AF catheter ablation group who have a recurrence of AF after a 3 month blanking period will be permitted a re-do procedure. The follow-up investigations will take place 6 months after the re-do procedure. If a patient has recurrence of AF after a second ablation procedure and it is felt a third procedure is indicated, this will be performed after the six month follow-up period has ended and the patient is no longer in the study. They will be included in the intention-to-treat analysis.

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Christopher A Rinaldi; Phone Number: 02071889257; Email: aldo.rinaldi@kcl.ac.uk
• Study Contact Backup: Name: Felicity de Vere; Phone Number: 02071889257; Email: felicity.de_vere@kcl.ac.uk

Study Locations

• United Kingdom
  • London, United Kingdom, SE1 7EH
    • Recruiting
    • Guys and St Thomas' NHS Foundation Trust
    • Contact: Christopher A Rinaldi; Phone Number: 02071889257; Email: aldo.rinaldi@kcl.ac.uk
    • Contact: Felicity de Vere; Phone Number: 02071889257; Email: felicity.de_vere@kcl.ac.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Ability to provide informed consent to participate and willing to comply with the clinical investigation plan and follow-up schedule.
• QRS duration >120ms on surface ECG, severe left ventricular systolic impairment (EF≤35%) and clinical symptoms of heart failure despite optimum medical therapy (NYHA class II-IV) at time of CRT implant or upgrade
• Successful CRT implant or upgrade including atrial lead
• Biventricular pacing percentage <95% secondary to atrial fibrillation at least 3 months post implant or upgrade
• Clinically indicated for AV node ablation

Exclusion Criteria:

• Life expectancy <1 year
• Presence of atrial or ventricular thrombus
• Permanent atrial fibrillation
• Mechanical aortic valve replacement
• Severe peripheral vascular disease
• Female participants who are pregnant, lactating or planning pregnancy during the course of the study.
• Participation in other studies with active treatment / investigational arm

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: AF catheter ablation	Procedure: AF catheter ablation; Isolation of all four pulmonary veins and additional lesions, considered indicated by the operator
Active Comparator: AV node ablation	Procedure: AV node ablation; AV node ablation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in ejection fraction	On 2D echocardiography	6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in left ventricular end systolic volume	On 2D echocardiography	6 months
Difference in biventricular pacing percentage	On pacemaker check	6 months
Difference in quality of life	Assessed by Packer's Clinical Composite Score	6 months
Difference in NYHA class	On clinical assessment	6 months
Difference in heart failure symptoms	Assessed by Minnesota Living with Heart Failure Questionnaire	6 months
Difference in 6-minute walk test		6 months
Difference in VO2 max	Assessed via cardio pulmonary exercise test (CPET)	6 months
Difference in AF burden	Assessed via pacing check	6 months

Collaborators and Investigators

• Sponsor: Guy's and St Thomas' NHS Foundation Trust
• Collaborators: King's College London
• Investigators: Principal Investigator: Christopher A Rinaldi, Guy's and St Thomas' NHS Foundation Trust

Study record dates

Study Major Dates

• Study Start (Actual): October 19, 2021
• Primary Completion (Estimated): September 30, 2027
• Study Completion (Estimated): September 30, 2027

Study Registration Dates

• First Submitted: December 10, 2020
• First Submitted That Met QC Criteria: December 10, 2020
• First Posted (Actual): December 11, 2020

Study Record Updates

• Last Update Posted (Actual): January 26, 2026
• Last Update Submitted That Met QC Criteria: January 23, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Pathological Conditions, Signs and Symptoms; Heart Failure; Atrial Fibrillation
• Other Study ID Numbers: 265388

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No