Absolute Coronary Flow in Patients With Heart Failure With Reduced Ejection Fraction and Left Bundle Branch Block With Cardiac Resynchronization Therapy (FLOW-LBBB)

Cardiac resynchronization therapy (CRT) is an effective therapeutic strategy in patients with symptomatic heart failure (HF) patients with LVEF of ≤35% and left bundle branch block (LBBB). However, approximately one-third of CRT-recipients do not improve after therapy (non-responders), despite meeting the required criteria.

Previous studies have documented that the positive respons to CRT is related to the delayed electrical activation of the left ventricle in patients with LBBB. It has also been illustrated that non-ischemic CRT-candidates with LBBB demonstrate lower regional myocardial blood flow and metabolism in the septum. Additionally, it has been suggested that LBBB can lead to impaired coronary blood flow in the left anterior descending artery (LAD). This observation is based on an echocardiography-based study, that showed that the percentage of diastolic flow duration (%DD) in LAD was shorter in patients with LBBB compared to the control-group and patients with right-ventricular pacing.

It has been demonstrated that CRT has positive effects on septal myocardial perfusion in patients with HF and LBBB. The dominant hypothesis explaining this phenomenon is built on improved septal myocardial work after CRT-implantation, which leads to increased myocardial energy and therefore increased myocardial perfusion. In contrast, it has been suggested that due to re-established synchronous left ventricular electrical activation, CRT reduces the septal intramyocardial pressure in early diastole, leading to a relatively longer antegrade flow duration in LAD. Therefore, the aim of the study is to evaluate the effect of CRT on coronary blood flow in LAD in patients with non-ischemic HF and LBBB.

The investigators hypothesize that increased LV-function after CRT not only is due to resynchronized LV ejection and filling, but also improved coronary flow.

The study aims to enroll 60 patients with heart failure due to non-ischemic dilated cardiomyopathy, LBBB, with or without CRT. All patients meeting the criteria will be recruited from the outpatient clinic at the Department of Cardiology, Aalborg University Hospital.

Invasive flow measurements in the LAD, including fractional flow reserve (FFR), absolute coronary flow and -reserve will be conducted with the CRT on and off, respectively.

Study Overview

• Status: Recruiting
• Conditions: Heart Failure; Left Bundle-Branch Block; Dilated Cardiomyopathy; Cardiac Resynchronization Therapy
• Intervention / Treatment: Procedure: Intracoronary flow and pressure

• Study Type: Observational
• Enrollment (Estimated): 60

Contacts and Locations

• Study Contact: Name: Ashkan Eftekhari; Phone Number: 004528973764; Email: asef@rn.dk
• Study Contact Backup: Name: Sanna Gunnarstein; Phone Number: 004542918950; Email: s.gunnarstein@rn.dk

Study Locations

• Denmark
  • Aalborg, Denmark, 9000
    • Recruiting
    • Aalborg Universityhospital
    • Contact: Ashkan Eftekhari; Email: asef@rn.dk
    • Contact: Sanna Gunnarstein; Phone Number: 42918950; Email: s.gunnarstein@rn.dk

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Probability Sample

Study Population

The study will include patients with heart failure due to non ischemic dilated cardiomyopathy and LBBB, with or without excisting CRT.

Eligible patients who are admitted to the Department of Cardiology or at a visit to the outpatient clinic at the Dept. Cardiology Aalborg University Hospital will be enrolled in the study.

Description

Inclusion Criteria:

• Age > 18
• QRS ≥ 150 ms before implantation
• Heart failure because of dilated cardiomypathy
• Sinus rhythm
• Stable medical therapy
• LBBB
• CRT device

Exclusion Criteria:

• eGFR < 30 ml/min
• Severe valvular heart disease
• Permanent atrial fibrillation or atrial flutter
• Prior PCI or CABG
• Prior myocardial infarction
• Heart failure due to ischemic heart disease
• Other type of device (pacemaker, ICD)
• Not able to give informed consent
• Does not understand Danish

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Other

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Patients with or in need of CRT, left bundle branch block, without ischemic heart disease	Procedure: Intracoronary flow and pressure; Measurement of absolute coronary flow and resistance

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Absolute coronary flow	Measurement of absolute coronary flow with/without CRT-function	During procedure

Collaborators and Investigators

• Sponsor: Ashkan Eftekhari
• Investigators: Principal Investigator: Ashkan Eftekhari, Department of Cardiology, Aalborg University Hospital

Study record dates

Study Major Dates

• Study Start (Actual): September 29, 2022
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): September 30, 2026

Study Registration Dates

• First Submitted: September 29, 2022
• First Submitted That Met QC Criteria: September 29, 2022
• First Posted (Actual): October 3, 2022

Study Record Updates

• Last Update Posted (Actual): June 18, 2025
• Last Update Submitted That Met QC Criteria: June 16, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: fractional flow reserve; absolute coronary flow
• Additional Relevant MeSH Terms: Cardiac Conduction System Disease; Laminopathies; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Genetic Diseases, Inborn; Arrhythmias, Cardiac; Cardiomegaly; Heart Failure; Cardiomyopathies; Cardiomyopathy, Dilated; Bundle-Branch Block; Heart Block
• Other Study ID Numbers: N-20220040

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No