Coronary blood flow testing in people with reduced ejection fraction and left bundle branch block after CRT

Absolute Coronary Flow in Patients With Heart Failure With Reduced Ejection Fraction and Left Bundle Branch Block With Cardiac Resynchronization Therapy

Observational Aalborg University Hospital · NCT05564689

This work will test whether direct intracoronary measurements of flow and pressure show reduced coronary blood flow in people with low ejection fraction and left bundle branch block who have a CRT device.

Quick facts

Study typeObservational
Enrollment60 (estimated)
Ages18 Years and up
SexAll
SponsorAalborg University Hospital Academic / other
Locations1 site (Aalborg)
Trial IDNCT05564689 on ClinicalTrials.gov

What this trial studies

This observational protocol collects invasive intracoronary flow and pressure measurements (absolute coronary flow and pressure-derived indices) in patients with non-ischemic dilated cardiomyopathy, left bundle branch block, and an implanted CRT device. Measurements focus on the left anterior descending artery and other target vessels to quantify regional blood flow and diastolic flow characteristics. Eligible participants are adults in sinus rhythm with QRS ≥150 ms on stable medical therapy, while patients with ischemic heart disease, prior MI or revascularization, permanent atrial fibrillation, severe valvular disease, or eGFR <30 ml/min are excluded. The investigators will relate flow patterns to ventricular activation and CRT status to explore mechanisms that might explain why some CRT recipients do not improve.

Who should consider this trial

Good fit: Adults with non-ischemic dilated cardiomyopathy, left bundle branch block, sinus rhythm, QRS ≥150 ms, stable medical therapy, and an implanted CRT device who can give informed consent in Danish are ideal candidates.

Not a fit: People with heart failure from ischemic disease, prior myocardial infarction or coronary revascularization, permanent atrial fibrillation, severe valvular disease, eGFR <30 ml/min, another implanted device type, or who cannot consent or understand Danish would not be eligible and would not benefit from participation.

Why it matters

Potential benefit: If successful, the findings could clarify why some CRT recipients fail to improve and help guide better patient selection or device optimization to improve outcomes.

How similar studies have performed: Prior echocardiography and perfusion studies have suggested regional flow and metabolic abnormalities in LBBB and links to CRT response, but direct intracoronary absolute flow measurements in this population are relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Aalborg

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Left Bundle-Branch BlockHeart FailureCardiac Resynchronization TherapyDilated Cardiomyopathyabsolute coronary flowfractional flow reserve
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.