Evaluating microvascular resistance in heart transplant patients

Index Microvascular Resistance (IMR) in Heart Transplant Patients

Observational Hospital Miguel Servet · NCT06656065

This study tests if measuring blood flow in the small vessels of heart transplant patients can help reduce the need for repeated heart tissue tests.

Quick facts

Study typeObservational
Enrollment100 (estimated)
Ages18 Years and up
SexAll
SponsorHospital Miguel Servet Academic / other
Locations2 sites (L'Hospitalet de Llobregat, Barcelona and 1 other locations)
Trial IDNCT06656065 on ClinicalTrials.gov

What this trial studies

This observational study aims to assess the index of microvascular resistance (IMR) in heart transplant patients to determine its effectiveness in reducing the need for endomyocardial biopsies (EMB). By measuring IMR, coronary flow reserve (CFR), and fractional flow reserve (FFR) within the first two months and one year post-transplant, the study seeks to improve patient care and minimize complications associated with repeated EMBs. The study will involve multiple centers and will include stable heart transplant patients who provide informed consent.

Who should consider this trial

Good fit: Ideal candidates are heart transplant patients over 18 years old who are stable and can provide informed consent.

Not a fit: Patients with hemodynamic instability, acute cellular rejection, or certain contraindications will not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could lead to fewer invasive procedures and better management of heart transplant patients.

How similar studies have performed: While non-invasive techniques have been explored, this specific approach using IMR has not been previously evaluated in this context.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Heart transplant patients \>18 years.
* Patients who have received and signed informed consent.

Exclusion Criteria:

* Patients with hemodynamic instability after HT, including cardiogenic shock or severe coagulopathy.
* Patients with acute cellular rejection before intracoronary physiological assessment.
* Patients with bronchial asthma or bronchopathy with a positive bronchodilation test, which contraindicates the use of adenosine.
* Patients with epicardial coronary lesions with a resting physiological index ≤0.89 or ≤0.80 at hyperemia.
* Patients unlikely to cooperate or with inability or unwillingness to give informed consent.

Where this trial is running

L'Hospitalet de Llobregat, Barcelona and 1 other locations

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 Heart Transplant RejectionMicrovascular ResistanceHeart TrasplantAcute cellular rejectionIMREndomyocardial biopsy
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.