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Updated: Aug 24, 2025
Author Spotlight: Enhancing Graft Viability Assessment Through Quantitative Metrics and Innovative Reservoir Systems
Published on: August 2, 2024
Noninvasive Physiologic Assessment of Cardiac Allograft Vasculopathy Is Prognostic for Post-Transplant Events
Kevin J Clerkin1, Veli K Topkara2, Maryjane A Farr3
1Milstein Division of Cardiology, Department of Medicine, Columbia University Irving Medical Center, New York, New York, USA.
Insights
Reduced myocardial blood flow reserve (MBFR) in heart transplant recipients indicates a high risk of death or retransplantation, even without epicardial cardiac allograft vasculopathy (CAV). MBFR assessment offers crucial prognostic insights beyond traditional CAV evaluation.
Area of Science:
- Cardiology
- Transplantation Immunology
- Medical Imaging
Background:
- Cardiac allograft vasculopathy (CAV) significantly impairs blood flow and is a major cause of mortality in heart transplant recipients, affecting 50% within 10 years.
- CAV involves both epicardial coronary arteries and microvasculature, leading to reduced myocardial blood flow reserve (MBFR).
Purpose of the Study:
- To evaluate the prognostic value of reduced MBFR and microvascular CAV detected by 13N-ammonia positron emission tomography (PET) in heart transplant recipients.
- To determine the association between MBFR levels and clinical outcomes, including death, retransplantation, and cardiovascular events.
Main Methods:
- 181 heart transplant recipients underwent PET myocardial perfusion imaging to assess CAV and MBFR.
- Patients were categorized based on MBFR: >2.0 (normal) and ≤2.0 (reduced).
- Microvascular CAV was defined by reduced MBFR without significant epicardial CAV on PET or angiography.
Main Results:
- 39% of patients (71/181) had an MBFR ≤2.0.
- Reduced MBFR (≤2.0) was associated with significantly increased risks: 7-fold for death/retransplantation, 12-fold for cardiovascular death, and 10-fold for cardiovascular hospitalization.
- Patients with MBFR ≤2.0 had 302 days less 5-year survival compared to those with MBFR >2.0.
- Microvascular CAV independently predicted a 3.86-fold increased risk of death or retransplantation.
Conclusions:
- Abnormal MBFR, even without epicardial CAV, identifies heart transplant recipients at high risk for adverse outcomes.
- Myocardial blood flow measurements provide valuable prognostic information beyond conventional CAV assessments.
- PET imaging of MBFR is crucial for risk stratification in heart transplant patients.
Background:
Cardiac allograft vasculopathy (CAV) causes impaired blood flow in both epicardial coronary arteries and the microvasculature. A leading cause of post-transplant mortality, CAV affects 50% of heart transplant recipients within 10 years of heart transplant.
Objectives:
This analysis examined the outcomes of heart transplant recipients with reduced myocardial blood flow reserve (MBFR) and microvascular CAV detected by 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging.
Methods:
A total of 181 heart transplant recipients who underwent PET to assess for CAV were included with a median follow-up of 4.7 years. Patients were classified into 2 groups according to the total MBFR: >2.0 and ≤2.0. Microvascular CAV was defined as no epicardial CAV detected by PET and/or coronary angiography, but with an MBFR ≤2.0 by PET.
Results:
In total, 71 (39%) patients had an MBFR ≤2.0. Patients with an MBFR ≤2.0 experienced an increased risk for all outcomes: 7-fold increase in death or retransplantation (HR: 7.05; 95% CI: 3.2-15.6; P < 0.0001), 12-fold increase in cardiovascular death (HR: 12.0; 95% CI: 2.64-54.12; P = 0.001), and 10-fold increase in cardiovascular hospitalization (HR: 10.1; 95% CI: 3.43-29.9; P < 0.0001). The 5-year mean survival was 302 days less than those with an MBFR >2.0 (95% CI: 260.2-345.4 days; P < 0.0001). Microvascular CAV (adjusted HR: 3.86; 95% CI: 1.58-9.40; P = 0.003) was independently associated with an increased risk of death or retransplantation.
Conclusions:
Abnormal myocardial blood flow reserve, even in the absence of epicardial CAV, identifies patients at a high risk of death or retransplantation. Measures of myocardial blood flow provide prognostic information in addition to traditional CAV assessment.
