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Author Spotlight: Enhancing Graft Viability Assessment Through Quantitative Metrics and Innovative Reservoir Systems
Published on: August 2, 2024
Myocardial Perfusion Reserve and Strain-Encoded CMR for Evaluation of Cardiac Allograft Microvasculopathy
Christian Erbel1, Nodira Mukhammadaminova1, Christian A Gleissner1
1Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany.
Objectives:
This study sought to evaluate myocardial perfusion reserve index (MPRI) and diastolic strain rate, both assessed by cardiac magnetic resonance (CMR) as a noninvasive tool for the detection of microvasculopathy.
Background:
Long-term survival of cardiac allograft recipients is limited primarily by cancer and cardiac allograft vasculopathy (CAV). Besides epicardial CAV, diagnosed by coronary angiography, stenotic microvasculopathy was found to be an additional independent risk factor for survival after heart transplantation.
Methods:
Sixty-three consecutive heart transplant recipients who underwent CMR, coronary angiography, and myocardial biopsy were enrolled. Stenotic vasculopathy in microvessels was considered in myocardial biopsies by immunohistochemistry and CAV was graded during coronary angiography according to International Society of Heart and Lung Transplantation criteria. In addition, by CMR microvasculopathy was assessed by myocardial perfusion reserve during pharmacologic hyperemia with adenosine and strain-encoded magnetic resonance using a modified spatial modulation of magnetization tagging pulse sequence in all patients.
Results:
Decreasing MPRI and diastolic strain rates were observed in patients with decreasing microvessel luminal radius to wall thickness ratio and decreasing capillary density (r = 0.45 and r = 0.61 for MPRI and r = 0.50 and r = 0.38 for diastolic strain rate, respectively; p < 0.005 for all). Using multivariable analysis, both MPRI and diastolic strain rate were robust predictors of stenotic microvasculopathy, independent of age, organ age, and CAV by International Society of Heart and Lung Transplantation criteria (hazard ratio: 0.07, p = 0.006 for MPRI; hazard ratio: 0.91, p = 0.002 for diastolic strain rate). Patients without stenotic microvasculopathy in the presence of no or mild CAV (n = 36) exhibited significantly higher median survival free of events, compared with patients with stenotic microvasculopathy in the presence of no or mild CAV (n = 18; p = 0.04 by log rank).
Conclusions:
CMR represents a valuable noninvasive diagnostic tool, which may be used for the early detection of transplant microvasculopathy before the manifestation of CAV during surveillance coronary angiographic procedures.
Insights
Cardiac magnetic resonance (CMR) can detect microvasculopathy in heart transplant recipients. Myocardial perfusion reserve index (MPRI) and diastolic strain rate are key indicators for early diagnosis, improving long-term survival.
Area of Science:
- Cardiology
- Transplantation Medicine
- Diagnostic Imaging
Background:
- Cardiac allograft vasculopathy (CAV) and cancer limit long-term survival in heart transplant recipients.
- Stenotic microvasculopathy is an independent risk factor for survival, distinct from epicardial CAV.
- Early detection of microvasculopathy is crucial for improving patient outcomes.
Purpose of the Study:
- To evaluate cardiac magnetic resonance (CMR) parameters, specifically myocardial perfusion reserve index (MPRI) and diastolic strain rate, for noninvasive detection of microvasculopathy.
- To assess the utility of CMR in identifying transplant microvasculopathy before its clinical manifestation.
- To correlate CMR findings with histological evidence of microvascular disease.
Main Methods:
- Sixty-three heart transplant recipients underwent CMR, coronary angiography, and myocardial biopsy.
- Microvasculopathy was assessed by CMR using MPRI during adenosine hyperemia and strain-encoded MRI.
- Histopathology and coronary angiography were used to confirm microvessel stenosis and CAV grading.
Main Results:
- Decreased MPRI and diastolic strain rates correlated with reduced microvessel radius and capillary density.
- Both MPRI and diastolic strain rate independently predicted stenotic microvasculopathy.
- Patients without microvasculopathy had significantly better event-free survival than those with microvasculopathy, even with mild CAV.
Conclusions:
- CMR is a valuable noninvasive tool for early detection of transplant microvasculopathy.
- MPRI and diastolic strain rate assessed by CMR can identify microvascular disease before CAV is evident on angiography.
- Noninvasive CMR assessment can guide surveillance strategies and potentially improve outcomes in heart transplant recipients.
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