Conditions: Heart Transplant Acute Graft Rejection Chronic Graft Rejection
Keywords: heart transplantation cardiac MRI graft rejection nonspecific allograft dysfunction allograft vasculopathy
Allocation: NON_RANDOMIZED | Intervention model: PARALLEL
Enrollment: 14
Healthy volunteers: no

Brief summary:
The investigators will use cardiac MRI to measure the myocardial perfusion reserve and amount of myocardial edema and fibrosis in heart-transplant patients with nonspecific allograft dysfunction in contrast to those with normal graft function. The investigators hypothesize that patients with nonspecific allograft dysfunction will demonstrate decreased myocardial perfusion reserve, related to microvascular allograft vasculopathy, compared to those with normal graft function.

Detailed description:
Adult heart-transplant patients, excluding those with a GFR less than 30 mL/min/1.73m2, contraindications to MRI and allergies to either regadenoson or gadolinium contrast, will be enrolled over 10 months. Patients will be recruited from UC San Diego and San Diego Veterans Affairs. The investigators will specifically enroll patients with nonspecific allograft dysfunction and patients with normal graft function.

Brief protocol:

Cardiac MRI is performed. Cine images in standard views are obtained. T2 mapping sequences are performed on short axis images. For stress imaging, intravenous regadenoson is given as a 0.4 mg bolus followed by a 5 mL saline flush. After 30 seconds, short-axis images are acquired for 30 consecutive heartbeats with administration of gadolinium. Rest imaging is performed 30 minutes after stress imaging. Lastly, late gadolinium enhancement images are obtained in standard views. Images are analyzed offline by a blinded independent reader. Patients will be followed for one month after enrollment for MACE.

Arms:
arm 1: Patients with nonspecific allograft dysfunction will undergo stress cardiac MRI with regadenoson in addition to performing late gadolinium enhancement and obtaining mean segmental T1 values of the heart. arm 2: Patients with normal graft function will undergo stress cardiac MRI with regadenoson in addition to performing late gadolinium enhancement and obtaining mean segmental T1 values of the heart.

Interventions: intervention 1: Regadenoson intervention 2: Gadolinium intervention 3: Cardiac MRI
Intervention descriptions: intervention 1: For use in stress myocardial perfusion imaging. intervention 2: For use in both perfusion imaging and late gadolinium enhancement. intervention 3: Cardiac MRI will be the imaging modality for perfusion imaging, late gadolinium enhancement and obtaining mean T1 segmental values of the heart.

Protocol document: