Abstract 10987: Is There an Association Between Myocardial Flow Reserve as Measured on Rubidium-82 Positron Emission Tomography and Allograft Rejection in Patients Following Cardiac Transplantation?
Background: Cardiac allograft rejection is a key prognostic determinant following cardiac transplantation. Detection of patients with rejection is reliant on histological sampling of the RV. Absolute myocardial blood flow is accurately quantified by positron emission tomography (PET) using rubidium-82 (Rb-82) and may have a role in this population.
Methods: Patients with prior cardiac transplantation undergoing Rb-82 PET at the Ottawa Heart Institute were prospectively enrolled. Relevant clinical data was obtained from medical records. Values for summed stress score (SSS) as well as the left ventricular ejection fraction (LVEF) at rest and stress were recorded based on visual analysis.
Automated absolute flow quantification both at rest and following dipyrimadole stress was calculated and the ratio of mean global flow at stress and at rest, termed Myocardial Flow Reserve (MFR), was recorded.
The primary end-point was > Grade-1 International Society of Heart and Lung Transplantation (ISHLT) allograft rejection on RV biopsy.
Results: A total of 140 patients (males 80%, mean age 59+/-14, mean follow-up 459+/-271 days) underwent Rb-82 PET scanning from July 2009- February 2013. There were 21 patients with documented > ISHLT-Grade 1 rejection on RV biopsy and global MFR was significantly lower in these patients (1.91+/-0.6 vs. 2.46+/-0.85, p=0.024). Global MFR had an OR of 0.43(95% CI;0.23-0.79, p=0.007) for presence of rejection on multivariate analysis.
There was no difference in mean values for SSS, rest or stress LVEF between patients with a history of rejection compared with those without.
Seven patients died during follow-up, 4 of whom from cardiovascular causes, with 3 admissions for symptomatic heart failure. Global MFR was significantly lower in patients who died (1.64+/-0.5 vs. 2.44+/-0.8, p=0.008) or experienced an outcome (1.67+/-0.5 vs. 2.45+/-0.8, p=0.002). Global MFR was not predictive of outcome or death on multivariate analysis.
Conclusions: Global MFR as measured by Rb-82 PET predicted > ISHLT-Grade 1 rejection on RV biopsy in cardiac transplantation patients; relative perfusion imaging and LVEF did not. The prognostic implications and of these findings requires larger prospective studies for confirmation.
- © 2013 by American Heart Association, Inc.