Abstract
Rationale: Cardiac allograft vasculopathy (CAV) is a major cause of graft failure after cardiac transplantation. CAV is characterized by diffuse involvement of epicardial coronary arteries and the microvasculature. Positron emission tomography (PET) allows quantification of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR), which may be accurate markers of CAV severity. We compared the diagnostic and prognostic utility of stress MBF and MFR following cardiac transplantation. Methods: This was a cohort study of consecutive cardiac transplant patients undergoing 82Rb PET scans. Semi-quantitative regional analysis and global measurement of stress MBF and MFR were performed. Associations with all-cause mortality were assessed with multivariable Cox analysis. The diagnostic accuracy for significant CAV (grade 2/3) and prognostic accuracy of stress MBF and MFR, corrected and uncorrected for rate pressure product, were compared. Results: A total of 99 patients, mean age 68.8 and 75.8% male, were followed for a median of 3.4 years, during which 26 deaths occurred. Stress MBF and MFR had similar diagnostic accuracy for significant CAV. However, uncorrected MFR had improved discrimination for all-cause mortality compared to stress MBF (area under the curve 0.748 vs 0.639, P = 0.048). Higher MFR (adjusted hazard ratio (aHR) 0.30, p<0.001), but not stress MBF (aHR 1.14, P = 0. 656), was associated with reduced all-cause mortality. Preserved MFR (>2.0) identified relatively low-risk patients (annual mortality 4.7%) while the presence of left ventricular ejection fraction <45% and MFR<1.7 identified high-risk patients (annual mortality 51.6%). Conclusion: Quantitative PET analysis, and particularly MFR, has diagnostic and prognostic utility. following heart transplantation. Preserved MFR identifies low-risk patients while the presence of multiple abnormal parameters identifies high-risk patients.
- Cardiology (basic/technical)
- Cardiology (clinical)
- PET
- Heart transplant
- Myocardial blood flow
- Myocardial flow reserve
- PET
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.