P3359Myocardial flow reserve using 13N ammonia PET for detection of cardiac allograft vasculopathy in heart transplant patients

Purpose Risk stratification and early detection of cardiac allograft vasculopathy (CAV) are essential in heart transplantation patients. CAV is associated with poor outcome in the chronic phase after heart transplantation. CAV presents a diffuse vascular involvement and has been difficult to noninvasively diagnose by the lack of a sensitive method to detect developing vascular pathology in the allograft. The present study investigates the ability of 13N-ammonia PET for detection of CAV in heart transplant patients. Methods Data of adenosine-stress 13N-ammonia PET imaging for thirty-one patients (mean age, 39 years-old) after 11 + 7 years from transplant was analyzed. Five patients had undergone percutaneous coronary intervention (PCI), and the remaining 26 patients had no history of definite myocardial ischemia. Myocardial flow was generated from the time activity curve of left ventricle input and myocardial uptake using 3-compartment model and the first 2 minutes' dataset of list-mode acquisition. Global - myocardial flow reserve (MFR) was calculated by stress to rest flow ratio. Patient with global-MFR 2 was identified as those having significant ischemia. Results The mean Global-MFR of our subjects were 2.3 (1.2 to 3.9). MFR using 13N-ammonia PET significantly decreases in one third of heart transplant patients in chronic stage. Eleven patients with Global-MFR 2 (26%) including three patients having a history of PCI. The proportion of patients with a history of PCI tends to be high with SDS >2 (38% vs 9%, p=0.056). Conclusion This modality using 13N ammonia PET is useful for easily detection of CAV before manifestation of symptomatic myocardial ischemia in heart transplant patients.