Abstract Body (Do not enter title and authors here): Background: Cardiac allograft vasculopathy (CAV) continues to be a major source of morbidity and mortality in heart transplant patients. Serial coronary angiography is the recommended modality to monitor for CAV after heart transplant.

Research Question: We aimed to characterize the incidence and distribution of CAV on coronary angiography in heart transplant patients.

Methods: In a cohort of 465 patients who had undergone orthotopic heart transplant at a single center, we identified 2451 associated coronary angiograms. Coronary stenosis lesions were extracted to perform CAV grading on each angiogram following the International Society of Heart and Lung Transplantation (ISHLT) grading system. Kaplan-Meier curves were generated for CAV incidence across gender and race. McNemar tests for paired proportions were used to compare involvement of different coronary arteries.

Results: Among 465 patients (age 53.8±12.6 years, 26.9% female, 75.9% white), the mean±SD follow-up time was 5.8±4.5 years, with 2451 associated coronary angiograms (5.3±4.2 angiograms per patient). Over the follow-up period, 156 (33.5%) patients experienced CAV with an average time after transplant for CAV diagnosis of 4.2±3.5 years. CAV incidence ranged from 9.0% at the first angiogram at around one year from the transplant date, to 24.5% at the 5th angiogram at around 5 years from the transplant date. Of those diagnosed with CAV, 12 (7.7%) underwent PCI at time of initial diagnosis and 44 (28.2%) underwent PCI during the total follow-up period. At time of diagnosis, 137 (87.8%) patients had ISHLT Grade I, 14 (9.0%) patients had Grade II, and 5 (3.2%) had Grade III CAV. There were significant differences in vessel involvement with CAV at time of diagnosis – 3.8% presented with left main (LM), 66.0% with left anterior descending (LAD), 27.6% with left circumflex (LCx), and 39.1% with right coronary artery (RCA) involvement, including the branches of each. There was markedly more main vessel (88.4%) compared to branch vessel (26.3%) CAV reported, likely due to limitations of coronary angiography in visualizing small vessel CAV. CAV incidence and severity was not significantly different across sex or race.

Conclusions: Within a large transplant patient cohort, CAV incidence was high and mostly reported in main vessels with the LAD being the most involved. Further work could be done to optimize earlier and more effective detection of CAV.