Novel Intravascular Ultrasound Measurements to Assess for Coronary Allograft Vasculopathy in Patients after Orthotopic Heart Transplant

Purpose Among patients who undergo orthotopic heart transplant (OHT), intravascular ultrasound (IVUS) detection of coronary allograft vasculopathy (CAV), defined as ≥ 0.5 mm increase in maximal intimal thickness (Δ MIT), is associated with worse outcomes at 5 years. Other IVUS-derived measurements of arterial plaque, while validated in studies of coronary atherosclerosis, have not been well studied in CAV. Methods From a single-center registry of 279 patients who underwent OHT from 1/09-1/16, a cohort of 10 randomly selected patients who experienced a cardiac event (defined as myocardial infarction or need for percutaneous coronary intervention) within 36 months post-OHT was compared with a control group of 10 randomly selected patients without post-OHT cardiac events. As a proof of concept analysis, IVUS data from baseline & 1 year were assessed to determine evidence of CAV development by Δ MIT & to measure change in Percent Atheroma Volume (PAV) & Total Atheroma Volume Normalized (TAVN). Presence of CAV by Δ MIT & median differences in PAV & TAVN were tested for association with cardiac events, using appropriate univariate statistics. Results Of 20 total patients, 30% were female, and median (IQR) age was 52.5 (42.5, 60.5) years. More patients in the non-event group had CAV at 1 year based on Δ MIT (4 vs. 3). Presence of CAV by Δ MIT & change in TAVN at 1 year were not significantly associated with cardiac events. However, a significant difference in PAV was present in patients within the event cohort, compared to the non-event cohort (median % change [IQR] = 7.6 [1.5, 10.9] vs. 0.6 [0.2, 4.8], p=0.049) (Table). Conclusion While increase in MIT at 1 year predicts worse outcomes at 5 years among patients after OHT, this retrospective proof of concept analysis suggests that PAV could have a stronger association with cardiac events than MIT or TAVN. Further studies are needed to investigate the accuracy & predictive utility of PAV as a measure of total allograft plaque burden.