During the first 4 years of this study, we plan to recruit patients within the first month after OHT. As has become routine at Stanford, study subjects will undergo baseline coronary angiography and IVUS assessment of their left anterior descending coronary artery. Coronary endothelial function will be assessed as well transmyocardial levels of ADMA and other mediators of endothelial function. Blood samples will be obtained for analyzing circulating EPC number and function. Epicardial and microvascular coronary physiology in the left anterior descending coronary artery will be determined by measuring FFR and IMR with a coronary pressure wire(in the adults only). Subjects will then be randomized to either the ACE I(Ramipril), or to placebo, in addition to their usual medications. During years 2 through 5 of this project, study subjects will undergo the above routine invasive assessments at 1 year after OHT. During the 5th year of this project, data analysis and manuscript preparation will occur.

Table 2. Patient Flowchart Time post OHT Event 0-4 Weeks Recruitment and enrollment 4-6 Weeks Baseline angiogram, endothelial function, coronary physiology and IVUS studies 4-6 (at time of baseline)Weeks Baseline blood sampling for circulating EPC studies 4-6 Weeks Randomization to ramipril or placebo to begin one week after baseline studies 5-7 Weeks Titration up of ramipril or placebo Month 3 and month 6: blood sampling for EPC studies. 11-13 Months 1 year angiogram, endothelial function, coronary physiology and IVUS studies 11-13 Months 1 year blood sampling for circulating EPC studies The primary endpoint of the study will be change in plaque volume as determined by IVUS analysis at baseline and 1 year later, between those treated with ramipril compared to those treated with placebo.

Secondary endpoints will include change in circulating EPC number and function, change in ADMA levels,change in coronary endothelium-dependent vasodilation, and change in coronary physiology (FFR and IMR)from baseline to 1 year. Although there are multiple potential mechanisms by which ACE I might reduce CAV, evaluating each of these is beyond the scope of this project. For this reason, we will focus on the likely common final pathway of endothelial dysfunction mediated by dysregulation of ADMA and NOS, as well as changes in EPCs. If this study shows a benefit to ACE I therapy in this population, the goal of future studies will be to determine the exact mechanism by which this occurs and to perform a large, multicenter study comparing ACE I to placebo with hard clinical endpoints. Study visits include two major time points 1) baseline angiogram and IVUS which include recording of angiographic data, lab data, clinical data. 2)assessment at the usual follow up periods post transplant, and these data points will also be collected for research purposes. after base line which usually occurs one month post transplant plus or minus 2 weeks. F/u = q 2 weeks until two months out from tx, then once per month until six months out from TX, then every two months until the patient is 12 months out from TX. Each routine f/u visit includes a physical exam,vital signs, echocardiogram, chest x-ray, a complete metabolic panel ( contains a Creatinine), Complete blood count, immunosuppressant drug blood levels, and a heart biopsy (at the same intervals described above).