Post-transplant Coronary Artery Disease Research Articles

Coronary artery intimal thickening and ventricular dynamics in pediatric heart transplant recipients.

Pediatric heart transplant recipients are at risk of posttransplant coronary artery disease known as cardiac allograft vasculopathy (CAV), and also may develop diastolic dysfunction. As CAV begins with a process of progressive intimal thickening, these occult diffuse changes may be detected using optical coherence tomography (OCT). We hypothesized that the development of CAV, as identified via OCT, may be a mechanism of declining ventricular function. Accordingly, the purpose of this study was to assess coronary artery intimal thickening and LV strain in children who have undergone heart transplantation. In 17 children, we analyzed OCT images for coronary intima and media thickness, and cross-sectional area (CSA). We also performed speckle tracking imaging (STI) of the LV to determine longitudinal strain and strain rate, in addition to standard echocardiographic measures. Longitudinal diastolic strain rate was associated with maximum intima thickness (r = -.497, P = .042), intima CSA, (r = -.489, P = .047), maximum media thickness (r = -.503, P = .039), and media CSA (r = -.614, P = .009). The intima maximum thickness, intima/media, and intima/lumen ratios were associated with stroke volume index (Std. β = -0.487, P = .023 and Std. β = -0.488, P = .022, respectively). These findings suggest coronary artery intimal thickening may be mechanistically linked to changes in ventricular function following cardiac transplantation.

Diagnosis of post-transplant coronary artery disease using contrast-enhanced coronary vessel wall imaging at 3.0 Tesla

Summary Coronary plaque characterization at 3.0 Tesla holds great potential for clinical benefit. Coronary allograft vasculopathy (CAV) occurs after heart transplantation and is an immune-mediated diffuse coronary intimal disease. We demonstrate the use of contrast-enhanced inversion-recovery prepared coronary vessel wall MRI at 3T for diagnosis. We further validate the technique in 23 patients with intravascular ultrasound (IVUS), showing an accuracy of 91%. Direct non-invasive imaging has great potential benefit for screening and prevention in these patients. The study has further significant implications for conventional coronary atherosclerosis. Background Coronary Allograft Vasculopathy (CAV) remains the leading cause of late death after heart transplantation in children but is poorly detected by X-ray angiography. Intravascular ultrasound (IVUS) is invasive and costly, which precludes close follow-up. We have previously demonstrated the feasibility of MRI late gadolinium enhancement (LGE) in the coronary vessel wall to detect and grade CAV. The purpose of this study was to demonstrate the clinical utility of the technique and if it could be improved by imaging at 3.0 Tesla. Methods Participants underwent IVUS and cardiac MRI. Maximal intimal thickness (MIT), mean intimal index (MII = mean intimal area/ mean vessel area) and Stanford grade (0 to 4(severe)) were recorded on IVUS. MRI included a coronary magnetic resonance angiogram (CMRA) of the left coronary artery and LGE vessel wall imaging after administration of 0.2 mmol/kg Gadolinium. Participants were randomised to 3T or 1.5T (Achieva, Philips Healthcare, Best, Netherlands). 32-element cardiac phased-array receiver coils were used. The mean enhancement diameter (ED) and index (Ei= mean enhancement area/ mean vessel area on MRI) was quantified on LGE images fused with CMRA as a roadmap. Additionally, images were scored for inter/intra-observer error in analysis and image quality (0 (not seen) to 4 (sharp image)). Location of LGE on MRI and location of significant intimal thickening on IVUS were also recorded for comparison. Results

Effects of a Mycophenolate Mofetil-Based Immunosuppressive Regimen in Chagas′ Heart Transplant Recipients

Mycophenolate Mofetil (MMF) has increasingly been used in the immunosuppressive protocol of cardiac transplant recipients worldwide because of its superiority in comparison to azathioprine, not only for decreasing the incidence of posttransplant coronary artery disease, but also for improving survival (1). Cardiac transplantation has been recommended for patients with end-stage heart failure secondary to Chagas’ cardiomyopathy (2), the leading cause of chronic heart failure in areas where the disease is endemic (3). Little is known about the impact of a MMF-based immunosuppressive regimen on posttransplantation morbidities as well as on the incidence of side-effects in Chagas′ heart transplant recipients. Thirty-one consecutive heart transplant recipients who survived the perioperative period (30 days after heart transplantation) at our Institution from September 2000 to December 2005 were given MMF as immunosuppressant along with a calcineurin inhibitor and prednisone. We have not analyzed data of the perioperative period because of the potential for confounding factors related to the cardiac procedure itself and MMF use. Ten (32%) patients who had a positive indirect immunofluorescence test for Chagas′ disease were compared to 21 (68%) non- Chagas’ disease patients regarding number of rejection and infection episodes, cardiac allograft vasculopathy, malignancy, and bone marrow and gastrointestinal side effects. Median follow up was 917 days (489 to 1607) in Chagas′ disease and 798 days (495 to 1636) in non-Chagas′ disease patients (P>0.05). One patient in the Chagas’ disease group and three patients in the non-Chagas’ disease group died during the study period (P>0.05). Table 1 lists posttransplant morbidities in Chagas’ disease and non- Chagas’ disease patients. Trypanosoma cruzi (T. cruzi) infection reactivation (treated with benznidazole, 5 mg/kg, bid, for 60 days) was detected in biopsy samples from the heart or subcutaneous tissue in 9 (90%) out of 10 Chagas′ heart transplant recipients.TABLE 1: Comparison of posttransplant morbidities in Chagas’ disease (n=10) and in non-Chagas’ disease (n=21) patientsThis study clearly shows that a MMF-based immunosuppressive regimen is associated with an incidence of posttransplant morbidities in Chagas’ disease patients similar to that found in non-Chagas’ disease patients. Importantly, infection episodes were less frequently found in Chagas’ disease than in non-Chagas’ disease patients, and the incidence of rejection episodes graded 3A or more (4) was similar in both groups. However, since the sample size was small, our encouraging results about efficacy and safety of a MMF-based immunosuppressive regimen in Chagas’ disease patients need to be confirmed in larger, prospective studies. A high incidence of T. cruzi infection reactivation was observed in Chagas’ disease patients. This is in accordance with the study by Bacal et al. (5) who found a high incidence of parasite infection reactivation in Chagas’ disease patients on a MMF-based immunosuppressive regimen. Since we have not measured mycophenolic acid plasma levels (6), it is conceivable that over-immunosuppression caused by a fixed daily dose of MMF has allowed T. cruzi infection reactivation to ensue. Nevertheless, a double-blinded, randomized, controlled trial comparing the effects of MMF and azathioprine is necessary to establish the role of MMF in the immunosuppressive protocol of Chagas’ heart tranplant recipients. Reinaldo B. Bestetti Tatiana R. Souza Milena F. Lima Tatiana A. D. Theodoropoulos Division of Cardiology, Hospital de Base, São José do Rio Preto, Brazil José A. Cordeiro Division of Statistics, FAMERP, São José do Rio Preto, Brazil Emmanuel A. Burdmann Division of Nephrology, Hospital de Base, São José do Rio Preto, Brazil

Effects of Early Steroid Withdrawal After Heart Transplantation

Managing immunosuppression is a significant aspect of posttransplantation patient care. Previously, our institution reported that prednisone could be withdrawn in cardiac allograft recipients without jeopardizing midterm survival. We returned to this group of patients to investigate the long-term effects of our steroid taper protocol. We reviewed the records of 162 consecutive cardiac transplant recipients from our institution. Patients who underwent transplantation between 1988 and 1990 were treated with traditional triple-therapy immunosuppression (cyclosporine, azathioprine, and prednisone). Beginning June 1990, we instituted a protocol of early steroid taper with discontinuation by 6 months after transplant. The two groups were comparable with respect to age, sex, ethnicity, cause of heart failure, ischemic time, body mass index, and creatinine at the time of transplantation. Fifty-seven percent of the patients in the early steroid taper group were successfully withdrawn from steroids at 6 months after transplantation. This group had a decreased freedom from and increased frequency of acute rejection (p < 0.01 for each) when compared with the traditional therapy group. There was, however, no difference in freedom from posttransplant coronary artery disease (p = 0.53). The early steroid taper group enjoyed an increased freedom from malignancy (p = 0.01) and trended toward a decreased frequency of infection (p = 0.10) and improved survival (p = 0.06). Steroid withdrawal is possible in 57% of patients at 6 months after transplantation. The institution of an early steroid taper protocol improves the overall freedom from malignancies and may decrease the frequency of infection and prolong overall survival without increasing the risk of posttransplant coronary artery disease.

ABO-Incompatible Living Donor Transplantation: Is It Economically “Compatible”?

The organ shortage remains the most serious constraint in transplantation. Living donor transplantation may be the most important strategy to reduce the organ shortage in kidney-transplantation. ABO blood antigen incompatibility is prime factor preventing living donor transplantation from reaching i

Of Mice and Men: Mouse Models and the Molecular Mechanisms of Post-transplant Coronary Artery Disease

m he threat posed to cardiac transplant recipients by the evelopment of post-transplant allograft coronary arery disease (ACD) is widely recognized. Multi-instituional outcomes studies show that ACD is the primary ause of death in approximately 22% of patients who ie 1 to 3 years post-transplantation. The proportion ncreases to as high as 29% beyond 3 years postransplantation. Yet, of all the major post-transplant henomena that adversely affect the outcome of cariac transplantation, ACD is arguably the most poorly nderstood. This is especially apparent when compared ith the rapid rate at which the understanding of ascular disease in the general population (i.e., “native” therosclerosis) has proceeded in recent years. In large part, this lag in understanding is due to the ncreased complexity of post-transplant disease, in hich established mechanisms of native atherosclerosis re overlaid by alloimmune responses of the recipient irected toward the donor organ. An additional imporant reason is that native atherosclerosis research has een facilitated by the development of a consensus round a relatively small number of standard animal odels, whereas no integrated hypothetical model has ppeared that incorporates the wide array of experiental systems used for the study of ACD. This review has 2 objectives. The first is to discuss he relative differences in current murine experimental ystems and the impact of these differences on the nterpretation of the data generated by them. The econd is to present a unified theoretical model of ACD. ecause of the paucity of data that directly address the echanisms of ACD, elements of the model presented ere are necessarily speculative since some evidence sed for building it must be drawn from experimental odels of other inflammatory diseases. Therefore, until

Expression of lectin-like oxidized low-density lipoprotein receptor-1 in allografted hearts

The pathogenesis of posttransplant coronary artery disease, which is thought to be a major form of chronic rejection after cardiac transplantation, is not fully understood. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) on endothelial cells induces reduction of NO release and up-regulation of adhesion molecules, thereby contributing to the development of vascular atherosclerosis. Herein, we investigated the expression of LOX-1 mRNA in murine allografted hearts that develop diffuse coronary obstruction. Allogeneic (C57BL/6 to BALB/c) and syngeneic (C57BL/6 to C57BL/6) heterotopic cardiac transplants were removed the 10th posttransplant day. LOX-1 mRNA expression was measured by RT-PCR. The heartbeat of the allografts gradually weakened and was almost stopped on day 10, whereas syngeneic hearts continued to pulsate throughout the experiment. Histologically, allografts showed fibrous luminal narrowing of the coronary arteries with severe mononuclear cell infiltration. In contrast, the vascular architecture of syngeneic grafts was almost normal. Marked increase in LOX-1 mRNA expression was observed only in allografts. The results indicate that alloimmune responses induce up-regulation of LOX-1 mRNA in transplanted hearts. Increased LOX-1 may be involved in the progression of obstructive vascular changes.

Pediatric cardiothoracic domino transplantation: the psychological costs and benefits.

The first domino transplants were carried out in the UK in 1987, since which time 52 such procedures have been carried out involving patients within the paediatric cardiothoracic transplant programmes of Harefield and Great Ormond Street Hospitals. Although there are medical advantages in using domino organs--such as the ability for preoperative cross-matching, the heart not being subjected to the biochemical changes of brain death and less post-transplant coronary artery disease in the recipients of domino hearts compared with the recipients of hearts from cadaveric donors--the psychological sequelae for both donor and recipient have not been previously studied. The objective of this study was to identify the main psychological themes for patients involved in the domino programmes at the two hospitals, focusing on those situations where both patients were cared for in the same tertiary centre. Patients and their families were interviewed during routine outpatient clinic visits. Negative themes identified by patients included anxiety, guilt, resentment and anger if either patient had a poor outcome or suffered significant complications, disappointment and low self-esteem for potential donors whose heart was not used and recipient awareness of donor characteristics. Positive themes included gratefulness, comfort for the recipient that someone had not had to die for them directly and the benefit to the donor of giving their heart to another patient. In conclusion, domino transplantation has many medical advantages but there are significant negative psychological concomitants which need to be addressed within the multi-disciplinary management of these patients.

Differential effects of rapamycin, cyclosporine A, and FK506 on human coronary artery smooth muscle cell proliferation and signalling

Background Immunosuppressive agents are at the forefront of preventing organ rejection after transplantation. However, their effects on vascular smooth muscle cell-mediated intimal hyperplasia that occurs in post-transplant coronary artery disease are less well known. Methods and results We investigated the in vitro effects of three immunosuppressive agents cyclosporine A (CsA), FK506 (tacrolimus), and rapamycin (sirolimus, Rapa) on cultured human coronary artery smooth muscle cells (cSMC). CsA inhibited both platelet-derived growth factor (PDGF)-stimulated DNA synthesis and serum-induced proliferation at high concentrations (≥1000 ng/ml). The growth-inhibitory effect of CsA was not altered by anti-TGF-β neutralising antibodies nor was autocrine TGF-β release detected in CsA-treated culture medium. At inhibitory doses, CsA inhibited ERK kinase activation by PDGF, although cytotoxicity was also apparent. Most notably, CsA visibly prevented PDGF-induced altered cell morphology. Rapa was a highly potent and effective inhibitor of cSMC proliferation (reduction in DNA synthesis by >50% from 0.01 ng/ml), acting through inhibition of 70-kDa S6 kinase (p70 S6k). FK506 (1–1000 ng/ml) did not affect cSMC proliferation alone, although a ≥250-fold excess of FK506 over Rapa completely reversed the inhibitory effect of Rapa, confirming that these two agents share a common intracellular receptor, the FK506-binding protein (FKBP). Conclusion Rapa is a powerful inhibitor of cSMC proliferation, while CsA slighly inhibits cSMC proliferation, although only at higher concentrations that may be toxic. These results indicate that therapeutic immunosuppression with Rapa may be additionally useful in prevention or delay of posttransplant coronary artery disease.

Pretransplant Cardiac Investigations in the Irish Renal Transplant Population—The Effectiveness of Our Current Screening Techniques in Predicting Cardiac Events

Background. Coronary artery disease (CAD) is prevalent among endstage renal failure patients and remains the major cause of mortality following renal transplantation. Death with a functioning transplant institute remains the most common cause of kidney graft failure. In this study we attempt to evaluate the effectiveness of the clinical history and current screening techniques available in predicting posttransplant CAD and also assess the role of coronary angiography as a pretransplant screening technique. Methods. Clinical data of 190 renal transplant patients was analyzed. Any clinical history of cardiac disease and all preoperative cardiac screening data was recorded for each patient. The study endpoints were the subsequent development of myocardial infarction (MI), undergoing coronary artery bypass graft (CABG) or death. Results. Factors that were significantly associated with reaching a study end‐point included: age at transplant [Hazard Ratio (HR) 1.91, P < 0.001], history of heart failure (HR 8.22, P < 0.001), presence of CAD on coronary angiography (HR 5.55, P = 0.033), anterior Q wave on electrocardiograph {ECG} (HR 8.6, P < 0.001), carotid artery disease (HR 3.74, P = 0.030) and history of a cerebrovascular accident (HR of 4.32, P = 0.008). The screening techniques of exercise stress testing and echocardiography were not conclusive as predictive variables of outcome. Conclusion. Clinical history and ECG results are good, practical and low‐cost screening methods. In our study exercise stress testing and echocardiography were found to be of limited value. Coronary angiography is appropriate in certain high‐risk groups but not necessary as part of screening in all potential renal transplant recipients.

Have we met the expectations of heart and lung transplantation in children?

Abstract Heart transplantation in children has been a relatively common practice for more than 15 years, and lung transplantation, while in use as a therapeutic modality for a shorter period of time, has 10 years of follow-up data for review. Because they are expensive, time-consuming, labor-intensive procedures, it is reasonable to review what has transpired to evaluate the effectiveness of these procedures, not only from the standpoint of survival, but in the applicability and availability to all who need it, and successful long-term outcomes including quality of life in those who receive it. Health care expense can be justified by improved results that reach expectations in the areas of applicability, availability, and survival. The applicability issue has, in large part, been achieved in transplantation in children. The goal of comprehensive availability can be met by providing alternatives to transplantation, advancing artificial organ research, and overhauling the organ donor programs to improve organ retrieval. To better meet expectations for survival, further advances in transplant immunology and solutions to the problems of post-transplant coronary artery disease and bronchiolitis obliterans will have to occur. Copyright 2003 Elsevier, Inc. All rights reserved.

Have we met the expectations of heart and lung transplantation in children?

Heart transplantation in children has been a relatively common practice for more than 15 years, and lung transplantation, while in use as a therapeutic modality for a shorter period of time, has 10 years of follow-up data for review. Because they are expensive, time-consuming, labor-intensive procedures, it is reasonable to review what has transpired to evaluate the effectiveness of these procedures, not only from the standpoint of survival, but in the applicability and availability to all who need it, and successful long-term outcomes including quality of life in those who receive it. Health care expense can be justified by improved results that reach expectations in the areas of applicability, availability, and survival. The applicability issue has, in large part, been achieved in transplantation in children. The goal of comprehensive availability can be met by providing alternatives to transplantation, advancing artificial organ research, and overhauling the organ donor programs to improve organ retrieval. To better meet expectations for survival, further advances in transplant immunology and solutions to the problems of post-transplant coronary artery disease and bronchiolitis obliterans will have to occur.

Impact of new therapies on the prevalence of coronary artery disease in heart transplant survivors: stanford experience

Background: The major cause of late graft failure is coronary artery disease (CAD). Evolution of post-transplantation (Tx) therapy has added calcium channel blockers (CCB) and statins (STN) in addition to new immunosuppressives. Annual coronary angiograms permitted identification of the onset and severity of CAD and correlation with new treatments. Methods: 647 patients(pts) underwent heart Tx between 11/80-12/97 at Stanford. Patients who survived I year and had at least 1 follow-up(F/U) angiogram were included in the study(n 473). Three cohorts were identified: (A) 11/80-07/86 received cyclosporine, azathioprine, prednisone, (n 151); (B) 07/86-12/93, same as A plus CCB; OKT3, ganciclovir(n 219); (C) 01/94-12/97, same as B plus statin, tacrolimus, Mycophenolate mofetil(n 103). F/U was 5 years. Results: Over all prevalence of TxCAD: Table 1 shows the initial appearance of TxCAD between 3 cohorts (p 0.002). 50% stenosis of TxCAD is shown in table 2 (p 0,001).The incidence of any CAD was 38%, 26% and 27%; and of 50% CAD was 21%, 12%, and 13% incohort A, B and C at 5 years post-Tx respectively. Comparisons of incidence of CAD between cohorts: cohort A vs B p 0.05; A vs C P 0.06; B vs C p 0.7. Similarly, the incidence of 50% CAD in cohort A vs B p 0.01; A vs C P 0.06; B vs C p 0.8. Conclusion: The introduction of CCB, statin and new immunosuppressives and steroid-sparing regimens have reduced the incidence and progression of post-transplant CAD.

Total lymphoid irradiation for refractory rejection in pediatric heart transplantation

Background We evaluated the role of total lymphoid irradiation (TLI) in the management of refractory rejection among pediatric heart transplant patients. Methods Eleven of 298 patients underwent TLI at 6 to 195 months of age and were divided into subgroups: those who survived (group A, n = 7) and those who did not survive beyond 1 year after TLI (group D, n = 4). Non–TLI recipient data were considered as the controls. Results Six out of 11 patients died eventually (54%). TLI was initiated 3 to 107 months after transplantation with a dosage of 600 to 840 cGy. The pre-TLI rejection rate (0.62 ± 0.40 per month) was higher ( p < 0.0001); however, the post-TLI rejection rate (0.24 ± 0.65 per month) showed no significant difference from the control rejection rate. The Cox proportional hazard model found significance for TLI as a risk factor for development of posttransplant coronary artery disease (relative risk, 4.8; 95% CI, 1.1 to 21.3) and posttransplant lymphoproliferative disease (relative risk, 47.9; 95% CI, 1.6 to 1,475.3), respectively. Although the rejection rate decreased after TLI in both groups (group A pre/post, 0.51 ± 0.31/0.06 ± 0.08 per month; group D pre/post, 0.82 ± 0.49/0.57 ± 1.09 per month), significance was obtained only in group A ( p = 0.018). Conclusions TLI was an effective adjunct for reversal of refractory rejection in pediatric heart transplantation by reducing the rejection rate. Great care must be taken for the risk of development of coronary artery disease or lymphoproliferative disease.

Duration of Graft Cold Ischemia Does Not Affect Outcomes in Pediatric Heart Transplant Recipients

Utilizing donor hearts with prolonged graft ischemia may extend the donor pool. The medical records of 363 infants and children, aged 1 day to 17 years, transplanted at Loma Linda University between November 1985 and March 2001, were retrospectively reviewed. Fourteen children received organs with prolonged ischemic times (>8 hours)(PIT) compared with 14 with short ischemic times (< or =90 minutes)(SIT). There were no significant differences when comparing donors for gender, age, weight, cause of death, or duration of cardiopulmonary resuscitation. Preoperative donor shortening fraction (%), as determined by echocardiography, was significantly higher in the SIT group (44.5 versus 36.5%; P=0.006). There were no significant differences between PIT and SIT recipients when comparing age at transplant, weight at transplant, waiting time, weight mismatch, postoperative days on ventilator, duration of inotropic support, and hospital stay. Cardiopulmonary bypass time was significantly longer in the PIT group (140.5 versus 80.5 minute; P=0.001). Median length of follow-up for both groups was approximately 5 years. Five grafts were lost in the PIT group; 7 were lost in the SIT group, with 1 early graft loss in each group. Significant posttransplant coronary artery disease was diagnosed in 2 recipients in each group (PIT: 80 and 42; SIT: 84 and 67 months posttransplant). There was no significant difference between groups in actuarial graft survival. Number of rejection episodes and hospital readmissions during the first posttransplantation year did not differ significantly between groups. Late outcomes were not adversely affected by donor hearts preserved by single dose cold crystalloid cardioplegia with greater than 8 hours of cold ischemia.

Retransplantation of multiple organs: how many organs should one individual receive?

Every year, the transplant waiting list gets longer, while donor numbers essentially remain the same. This makes the responsibility of being good stewards of this precious and limited resource greater than ever. Transplant teams, who are both committed to their patients and aware of this important responsibility, are left to make the difficult and ethical decisions regarding retransplantation. Retransplantation of organs in pediatric patients presents a different set of issues to consider, and the results are promising. This case study presents a boy who received a kidney transplant for focal segmental glomerulosclerosis at age 5. At age 11, because of the recurrence of focal segmental glomerulosclerosis and severe cardiomyopathy, he required a rare combined kidney-heart transplant. At age 17, he developed chronic renal failure and posttransplant coronary artery disease, most likely related to a period of noncompliance, and required yet another combined kidney-heart transplant. He is currently alive and well 2 years after transplantation.

Risk factors associated with posttransplant coronary artery disease in pediatric cardiac transplant recipients

Risk factors associated with posttransplant coronary artery disease in pediatric cardiac transplant recipients

Does transplantation in early infancy protect against Post-Transplant Coronary Artery Disease (PTCAD)? Evaluation by Intravascular Ultrasound (IVUS)

Does transplantation in early infancy protect against Post-Transplant Coronary Artery Disease (PTCAD)? Evaluation by Intravascular Ultrasound (IVUS)

Management of post-transplant coronary artery disease (PTCAD) using intravascular ultrasound (IVUS) improves outcome in pediatric heart transplant (htx) recipients

Management of post-transplant coronary artery disease (PTCAD) using intravascular ultrasound (IVUS) improves outcome in pediatric heart transplant (htx) recipients

Preliminary experience with IVUS in pediatric heart transplant recipients

Post-transplant coronary artery disease (PTCAD) in children leads to late mortality and may be underdetected by coronary angiography (CA). Intravascular ultrasound (IVUS) for PTCAD surveillance has been advocated in adults, but is not routine in children. The purpose of this study was to review our initial experience with IVUS in this cohort. Procedures: Since 1/1/1998 we have performed IVUS in transplant recipients .12 y/o undergoing annual CA. Following baseline CA, IVUS was performed using a 7Fr guide catheter to place a 3.2 Fr ultrasound catheter in each coronary artery. The presence and extent of PTCAD were quantified by determining the maximal intimal thickness (MIT) and highest Stanford score (0-4) for each coronary artery examined. IVUS findings were compared with selective CA. Serial studies were compared and complications were recorded. Results: A total of 25 IVUS studies were performed in 16 pts. Age at IVUS was 18.01/-2.9yrs (12-23yrs); wt. was 59.21/-15.4kg (34-87kg); time since transplantation was 4.31/-2.3yrs (1-9yrs). (Table 1). Follow up IVUS over a 1-2 yr period was available for 10 coronaries in six pts. The Stanford score increased in 5/10 coronaries; the MIT increased in 7/10 coronaries. Complications included 1) a cardiopulmonary arrest in a 13y/o pt due to coronary air embolus during LCA IVUS; she was resuscitated and completely recovered; 2) two pts had prolonged ST elevation ($ 30 minutes) and were monitored overnight. Eight others had transient ST changes. Conclusions: IVUS is much more sensitive than CA in detecting the presence and progression of PTCAD in children. Abnormalities were detected in the majority of pts; however, IVUS may lead to additional complications. Since the clinical utility has not been demonstrated, IVUS should remain investigational in pediatric pts. Table 1