Cardiac allograft vasculopathy: advances in diagnosis. Cardiol Rev. 2011;19:30-35. [PMID: 21135600 DOI: 10.1097/crd.0b013e3181fbde2f]

Paediatric heart transplantation recipients ≥7 years of age receiving donors with pre-existing coronary atherosclerosis showed progressive coronary artery disease

BACKGROUND

This study aimed to determine the effect of donor-transmitted atherosclerosis on the late aggravation of cardiac allograft vasculopathy in paediatric heart recipients aged ≥7 years.

METHODS

In total, 48 patients were included and 23 had donor-transmitted atherosclerosis (baseline maximal intimal thickness of >0.5 mm on intravascular ultrasonography). Logistic regression analyses were performed to identify risk factors for donor-transmitted atherosclerosis. Rates of survival free from the late aggravation of cardiac allograft vasculopathy (new or worsening cardiac allograft vasculopathy on following angiograms, starting 1 year after transplantation) in each patient group were estimated using the Kaplan-Meier method and compared using the log-rank test. The effect of the results of intravascular ultrasonography at 1 year after transplantation on the late aggravation of cardiac allograft vasculopathy, correcting for possible covariates including donor-transmitted atherosclerosis, was examined using the Cox proportional hazards model.

RESULTS

The mean follow-up duration after transplantation was 5.97 ± 3.58 years. The log-rank test showed that patients with donor-transmitted atherosclerosis had worse survival outcomes than those without (p = 0.008). Per the multivariate model considering the difference of maximal intimal thickness between baseline and 1 year following transplantation (hazard ratio, 22.985; 95% confidence interval, 1.948-271.250; p = 0.013), donor-transmitted atherosclerosis was a significant covariate (hazard ratio, 4.013; 95% confidence interval, 1.047-15.376; p = 0.043).

CONCLUSION

Paediatric heart transplantation recipients with donor-transmitted atherosclerosis aged ≥7 years had worse late cardiac allograft vasculopathy aggravation-free survival outcomes.

Elevated serum vascular endothelial growth factor and development of cardiac allograft vasculopathy in children

BACKGROUND

Cardiac allograft vasculopathy (CAV) is a leading cause of retransplantation and death in pediatric heart transplant recipients. Our aim was to evaluate the association between serum vascular endothelial growth factor-A (VEGF) and CAV development in the pediatric heart transplant population.

METHODS

In this retrospective study performed at a university hospital, VEGF concentrations were measured by enzyme-linked immunosorbent assay in banked serum from pediatric heart transplant recipients undergoing routine cardiac catheterization. In subjects with CAV (n = 29), samples were obtained at 2 time-points: before CAV diagnosis (pre-CAV) and at the time of initial CAV diagnosis (CAV). In subjects without CAV (no-CAV, n = 16), only 1 time-point was used. VEGF concentrations (n = 74) were assayed in duplicate.

RESULTS

Serum VEGF is elevated in pediatric heart transplant recipients before catheter-based diagnosis of CAV (no-CAV mean: 144.0 ± 89.05 pg/ml; pre-CAV mean: 316.2 ± 118.3 pg/ml; p = 0.0002). Receiver-operating characteristic curve analysis of pre-CAV VEGF levels demonstrated an area under the curve of 87.7% (p = 0.0002), with a VEGF level of 226.3 pg/ml predicting CAV development with 77.8% sensitivity and 91.7% specificity. VEGF is similarly elevated in subjects with angiographically diagnosed CAV and in those with normal angiography but intravascular ultrasound (IVUS) evidence of CAV.

CONCLUSIONS

The increase in serum VEGF before onset of detectable CAV is fundamental to its utility as a predictive biomarker and suggests further investigations of VEGF in the pathogenesis of CAV are warranted in the pediatric heart transplant population.

Worsening in Longitudinal Strain and Strain Rate Anticipates Development of Pediatric Transplant Coronary Artery Vasculopathy as Soon as One Year Following Transplant

Transplant coronary artery vasculopathy (TCAV) following orthotopic heart transplantation (OHT) continues to be the primary reason for late graft failure in children. The current gold standard of diagnosis of TCAV is coronary angiography with or without intravascular ultrasound. This study investigates the longitudinal use of speckle-tracking echocardiographic strain imaging as an early non-invasive marker to screen for development of TCAV. Echocardiograms from patients who underwent OHT between 2006 and 2010 at Children's Hospital Colorado (n = 50) were retrospectively assessed. Studies were evaluated at baseline (within a month of transplant), then at each annual clinical follow-up for peak longitudinal (LS) and circumferential (CS) strain, systolic strain rate, and diastolic strain rate using Siemens Velocity Vector Imaging software. Comparisons were made between subjects who did and did not develop TCAV. Mean time to TCAV diagnosis following OHT was 3.2 years (range 1-5.1 years). One year after transplant, significant differences were seen between groups in LS (non-TCAV mean -19.6%, TCAV mean -17.3%, p = 0.03) and longitudinal strain rate (non-TCAV mean -1.7%/s, TCAV mean -1.4%/s, p = 0.04). These differences persisted in subsequent years. Differences in LS preceded the catheterization-based diagnosis of TCAV in pediatric heart recipients and were noted as early as one year post transplant. Additionally, within-subject LS changes may have utility as a non-invasive screening tool to predict those patients at increased risk for development of TCAV.

Cardiac Transplantation in the New Era

The prevalence of heart failure continues to rise due to the aging population and longer survival of people with conditions that lead to heart failure, eg, hypertension, diabetes, and coronary artery disease. Although medical therapy has had an important impact on survival of patients and improving quality of life, heart transplantation remains the definitive therapy for patients that eventually deteriorate. Since the first successful heart transplantation in 1967, significant improvements have been made regarding donor and recipient selection, surgical techniques, and postoperative care. However, the number of potential organ donors has not changed and the growing number of patients in need for transplantation has resulted an increase in waiting list time, and the need for mechanical support. To overcome this issue, the United Network for Organ Sharing implemented an allocation system to prioritize the sickest patients on the list to receive organs. Despite the careful selection of patients, pretransplant immunological screening, and multidrug immunosuppressive regimens, acute and chronic rejections occur and potentially limit graft and patient survival. Treatment for rejection largely depends on the type of rejection, the presence of hemodynamic compromise, and time after transplantation. The limiting factor for long-term graft survival is allograft vasculopathy, an immune-mediated process causing diffuse narrowing of the coronary arteries. Percutaneous coronary intervention and coronary artery bypass surgery are often not an option for this vasculopathy due to the lack of focal lesions, and retransplantation is the only option in appropriate patients.

Reduced progression of cardiac allograft vasculopathy with routine use of induction therapy with basiliximab

Background

Cardiac allograft vasculopathy (CAV) is a major limitation for long-term survival of patients undergoing heart transplantation (HT). Some immunosuppressants can reduce the risk of CAV.

Objectives

The primary objective was to evaluate the variation in the volumetric growth of the intimal layer measured by intracoronary ultrasound (IVUS) after 1 year in patients who received basiliximab compared with that in a control group.

Methods

Thirteen patients treated at a single center between 2007 and 2009 were analyzed retrospectively. Evaluations were performed with IVUS, measuring the volume of a coronary segment within the first 30 days and 1 year after HT. Vasculopathy was characterized by the volume of the intima of the vessel.

Results

Thirteen patients included (7 in the basiliximab group and 6 in the control group). On IVUS assessment, the control group was found to have greater vessel volume (120–185.43 mm³ vs. 127.77–131.32 mm3; p = 0.051). Intimal layer growth (i.e., CAV) was also higher in the control group (27.30–49.15 mm³ [∆80%] vs. 20.23–26.69 mm³ [∆33%]; p = 0.015). Univariate regression analysis revealed that plaque volume and prior atherosclerosis of the donor were not related to intima growth (r = 0.15, p = 0.96), whereas positive remodeling was directly proportional to the volumetric growth of the intima (r = 0.85, p < 0.001).

Conclusion

Routine induction therapy with basiliximab was associated with reduced growth of the intima of the vessel during the first year after HT.

Coronary microvasculopathy in heart transplantation: Consequences and therapeutic implications

Despite the progress made in the prevention and treatment of rejection of the transplanted heart, cardiac allograft vasculopathy (CAV) remains the main cause of death in late survival transplanted patients. CAV consists of a progressive diffuse intimal hyperplasia and the proliferation of vascular smooth muscle cells, ending in wall thickening of epicardial vessels, intramyocardial arteries (50-20 μm), arterioles (20-10 μm), and capillaries (< 10 μm). The etiology of CAV remains unclear; both immunologic and non-immunologic mechanisms contribute to endothelial damage with a sustained inflammatory response. The immunological factors involved are Human Leukocyte Antigen compatibility between donor and recipient, alloreactive T cells and the humoral immune system. The non-immunological factors are older donor age, ischemia-reperfusion time, hyperlipidemia and CMV infections. Diagnostic techniques that are able to assess microvascular function are lacking. Intravascular ultrasound and fractional flow reserve, when performed during coronary angiography, are able to detect epicardial coronary artery disease but are not sensitive enough to assess microvascular changes. Some authors have proposed an index of microcirculatory resistance during maximal hyperemia, which is calculated by dividing pressure by flow (distal pressure multiplied by the hyperemic mean transit time). Non-invasive methods to assess coronary physiology are stress echocardiography, coronary flow reserve by transthoracic Doppler echocardiography, single photon emission computed tomography, and perfusion cardiac magnetic resonance. In this review, we intend to analyze the mechanisms, consequences and therapeutic implications of microvascular dysfunction, including an extended citation of relevant literature data.

The risk of adverse events associated with atropine administration during dobutamine stress echocardiography in cardiac transplant patients: a 28-year single-center experience

BACKGROUND

Although dobutamine stress echocardiography (DSE) is performed in heart transplant patients, the safety profile of atropine administration in DSE in this setting is unclear.

METHODS AND RESULTS

We identified heart transplant patients who received atropine during DSE from January 1984 to August 2011 at our institution and compared them with a propensity-scored matched control group of heart transplant patients who underwent DSE without atropine. Adverse events were defined as significant arrhythmias (sinus arrest, Mobitz type II heart block, complete heart block, ventricular tachycardia, or ventricular fibrillation), hypotension requiring hospitalization, syncope or presyncope, myocardial infarction, and death. Forty-five heart transplant patients (median age 62 years, 82% male) received 0.2-1 mg atropine during DSE. Of these, 1 patient (2.2%) developed temporary complete heart block. No adverse events were identified in the control group of 154 patients who received dobutamine without atropine.

CONCLUSIONS

Our findings suggest that complete heart block can occur infrequently with the administration of atropine in heart transplant patients undergoing DSE. Therefore, patients should be appropriately monitored for these adverse events during and after DSE.

Clinical and angiographic outcomes with everolimus eluting stents for the treatment of cardiac allograft vasculopathy

OBJECTIVES

This study aimed to examine clinical efficacy, safety, and intermediate clinical outcomes with everolimus-eluting stents (EESs) in patients with transplant coronary artery disease (TCAD).

BACKGROUND

TCAD is a major cause of mortality in patients following orthotopic heart transplantation (OHT). Systemic everolimus in OHT patients has been shown to reduce TCAD. The safety and efficacy of an EES, the Xience V, have not been evaluated in this population.

METHODS

Patients post-OHT with hemodynamically significant CAD who underwent percutaneous coronary intervention (PCI) with EES were included. Participants were maintained on dual antiplatelet therapy for 1-year post-PCI. We examined procedural success, in-hospital and 1-year mortality, stent thrombosis, angiographic restenosis, and myocardial infarction rates. All patients had follow-up angiography 1-year after PCI. Target vessel revascularization (TVR), target lesion revascularization (TLR), in-segment restenosis, target vessel failure (TVF), and lumen late loss were noted.

RESULTS

PCI was performed in 34 de novo lesions in 21 patients, and 40 EES were placed. Procedural success rate was 100%. Average stent was 16.5 ± 5.1 mm long and 3.0 ± 0.6 mm in diameter. All patients had angiographic follow-up (409 ± 201 days). There was no stent thrombosis, deaths, or myocardial infarctions during follow-up. Two patients had focal in-stent restenosis. TLR rate was 5.9% (2/34), and TVR rate was 11.1% (3/27). Quantitative coronary angiography (QCA) showed stenosis diameter to be 19.98 ± 17.57%.

CONCLUSIONS

Use of an EES is associated with a low incidence of TVR and TLR in patients with TCAD. Further studies are needed to determine whether PCI with EES changes long-term outcomes.

Primary Angioplasty for Cardiac Allograft Vasculopathy Presenting as ST-Elevation Acute Myocardial Infarction during Endomyocardial Biopsy

Cardiac allograft vasculopathy is still a major issue, with significative mortality in heart transplant patients, and the best therapeutic options are not yet established. The progressively higher survival rates after transplantation have made it a major concern. This is a case report about a patient who underwent cardiac transplantation due to chagasic cardiomiopathy. During an endomyocardial biopsy more than 2 years after the transplant, the patient arrested in ventricular fibrillation, with ST-elevation in anterior leads after defibrillation. The angiography showed total occlusion of proximal left anterior descending artery, promptly treated with primary angioplasty, with excellent angiographic and clinical results.

VEGF-C, VEGF-A and related angiogenesis factors as biomarkers of allograft vasculopathy in cardiac transplant recipients

BACKGROUND

Cardiac allograft vasculopathy (CAV), the major cause of late allograft loss after cardiac transplantation, results from donor-directed cellular and humoral alloimmune responses. Graft vascular endothelial cells (EC) are primary targets of these destructive responses, suggesting that factors associated with endothelial injury and repair could serve as biomarkers of CAV.

METHODS

Using a protein profiler array platform, we measured the levels of 55 angiogenesis-related proteins in sera from 33 adult heart transplant recipients, including 17 with angiographically documented CAV and 16 age- and gender-matched controls without CAV. All patients were >2 years after heart transplant.

RESULTS

The study population was 75% male with a mean age of 62 ± 11 years. On average, patients were 12 ± 5 years after heart transplantation. We found that vascular endothelial growth factor (VEGF)-C, VEGF-A, angiopoietin-2, artemin, urokinase-type plasminogen activator and vasohibin were strongly associated with established CAV (all p < 0.01). Multivariable modeling identified VEGF-C, VEGF-A and platelet factor-4 (PF-4) as significant independent biomarkers of CAV. Furthermore, receiver-operating characteristic curve analysis demonstrated that the combination of all 3 molecules provided outstanding performance for the diagnosis of CAV (area under the curve [AUC] = 0.98; p < 0.001).

CONCLUSIONS

Serum levels of VEGF-C, VEGF-A and PF-4 demonstrate strong associations with established CAV and, together with related angiogenesis factors, may serve as a reliable, non-invasive diagnostic test for CAV in cardiac transplant recipients.

Long-term outcome after heart transplantation predicted by quantitative myocardial blush grade in coronary angiography

The purpose of our study was to investigate whether the quantification of myocardial blush grade (MBG) during surveillance coronary angiography can predict long-term outcome after heart transplantation (HT). In 105 HT recipients who underwent cardiac catheterization, cardiac allograft vasculopathy (CAV) was assessed visually using the ISHLT grading scale (prospective cohort study). MBG was quantified by dividing the plateau of contrast agent gray-level intensity (G(max)) by the time-to-peak intensity (T(max)). In a subgroup (n = 72), myocardial perfusion index by cardiac magnetic resonance imaging (CMR) was assessed. During a mean follow-up duration of 2.7 (standard deviation [SD] 1.0) years, 26 patients experienced cardiac events, including 7 with cardiac death and 19 who underwent coronary revascularization. G(max)/T(max) was related to CAV by ISHLT criteria and to subsequent cardiac events. By univariate analysis, patient age, organ age, CAV, MBG and myocardial perfusion index by CMR were all predictive for cardiac events. Multivariable analysis demonstrated that G(max)/T(max) provided the most robust prediction of cardiac death (hazard ratio [HR] = 0.2, 95% confidence interval [CI] = 0.06-0.64, p < 0.01) and cardiac events (HR = 0.52, 95% CI = 0.32-0.84, p < 0.01), beyond clinical parameters and the presence of CAV. G(max)/T(max) is a valuable surrogate parameter of microvascular integrity, which is associated with cardiac death and revascularization procedures after HT.

Endothelial function in children and adolescents with mucopolysaccharidosis

BACKGROUND

Although coronary artery pathology is a prominent feature of mucopolysaccharidosis (MPS), it may be underestimated by coronary angiography because of its diffuse nature. It is also generally assumed that cardiovascular risk is increased in MPS and reduced following hematopoietic stem cell transplantation (HSCT) or enzyme replacement therapy (ERT), but this has never been formally evaluated. Non-invasive methods of assessing vascular endothelial function may provide a measure of cardiovascular risk in MPS. We evaluated endothelial function, using digital reactive hyperemia, in youth with MPS and in healthy controls.

METHODS

Digital reactive hyperemic index (RHI) was measured in 12 children and adolescents (age 10.3 ± 3.9 years old; 11 boys) with treated MPS and nine age- and gender-matched (11.4 ± 4.0; 8 boys) healthy controls. An independent t-test was used to compare RHI between individuals with MPS and controls.

RESULTS

Children and adolescents with MPS (MPS type II: N = 5; type I: N = 4; type VI: N = 3) whether treated by HSCT (N = 4) or ERT (N = 8) had significantly lower RHI compared to controls (MPS 1.22 ± 0.19 vs. controls 1.46 ± 0.32, p < 0.05).

CONCLUSION

These preliminary findings suggest that children and adolescents with treated MPS have significantly poorer endothelial function when compared to healthy controls. Further investigation into the utility of endothelial function for risk stratification and the long term implications of reduced endothelial function in MPS is warranted.

Early cardiac allograft vasculopathy: are the viruses to blame?

This paper describes a case of early (7 months after transplant) cardiac allograft vasculopathy. This-43-year-old (CMV positive, EBV negative) female patient underwent an orthotopic heart transplant with a (CMV negative, EBV positive) donor heart. She had a history of herpes zoster infection and postherpetic neuralgia in the past. The patient's panel reactive antibodies had been almost undetectable on routine surveillance testing, and her surveillance endomyocardial biopsies apart from a few episodes of mild-to-moderate acute cellular rejection (treated adequately with steroids) never showed any evidence of humoral rejection. The postoperative course was complicated by multiple admissions for upper respiratory symptoms, and the patient tested positive for entero, rhino, and coronaviruses serologies. During her last admission (seven months postoperatively) the patient developed mild left ventricular dysfunction with an ejection fraction of 40%. The patient's endomyocardial biopsy done at that time revealed concentric intimal proliferation and inflammation resulting in near-total luminal occlusion in the epicardial and the intramyocardial coronary vessels, suggestive of graft vasculopathy with no evidence of rejection, and the patient had a fatal ventricular arrhythmia.

Prolonged cold ischemic times and less donor-recipient histocompatibility accelerate graft vascular disease

INTRODUCTION

The long-term success of cardiac transplantation is limited by graft atherosclerosis, also known as graft vascular disease (GVD). GVD is currently the leading cause of late allograft failure in cardiac transplant recipients. The aim of this study was to assess the effects of cold ischemic preservation time (CIPT) and degree of donor-recipient histocompatibility on GVD using a rat heterotopic cardiac transplantation model.

METHODS

ACI-Lewis (n=9), Lewis-F344 (n=9), and Lewis-Lewis (n=9) donor-recipient rat strain combinations were subjected to variable durations of CIPT (0, 4, and 24 hours in University of Wisconsin solution at 4°C) prior to transplantation (n=81 total). The ACI-Lewis allografts differed in both major histocompatibility complex (MHC) class I and II antigens, the Lewis-F344 allograft combination differed in multiple non-MHC antigens, and the Lewis-Lewis isograft combination was syngeneic. Grafts were harvested at 90 days. Intimal area ratio (IAR), intimal thickness score (ITS), and rejection score (RS) were determined for each specimen.

RESULTS

The Lewis-Lewis transplant group had a significantly higher mean RS (P=.036) with 24 hours than with 0 hours of CIPT in this rat heterotopic transplantation model at 90 days. The Lewis-F344 group had a significantly higher IAR (P=.035), ITS (P=.030), and RS (P=.017) with 24 hours than with 0 hours of CIPT. The ACI-Lewis group had high levels of GVD with all durations of CIPT (0, 4, and 24 hours); as a consequence, there were no significant differences in the ITS, IAR, or RS. With 0 hours of CIPT, the ACI-Lewis transplantation group yielded a significantly higher mean IAR (P=.029), ITS (P=.003), and RS (P=5.02×10(-5)) than the Lewis-Lewis group. The Lewis-F344 group had a significantly higher mean RS (P=.003) than the Lewis-Lewis (syngeneic) group. The ACI-Lewis transplantation group had a significantly higher mean IAR (P=.035), and trended toward a higher ITS (P=.058) than the Lewis-F344 group.

CONCLUSION

Longer cold ischemic preservation time and less donor-recipient histocompatibility were associated with more advanced GVD in a rat heterotopic transplantation model, especially when there were multiple MHC mismatches as in ACI-Lewis allografts, but also occurred when there were differences in multiple non-MHC antigens as in the Lewis-F344 allografts. There was a lesser effect of longer cold ischemic time on GVD in the Lewis-Lewis syngeneic (isograft) group, suggesting that greater histocompatibility can mitigate the adverse effects of longer ischemic times.