Plasma C-reactive protein as a marker of cardiac allograft vasculopathy in heart transplant recipients

The novel proteomic signature for cardiac allograft vasculopathy

AIMS

Cardiac allograft vasculopathy (CAV) is the major long-term complication after heart transplantation, leading to mortality and re-transplantation. As available non-invasive biomarkers are scarce for CAV screening, we aimed to identify a proteomic signature for CAV.

METHODS AND RESULTS

We measured urinary proteome by capillary electrophoresis coupled with mass spectrometry in 217 heart transplantation recipients (mean age: 55.0 ± 14.4 years; women: 23.5%), including 76 (35.0%) patients with CAV diagnosed by coronary angiography. We randomly and evenly grouped participants into the derivation cohort (n = 108, mean age: 56.4 ± 13.8 years; women: 22.2%; CAV: n = 38) and the validation cohort (n = 109, mean age: 56.4 ± 13.8 years; women: 24.8%, CAV: n = 38), stratified by CAV. Using the decision tree-based machine learning methods (extreme gradient boost), we constructed a proteomic signature for CAV discrimination in the derivation cohort and verified its performance in the validation cohort. The proteomic signature that consisted of 27 peptides yielded areas under the curve of 0.83 [95% confidence interval (CI): 0.75-0.91, P < 0.001] and 0.71 (95% CI: 0.60-0.81, P = 0.001) for CAV discrimination in the derivation and validation cohort, respectively. With the optimized threshold of 0.484, the sensitivity, specificity, and accuracy for CAV differentiation in the validation cohort were 68.4%, 73.2%, and 71.6%, respectively. With adjustment of potential clinical confounders, the signature was significantly associated with CAV [adjusted odds ratio: 1.31 (95% CI: 1.07-1.64) for per 0.1% increment in the predicted probability, P = 0.012]. Diagnostic accuracy significantly improved by adding the signature to the logistic model that already included multiple clinical risk factors, suggested by the integrated discrimination improvement of 9.1% (95% CI: 2.5-15.3, P = 0.005) and net reclassification improvement of 83.3% (95% CI: 46.7-119.5, P < 0.001). Of the 27 peptides, the majority were the fragments of collagen I (44.4%), collagen III (18.5%), collagen II (3.7%), collagen XI (3.7%), mucin-1 (3.7%), xylosyltransferase 1 (3.7%), and protocadherin-12 (3.7%). Pathway analysis performed in Reactome Pathway Database revealed that the multiple pathways involved by the signature were related to the pathogenesis of CAV, such as collagen turnover, platelet aggregation and coagulation, cell adhesion, and motility.

CONCLUSIONS

This pilot study identified and validated a urinary proteomic signature that provided a potential approach for the surveillance of CAV. These proteins might provide insights into CAV pathological processes and call for further investigation into personalized treatment targets.

Donor-derived cell-free DNA is associated with cardiac allograft vasculopathy

BACKGROUND

The role of donor-derived cell-free DNA (dd-cfDNA) in screening for cardiac allograft vasculopathy (CAV) is unknown. We hypothesized that dd-cfDNA correlates with CAV, markers of inflammation, and angiogenesis in stable heart transplant (HT) recipients.

METHODS

Sixty-five HT recipients ≥2 years post-transplant, without recent rejection, were stratified by high (≥0.12%) versus low levels (<0.12%) of dd-cfDNA. A targeted amplification, next-generation sequencing assay (AlloSure^® ; CareDx, Inc.) was used to detect dd-cfDNA. Peripheral blood inflammatory and angiogenesis markers were assessed using a multiplex immunoassay system (Bioplex^® ).

RESULTS

Of 65 patients, 58 patients had a known CAV status and were included. Thirty had high levels of dd-cfDNA (≥0.12%), and 28 had low levels (<0.12%). CAV was present in 63% of patients with high dd-cfDNA vs. 35% with low dd-cfDNA (p = .047). Donor-specific antibodies were present in 25% of patients with high dd-cfDNA vs. 3.8% in those with low dd-cfDNA (p = .03). There were no differences in rejection episodes, inflammatory, or angiogenesis markers. Importantly, dd-cfDNA levels were not different when stratified by time post-transplant.

CONCLUSIONS

Higher dd-cfDNA levels were associated with CAV in stable chronic HT recipients. Further studies are warranted to investigate a possible association between dd-cfDNA levels and CAV severity and whether dd-cfDNA can predict CAV progression.

Cardiac allograft vasculopathy: Differences of absolute and relative intimal hyperplasia in children versus adults in optical coherence tomography

BACKGROUND

Intracoronary imaging enables an early detection of intimal changes. To what extend the development of absolute and relative intimal hyperplasia in intracoronary imaging differs depending on age and post-transplant time is not known.

METHODS

Aim of our retrospective study was to compare findings between 24 pediatric (cohort P) and 21 adult HTx patients (cohort A) using optical coherence tomography (OCT) at corresponding post-transplant intervals (≤5 years: P1 (n = 11) and A1 (n = 10); >5 and ≤ 10 years: P2 (n = 13) and A2 (n = 11),. Coronary intima thickness (IT), media thickness (MT) and intima to media ratio (I/M) were assessed per quadrant. Maximal IT >0.3 mm was considered absolute, I/M > 1 relative intimal hyperplasia.

RESULTS

Compared to A1, I/M was significantly higher in P1 (maximal I/M: P1: 5.41 [2.81-13.39] vs. A1: 2.30 [1.55-3.62], p = 0.005), whereas absolute IT values were comparable. In contrast, I/M was comparable between P2 and A2, but absolute IT were significantly higher in A2 (maximal IT: P2: 0.16 mm [0.11-0.25] vs. A2: 0.40 mm [0.30-0.71], p < 0.001). A2 presented with higher absolute IT (maximal: A1: 0.16 mm [0.12-0.44] vs. A2: 0.40 mm [0.30-0.71], p = 0.02) and I/M (maximal I/M A1: 2.30 [1.55-3.62] vs. A2: 3.79 [3.01-5.62], p = 0.04).

CONCLUSION

Our results suggest an age- and time-dependent difference in the prevalence of absolute and relative intimal hyperplasia in OCT, with an early peak in children and a progressive increase in adults.

Noninvasive biomarkers for prediction and diagnosis of heart transplantation rejection

For most patients with end-stage heart failure, heart transplantation is the treatment of choice. Allograft rejection is one of the major post-transplantation complications affecting graft outcome and survival. Recent advancements in science and technology offer an opportunity to integrate genomic and other omics-based biomarkers into clinical practice, facilitating noninvasive evaluation of allograft for diagnostic and prognostic purposes. Omics, including gene expression profiling (GEP) of blood immune cell components and donor-derived cell-free DNA (dd-cfDNA) are of special interest to researchers. Several studies have investigated levels of dd-cfDNA and miroRNAs in blood as potential markers for early detection of allograft rejection. One of the achievements in the field of transcriptomics is AlloMap, GEP of peripheral blood mononuclear cells (PBMC), which can identify 11 differentially expressed genes and help with detection of moderate and severe acute cellular rejection in stable heart transplant recipients. In recent years, the utilization of GEP of PBMC for identifying differentially expressed genes to diagnose acute antibody-mediated rejection and cardiac allograft vasculopathy has yielded promising results. Advancements in the field of metabolomics and proteomics as well as their potential implications have been further discussed in this paper.

Investigation of the Role of Oxidative Stress and Factors Associated with Cardiac Allograft Vasculopathy in Patients after Heart Transplantation

Oxidative stress is defined as an imbalance between the production of free radicals and their elimination by the antioxidant defense system. However, the role of oxidative stress in cardiac allograft vasculopathy (CAV) has not been fully understood. Therefore, this study is aimed at determining the role of oxidative-antioxidative balance disturbances in patients after HT. Furthermore, we sought to analyze factors associated with the presence of CAV, with particular emphasis placed on oxidative stress markers. The study analyzed data of 194 consecutive patients after HT who underwent routine visits in the Transplantation Clinic between 2015 and 2016. Total oxidant status (TOS) and total antioxidant capacity (TAC) were measured by the method described by Erel. The oxidative stress index (OSI) was defined as the ratio of the TOS to TAC levels. Patients' mean age was 55.4 ± 15.0 years, and 73.4% were men. The frequency of CAV was 50%. The area under the receiver operating characteristic curves indicated a good discriminatory power of TAC and TOS (0.8940 (0.8515-0.9365); 0.8620 (0.8126-0.9114), respectively) as well as excellent discriminatory power of OSI (0.9530 (0.9279-0.9781)) for CAV detection. Multivariate analysis of the Cox proportional hazard model confirmed that OSI (hazard ratio (HR) = 1.294 (1.204-1.391), p < 0.0001), age (HR = 1.023 (1.006-1.041), p = 0.0091), and high-sensitivity C-reactive protein (HR = 1.049 (1.016-1.083), p = 0.0151) were independently associated with CAV presence. In conclusion, TAC and TOS had a good discriminatory power and OSI had excellent strength for detecting CAV. The independent factors of CAV were higher OSI and CRP levels, as well as older recipient age.

Prognostic Value of Biomarkers in Cardiac Allograft Vasculopathy following Heart Transplantation: A Literature Review

Cardiac allograft vasculopathy (CAV), also known as cardiac transplant vasculopathy, is a major determinant of long-term survival among cardiac transplantation recipients. Histologically, CAV is featured by diffuse, concentric thickening of the vascular wall, and primarily affects large and small epicardial coronary arteries, intramyocardial arteries, and veins. Owing to graft denervation, CAV typically follows an insidious course, and patients may not experience classic angina symptoms but instead present with progressive heart failure or ventricular arrhythmias. Recent studies on biomarkers have furthered the knowledge concerning the prediction and prognosis of CAV. Given its association with metabolic, thrombotic, inflammatory, and immunologic markers, CAV is likely to represent a complex multifactorial process that involves both immune-mediated and non-immune-mediated pathways. In order to identify the high-risk patients that would benefit from early intervention, future research is warranted to examine the usefulness of a biomarker panel in CAV risk stratification.

Biomarkers in Advanced Heart Failure: Implications for Managing Patients With Mechanical Circulatory Support and Cardiac Transplantation

Biomarkers have a well-defined role in the diagnosis and management of chronic heart failure, but their role in patients with left ventricular assist devices and cardiac transplant is uncertain. In this review, we summarize the available literature in this patient population, with a focus on clinical application. Some ubiquitous biomarkers, for example, natriuretic peptides and cardiac troponin, may assist in the diagnosis of left ventricular assist device complications and transplant rejection. Novel biomarkers focused on specific pathological processes, such as left ventricular assist device thrombosis and profiling of leukocyte activation, continue to be developed and show promise in altering the management of the advanced heart failure patient. Few biomarkers at this time have been assessed with sufficient scrutiny to warrant broad, universal application, but encouraging limited data and large potential for impact should prompt ongoing investigation.

CXCR4 Antagonist Reduced the Incidence of Acute Rejection and Controlled Cardiac Allograft Vasculopathy in a Swine Heart Transplant Model Receiving a Mycophenolate-based Immunosuppressive Regimen

BACKGROUND

CXC motif chemokine receptor 4 (CXCR4) blockade is pursued as an alternative to mesenchymal stem cell treatment in transplantation based on our previous report that burixafor, through CXCR4 antagonism, mobilizes immunomodulatory mesenchymal stem cells. Here, we explored the efficacy of combining mycophenolate mofetil (MMF)-based immunosuppressants with repetitive burixafor administration.

METHODS

Swine heterotopic cardiac allograft recipients received MMF and corticosteroids (control, n = 10) combined with burixafor as a 2-dose (burixafor2D, n = 7) or 2-dose plus booster injections (burixafor2D + B, n = 5) regimen. The efficacy endpoints were graft survival, freedom from first acute rejection, and the severity of intimal hyperplasia. Each specimen was sacrificed either at its first graft arrest or after 150 days.

RESULTS

After 150 days, all specimens in the control group had died, but 28.5% of the burixafor2D group survived, and 60% of the burixafor2D + B group survived (P = 0.0088). Although the control group demonstrated acute rejection at a median of 33.5 days, the burixafor2D + B group survived without acute rejection for a median of 136 days (P = 0.0209). Burixafor administration significantly attenuated the incidence rate of acute rejection (P = 0.002) and the severity of intimal hyperplasia (P = 0.0097) at end point relative to the controls. These findings were associated with reduced cell infiltrates in the allografts, and modulation of C-reactive protein profiles in the circulation.

CONCLUSIONS

The augmentation of conventional MMF plus corticosteroids with a CXCR4 antagonist is potentially effective in improving outcomes after heart transplantation in minipigs. Future studies are warranted into optimizing the therapeutic regimens for humans.

Levels of High-Sensitivity C-Reactive Protein in Heart Transplant Patients With and Without Periodontitis

OBJECTIVES

The outcomes of heart transplantation are very favorable, but inflammation still plays a critical role in deterioration of chronic transplants. Periodontal diseases are not limited to supporting the structures of the teeth, but they also cause systemic inflammation. Based on the importance of inflammation in heart transplant recipients and the association between periodontal disease and systemic inflammation, this study explored whether periodontitis may be a modifier of serum high-sensitivity C-reactive protein in heart transplant patients.

MATERIALS AND METHODS

Our study included 33 patients who had heart transplant procedures at the Baskent University Hospital. Clinical periodontal parameters were recorded to assess the periodontal status. On the same day as clinical measurements, blood samples were collected to measure the serum levels of highsensitivity C-reactive protein.

RESULTS

Of the 33 heart transplant patients, 9 patients (27.3%) were diagnosed with periodontitis, 4 (12.1%) were periodontally healthy, and 20 (60.6%) had gingivitis. In the group with periodontitis, serum highsensitivity C-reactive protein levels were significantly higher than the periodontally healthy and gingivitis groups (P = .006). In addition, Spearman correlation analyses showed that serum high-sensitivity C-reactive protein was positively correlated with probing depth (r = 0.358; P = .041), clinical attachment level (r = 0.352; P = .045), and gingival recession (r = 0.422; P = .014).

CONCLUSIONS

We found that elevated levels of serum high-sensitivity C-reactive protein in heart transplant patients were associated with periodontitis. Thus, these findings reinforce the need for the inclusion of regular periodontal visits after transplant.

Inflammatory Cytokines, Endothelial Function, and Chronic Allograft Vasculopathy in Children: An Investigation of the Donor and Recipient Vasculature After Heart Transplantation

Chronic allograft vasculopathy (CAV) limits the lifespan of pediatric heart transplant recipients. We investigated blood markers of inflammation, endothelial dysfunction, and damage to both the native and transplanted vasculature in children after heart transplantation. Serum samples were taken from pediatric heart transplant recipients for markers of inflammation and endothelial activation. The systemic vasculature was investigated using brachial artery flow-mediated dilatation and carotid artery intima-medial hyperplasia. CAV was investigated using intravascular ultrasound. Mean intima-media thickness (mIMT) > 0.5 mm was used to define significant CAV. Forty-eight children (25 male) aged 8-18 years were enrolled in the study. Patients were a median (interquartile range) 4.1 (2.2-8.7) years after transplant. Patients had increased levels of circulating IL6 (3.86 [2.84-4.95] vs. 1.66 [1.22-2.63] p < 0.0001), vascular cell adhesion molecule 1 (539 [451-621] vs. 402 [342-487] p < 0.001), intracellular adhesion molecule 1 305 (247-346) vs. 256 (224-294) p = 0.002 and thrombomodulin (7.1 [5.5-8.1] vs. 3.57 [3.03-4.71] p < 0.0001) and decreased levels of tumor necrosis factor-α, E selectin, and P selectin, compared with controls. The systemic vasculature was unaffected. Patients with severe CAV had raised serum von Willebrand factor and decreased serum thrombomodulin. Posttransplant thrombomodulin levels are elevated after transplant but significantly lower in those with mIMT > 0.5 mm. This suggests that subclinical inflammation is present and that natural anticoagulant/thrombomodulin activity is important after transplant.

Risk factors of cardiac allograft vasculopathy

Despite advances in prevention and treatment of heart transplant rejection, development of cardiac allograft vasculopathy (CAV) remains the leading factor limiting long-term survival of the graft. Cardiac allograft vasculopathy etiopathogenesis is not fully understood, but a significant role is attributed to endothelial cell damage, caused by immunological and non-immunological mechanisms. Immunological factors include the differences between the recipient's and the donor's HLA systems, the presence of alloreactive antibodies and episodes of acute rejection. Among the non-immunological factors the most important are the age of the donor, ischemia-reperfusion injury and cytomegalovirus infection. The classical cardiovascular risk factors (diabetes, hypertension, obesity and hyperlipidemia) are also important. This study presents an up-to-date overview of current knowledge on the vasculopathy etiopathogenesis and the role played by endothelium and inflammatory processes in CAV, and it also investigates the factors which may serve as risk markers of cardiac allograft vasculopathy.

Cardiac allograft vasculopathy: diagnosis, therapy, and prognosis

Development of cardiac allograft vasculopathy represents the major determinant of long-term survival in patients after heart transplantation. Due to graft denervation, these patients seldom present with classic symptoms of angina pectoris, and the first clinical presentations are progressive heart failure or sudden cardiac death. Although coronary angiography remains the routine technique for coronary artery disease detection, it is not sensitive enough for screening purposes. This is especially the case in the first year after transplantation when diffuse and concentric vascular changes can be easily detected only by intravascular ultrasound. The treatment of the established vasculopathy is disappointing, so the primary effort should be directed toward early prevention and diagnosis. Due to diffuse vascular changes, revascularization procedures are restricted only to a relatively small proportion of patients with favorable coronary anatomy. Percutaneous coronary intervention is preferred over surgical revascularization since it leads to better acute results and patient survival. Although there is no proven long-term advantage of drug-eluting stents for the treatment of in-stent restenosis, they are preferred over bare-metal stents. Severe vasculopathy has a poor prognosis and the only definitive treatment is retransplantation. This article reviews the present knowledge on the pathogenesis, diagnosis, treatment, and prognosis of cardiac allograft vasculopathy.

Early inflammatory markers are independent predictors of cardiac allograft vasculopathy in heart-transplant recipients

BACKGROUND

Identification of risk is essential to prevent cardiac allograft vasculopathy (CAV) and graft failure due to CAV (GFDCAV) in heart transplant patients, which account for 30% of all deaths. Early CAV detection involves invasive, risky, and expensive monitoring approaches. We determined whether prediction of CAV and GFDCAV improves by adding inflammatory markers to a previously validated atherothrombotic (AT) model.

METHODS AND FINDINGS

AT and inflammatory markers interleukin-6 (IL-6) and C-reactive protein (CRP) were measured in heart biopsies and sera of 172 patients followed prospectively for 8.9±5.0 years. Models were estimated for 5- and 10-year risk using (1) the first post-transplant biopsy only, or (2) all biopsies obtained within 3 months. Multivariate models were adjusted for other covariates and cross-validated by bootstrapping. After adding IL-6 and CRP to the AT models, we evaluated the significance of odds ratios (ORs) associated with the additional inflammatory variables and the degree of improvement in the area under the receiver operating characteristic curve (AUROC). When inflammatory markers were tested alone in prediction models, CRP (not IL-6) was a significant predictor of CAV and GFDCAV at 5 (CAV: p<0.0001; GFDCAV: p = 0.005) and 10 years (CAV: p<0.0001; GFDCAV: p = 0.003). Adding CRP (not IL-6) to the best AT models improved discriminatory power to identify patients destined to develop CAV (using 1st biopsy: p<0.001 and p = 0.001; using all 3-month biopsies: p<0.04 and p = 0.008 at 5- and 10-years, respectively) and GFDCAV (using 1st biopsy: 0.92 vs. 0.95 and 0.86 vs. 0.89; using all 3-month biopsies: 0.94 vs. 0.96 and 0.88 vs. 0.89 at 5- and 10-years, respectively), as indicated by an increase in AUROC.

CONCLUSIONS

Early inflammatory status, measured by a patient's CRP level (a non-invasive, safe and inexpensive test), independently predicts CAV and GFDCAV. Adding CRP to a previously established AT model improves its predictive power.

Ischemic cardiomyopathy is associated with coronary plaque progression and higher event rate in patients after cardiac transplantation

Background

Cardiac allograft vasculopathy is the leading cause of graft failure and death in heart transplant (HTx) recipients; however, the association between the etiology of heart failure (ischemic cardiomyopathy [ICM] or non‐ICM) that led to HTx and progression of cardiac allograft vasculopathy, and adverse events after HTx has not been explored.

Methods and Results

We retrospectively included 165 HTx patients, who were followed‐up with at least 2 virtual histology–intravascular ultrasound examinations after HTx, and grouped them as ICM (n=46) or non‐ICM (n=119). Coronary artery plaque volume was analyzed using virtual histology–intravascular ultrasound, and cardiovascular event data—a composite of myocardial infarction, hospitalization for heart failure and arrhythmia, revascularization, retransplantation, and death including cardiovascular death—were collected from the medical records of all study subjects. ICM patients had significantly higher plaque volume at both first (P=0.040) and follow‐up (P=0.015) intravascular ultrasound examinations. After multivariate adjustment for traditional coronary risk factors, ICM was significantly associated with plaque progression (odds ratio 3.10; CI 1.17 to 9.36; P=0.023). Ten‐year cardiovascular event‐free survival was 50% in ICM patients compared with 84% in non‐ICM patients (log‐rank test P=0.003). In multivariate Cox proportional hazard analysis, ICM was significantly associated with a higher event rate after HTx (hazard ratio 2.02; 95% CI 1.01 to 4.00; P=0.048).

Conclusion

Our study demonstrates that ischemic etiology of cardiomyopathy prior to HTx may be independently associated with plaque progression and higher event rate after HTx.

Toxoplasma gondii serostatus is not associated with impaired long-term survival after heart transplantation

Background

Conflicting data have been reported about the effect of Toxoplasma serostatus on mortality after heart transplantation. Either a positive or a negative recipient Toxoplasma serostatus was found to be associated with increased mortality.

Methods

We evaluated the effects of T. gondii infection on survival of our 582 cardiac allograft recipients operated upon between June 1984 and July 2011.

Results

The 258 Toxoplasma seronegative and 324 seropositive recipients differed in age, pretransplantation diagnosis, ischemia time, renal function, donor Toxoplasma serology, and maintenance immunosuppression. After a median follow-up time of 8.3 years (range, 0–26 years), 117 (45%) seronegative and 219 (67%) seropositive patients died. No difference was found in deaths due to cardiac allograft vasculopathy. After adjustment for all relevant clinical characteristics, the recipient Toxoplasma serostatus was not associated with mortality (hazard ratio, 1.21; 95% confidence interval [CI], 0.95–1.54). With the Toxoplasma serostatus combination donor negative/recipient negative as a reference, univariate hazard ratios for the Toxoplasma serostatus combinations were D+/R- 0.52 (95% CI, 0.37–0.73), D-/R+ 0.65 (95% CI, 0.40–1.05), and D+/R+ 0.78 (95% CI, 0.57–1.07). Multivariate analysis, however, showed that donor Toxoplasma serostatus was not independently associated with mortality.

Conclusions

The Toxoplasma serostatus of both the recipient and donor appeared not to be independent risk factors for mortality after heart transplantation.

Everolimus therapy is associated with reduced lipoprotein-associated phospholipase A2 (Lp-Pla2) activity and oxidative stress in heart transplant recipients

BACKGROUND

Several studies demonstrated decreased severity and incidence of cardiac allograft vasculopathy (CAV) in heart transplant recipients receiving immunosuppressive therapy with everolimus. However, data regarding the influence of everolimus on risk factors predisposing to CAV are hitherto limited. We here systematically evaluated cardiovascular risk factors in heart transplanted patients, who underwent conversion to everolimus or were maintained on conventional therapy with calcineurin inhibitors (CNI).

METHODS

50 Patients receiving everolimus and 91 patients receiving CNI in addition to mycophenolate mofetil and low-dosed steroids were included in the study. CAV risk factors were determined in plasma or urine using standard enzymatic or immunochemical methods.

RESULTS

No significant differences were observed between both groups with regard to lipid (total, LDL- and HDL-cholesterol), metabolic (glucose, insulin), inflammatory (C-reactive protein, IL-6, myeloperoxidase) and cardiac (troponin I, NT-proBNP) risk factors. However, significantly lower activity of lipoprotein-associated phospholipase A2 (Lp-PLA2) and a negative correlation between the Lp-PLA2 activity and the everolimus concentration were observed in plasmas from everolimus-treated patients. Conversion to everolimus significantly lowered Lp-PLA2 activity in heart transplant recipients. Studies in vitro revealed reduced Lp-PLA2 expression in hepatocytes and macrophages pre-exposed to everolimus. In addition, reduced plasma markers of oxidative stress including oxidized LDL, 8-iso-prostaglandin F2α and protein carbonyls were noted in heart transplant recipients receiving everolimus therapy.

CONCLUSION

Our results suggest that everolimus specifically lowers plasma activity and cellular production of Lp-PLA2 and thereby dampens oxidative stress. These effects may additionally contribute to the reduced CAV incidence observed in heart transplant recipients receiving everolimus therapy.

Thoracic organ transplantation: laboratory methods

Although great progress has been achieved in thoracic organ transplantation through the development of effective immunosuppression, there is still significant risk of rejection during the early post-transplant period, creating a need for routine monitoring for both acute antibody and cellular mediated rejection. The currently available multiplexed, microbead assays utilizing solubilized HLA antigens afford the capability of sensitive detection and identification of HLA and non-HLA specific antibodies. These assays are being used to assess the relative strength of donor specific antibodies; to permit performance of virtual crossmatches which can reduce the waiting time to transplantation; to monitor antibody levels during desensitization; and for heart transplants to monitor antibodies post-transplant. For cell mediated immune responses, the recent development of gene expression profiling has allowed noninvasive monitoring of heart transplant recipients yielding predictive values for acute cellular rejection. T cell immune monitoring in heart and lung transplant recipients has allowed individual tailoring of immunosuppression, particularly to minimize risk of infection. While the current antibody and cellular laboratory techniques have enhanced the ability to manage thoracic organ transplant recipients, future developments from improved understanding of microchimerism and graft tolerance may allow more refined allograft monitoring techniques.

Endothelial dysfunction and cardiac allograft vasculopathy

Cardiac allograft vasculopathy remains a major challenge to long-term survival after heart transplantation. Endothelial injury and dysfunction, as a result of multifactorial immunologic and nonimmunologic insults in the donor and the recipient, are prevalent early after transplant and may be precursors to overt cardiac allograft vasculopathy. Current strategies for managing cardiac allograft vasculopathy, however, rely on the identification and treatment of established disease. Improved understanding of mechanisms leading to endothelial dysfunction in heart transplant recipients may provide the foundation for the development of sensitive screening techniques and preventive therapies.

[Diagnosis, prevention and treatment of cardiac allograft vasculopathy]

The major limitation of long-term survival after cardiac transplantation is allograft vasculopathy, which consists of concentric and diffuse intimal hyperplasia. The disease still has a significant incidence, estimated at 30% five years after cardiac transplantation. It is a clinically silent disease and so diagnosis is a challenge. Coronary angiography supplemented by intravascular ultrasound is the most sensitive diagnostic method. However, new non-invasive diagnostic techniques are likely to be clinically relevant in the future. The earliest possible diagnosis is essential to prevent progression of the disease and to improve its prognosis. A new nomenclature for allograft vasculopathy has been published in July 2010, developed by the International Society for Heart and Lung Transplantation (ISHLT), establishing a standardized definition. Simultaneously, the ISHLT published new guidelines standardizing the diagnosis and management of cardiac transplant patients. This paper reviews contemporary concepts in the pathophysiology, diagnosis, prevention and treatment of allograft vasculopathy, highlighting areas that are the subject of ongoing research.

Biomarkers of heart transplant rejection: the good, the bad, and the ugly!

Acute cellular rejection (ACR), antibody-mediated rejection (AMR), and cardiac allograft vasculopathy (CAV) are important limitations for the long-term survival of heart transplant recipients. Although much progress has been made in reducing ACR with modern immunosuppressive treatments and continuous biopsy surveillance, there is still a long way to go to better understand and treat AMR, to enable early detection of patients at risk of CAV, and to reduce the development and sustained progression of this irreversible disease that permanently compromises graft function. This review considers the advances made in ACR detection and treatment allowing a more prolonged survival and the risk factors leading to endothelial injury, dysfunction, inflammation, and subsequent CAV, as well as new treatment modalities for CAV. The review also evaluates the controversies around the definition, pathogenesis, and treatment of AMR. To date, much progress is still needed to significantly reduce post-transplant complications and increase graft and patient survival.

Cardiac allograft vasculopathy: current knowledge and future direction

Cardiac allograft vasculopathy (CAV) is a unique form of coronary artery disease affecting heart transplant recipients. Although prognosis of heart transplant recipients has improved over time, CAV remains a significant cause of mortality beyond the first year of cardiac transplantation. Many traditional and non-traditional risk factors for the development of CAV have been described. Traditional risk factors include dyslipidemia, diabetes and hypertension. Non-traditional risk factors include cytomegalovirus infection, HLA mismatch, antibody-mediated rejection, and mode of donor brain death. There is a complex interplay between immunological and non-immunological factors ultimately leading to endothelial injury and exaggerated repair response. Pathologically, CAV manifests as fibroelastic proliferation of intima and luminal stenosis. Early diagnosis is paramount as heart transplant recipients are frequently asymptomatic owing to cardiac denervation related to the transplant surgery. Intravascular ultrasound (IVUS) offers many advantages over conventional angiography and is an excellent predictor of prognosis in heart transplant recipients. Many non-invasive diagnostic tests including dobutamine stress echocardiography, CT angiography, and MRI are available; though, none has replaced angiography. This review discusses the risk factors, pathogenesis, and diagnosis of CAV and highlights some current concepts and recent developments in this field.

Systemic markers of inflammation are associated with cardiac allograft vasculopathy and an increased intimal inflammatory component

We evaluated an extensive profile of clinical variables and immune markers to assess the inflammatory milieu associated with cardiac allograft vasculopathy (CAV) assessed by intravascular ultrasound (IVUS) and virtual histology (VH). In total, 101 heart transplant (HTx) recipients were included and underwent IVUS/VH examination and measurement of plasma C-reactive protein (CRP), soluble tumor necrosis factor receptor-1, interleukin-6, osteoprotegerin, soluble gp130, von Willebrand factor, vascular cell adhesion molecule-1 (VCAM-1) and neopterin. Mean Maximal Intimal Thickness (MIT) was 0.61 +/- 0.19 mm and mean fibrotic, fibrofatty, dense calcified and necrotic core components were 55 +/- 15, 14 +/- 10, 15 +/- 13 and 17 +/- 9%, respectively. In multivariate analysis, CRP > 1.5 mg/L (OR 4.6, p < 0.01), VCAM-1 > 391 ng/mL (adjusted OR 3.2, p = 0.04) and neopterin > 7.7 nmol/L (OR 3.8, p = 0.02) were independently associated with MIT > 0.5 mm. Similarly, CRP > 1.5 mg/L (OR 3.7, p < 0.01) and VCAM-1 > 391 (OR 2.7, p = 0.04) were independently associated with an increased intimal inflammatory component (dense calcified/necrotic core component > 30%). Advanced CAV is associated with elevated CRP, VCAM-1 and neopterin and the two former biomarkers are also associated with an increased intimal inflammatory component. Forthcoming studies should clarify if routine measurements of these markers can accurately identify HTx recipients at risk of developing advanced CAV and vulnerable lesions.

Acute cellular rejection and the subsequent development of allograft vasculopathy after cardiac transplantation

BACKGROUND

Cardiac allograft vasculopathy (CAV) is primarily immune-mediated. We investigated the role of cellular rejection in CAV development.

METHODS

The study comprised 252 cardiac transplant recipients (mean age, 49.02 +/- 17.05 years; mean follow-up, 7.61 +/- 4.49 years). Total rejection score (TRS) based on the 2004 International Society of Heart and Lung Transplantation R grading system (0R = 0, 1R = 1, 2R = 2, 3R = 3) and any rejection score (ARS; calculated as 0R = 0, 1R = 1, 2R = 1; 3R = 1, or the number of rejections of any grade) were normalized for the total number of biopsy specimens. CAV was defined as coronary stenosis of 40% or more and/or distal pruning of secondary side branches. Thirty-two patients had undergone 3-dimensional intravascular ultrasound (IVUS) at baseline and with virtual histology (VH) IVUS at 24 months.

RESULTS

In univariate analysis, 6-month TRS (hazard ratio [HR], 1.9; 95% confidence interval [CI], 0.99-3.90, p = 0.05) and ARS (HR, 2.22; 95% CI, 1.01-4.95; p = 0.047) were associated with increased risk of CAV. In multivariate analysis, 6-month TRS (HR, 2.84; 95% CI, 1.44-6.91, p = 0.02) was significantly associated with increased risk of CAV onset. The 12- and 24-month rejection scores were not risk factors for the onset of CAV. By Kaplan-Meier analysis, 6-month TRS exceeding 0.3 was associated with a significantly shorter time to CAV onset (p = 0.018). There was direct correlation (r = 0.44, p = 0.012) between TRS at 6 months and the percentage of necrotic core demonstrated by VH-IVUS at 24 months.

CONCLUSION

Recurrent cellular rejection has a cumulative effect on the onset of CAV. The mechanism may be due to increased inflammation resulting in increased plaque burden suggesting a relationship between the immune basis of cellular rejection and CAV.

Assessment of peripheral endothelial-dependent vasodilatation within the first year after heart transplantation

BACKGROUND

Peripheral endothelial dysfunction (ED) has been found in patients with severe heart failure. Whether ED improves after heart transplantation (HTx) is still a matter of controversy.

METHODS

Forearm endothelium-dependent vasoreactivity was assessed in 40 patients after HTx. Flow-mediated vasodilatation (FMD) was measured by high-resolution brachial artery ultrasound to assess endothelial function at 1, 6, and 12 months after HTx. Cardiac allograft vasculopathy (CAV) was assessed by coronary angiography at 1 and 12 months and by intravascular ultrasound (IVUS) at 1 year.

RESULTS

Mean FMD at 1 month was 1.9% +/- 2.6%, improving to 3.3% +/- 3.2% at 6 months (p < 0.005) and to 5.1% +/- 3.4% at 1 year (p < 0.0001). FMD was significantly impaired in 33 patients (82%) at 1 month, in 27 (67%) at 6 months, and in 19 (47%) at 1 year after HTx. CAV was diagnosed by IVUS in 19 patients (63%) at 1 year. Patients without peripheral ED at 1 month had lower incidence of increased intimal thickness of 0.5 mm or more at 1 year after HTx (20% vs 75%, p < 0.01).

CONCLUSIONS

Impairment of peripheral FMD was highly prevalent soon after HTx and was present in nearly 50% of patients at 1 year. Patients without peripheral ED at 1 month were associated with lower probability of CAV. Although more studies are needed, the evaluation of peripheral endothelial function at 1 month after HTx could be potentially useful to identify patients at lower risk of CAV.

Inflammatory burden of cardiac allograft coronary atherosclerotic plaque is associated with early recurrent cellular rejection and predicts a higher risk of vasculopathy progression

OBJECTIVES

This study was designed to investigate tissue characterization of the coronary allograft atherosclerotic plaque with virtual histology intravascular ultrasound (VH-IVUS) imaging to assess the presence and predictors of vessel wall inflammation and its significance in cardiac allograft vasculopathy (CAV) progression.

BACKGROUND

A unique form of accelerated atherosclerosis, CAV remains the leading cause of late morbidity and mortality in heart transplant patients. The pathogenesis of CAV is not fully elucidated.

METHODS

A total of 86 patients with coronary allograft vasculopathy underwent VH-IVUS examination of the left anterior descending coronary artery 3.61 +/- 3.04 years following cardiac transplantation. Based on the VH-IVUS plaque characteristics, coronary allograft plaque was divided on virtual histology intravascular ultrasound-derived "inflammatory" (VHD-IP) (necrotic core and dense calcium > or =30%) and "noninflammatory" plaque (VHD-NIP) (necrotic core and dense calcium <30%). Total rejection scores were calculated based on the 2004 International Society of Heart and Lung Transplantation rejection grading system.

RESULTS

In the whole study population, the mean percentage of fibrous, fibrofatty, dense calcified, and necrotic core plaques in a mean length of 62.3 +/- 17.4 mm of the left anterior descending coronary artery were 50 +/- 17%, 16 +/- 11%, 15 +/- 11%, and 18 +/- 9%, respectively. Patients with a 6-month total rejection score >0.3 had significantly higher incidence of VHD-IP than those with a 6-month total rejection score < or =0.3 (69% vs. 33%, p = 0.011). The presence of VHD-IP at baseline was associated with a significant increase in plaque volume (2.42 +/- 1.78 mm(3)/mm vs. -0.11 +/- 1.65 mm(3)/mm, p = 0.010), plaque index (7 +/- 9% vs. 0 +/- 8%, p = 0.04), and remodeling index (1.24 +/- 0.44 vs. 1.09 +/- 0.36, p = 0.030) during 12 months of follow-up when compared with the presence of VHD-NIP at baseline and during follow-up.

CONCLUSIONS

The presence of VHD-IP as assessed by VH-IVUS is associated with early recurrent rejection and with higher subsequent progression of CAV. A VH-IVUS assessment may add important information in the evaluation of transplant recipients.

'Lone' increase in C-reactive protein after cardiac surgery: prevalence, clinical characteristics, in-hospital course, and prognostic value

BACKGROUND

Serum C-reactive protein (CRP) is involved in the acute phase reaction after surgery, even though its clinical significance remains a matter of debate. We evaluated CRP levels in cardiac surgery patients without clinical or laboratory signs of infection.

METHODS

We screened 737 consecutive patients referred to our center 8+/-5 days after cardiac surgery. Patients with fever (>37.2 degrees C), elevated white blood cell count (>11,000/ml), neutrophilia (>70%), or any inflammatory, infective or malignant disease were excluded. CRP levels were measured on admission and at discharge and the values were related to the following variables: age, sex, diabetes mellitus, renal failure, type of surgery, postoperative atrial fibrillation, pericardial or pleural effusion, and length of hospital stay. Follow-up (mean: 23+/-8.5 months) was available for 175 patients (94%).

RESULTS

In the 187 patients enrolled in the study, the CRP values were significantly elevated (median: 4.23 mg/dl, interquartiles range: 2.68-6.64) independent of any variable analyzed. At discharge, CRP levels were significantly reduced compared with values on admission (median: 1.55 mg/dl, interquartiles range: 0.84-2.37, P<0.001). At follow-up, 19 events (10.8%) occurred (two noncardiac deaths, 17 hospital readmissions for cardiac reasons); nonetheless, no correlation was found with CRP values either on admission or at discharge.

CONCLUSION

Early after cardiac surgery, in patients without clinical or laboratory signs of acute infection, CRP levels are significantly elevated, do not correlate with clinical variables, and decrease at discharge. These findings suggest a systemic inflammatory response to surgery-related stress, which carries a favorable prognosis at follow-up.

Lipoprotein-associated phospholipase A2 predicts progression of cardiac allograft vasculopathy and increased risk of cardiovascular events in heart transplant patients

BACKGROUND

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a risk factor for coronary artery disease (CAD) in nontransplant patients. We evaluated the association between Lp-PLA2, cardiac allograft vasculopathy (CAV) assessed by 3D intravascular ultrasound, and incidence of cardiac adverse events in heart transplant recipients.

MATERIALS AND METHODS

Fasting blood samples were obtained and stored from a cross-section of 112 cardiac transplant recipients attending the Mayo cardiac transplant clinic in 2000 to 2001, mean of 4.7 years after transplant. Lp-PLA2 was measured in plasma aliquots using an enzyme-linked immunoassay. Fifty-six of these patients subsequently underwent two 3D intravascular ultrasound studies in 2004 to 2006 12 months apart. Cardiovascular (CV) events included percutaneous coronary intervention, coronary artery bypass grafting (CABG), reduction in left ventricular ejection fraction (LVEF) < or =45% secondary to CAV and CV death.

RESULTS

High Lp-PLA2 level was associated with increase in plaque volume (r=0.43, P=0.0026) and percent plaque volume (r=0.45, P=0.0004). The association remained significant after adjusting for clinical and lipid variables. During follow-up of 5.1+/-1.6 years, 24 CV adverse events occurred in 15 of 112 (13%) heart transplant patients. Lp-PLA2 level>236 ng/mL (higher tertile) identified a subgroup of patients having a 2.4-fold increase of relative risk for combined endpoint of CV events (percutaneous coronary intervention, CABG, LVEF<45%, and CV death; 95% CI 1.16-5.19, P=0.012) compared with patients with Lp-PLA2< or =236 ng/mL.

CONCLUSIONS

Lp-PLA2 is independently associated with progression of CAV and predicts a higher incidence of CV events and CV death in transplant patients. This finding supports the concept that systemic inflammation is an important mediator of CAV. Lp-PLA2 may be a useful marker for risk of CAV and a therapeutic target in posttransplant patients.

Systemic inflammation and metabolic syndrome in cardiac allograft vasculopathy

BACKGROUND

Metabolic syndrome and elevation of inflammatory markers is common in transplant recipients. We investigated the role of insulin resistance and C-reactive protein (CRP) in predicting development of angiographic cardiac allograft vasculopathy (CAV).

METHODS

CRP and lipid profile were measured in 114 cardiac transplant recipients at 4.7 +/- 3.1 years post-transplant. A triglyceride/high-density lipoprotein cholesterol (TG/HDL) ratio of >or=3 was considered a marker of insulin resistance. Ninety-seven patients (mean age +/- SD: 48.2 +/- 16.7 years) subsequently underwent routine coronary angiography at 8.6 +/- 3.2 years post-transplantation. Diagnosis of CAV required the presence of stenosis of >or=40% in any major branch, and/or distal pruning of secondary side branches. Coronary artery stenosis >or=70% was defined as severe.

RESULTS

Eighty-one percent of patients were treated with statins. Low-density lipoprotein (LDL)-cholesterol level was 98 +/- 26 mg/dl at study entry. CRP and TG/HDL were found to be predictors of development of CAV. CAV severity correlated with TG/HDL (p < 0.005), but not with CRP level. Freedom from CAV 5 years after study entry was 9% in patients with TG/HDL >3, CRP >3 mg/liter, as compared with 65% in patients with TG/HDL <3, CRP <3 mg/liter (p = 0.003). The combination of CRP >3 mg/liter and TG/HDL >3 identified a sub-group of patients having a 2.8-fold increased odds ratio for a combined end-point of cardiovascular (CV) events (percutaneous coronary intervention, coronary artery bypass graft, left ventricular ejection fraction <45%) and death (95% confidence interval 0.90 to 8.45, p = 0.07) compared to patients with CRP <3 mg/liter and TG/HDL <3.

CONCLUSIONS

CRP >3 mg/liter and TG/HDL >3 are cumulative risk factors for angiographic CAV and the combined end-point of CV events and death in transplant patients and these patients should be targeted for intervention.

Probrain Natriuretic Peptide and C-Reactive Protein as Markers of Acute Rejection, Allograft Vasculopathy, and Mortality in Heart Transplantation

BACKGROUND

N-terminal probrain natriuretic peptide (NT-proBNP) and C-reactive protein (CRP) are useful in risk stratification of patients with congestive heart failure. They could also be markers of distinctly altered hormonal and immunological milieus, but the combined prognostic value of these biomarkers in heart transplant (HTx) recipients has not been assessed previously.

METHODS

We sought to assess the individual and combined value of NT-proBNP and CRP as markers of acute rejection, cardiac allograft vasculopathy (CAV) and all-cause mortality in HTx recipients. We evaluated 101 patients for acute rejection and 210 patients for CAV and all-cause mortality. Patients evaluated for rejection had serial endomyocardial biopsies and plasma sampling performed during the first year postHTx. All other patients had plasma samples taken upon inclusion at an annual visit. Median follow-up for CAV and all-cause mortality was 2.2 years and 5.4 years, respectively.

RESULTS

Altogether, 1131 biopsy procedures were performed, and increased NT-proBNP and CRP levels were not useful markers of acute cellular rejection. In total, 78 (37%) patients developed CAV, and 39 (19%) patients died. Neither biomarker was a predictor of CAV, but both were independent predictors of mortality. When combining both biomarkers, elevated levels of both NT-proBNP and CRP identified patients at highest risk for CAV (HR 2.10, P=0.01) and all-cause mortality (HR 3.14, P=0.01).

CONCLUSIONS

In HTx recipients, NT-proBNP and CRP are not useful as markers of acute cellular rejection during the first year postHTx, but combined analysis adds significantly to their predictive value for development of CAV and all-cause mortality.

Interplay Between Systemic Inflammation and Markers of Insulin Resistance in Cardiovascular Prognosis After Heart Transplantation

BACKGROUND

Metabolic and immuno-inflammatory risk factors contribute to cardiac allograft vasculopathy (CAV) pathogenesis. Although systemic inflammation, as detected by C-reactive protein (CRP), predicts CAV development, the relationship between CRP and markers of metabolic abnormalities remains unexplored.

METHODS

CRP and the entire metabolic panel were evaluated in 98 consecutive heart transplant recipients at the time of annual coronary angiography, 5.8 years after transplant (range, 1-12 years). A ratio of triglycerides (TG) to high-density lipoproteins (HDL) of 3.0 or more was considered a marker of insulin resistance. CAV prevalence was defined by angiography, and subsequent prognosis was evaluated as incidence of major cardiac adverse events.

RESULTS

CRP was higher in the 34 patients with angiographic CAV than in those without CAV (1.10 +/- 0.20 vs 0.50 +/- 0.05 mg/dl, p < 0.001). Patients with insulin resistance had higher CRP concentrations (p = 0.023) and higher CAV prevalence (p = 0.005). High CRP and a TG/HDL of 3.0 or more were independently associated with an increased likelihood of CAV (odds ratio, > or = 3.9; p = 0.02) and predicted an increased risk of major cardiac adverse events. The combination of high CRP and a TG/HDL of 3.0 or more identified a subgroup of patients having a 4-fold increased risk for CAV and a 3-fold increased risk for major cardiac adverse events compared with patients with low CRP and normal values for metabolic indicators.

CONCLUSIONS

Both CRP and insulin resistance, as estimated by TG/HDL, appear to be strong, synergic risk factors for CAV and for major cardiac adverse events. These findings support the hypothesis that in heart transplant recipients, systemic inflammation may be an important mediator of graft vascular injury associated with metabolic syndrome.

Critical appraisal of C-reactive protein throughout the spectrum of cardiovascular disease

Clinicians involved in the care of patients with cardiovascular conditions have recently been confronted with an important body of literature linking inflammation and cardiovascular disease. Indeed, the level of systemic inflammation as measured by circulating levels of C-reactive protein (CRP) has been linked to prognosis in patients with atherosclerotic disease, congestive heart failure, atrial fibrillation, myocarditis, aortic valve disease and heart transplantation. In addition, a number of basic science reports suggest an active role for CRP in the pathophysiology of cardiovascular diseases. This article explores the potential role of CRP in disease initiation, progression, and clinical manifestations and reviews its role in the prediction of future events in clinical practice. Therapeutic interventions to decrease circulating levels of CRP are also reviewed.

Diagnosis of graft coronary artery disease

PURPOSE OF REVIEW

Graft coronary artery disease is the leading cardiac cause of death in patients who have undergone cardiac transplantation. Due to denervation, classic symptoms of angina are not reliable. Many transplant centers have a protocol of routine annual surveillance cardiac angiography because treatment options are limited, especially with advanced disease. Angiography is an assessment of the arterial lumen, however, and can miss nonfocal disease. This paper reviews invasive and noninvasive diagnostic tools for graft coronary artery disease. Intravascular ultrasound is the most sensitive, but the cost and lack of widespread expertise make it unpopular. Noninvasive techniques have been studied. An ideal test would be sufficiently sensitive to detect disease and allow for prognostic information. Dobutamine echocardiography is the most sensitive noninvasive test but can have a high false-positive rate. It is also not universally available. Exercise nuclear imaging is specific and can be used as a confirmatory test in patients with positive dobutamine echocardiograms.

RECENT FINDINGS

Computed tomographic imaging and cardiac magnetic resonance imaging are exciting new modalities but require further study.

SUMMARY

There is no test sensitive and specific enough yet that can be confidently used to replace coronary angiography.

Cardiac Allograft Vasculopathy: An Update

Allograft vasculopathy remains the nemesis of long-term survival in heart transplantation. Possible modifying risk factors such as obesity, diabetes, and hypertension should continue to be pursued aggressively. All patients should receive statins. Clinical trials will provide the evidence needed to ascertain whether mammalian target of rapamycin inhibitors should be used in de novo cardiac transplant recipients to attenuate cardiac allograft vasculopathy (CAV). Intravascular ultrasound appears to play a key role in the diagnosis and evaluation of new treatments, and may indeed represent a surrogate marker that can be used to tailor management and improve outcomes. A better understanding of CAV is needed to develop targeted preventive therapies. Ongoing research in native atherosclerosis and vascular biology may provide answers within the next decade.

Allograft vasculopathy versus atherosclerosis

Over the last 4 decades, heart transplantation (HTx) has evolved as a mainstream therapy for heart failure. Approximately half of patients needing HTx have organ failure consequent to atherosclerosis. Despite advances in immunosuppressive drugs, long-term success of HTx is limited by the development of a particular type of coronary atherosclerosis, referred to as cardiac allograft vasculopathy (CAV). Although the exact pathogenesis of CAV remains to be established, there is strong evidence that CAV involves immunologic mechanisms operating in a milieu of nonimmunologic risk factors. The immunologic events constitute the principal initiating stimuli, resulting in endothelial injury and dysfunction, altered endothelial permeability, with consequent myointimal hyperplasia and extracellular matrix synthesis. Lipid accumulation in allograft arteries is prominent, with lipoprotein entrapment in the subendothelial tissue, through interactions with proteoglycans. The apparent endothelial "intactness" in human coronary arteries of the transplanted heart suggest that permeability and function of the endothelial barrier altered. Various insults to the vascular bed result in vascular smooth muscle cell (SMC) activation. Activated SMCs migrate from the media into the intima, proliferate, and elaborate cytokines and extracellular matrix proteins, resulting in luminal narrowing and impaired vascular function. Arteriosclerosis is a broad term that is used to encompass all diseases that lead to arterial hardening, including native atherosclerosis, postangioplasty restenosis, vein bypass graft occlusion, and CAV. These diseases exhibit many similarities; however, they are distinct from one another in numerous ways as well. The present review summarizes the current understanding of the risk factors and the pathophysiological similarities and differences between CAV and atherosclerosis.

Subclinical Inflammation and Prothrombotic State in Heart Transplant Recipients: Impact of Cyclosporin Microemulsion vs. Tacrolimus

BACKGROUND

Subclinical inflammation is related to adverse events in patients with coronary artery disease. In the present study, we determined the changes in hemostatic parameters and inflammatory markers in a large cohort of dyslipidemic cardiac transplant recipients compared with dyslipidemic healthy controls, and the effect of cyclosporin microemulsion (CsA) vs. tacrolimus immunoprophylaxis on these parameters.

METHODS

Stable cardiac transplant recipients (n=129) aged 56.7+/-10.1 years, 79+/-42 months postcardiac transplantation, and 26 mildly dyslipidemic healthy control subjects had serum measurements for lipids and lipoproteins, hemostatic parameters, and selected inflammatory markers. Transplant recipients were randomized to either continuation of CsA maintenance or conversion to tacrolimus immunoprophylaxis and were reassessed after six months.

RESULTS

CsA-maintained cardiac transplant recipients exhibited a significant elevation in Factor VIII, Von Willebrand factor, fibrinogen and PAI-I compared with healthy control subjects (all P<0.05). Similarly, cardiac transplant patients yielded a significantly elevated C-reactive protein (CRP) (4.11+/-6.25 [transplant group (TX)] vs. 2.09+/-2.21 mg/L [control group (CTL)]; P=0.0195), and homocysteine (19.2+/-8.8 [TX] vs. 9.70+/-2.45 microM [CTL]; P<0.001). VCAM, ICAM, E- and P-selectins were also significantly higher in transplant patients than in controls (all P<0.05). The conversion from CsA to tacrolimus resulted in a significant decrease in uric acid, total- and LDL-cholesterol, apolipoprotein B, creatinine, and homocysteine levels (all P<0.05).

CONCLUSIONS

Stable long-term CsA-maintained cardiac transplant patients exhibit a significant and general increase in hemostatic parameters and markers for subclinical inflammation. Tacrolimus conversion improved the patient lipid profile and decreased serum creatinine, uric acid, and homocysteine without any significant effect on the other markers.

Contemporary concepts in prevention and treatment of cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV), is characterized by heterogeneous proliferative thickening of the vascular intima of the cardiac allograft vasculature. Since its presentation is commonly clinically silent, early diagnosis and preventative therapy are critical. Preventative therapy including optimization of immunosuppressive therapy and treatment of comorbidities associated with CAV progression must be initiated early since most of the intimal thickening occurs during the first year posttransplant. Long-term use of calcineurin inhibitors is associated with a high incidence of chronic renal disease and also contributes to hyperlipidemia and hypertension, all of which may exacerbate CAV. In addition, statins, antihypertensive agents and anti-CMV agents all have demonstrated benefits in reducing CAV. Once established, the limited treatment options include nonpharmacologic interventions such as retransplantation, percutaneous coronary interventions, coronary artery bypass grafting, transmyocardial laser revascularization and heparin-induced/mediated extracorporeal LDL plasmapheresis (HELP). As the use of new assessment tools increases our understanding of this disease, better preventative and treatment strategies are evolving.