Coronary artery disease in heart transplantation: new concepts for an old disease

Assessing the Relationship Between Molecular Rejection and Parenchymal Injury in Heart Transplant Biopsies

BACKGROUND

The INTERHEART study (ClinicalTrials.gov #NCT02670408) used genome-wide microarrays to detect rejection in endomyocardial biopsies; however, many heart transplants with no rejection have late dysfunction and impaired survival. We used the microarray measurements to develop a molecular classification of parenchymal injury.

METHODS

In 1320 endomyocardial biopsies from 645 patients previously studied for rejection-associated transcripts, we measured the expression of 10 injury-induced transcript sets: 5 induced by recent injury; 2 reflecting macrophage infiltration; 2 normal heart transcript sets; and immunoglobulin transcripts, which correlate with time. We used archetypal clustering to assign injury groups.

RESULTS

Injury transcript sets correlated with impaired function. Archetypal clustering based on the expression of injury transcript sets assigned each biopsy to 1 of 5 injury groups: 87 Severe-injury, 221 Late-injury, and 3 with lesser degrees of injury, 376 No-injury, 526 Mild-injury, and 110 Moderate-injury. Severe-injury had extensive loss of normal transcripts (dedifferentiation) and increase in macrophage and injury-induced transcripts. Late-injury was characterized by high immunoglobulin transcript expression. In Severe- and Late-injury, function was depressed, and short-term graft failure was increased, even in hearts with no rejection. T cell-mediated rejection almost always had parenchymal injury, and 85% had Severe- or Late-injury. In contrast, early antibody-mediated rejection (ABMR) had little injury, but late ABMR often had the Late-injury state.

CONCLUSION

Characterizing heart transplants for their injury state provides new understanding of dysfunction and outcomes and demonstrates the differential impact of T cell-mediated rejection versus ABMR on the parenchyma. Slow deterioration from ABMR emerges as a major contributor to late dysfunction.

Coronary Artery Revascularization in Heart Transplant Patients: A Systematic Review and Meta-analysis

BACKGROUND

Cardiac allograft vasculopathy (CAV) is the primary cause of late mortality after heart transplantation (HTx). We look to provide a comprehensive review of contemporary revascularization strategies in CAV.

METHODS

PubMed and Web of Science were systematically searched by 3 authors. 1,870 articles were initially screened and 24 were included in this review.

RESULTS

PCI is the main revascularization technique utilized in CAV. The pooled estimates for restenosis significantly favored DES over BMS (OR 4.26; 95% CI, 2.54-7.13; p< 0.00001; I2=4%). There was insufficient data to quantitatively compare mortality following DES versus BMS. There was no difference in short-term mortality between CABG and PCI. In-hospital mortality was 0.0% for CABG and ranged from 0.0-8.34% for PCI. 1-year mortality was 8.0% for CABG and 5.0-25.0% for PCI. CABG had a potential advantage at 5 years. 5-year mortality was 17.0% for CABG and ranged from 14-40.4% following PCI. Select measures of postoperative morbidity trended towards superior outcomes for CABG.

CONCLUSIONS

In CAV, PCI is the primary revascularization strategy utilized, with DES exhibiting superiority to BMS regarding postoperative morbidity. Further investigation into outcomes following CABG in CAV is required to conclusively elucidate the superior management strategy in CAV.

The Association Between Cytomegalovirus Infection and Cardiac Allograft Vasculopathy in the Era of Antiviral Valganciclovir Prophylaxis

Supplemental Digital Content is available in the text.

Previous studies on the association between cytomegalovirus (CMV) infection and cardiac allograft vasculopathy (CAV) were conducted on patients transplanted in the prevalganciclovir prophylaxis era. The aim of our study is to evaluate this relation in heart transplantation (HTx) recipients treated according to current prophylactic and immunosuppressive regimens.

Quantitative coronary computed tomography angiography for the detection of cardiac allograft vasculopathy

Objectives

To associate coronary wall volume and composition, derived from coronary computed tomography angiography (CTA), with cardiac allograft vasculopathy (CAV) detected on invasive coronary angiography (ICA) in heart-transplanted (HTX) patients.

Methods

We included consecutive adults who received ICA and coronary CTA for evaluation of CAV ≥ 10 months after HTX. In all coronary segments, we assessed lumen and wall volumes and segmental length, calculated volume-length ratio (VLR) (volumes indexed by segmental length; mm³/mm), wall burden (WB) (wall/wall + lumen volumes; %), and assessed proportions of calcified, fibrotic, fibro-fatty, and low-attenuation tissue (%) in coronary wall. We rendered independent CTA measures associated with CAV by ICA, tested their discriminatory capacity, and assessed concordance between CTA and ICA.

Results

Among 50 patients (84% men; 53.6 ± 11.9 years), we analyzed 632 coronary segments. Mean interval between HTX and CTA was 6.7 ± 4.7 years and between ICA and CTA 1 (0–1) day. Segmental VLR, WB, and proportion of fibrotic tissue were independently associated with CAV (OR = 1.06–1.27; p ≤ 0.002), reaching a high discriminatory capacity (combination of all three: AUC = 0.84; 95%CI, 0.75–0.90). Concordance between CTA and ICA was higher in advanced CAV (88%) compared with that in none (37%) and mild (19%) CAV. Discordance was primarily driven by a large number of segments with coronary wall changes on CTA but without luminal stenoses on ICA (177/591; 25%).

Conclusion

CTA-derived coronary wall VLR, WB, and the proportion of fibrotic tissue are independent markers of CAV. Combination of these three parameters may aid the detection of early CAV not detected by ICA, the current standard of care.

Key Points

• Coronary CTA detects CAV in HTX patients.

• Coronary wall volume-length ratio, wall burden, and proportion of fibrotic tissue are independently associated with CAV.

• In contrast to ICA, coronary CTA may identify the early stages of CAV.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06653-3) contains supplementary material, which is available to authorized users.

Cardiac allograft vasculopathy: Insights on pathogenesis and therapy

Cardiac allograft vasculopathy (CAV) is a unique accelerated form of coronary vascular disease affecting heart transplant recipients. This complication is a significant contributor to medium- to long-term post-transplant morbidity and mortality. There is a high prevalence of CAV with approximately one in three patients developing CAV by 5 years post-transplant. Morphologically, CAV is characterized by concentric coronary intimal hyperplasia in both the epicardial arteries and intramural microvasculature. Although several immune and non-immune factors have been identified, their precise pathogenic mechanisms, interactions, and relative importance in the development of CAV are not well defined. The advent of improved imaging surveillance modalities has resulted in earlier detection during the disease process. However, overall management of CAV remains challenging due to paucity of treatment. This review aims to discuss key concepts on the pathogenesis of CAV and current management strategies, focusing on the use of mammalian target of rapamycin inhibitors.

Does the antibody mediated rejection grading scale have prognostic prediction? Yes, but the picture is still blurry

PURPOSE OF REVIEW

Antibody-mediated rejection (ABMR) is a condition difficult to diagnose and treat, which may significantly impair the outcome of heart transplant recipients. In clinical practice, diagnosis is based on immunopathology grading of endomyocardial biopsies (EMB). Despite its value, the current diagnostic system has several pitfalls that have been addressed in recent literature.

RECENT FINDINGS

Pathology grading of ABMR (pAMR) has a relevant prognostic factor. However, it does not capture several nuances, such as chronic vs. acute ABMR, mixed rejection or microvascular inflammation. Molecular biology-based assays are shedding new light on the mechanisms of ABMR, which could improve the precision of ABMR diagnosis.

SUMMARY

These new findings have the potential to rearrange EMB grading system and to guide more precisely decision-making, but studies validating the therapeutic management based on molecular-pathology coupling are still missing.