Donor-Transmitted Atherosclerosis Associated With Worsening Cardiac Allograft Vasculopathy After Heart Transplantation: Serial Volumetric Intravascular Ultrasound Analysis

Transplant Vasculopathy Versus Native Atherosclerosis: Similarities and Differences

Cardiac allograft vasculopathy (CAV) is one of the leading causes of graft failure and death after heart transplantation. Alloimmune-dependent and -independent factors trigger the pathogenesis of CAV through activation of the recipients' (and to a lesser extent donor-derived) immune system. Early diagnosis of CAV is complicated by the lack of clinical symptoms for ischemia in the denervated heart, by the impact of early functional coronary alterations, by the insensitivity of coronary angiography, and by the involvement of small intramyocardial vessels. CAV in general is a panarterial disease confined to the allograft and characterized by diffuse concentric longitudinal intimal hyperplasia in the epicardial coronary arteries and concentric medial disease in the microvasculature. Plaque composition in CAV may include early fibrous and fibrofatty tissue and late atheromatous calcification. In contrast, native coronary atherosclerosis usually develops over decades, is focal, noncircumferential, and typically diminishes proximal parts of the epicardial vessels. The rapid and early development of CAV has an adverse prognostic impact, and current prevention and treatment strategies are of limited efficacy compared with established strategies in native atherosclerosis. Following acute coronary syndromes, patients after heart transplantation were more likely to have accompanying cardiogenic shock and higher mortality compared with acute coronary syndromes patients with native hearts.

Uncertain benefit of statins in pediatric heart transplant recipients: A PHTS analysis

BACKGROUND

Cardiac allograft vasculopathy (CAV) is a leading cause of graft failure in pediatric heart transplant recipients (HTRs). Early statin use has been shown to reduce CAV incidence and all-cause mortality in adult HTRs. We sought to evaluate the contemporary prevalence and trends of statin use in pediatric HTRs and the association between statin use with CAV development and graft failure.

METHODS

Patients aged <17 years at the time of primary heart transplant who survived to ≥3 years without CAV were identified from the Pediatric Heart Transplant Society database (2001-2018). Statin use in the first 3 years posttransplant was defined as consecutive, intermediate, or absent. Kaplan-Meier survival, multivariable modeling, and propensity score-matched analyses evaluated associations between statin use and CAV incidence and graft survival, with subanalyses performed on subjects aged ≥10 years at transplant.

RESULTS

Among 3,485 (of which 1,086 aged ≥10 years) HTRs, 584 (17%) received consecutive statin therapy, 647 (19%) received intermediate use, and 2,254 (65%) received no statin therapy. Statin use varied widely between sites, with increasing use in the ≥10-year-old cohort over time. By multivariate analysis, statin use was not associated with graft loss. Consecutive statin use was also not associated with graft survival or freedom from CAV development when compared to absent statin use in unmatched or propensity-matched analyses.

CONCLUSIONS

While statins remain commonly utilized in pediatric HTRs, early consecutive statin therapy did not decrease CAV incidence or graft loss. The differing effects of statins on CAV development and progression in pediatric vs adult HTRs suggest differing risk and mediating factors and require further study.

Prevalence, Characteristics, and Prognostic Relevance of Donor-Transmitted Coronary Artery Disease in Heart Transplant Recipients

BACKGROUND

The reported prevalence of donor-transmitted coronary artery disease (TCAD) in heart transplantation (HT) is variable, and its prognostic impact remains unclear.

OBJECTIVES

The goal of this study was to characterize TCAD in a contemporary multicentric cohort and to study its prognostic relevance.

METHODS

This was a retrospective study of consecutive patients >18 years old who underwent HT in 11 Spanish centers from 2008 to 2018. Only patients with a coronary angiography (c-angio) within the first 3 months after HT were studied. Significant TCAD (s-TCAD) was defined as any stenosis ≥50% in epicardial coronary arteries, and nonsignificant TCAD (ns-TCAD) as stenosis <50%. Clinical outcomes were assessed by means of Cox regression and competing risks regression. Patients were followed-up for a median period of 6.3 years after c-angio.

RESULTS

From a cohort of 1,918 patients, 937 underwent c-angio. TCAD was found in 172 patients (18.3%): s-TCAD in 65 (6.9%) and ns-TCAD in 107 (11.4%). Multivariable Cox regression analysis did not show a statistically significant association between s-TCAD and all-cause mortality (adjusted HR: 1.44; 95% CI: 0.89-2.35; P = 0.141); however, it was an independent predictor of cardiovascular mortality (adjusted HR: 2.25; 95% CI: 1.20-4.19; P = 0.011) and the combined event cardiovascular death or nonfatal MACE (adjusted HR: 2.42; 95% CI: 1.52-3.85; P < 0.001). No statistically significant impact of ns-TCAD on clinical outcomes was detected. The results were similar when reassessed by means of competing risks regression.

CONCLUSIONS

TCAD was not associated with reduced survival in patients alive and well enough to undergo post-HT angiography within the first 3 months; however, s-TCAD patients showed increased risk of cardiovascular death and MACE.

Change in First-year Intravascular Ultrasound Results Predicts Adverse Events in Heart Transplant Recipients: Implications for Clinical Trial Endpoints

BACKGROUND

Heart transplantation (HTx) is an established therapeutic option for patients with advanced heart failure who are refractory to conventional guideline-directed treatments. This study aimed to reassess whether intravascular ultrasound variables could predict adverse events after HTx in the modern era.

METHODS

One hundred primary HTx recipients with available serial intravascular ultrasound examination results of the left anterior descending artery 4-8 wk and 1 y after HTx were enrolled, with an average follow-up duration of 5.7 y. The primary endpoint was a composite of all-cause death, nonfatal major adverse cardiac events, and angiographic cardiac allograft vasculopathy.

RESULTS

Forty-three patients developed primary endpoints. The baseline maximal intimal thickness was independently associated with the primary endpoint (hazard ratio, 8.24; 95% confidential interval [CI], 3.21-21.21; P  < 0.001), and the optimal cutoff value was 0.64 mm. A change in the plaque atheroma volume in a proximal 20-mm segment from the left anterior descending artery bifurcation >1.05 mm 3 /mm (hazard ratio, 2.75; 95% CI, 1.28-5.89; P  = 0.009) and a change in the first-year maximal intimal thickness >0.27 mm (hazard ratio, 2.63; 95% CI, 1.05-6.56; P  = 0.04) were independent predictors of the primary endpoint 1 y after intravascular ultrasonography.

CONCLUSIONS

The aforementioned important clinical implications of intravascular ultrasound parameters are useful predictors of outcomes, which may be considered endpoints in modern clinical HTx trials.

Prognostic value of comprehensive intracoronary physiology assessment early after heart transplantation

AIMS

We evaluated the long-term prognostic value of invasively assessing coronary physiology after heart transplantation in a large multicentre registry.

METHODS AND RESULTS

Comprehensive intracoronary physiology assessment measuring fractional flow reserve (FFR), the index of microcirculatory resistance (IMR), and coronary flow reserve (CFR) was performed in 254 patients at baseline (a median of 7.2 weeks) and in 240 patients at 1 year after transplantation (199 patients had both baseline and 1-year measurement). Patients were classified into those with normal physiology, reduced FFR (FFR ≤ 0.80), and microvascular dysfunction (either IMR ≥ 25 or CFR ≤ 2.0 with FFR > 0.80). The primary outcome was the composite of death or re-transplantation at 10 years. At baseline, 5.5% had reduced FFR; 36.6% had microvascular dysfunction. Baseline reduced FFR [adjusted hazard ratio (aHR) 2.33, 95% confidence interval (CI) 0.88-6.15; P = 0.088] and microvascular dysfunction (aHR 0.88, 95% CI 0.44-1.79; P = 0.73) were not predictors of death and re-transplantation at 10 years. At 1 year, 5.0% had reduced FFR; 23.8% had microvascular dysfunction. One-year reduced FFR (aHR 2.98, 95% CI 1.13-7.87; P = 0.028) and microvascular dysfunction (aHR 2.33, 95% CI 1.19-4.59; P = 0.015) were associated with significantly increased risk of death or re-transplantation at 10 years. Invasive measures of coronary physiology improved the prognostic performance of clinical variables (χ2 improvement: 7.41, P = 0.006). However, intravascular ultrasound-derived changes in maximal intimal thickness were not predictive of outcomes.

CONCLUSION

Abnormal coronary physiology 1 year after heart transplantation was common and was a significant predictor of death or re-transplantation at 10 years.

Validation of multiparametric rubidium-82 PET myocardial blood flow quantification for cardiac allograft vasculopathy surveillance

BACKGROUND

We previously demonstrated high diagnostic accuracy of Rubidium-82 positron emission tomography (PET) myocardial blood flow (MBF) quantification for CAV. The purpose of this study was to validate multiparametric PET detection of CAV by combined rate-pressure-product-corrected myocardial flow reserve (cMFR), stress MBF, and coronary vascular resistance (CVR) assessment.

METHODS AND RESULTS

Diagnostic CAV cut-offs of cMFR < 2.9, stress MBF < 2.3, CVR > 55 determined in a previous study (derivation) were assessed in heart transplant recipients referred for coronary angiography and intravascular ultrasound (IVUS) (validation). CAV was defined as International Society of Heart and Lung Transplantation CAV1-3 on angiography; and maximal intimal thickness ≥ 0.5 mm on IVUS. Eighty patients (derivation n = 40, validation n = 40) were included: 80% male, mean age 54±14 years, 4.5±5.6 years post transplant. The prevalence of CAV was 44% on angiography and 78% on IVUS. Combined PET cMFR < 2.9, stress MBF < 2.3, CVR > 55 CAV assessment yielded high 88% (specificity 75%) and 83% (specificity 40%) sensitivity for ≥ 1 abnormal parameter and high 88% (sensitivity 59%) and 90% (sensitivity 43%) specificity for 3 abnormal parameters, in the derivation and validation cohorts, respectively.

CONCLUSION

We validate the diagnostic accuracy of multiparametric PET flow quantification by cMFR, stress MBF, and CVR for CAV.

A retrospective cohort of coronary artery disease development after at least two angiograms in patients with normal coronary angiograms or mild coronary artery disease

Background

Coronary Artery Disease is one of the leading causes of death in the world. CAD usually progresses slowly during time and patients with normal or near-normal coronary arteries are also at risk of developing CAD. It is now believed that even mild atherosclerosis can increase the rate of CAD.

Methods

This is a retrospective, descriptive and analytic study. We selected patients who had undergone at least two diagnostic coronary angiographies at Tehran Heart Center and had normal coronary structure or mild CAD in initial angiography. The data was obtained from the Tehran Heart Center Angiography Databank. Predicting factors in the development of CAD were determined.

Results

Data on 556 patients were reviewed. The median interval between the initial and final coronary catheterization was 37.6 months. On the final evaluation, 216 patients (38.8%) found to have developed some degrees of coronary artery disease. Based on the multivariate analysis, age, hematocrit, cigarette smoking, hypertension, and initial presentation with stable and unstable angina were found to be independent predictors of progression to CAD in patients.

Conclusion

In the end, 40% of patients who had normal coronary arteries or minimal CAD in the initial angiography report, developed some degrees of CAD and some clinical indices can predict the risk of CAD.

Influence of donor-transmitted coronary artery disease on long-term outcomes after heart transplantation - a retrospective study

BACKGROUND

Cardiac allograft vasculopathy (CAV) is an important cause of late mortality after heart transplantation, which may be influenced by preexisting coronary disease (CAD) in the donor heart.

METHODS

The aim of this study was to verify whether CAD in the donor heart had any influence on survival, cardiac-related adverse events (CRAEs), and coronary disease progression after transplantation. Donor coronary angiography performed in 289 hearts showed absence of CAD in 232 (no-CAD group) and moderate (≤50%) stenoses (CAD group) in 57. The 2 groups were compared for survival, freedom from CRAEs, and development of grade ≥ 2 CAV after transplantation.

RESULTS

Of 30-day mortality and postoperative complication rate was similar as mean follow-up (76 ± 56 and 75 ± 55 months) for no-CAD and CAD (P = 0.8). Ten-year actuarial survival was 58 ± 4% and 62 ± 7% for no-CAD and CAD (P = 0.4). Ten-year freedom from grade ≥ 2 CAV and from CRAEs was 81 ± 4% and 66 ± 5% vs 75 ± 8% and 67 ± 9% in no-CAD and CAD (P = 0.9 and 0.9, respectively).

CONCLUSIONS

Donor hearts with moderate CAD did not affect survival, freedom from CRAEs and did not accelerate development of high-grade CAV after transplantation supporting the use of such grafts to expand the donor pool. Routine use of coronary angiography in donor selection appears justified.

Influence of Induction Therapy Using Basiliximab With Delayed Tacrolimus Administration in Heart Transplant Recipients - Comparison With Standard Tacrolimus-Based Triple Immunosuppression

BACKGROUND

Appropriate indications and protocols for induction therapy using basiliximab have not been fully established in heart transplant (HTx) recipients. This study elucidated the influence of induction therapy using basiliximab along with delayed tacrolimus (Tac) initiation on the outcomes of high-risk HTx recipients.Methods and Results:A total of 86 HTx recipients treated with Tac-based immunosuppression were retrospectively reviewed. Induction therapy was administered to 46 recipients (53.5%) with impaired renal function, pre-transplant sensitization, and recipient- and donor-related risk factors (Induction group). Tac administration was delayed in the Induction group. Induction group subjects showed a lower cumulative incidence of acute cellular rejection grade ≥1R after propensity score adjustment, but this was not significantly different (hazard ratio [HR]: 0.63, 95% confidence interval [CI]: 0.37-1.08, P=0.093). Renal dysfunction in the Induction group significantly improved 6 months post-transplantation (P=0.029). The cumulative incidence of bacterial or fungal infections was significantly higher in the Induction group (HR: 10.6, 95% CI: 1.28-88.2, P=0.029).

CONCLUSIONS

These results suggest that basiliximab-based induction therapy with delayed Tac initiation may suppress mild acute cellular rejection and improve renal function in recipients with renal dysfunction, resulting in its non-inferior outcome, even in high-risk patients, when applied to the appropriate recipients. However, it should be carefully considered in recipients at a high risk of bacterial and fungal infections.

Canadian Cardiovascular Society/Canadian Cardiac Transplant Network Position Statement on Heart Transplantation: Patient Eligibility, Selection, and Post-Transplantation Care

Significant practice-changing developments have occurred in the care of heart transplantation candidates and recipients over the past decade. This Canadian Cardiovascular Society/Canadian Cardiac Transplant Network Position Statement provides evidence-based, expert panel recommendations with values and preferences, and practical tips on: (1) patient selection criteria; (2) selected patient populations; and (3) post transplantation surveillance. The recommendations were developed through systematic review of the literature and using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. The evolving areas of importance addressed include transplant recipient age, frailty assessment, pulmonary hypertension evaluation, cannabis use, combined heart and other solid organ transplantation, adult congenital heart disease, cardiac amyloidosis, high sensitization, and post-transplantation management of antibodies to human leukocyte antigen, rejection, cardiac allograft vasculopathy, and long-term noncardiac care. Attention is also given to Canadian-specific management strategies including the prioritization of highly sensitized transplant candidates (status 4S) and heart organ allocation algorithms. The focus topics in this position statement highlight the increased complexity of patients who undergo evaluation for heart transplantation as well as improved patient selection, and advances in post-transplantation management and surveillance that have led to better long-term outcomes for heart transplant recipients.

Use of Ventricular Assist Devices and Heart Transplantation for Advanced Heart Failure

There are only 2 treatments for the thousands of patients who progress to the most advanced form of heart failure despite the application of guideline-based medical therapy, use of ventricular assist devices and heart transplantation. There has been a great deal of progress in both of these therapies that have led to improved outcomes including significant improvement in survival and functional capacity. Heart transplantation offers the best short- and long-term survival for patients with end-stage heart failure, and the majority of these recipients achieve relatively limitless functional capacity for their age. However, the chronic shortage of available donors limits the number of recipients in the United States to an only 2500 patients/y or only a fraction of potential candidates. The significant improvement in outcomes now possible with durable ventricular assist devices has led to a significant increase in their use, which now exceeds the volume of heart transplants in the United States, with the greatest growth in use for those not considered to be candidates for heart transplantation, previously referred to as destination therapy. This article will review the substantial progress that has taken place for both of these life-saving treatment options, as well as the future directions.

Variability in donor selection among pediatric heart transplant providers: Results from an international survey

There is considerable variability in donor acceptance practices among adult heart transplant providers; however, pediatric data are lacking. The aim of this study was to assess donor acceptance practices among pediatric heart transplant professionals. The authors generated a survey to investigate clinicians' donor acceptance practices. This survey was distributed to all members of the ISHLT Pediatric Council in April 2018. A total of 130 providers responded from 17 different countries. There was a wide range of acceptable criteria for potential donors. These included optimal donor-to-recipient weight ratio (lower limit: 50%-150%, upper limit: 120%-350%), maximum donor age (25-75 years), and minimum acceptable left ventricular EF (30%-60%). Non-US centers demonstrated less restrictive donor selection criteria and were willing to accept older donors (50 vs 35 years, P < 0.001), greater size discrepancy (upper limit weight ratio 250% vs 200%, P = 0.009), and donors with a lower EF (45% vs 50%, P < 0.001). Recipient factors were most influential in the decision to accept marginal donors including recipients requiring ECMO support, ventilator support, and highly sensitized patients with a negative XM. However, programmatic factors impacted the decision to decline marginal donors including recent programmatic mortalities and concerns for programmatic restrictions from regulatory bodies. There is significant variation in donor acceptance practices among pediatric heart transplant professionals. Standardization of donor acceptance practices through the development of a consensus statement may help to improve donor utilization and reduce waitlist mortality.

Impact of Coronary Artery Calcification in the Donor Heart on Transmitted Coronary Artery Disease in Heart Transplant Recipients

BACKGROUND

Coronary artery disease (CAD) after heart transplantation (HTx) develops as a combination of donor-transmitted coronary atherosclerosis (DTCA) and cardiac allograft vasculopathy. Assessing donor CAD before procurement is important. Because coronary artery calcification (CAC) is a predictor for CAD, donor-heart CAC is usually evaluated to estimate the risk of donor CAD. The usefulness of CAC for predicting DTCA, however, is not known. Methods and Results: Sixty-four HTx recipients whose donor underwent chest computed tomography before procurement or ≤2 weeks after HTx and who underwent coronary angiography and intravascular ultrasound (IVUS) ≤3 months after HTx were enrolled. Eight patients had CAC (CAC group) and 56 patients did not have CAC (no-CAC group). Patients in the CAC group were significantly older and had a higher prevalence of maximum intimal thickness (MIT) of the coronary artery ≥0.5 mm at initial IVUS than patients in the no-CAC group (100% vs. 55%, P=0.02). Adverse cardiac events and death were not significantly different. Everolimus tended to be used more often in the CAC group.

CONCLUSIONS

Donor-heart CAC is a significant predictor for MIT of the coronary artery ≥0.5 mm after HTx. The presence of CAC, however, is not associated with future cardiac events. The higher prevalence of everolimus use in the CAC group may have affected the results.