Accuracy of risk models used for public reporting of heart transplant center performance.

BACKGROUND: Heart transplant programs and regulatory entities require highly accurate performance metrics to support internal quality improvement activities and national oversight of transplant programs, respectively. We assessed the accuracy of publicly reported performance measures. METHODS: We used the United Network for Organ Sharing registry to study patients who underwent heart transplantation between January 1, 2016 and June 30, 2018. We used tests of calibration to compare the observed rate of 1-year graft failure to the expected risk of 1-year graft failure, which was calculated for each recipient using the July 2019 method published by the Scientific Registry of Transplant Recipients (SRTR). The primary study outcome was the joint test of calibration, which accounts for both the total number of events predicted (calibration-in-the-large) and dispersion of risk predictions (calibration slope). RESULTS: 6,528 heart transplants were analyzed. The primary test of calibration failed (p <0.0001), indicating poor accuracy of the SRTR model. The calibration-in-the-large statistic (0.63, 95% confidence interval [CI] 0.58-0.68, p < 0.0001) demonstrated overestimation of event rates while the calibration slope statistic (0.56, 95% CI 0.49-0.62, p <0.0001) indicated over-dispersion of event rates. Pre-specified subgroup analyses demonstrated poor calibration for all subgroups (each p <0.01). After recalibration, program-level observed/expected ratios increased by a median of 0.14 (p <0.0001). CONCLUSIONS: Risk models employed for publicly-reported graft survival at U.S. heart transplant centers lack accuracy in general and in all subgroups tested. The use of disease-specific models may improve the accuracy of program performance metrics.

Long-term adult congenital heart disease survival after heart transplantation: A restricted mean survival time analysis.

BACKGROUND: Adult Congenital Heart Disease (ACHD) heart transplant recipients may have lower post-transplant survival resulting from higher peri-operative mortality than non-ACHD patients. However, the late risk of mortality appears lower in ACHD recipients. This study seeks to establish whether long-term heart transplant survival is reduced among ACHD recipients relative to non-ACHD recipients. METHODS: Adult patients who received a heart transplant between January, 2000 and December, 2019 in the United Network for Organ Sharing database were stratified by the presence of ACHD. Propensity-matched cohorts (1:4) were created to adjust for differences between groups. Graft survival at time points from 1 to 18 years was compared between groups using restricted mean survival time (RMST) analysis. RESULTS: The matched cohort included 1,139 ACHD and 4,293 non-ACHD patients. Median age was 35 years and 61% were male. Average survival time at 1 year was 0.85 years for ACHD patients and 0.93 years for non-ACHD patients (average difference: -0.08 years, 95% Confidence Interval [CI] -0.10 to -0.06, p < 0.001), reflecting higher immediate post-transplant mortality. Average survival time at 18 years was not clinically or statistically different: 11.14 years for ACHD patients and 11.40 years for non-ACHD patients (average difference: -0.26 years, 95% CI: -0.85 to + 0.32 years, p = 0.38). CONCLUSIONS: Despite increased medium-term mortality among ACHD patients after heart transplant, differences in long-term survival are minimal. Allocation of hearts to ACHD patients results in acceptable utility of donor hearts.

Heart Failure in Adult Congenital Heart Disease.

As the population of adult congenital heart disease patients ages and grows, so too does the burden of heart failure in this population. Despite the advances in medical and surgical therapies over the last decades, heart failure in adult congenital heart disease remains a formidable complication with high morbidity and mortality. This review focuses on the challenges in determining the true burden and management of heart failure in adult congenital heart disease. There is a particular focus on the need for developing a common language for classifying and reporting heart failure in adult congenital heart disease, the clinical presentation and prognostication of heart failure in adult congenital heart disease, the application of hemodynamic evaluation, and advanced heart failure treatment. A common case study of heart failure in adult congenital heart disease is utilized to illustrate these key concepts.

Utility of biomarkers in adult Fontan patients with decompensated heart failure.

BACKGROUND: The incidence of heart failure is increasing within the Fontan population. The use of serological markers, including B-type natriuretic peptide, has been limited in this patient population. METHODS: This was a single-centre retrospective study of Fontan patients in acute decompensated heart failure. Fontan patients underwent a 1:2 match with non-Fontan patients for each heart failure hospitalisation for comparative analysis. A univariate logistic regression model was used to assess associations between laboratory and echocardiographic markers and a prolonged length of stay of 7 days or greater. RESULTS: B-type natriuretic peptide levels were significantly lower in Fontan patients admitted for heart failure than that in non-Fontan patients [390.9 (±378.7) pg/ml versus 1245.6 (±1160.7) pg/ml, respectively, p < 0.0001] and were higher in Fontan patients with systemic ventricular systolic or diastolic dysfunction than that in Fontan patients with normal systemic ventricular function [833.6 (±1547.2) pg/ml versus 138.6 (±134.0) pg/ml, p = 0.017]. The change from the last known outpatient value was smaller in Fontan patients in comparison with non-Fontan patients [65.7 (±185.7) pg/ml versus 1638.0 (±1444.7) pg/ml, respectively, p < 0.0001]. Low haemoglobin and high blood urea nitrogen levels were associated with a prolonged length of stay. CONCLUSION: B-type natriuretic peptide levels do not accurately reflect decompensated heart failure in Fontan patients when compared to non-Fontan heart failure patients and should, therefore, be used with caution in this patient population.

Patterns of Hospital Bypass and Interhospital Transfer Among Patients With Heart Failure.

BACKGROUND: We describe how patient characteristics influence hospital bypass, interhospital transfer, and in-hospital mortality in patients with heart failure in Washington. Rural patients with heart failure may bypass their nearest hospital or be transferred for appropriate therapies. The frequency, determinants, and outcomes of these practices remain uncharacterized. METHODS AND RESULTS: Mean excess travel times based on hospital and patient residence ZIP codes were calculated using published methods. Hospitals and servicing areas were coded based on bed size and ZIP code, respectively. Transfer patterns were analyzed using bootstrap inference for clusters. Analysis of mortality and transfer-associated factors was performed using logistic regression with generalized estimating equations. There were 48,163 patients, representing 1106 instances of transfer, studied. The mean excess travel time increased 7.14 minutes per decrease in population density (metropolitan, micropolitan, small town, rural; P < .0001). The rural mean excess travel time was greatest at 28.56 minutes. Transfer likelihood increased with younger age, male gender, admitting hospital rurality, higher Charlson Comorbidity Index, and stroke. Transfer was less likely among women (odds ratio [OR], 0.82; 95% confidence interval [CI], 0.72-0.94) and patients over 70 years old (OR, 0.15-0.46; 95% CI, 0.10-0.65). Adjusting for comorbidities and transfer propensity, transfer exhibited a stronger association with mortality than any other measured patient risk factor (OR, 2.15; 95% CI, 1.69-2.73), excluding stroke (OR, 7.09; 95% CI, 4.99-10.06). CONCLUSIONS: Rural hospital bypass is prevalent among patients with heart failure, although its clinical significance is unclear. Female and older patients were found to have a lesser likelihood of transfer adjusted for other factors. Interhospital transfer is associated with increased mortality when adjusted for comorbidities.

Antibody-medicated rejection after heart transplantation: diagnosis and clinical implications.

PURPOSE OF REVIEW: The present article will review the diagnosis of antibody-mediated rejection in heart transplant recipients and further explore the clinical implications. RECENT FINDINGS: Improved diagnostic techniques have led to increased recognition of antibody-mediated rejection and better understanding of the long-term consequences in heart transplant recipients. Endomyocardial biopsy remains the gold standard for the diagnosis of antibody-medicated ejection; however, several advances in molecular testing have emerged, including the use of gene expression profiling, messenger RNA, and microRNA. Routine surveillance of donor-specific antibodies identifies recipients at high risk for graft compromise. Additionally, new monoclonal antibody therapies have broadened our repertoire in the treatment of rejection. SUMMARY: Advances in molecular testing for antibody-mediated rejection may improve the associated long-term complication, while minimizing risk to the patient.

Improved Outcomes of Heart Transplantation in Adults With Congenital Heart Disease Receiving Regionalized Care.

BACKGROUND: The number of adult congenital heart disease (CHD) patients undergoing heart transplantation is increasing rapidly. CHD patients have higher surgical risk at transplantation. High-volume adult CHD transplant centers may have better transplant outcomes. OBJECTIVES: This study aimed to evaluate the effect of center CHD transplant volume and expertise on transplant outcomes in CHD patients. METHODS: The authors studied heart transplantations in CHD patients age ≥18 years using the United Network of Organ Sharing (UNOS) database for the primary outcomes of waitlist mortality and post-transplant outcomes at 30 days and 1 year. Transplant centers were assessed by status as the highest CHD transplant volume center in a UNOS region versus all others, presence of Adult Congenital Heart Association accreditation, and adult versus pediatric hospital designation. RESULTS: Between January of 2000 and June of 2018, 1,746 adult CHD patients were listed for transplant; 1,006 (57.6%) of these underwent heart transplantation. After adjusting for age, sex, listing status, and inotrope requirement, waitlist mortality risk was lower at Adult Congenital Heart Association accredited centers (hazard ratio: 0.730; p = 0.020). Post-transplant 30-day mortality was lower at the highest volume CHD transplant center in each UNOS region (hazard ratio: 0.706; p = 0.014). CONCLUSIONS: Designated expertise in CHD care is associated with improved waitlist outcomes for CHD patients listed for transplantation. Post-transplant survival was improved at the highest volume regional center. These findings suggest a possible advantage of regionalization of CHD transplantation.

Three-dimensional echocardiography of mechanical circulatory support devices.

Two-dimensional echocardiography is a crucial component for assessing the position and function of mechanical circulatory support devices, but three-dimensional echocardiography provides additional information to aid in management and may improve accuracy in the assessment of these devices. In this article, we review the utility of three-dimensional echocardiography of various mechanical circulatory support devices.

The Benefit of Donor-Recipient Matching for Patients Undergoing Heart Transplantation.

BACKGROUND: Heart transplant volumes are not matching growing demand, and donor heart use may be decreasing. OBJECTIVES: This study sought to investigate the benefit of heart transplantation compared with waiting while accounting for the estimated risk of a given donor-recipient match. METHODS: This study identified 28,548 heart transplant candidates in the Organ Procurement and Transplant Network between July 2006 and December 2015. Donor-recipient match quality was estimated from the donor risk index. A time-dependent covariate Cox model was used to determine the effect of donor-recipient match quality on the likelihood of a composite outcome while waiting for a transplant or after transplantation. The composite outcome was death or delisting as too ill. RESULTS: Donor and recipient risk estimates were inversely related to the candidate urgency. Net benefit from heart transplantation was evident across all estimates of donor-recipient status 1A and 1B candidates: status 1A (lowest-risk quartile hazard ratio [HR]: 0.37; 95% confidence interval [CI]: 0.31 to 0.43; highest-risk quartile HR: 0.52; 95% CI: 0.44 to 0.61) and status 1B candidates (lowest-risk quartile HR: 0.41; 95% CI: 0.36 to 0.47; highest-risk quartile HR: 0.66; 95% CI: 0.58 to 0.74). Status 2 candidates showed a benefit from heart transplantation; however, survival benefit was delayed. For the highest-risk donor-recipient matches, a net benefit of transplantation occurred immediately for status 1A candidates, after 12 months for status 1B candidates, and after 3 years for status 2 candidates. CONCLUSIONS: This study demonstrated a survival benefit of heart transplantation across all ranges of estimated donor-recipient match risk for status 1A and status 1B candidates. Donor heart acceptance should be the favored strategy for these candidates. The benefit of transplantation for status 2 candidates was less apparent and dependent on estimated donor-recipient match risk, suggesting that a measure of donor-recipient match quality may be useful when considering the immediate benefit of heart transplantation for status 2 candidates in stable condition.

Effect of regional competition on heart transplant waiting list outcomes.

BACKGROUND: Heterogeneity of risk within heart transplant urgency designations is undesirable. Regional competition for donor hearts may contribute to this variation in risk. In this study we assessed whether an association exists between center competition and variation in event rates within status designations on the waiting list. METHODS: Our study sample included 20,237 adult transplant registrants initially listed between July 1, 2006 and July 1, 2013. Market competition was quantified using the Herfindahl-Hirshman Index (HHI) and number of centers within a donor service area (DSA) per 1 million people. A Cox model was used to assess for variation in waiting list outcomes within status designation by both HHI and DSA density. The primary outcome was death or delisting as too ill. RESULTS: Outcome rates within status designations differed significantly between centers: Status 1A, center p < 0.0001; Status 1B, center p < 0.0001; and Status 2, center p < 0.0001. Market competition (decreasing HHI) was associated with differential outcome rates within higher urgency status designation [Status 1A hazard ratio (HR) 0.94, p = 0.012; Status 1B HR 0.95, p = 0.010; and Status 2 HR 1.02, p = 0.360]. Center density within the DSA was not associated with outcome rates within each status designation (Status 1A HR 0.99, p = 0.961; Status 1B HR 1.03, p = 0.901; and Status 2 HR 1.20, p = 0.399). CONCLUSIONS: The rate of death or delisting as too ill within urgency designations varies between transplant centers and is partially explained by competition between transplant programs. Further methods of normalizing risk within status designations are necessary.