A novel donor-derived cell-free DNA assay for the detection of acute rejection in heart transplantation

BACKGROUND

Endomyocardial biopsy (EMB), the reference surveillance test for acute rejection (AR) in heart transplant (HTx) recipients, is invasive, costly, and shows significant interobserver variability. Recent studies indicate that donor-derived cell-free DNA (dd-cfDNA), obtained non-invasively from blood, is associated with AR and could reduce the frequency of EMB surveillance. The aim of this study was to examine the performance characteristics of a novel test for detecting AR in adult HTx recipients.

METHODS

Plasma samples with contemporaneous EMBs were obtained from HTx recipients. A clinically available SNP-based massively multiplexed-PCR dd-cfDNA assay was used to measure dd-cfDNA fraction. dd-cfDNA fractions were compared with EMB-defined rejection status and test performance was assessed by constructing ROC curves and calculating accuracy measures.

RESULTS

A total of 811 samples from 223 patients with dd-cfDNA testing and contemporaneous EMB were eligible for the study. dd-cfDNA fraction was significantly higher in AR (median 0.58%, IQR, 0.13%-1.68%) compared to non-AR (median 0.04%, IQR, 0.01%-0.11%, pc < 0.001). ROC analysis produced an area under the curve (AUC-ROC) of 0.86 (95% CI, 0.77-0.96). Defining samples with dd-cfDNA fraction ≥0.15% as AR yielded 78.5% sensitivity (95% CI, 60.7%-96.3%) and 76.9% specificity (95% CI, 71.1%-82.7%). Positive and negative predictive values were 25.1% (95% CI, 18.8%-31.5%) and 97.3% (95% CI, 95.1%-99.5%) respectively, calculated using the cohort AR prevalence of 9.0% (95% CI, 5.3%-12.8%) with adjustment for repeat samples.

CONCLUSIONS

This novel dd-cfDNA test detects AR in HTx recipients with good accuracy and holds promise as a noninvasive test for AR in HTx recipients.

Medical decisions in organ donors and heart transplant candidates with history of COVID-19 infection: An international practice survey

Background

A growing proportion of transplant donors and recipients have a history of COVID‐19 infection. This study sought to characterize clinical practice after recipient or donor COVID‐19 infection.

Methods

An online survey was distributed to heart transplant clinicians through a professional society message board and social media. Responses were collected between September 29 and November 5, 2021.

Results

There were 222 health care professionals (68% transplant cardiologists, 22% transplant surgeons, 10% other) across diverse geographic regions who completed the survey. While there was significant variation in donor acceptance, as it relates to past and current COVID‐19 infection, the respondents were fairly cautious: 28% would not typically accept a donor with a history of COVID‐19 regardless of the infection course and > 80% would not accept donors who had evidence of myocardial dysfunction during past COVID‐19 infection, or who died of COVID‐19 or its complications. The timing of candidate reactivation on the waiting list after COVID‐19 infection also varied and often diverged from scenarios addressed by social guidelines. Eighty‐one percent of the respondents felt COVID‐19 vaccine should be mandatory before transplant, but this rate varied by geographic region.

Conclusion

Our results reflect evolving experience of the heart transplant field at a time of lack of high‐quality evidence. In the absence of longer‐term outcome data for donors and transplant candidates with history of COVID‐19 infection, clinicians remain cautious; however, this approach will likely need to be refined as an increasing proportion of the population will continue to be infected with COVID‐19.

Risk stratification and prognosis of human immunodeficiency virus-infected patients with known or suspected coronary artery disease referred for stress echocardiography

BACKGROUND

Patients with human immunodeficiency virus (HIV) infection are at increased risk of accelerated coronary artery disease (CAD) and cardiovascular events. Stress echocardiography (SE) is routinely used for risk stratification and prognosis of patients with known or suspected CAD. The prognostic value of SE in this high-risk group is unknown. The purpose of this study was to evaluate the prognostic value of SE in HIV-infected patients with known or suspected CAD.

METHODS AND RESULTS

We evaluated 311 patients (age, 52 ± 9 years; 74% men; left ventricular ejection fraction, 54 ± 12%) with history of HIV, undergoing SE (56% dobutamine). Left ventricular wall motion was evaluated on a 16-segment model, 5-point scale. An abnormal SE was defined by a fixed (infarction), biphasic, or new (ischemia) wall motion abnormality on stress. Follow-up for cardiac death and myocardial infarction was obtained. Seventy-nine (26%) patients had an abnormal SE. After 2.9 ± 1.9 years, 17 confirmed myocardial infarction and 14 cardiac deaths occurred. SE risk-stratified patients into normal versus abnormal subgroups (event rate, 0.6% per year versus 11.8% per year; P < 0.0001). Both abnormal SE (hazard ratio, 28.2; 95% confidence interval, 6.2 to 128.0; P < 0.0001) and the presence of any ischemia on SE (hazard ratio, 3.4; 95% confidence interval, 1.3 to 8.6; P = 0.009) were independent predictors of cardiac events. On a forward conditional Cox proportional hazards regression model, SE provided incremental prognostic value over clinical, stress ECG, and resting echocardiographic variables (global χ(2) increased from 17.8 to 24.5 to 65 to 109, P < 0.05 across all groups).

CONCLUSIONS

SE can effectively risk-stratify and prognosticate patients with HIV. The presence of ischemia and scar during SE provides independent and incremental prognostic value over traditional variables. A normal SE response portends a benign prognosis even in this high-risk subset.