Blood Tests for Heart Transplant Rejection: BNP Peptide Has Limited Value as Molecular Markers Take Over | Research

The takeaway

Conventional peptide biomarkers like BNP and cardiac troponins have limited specificity for detecting heart transplant rejection, while newer molecular tools — donor-derived cell-free DNA and gene expression profiling — offer superior discrimination.

BNP: limited specificity for rejection
Despite being a cornerstone cardiac biomarker, B-type natriuretic peptide cannot reliably distinguish transplant rejection from other causes of cardiac stress, driving the shift toward molecular diagnostics.

What the researchers found

The review categorizes rejection biomarkers by clinical utility:

- Well-validated molecular tools: Donor-derived cell-free DNA (ddcfDNA) and gene expression profiling (GEP) demonstrate strong discriminative capacity for acute rejection and are commercially available

- Emerging biomarkers: MicroRNAs (miRs) and extracellular vesicles (EVs) show considerable potential but require further validation

- Conventional biomarkers with limitations: B-type natriuretic peptide (BNP), cardiac troponins, and creatine kinase-MB (CK-MB) offer limited specificity for rejection — they detect cardiac stress broadly but cannot distinguish rejection from other causes

The review highlights a clear shift from conventional peptide/protein biomarkers toward molecular-based approaches for post-transplant surveillance.

Why it matters

Heart transplant recipients currently undergo routine invasive cardiac biopsies to check for rejection — a procedure that carries risk and discomfort. Reliable blood tests could replace many of these biopsies, improving patient quality of life and reducing healthcare costs. While BNP and troponins were early candidates, this review confirms they are being superseded by more specific molecular approaches, marking a paradigm shift in transplant monitoring.

How the study worked

This is a narrative review synthesizing current evidence on blood-based biomarkers for noninvasive monitoring of cardiac allograft rejection. The authors evaluated the clinical utility, methodological challenges, and integration strategies of established and emerging biomarkers across multiple categories.

What this study cannot tell us

As a narrative review, the literature search may not be comprehensive. Most biomarker studies are single-center with varying definitions of rejection and different assay methodologies, making direct comparisons difficult. The commercially available molecular tests (ddcfDNA, GEP) are expensive and not universally accessible. Long-term outcome data comparing biomarker-guided versus biopsy-guided monitoring strategies are limited. The review does not provide quantitative sensitivity/specificity comparisons across all biomarker classes.

How to read the evidence

This is a narrative review synthesizing published evidence on transplant biomarkers. It provides a comprehensive overview of the field but does not include meta-analysis or systematic quality assessment of individual studies.

When this study was published

Published in 2026, this is a very current review capturing the latest advances in noninvasive transplant rejection monitoring, including commercially available molecular diagnostic platforms.

The bigger picture

BNP (B-type natriuretic peptide) has been a cornerstone biomarker in cardiology for decades, particularly for heart failure diagnosis. However, this review illustrates its limitations in the transplant setting — it reflects cardiac stress broadly rather than rejection specifically. The shift toward molecular biomarkers (cfDNA, gene expression) mirrors broader trends in precision medicine, where disease-specific molecular signatures are replacing nonspecific protein/peptide markers. This has implications for how peptide biomarkers are used across cardiology.

Questions still open

Can a multi-biomarker panel combining molecular markers with BNP outperform any single test for rejection detection?
Will cost reductions in ddcfDNA testing make it accessible enough to replace routine biopsies worldwide?
Could BNP retain a role as a first-line screening test with molecular markers reserved for confirmation?

Common questions

Why can't a simple blood test like BNP detect heart transplant rejection?

BNP is released whenever the heart is under stress — from rejection, but also from infection, fluid overload, or any other cardiac problem. It can't tell doctors WHY the heart is stressed, just that it is. Newer molecular tests like donor cell-free DNA are much more specific: they detect fragments of the donor heart's DNA in the patient's blood, which increase specifically when rejection damages donor heart cells.

Could heart transplant patients eventually avoid biopsies entirely?

That's the goal. Donor-derived cell-free DNA and gene expression profiling are already reducing biopsy frequency for many patients. While biopsies may still be needed for confirming suspected rejection or monitoring complex cases, molecular blood tests are progressively replacing routine surveillance biopsies, making post-transplant care less invasive.

Read the original research

Noninvasive Biomarkers for Cardiac Allograft Rejection Monitoring: Advances, Challenges, and Future Directions.

Journal of clinical medicine, 15(3)

View on PubMed ↗Publisher’s paper ↗

Citation

Luo, Yijie; Lai, Junlin; Li, Chenghao; Wang, Guohua. (2026). Noninvasive Biomarkers for Cardiac Allograft Rejection Monitoring: Advances, Challenges, and Future Directions.. Journal of clinical medicine, 15(3). https://doi.org/10.3390/jcm15030986