CMR-Derived Myocardial Strain May Reflect Advanced Graft Injury Rather Than Acute Rejection After Heart Transplantation

Pediatric right ventricular longitudinal strain from 1.5T CMR shows the highest diagnostic accuracy for acute heart transplant rejection (AUC 0.782, 95% CI 0.565–0.999).

• Why it matters: CMR T1/T2 mapping can detect acute rejection, but the added value of CMR-derived strain—especially right ventricular strain—and its performance against a dd-cfDNA–informed reference standard are unclear.
• What they did: Blinded semi-automated quantification of left and right ventricular strain and ejection fraction was performed on 214 CMR studies from 58 pediatric and adult recipients (1–24 months post-transplant, plus five later rejection episodes). Acute rejection used a composite reference standard combining endomyocardial biopsy, clinical assessment, and donor-derived cell-free DNA.
• The result: Beyond pediatric right ventricular longitudinal strain, discrimination was limited across pediatric and adult groups (AUC 0.536–0.739), and models using EMB, clinical assessment, and dd-cfDNA alone also performed poorly, implying strain abnormalities may reflect more advanced graft injury.

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