Cardiac magnetic resonance imaging in heart transplant recipients with biopsy-negative graft dysfunction.

Abstract

Graft dysfunction (GD) after heart transplantation (HTx) can develop without evidence of cell- or antibody-mediated rejection. Cardiac magnetic resonance imaging (CMR) has an evolving role in detecting rejection; however, its role in biopsy-negative GD has not been described. This study examines CMR findings, evaluates outcomes based on CMR results, and seeks to identify the possibility of rejection missed through endomyocardial biopsy by using CMR in HTx recipients with biopsy-negative GD. HTx recipients with GD [defined as a decrease in left ventricular ejection fraction (LVEF) by >5% and LVEF<50%] in the absence of rejection by biopsy or allograft vasculopathy and who underwent CMR were included in the study. The primary outcome was a composite of all-cause mortality, re-transplantation, or persistent LVEF<50%. Overall, 34 HTx recipients developed biopsy-negative GD and underwent CMR. Left ventricular late gadolinium enhancement (LGE) on CMR was observed in 16 patients with two distinct patterns: diffuse epicardial (n=13) and patchy (n=3) patterns. Patients with LGE developed GD later after HTx [4 (1.4-6.8) vs. 0.8 (0.3-1.2) years, P<0.001], were more often symptomatic (88% vs. 56%, P=0.06), and had greater haemodynamic derangement (pulmonary capillary wedge pressure: 19±7 vs. 13±3mmHg, P=0.002) as compared with those without LGE. No significant difference was observed in the primary composite outcome between patients with LGE and those without LGE (50% vs. 38% of patients with events, P=0.515). During a median follow-up of 3.8years, mean LVEF improved similarly in the LGE-negative (37-55%) and LGE-positive groups (32-55%) (P=0.16). Biopsy-negative GD occurs with and without LGE when assessed by CMR, indicative of possible rejection/inflammation occurring only in a subset of patients. Irrespective of LGE, LVEF improvement occurs in most GD patients, suggesting that other neurohormonal or immunomodulatory mechanisms may also contribute to GD development.