Dynamic pericoronary fat attenuation as a non-invasive marker of CAV progression after heart transplantation

BACKGROUND: Pericoronary adipose tissue (PCAT) density on coronary computed tomography angiography (CCTA) has emerged as a non-invasive marker of perivascular inflammation and a potential prognostic biomarker in heart transplant recipients. However, relationship between the longitudinal changes in PCAT attenuation and cardiac allograft vasculopathy (CAV) progression remains poorly defined. OBJECTIVES: To evaluate whether static PCAT density values and their longitudinal change predict CAV progression and adverse evolution in stable heart transplant recipients. METHODS: We retrospectively enrolled 127 recipients with clinical, echocardiographic, and biopsy-proven stability undergoing paired CCTA at Padua University Hospital. Proximal, pancoronary, and right coronary artery pericoronary fat attenuation were measured at baseline and follow-up CCTA. RESULTS: Baseline CCTA was performed a median of 7.5 years after transplantation and follow-up 2.0 years later. Radiological CAV progression occurred in 14 patients (11.0%) according to International Society for Heart and Lung Transplantation criteria; 20 patients (15.7%) met the composite radiological or clinical endpoint (worsening of New York Heart Association functional class, or hospitalization for cardiovascular causes). Cohort-level PCAT density values and in event-free patients were stable, while subjects presenting composite events showed longitudinal increases in all six attenuation metrics. A newly proposed biomarker, the dynamic PCAT ratio (baseline/follow-up) was consistently higher than 1 in patients with radiological or clinical progression, while remaining close to 1 in event-free subjects. In Firth penalized regression, dynamic PCAT ratios remained associated with the composite endpoint after multivariable and multiplicity adjustment, whereas associations with static measurements did not remain significant after correction. CONCLUSIONS: In heart transplant recipients, temporal evolution of PCAT density, rather than single measurements, appears to capture the biological activity associated with subsequent clinical deterioration, but warrants prospective multicentre validation.