Cardiac transplantation: towards a new noninvasive approach of cardiac allograft rejection.

Cardiac allograft rejection (CAR) may occur after transplantation and remains silent, until hemodynamic deterioration takes place. Endomyocardial biopsy (EMB) is applied to early detect CAR. Although, flexible bioptoms have decreased the incidence of lethal complications, EMB remains an invasive procedure carrying risk of tamponade and permanent heart block. Therefore, a new non-invasive approach is needed. Areas covered: AlloMap molecular expression testing and graft-derived cell-free DNA (GcfDNA) test can be used as blood indices of acute and chronic CAR, respectively. Among diagnostic techniques, only echocardiography and cardiovascular magnetic resonance (CMR) have shown a strong correlation with EMB. Echocardiography is bedside, cost and time saving. However, the currently used indices are insensitive markers of CAR. Global longitudinal strain (GLS) can diagnose the subclinical CAR and be used together with EMB to monitor acute CAR. CMR can improve our diagnostic accuracy using T2STIR, T1, T2 mapping, early/late gadolinium enhancement and functional assessment. Expert commentary: A new non-invasive approach in asymptomatic transplanted patients should be based on a serial assessment of AlloMap, GcfDNA testing, echocardiographic and CMR indices that will guide the indication for EMB. In symptomatic patients immediate EMB is the approach of choice, since they have high likelihood for CAR.