Structural and functional cardiac changes after transplantation: experiences of the first year of the prospective Heart-TIming CMR substudy
Authors: Dohy Z , Szabo L , Czimbalmos C , Szakal-Toth Z.S , Parazs N , Teszak T , Tarjanyi Z , Kiraly Ά , Suhai F.I , Sax B , Becker D , Merkely B , Vago H 
Published: November 2020

Abstract

Background
In case of heart transplantation (HTX) the heart is affected by several factors e.g. ischaemia/reperfusion, denervation, immunosuppression. During the adaptation, the heart may show marked temporal changes in terms of myocardial mechanics, function and tissue characteristics. To better understand cardiac temporal characteristics after orthotopic bicaval HTX we started the prospective Heart-TIming (Transplantation Imaging) trial in January 2018.

Purpose
In our CMR substudy we aimed to evaluate the physiological structural and functional left and right ventricular characteristics and their temporal changes after HTX using cardiac magnetic resonance.

Methods
As part of the study HTX patients underwent CMR at one, three, six and twelve months after HTX (n=49; 53±11y, 39 male). Cine images, T2-weighted, native T1 and T2 mapping, late gadolinium enhancement (LGE) and adenosine stress perfusion (at 1 and 12 month) images were acquired. In order to describe physiological characteristics of the transplanted heart we excluded pts with significant coronary artery disease, ischaemic scar, ≥Grade II allograft rejection from this present study (n=9). We evaluated the left (LV) and right ventricular (RV) ejection fractions (EF), volumes, masses (M) and the global LV strain values: longitudinal (GLS), circumferential (GCS) strain and the standard deviation (SD) of the peak longitudinal strain (LS) and the mechanical dispersion. In a basal short axis slice the native T1 and T2 mapping values were evaluated. We compared baseline CMR parameters to age and gender matched healthy controls (n=20; 48±10y, 16 male), and analyzed the temporal changes after HTX.

Results
Comparing the HTX patients' CMR parameters at one month with normal controls, HTX patients had lower end-diastolic volumes (LVEDVi: 74±15 vs 89±13 ml/m2; RVEDVi: 72±16 vs 89±15 ml/m2 p&lt;0.05), stroke volumes (LVSVi: 45±7 vs 55±8 ml/m2, RVSVi: 43±8 vs 54±8 ml/m2, p&lt;0.0001), higher LVMi (63±2 vs 55±3 g/m2, p&lt;0.05), increased SD of peak LS (14±2 vs 10±2, p&lt;0.0001) and more pronounced mechanical dispersion (18±5 vs 12±4, p&lt;0.0001). The native T1 mapping values were significantly higher in HTX pts (1007±40 vs 975±24 ms, p&lt;0,01). Examining temporal changes in HTX pts we found a decrease in LVMi (66±14 vs 59±10 g/m2, p&lt;0.01) already at three months. At 12 months LVMi decreased further, less negative GLS (−25±4 vs −20±4, p&lt;0.01) and GCS (−38±7 vs −34±4, p&lt;0.05), and lower SD of the peak LS (14±2 vs 11±2, p&lt;0.01) were measured.

Conclusions
Understanding the temporal changes of cardiac mechanics, function and tissue characteristics, furthermore the establishment of physiological values may help in the early, noninvasive identification of pathological changes in HTX pts.
Tissue specific information in HTX pts

Funding Acknowledgement
Type of funding source: Public grant(s) – National budget only. Main funding source(s): Project no. NVKP_16-1-2016-0017 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the NVKP_16 funding scheme. Supported by the ÚNKP-18-3-IV New National Excellence Program of Human Capacities.