Development of fibrosis in cardiac allografts: a comparative single-centre study of two consecutive decades

Background & Objective: The use of mechanical circulatory support as bridge-to-transplant is growing due to limited donor availability. It isuncertain whether development of cardiac fibrosis in heart transplant allografts is influenced by previous mechanical circulatory support.This is particularly important, because cardiac fibrosis is causative for progressive deterioration of cardiac function. Method: We compared levels of fibrosis in consecutive right ventricular endomyocardial biopsies harvested over two calendar years separated bya decade from which fibrosis data were available (n= 101 in 2001 versusn= 248 in 2011). Gender, age of both recipient and donor at time of transplantation and time after transplantation were considered, beforethe patients were subdivided into distinct groups by use of mechanicalcirculatory support. Results: Overall fibrosis levels differed only insignificantly (non-MCSgroup 9.2%vs6.0%MCS group in2001;non-MCSgroup 8.8%vsMCSgroup5.9%in2011).Butsignificantdifferencesinscarlevelswerefound between decades, which were increasing in the MCS group (p<0.001, 14.9% in 2001 vs 18.4% in 2011 and decreasing in the non MCS-group22% in 2001 vs 15.3% in 2011). Conclusion: No relevant variation in fibrosis, but in scar levels inendomyocardialrightventricularbiopsiesinthetwodifferentconsecutivedecades could be demonstrated. Given similar donor age, difference inscar levels may be viewed as consequence of longer support times onMCS during the last decade and differences in underlying pathology of heart failure. Our findings merit further investigations.