Pathology of heart transplantation: Study of autopsied and explanted allografts with emphasis on possible biopsy findings

We studied 28 cardiac allografts (26 autopsied, 2 explanted) from 27 patients aged 4 to 57 years (mean 35 yr). The duration of transplant was 1 day to 6 yr (mean 13 months). A spectrum of pathology was seen in the whole hearts including chronic transplant vasculopathy (12 cases), acute cellular rejection (7 cases), fungal infection (4 cases), and Epstein-Barr virus-related lymphoma (1 case). Length of transplant for cases with chronic transplant vasculopathy was 38 d to 6 yr and all transplants over 1 yr duration had chronic transplant vasculopathy. The lymphocytic infiltrate in acute cellular rejection was diffuse in 2 cases, but patchy in 5 with areas of spared myocardium. Subendocardial involvement was equal to that of other myocardial areas. Four patients with acute cellular rejection were biopsied within 4 d of death and only 1 biopsy was positive for rejection. Reasons for false negative results included a previous biopsy site confusing the inflammatory picture, a change in the clinical course after biopsy, and sampling error due to patchy lymphocytic infiltrate. A recent biopsy of the heart with lymphoma was misinterpreted as acute cellular rejection. We conclude that patchy lymphocytic infiltrates are common in acute cellular rejection, but a variety of factors produced false results in endomyocardial biopsies. Chronic transplant vasculopathy was universal in long-term allografts that failed.