Pathological findings in 2300 consecutive endomyocardial biopsies.

Endomyocardial biopsy (EMB) is a valuable diagnostic procedure for rejection surveillance in heart allograft recipients and is widely used for evaluation of native heart disease. However, the spectrum and incidence of diagnoses encountered on a heart failure/cardiac transplant service deserve clarification. Of 2300 consecutive EMBs performed during a 2.5-yr period, 79.9% had been performed for rejection surveillance in heart allograft recipients. Of these, 1281 (69.7%) were negative for rejection; 536 (29.1%) were positive (18.9% mild, 9.7% moderate, 0.5% severe); 21 (1.1%) were not interpretable due to insufficient samples. Endocardial lymphocytic infiltrates ("Quilty" effect) were present in 86 (4.7%), ischemia in 12 (0.7%), myocardial calcification in five (0.3%), foreign body giant cells in two (0.1%), valvular tissue in two (0.1%), and liver tissue in one (0.05%). Of the 20.1% of EMBs performed in patients with native heart disease, 298 (64.5%) were abnormal. A total of 239 (51.7%) had myocyte hypertrophy and/or fibrosis, while 37 (8.0%) had active or ongoing myocarditis, two of which were of the giant cell type. Other diagnoses included anthracycline cardiotoxicity in 11 (2.4%), amyloidosis in five (1.1%), hemochromatosis in two (0.4%), healed infarct in two (0.4%), scleroderma in one (0.2%), and foreign body granuloma in one (0.2%). A total of 159 (34.4%) samples had no diagnostic abnormalities; five (1.1%) were insufficient samples. As the number of EMBs performed grows, pathologists must develop expertise in the detection of morphological features pertaining to various cardiac conditions which may have similar clinical presentations.