Clinical, histochemical, and ultrastructural correlation in septal endomyocardial biopsies from chronic chagasic patients: detection of early myocardial damage.

In order to recognize early signs of myocardial damage, histologic, histochemical, and ultrastructural studies were performed on septal endomyocardial biopsy tissue obtained from 79 chronic chagasic patients and from 18 patients with atypical chest pain (control group). Abnormal biopsy findings were recognized in 9 of 16 (60%) chagasic patients with no clinical evidence of myocardial damage. In cases of segmental asynergy only, biopsies were abnormal in 18 of 19 patients. When signs of advanced myocardial damage were evidenced by clinical examination or ECGs, all biopsies were abnormal. Mitochondrial, nuclear, and cell membrane irregularities were consistent findings. A peculiar dilatation and filling of the T tubule system with a glycoprotein-like substance and a remarkable increase in monoamine oxidase activity were observed early in the disease and progressed in magnitude and frequency as myocardial damage became more evident by other diagnostic methods. Septal endomyocardial biopsy is a sensitive method for detection of early myocardial damage in chronic chagasic patients. Based on these findings, a modification of the currently used classification is proposed.