[Endomyocardial biopsy in the monitoring of treatment with anthracyclines. Value of the assay of lactate dehydrogenase and its isoenzymes]

Abstract

Determination of intramyocardial lactate dehydrogenase (LDH) and its isoenzymes (LDH 1 to 5) has been conducted on biopsy material obtained from the right ventricle in 18 patients who had received the theoretical maximal dose of anthracyclines. Total LDH activity, expressed in mU/mg of myocardial protein is higher (852.61 +/- 87.98) than in subjects with good left ventricular function (334 +/- 208), p less than 0.02. The activity of LDH 1 is decreased in the treated group, whereas that of LDH 3,4 and 5 is raised: LDH 1 = 41.95 +/- 7.25 per cent instead of 47.76 +/- 7.93 per cent (p less than 0.03); LDH 3 = 15.34 +/- 5.09 per cent instead of 9.18 +/- 4.56 per cent (p less than 0.05). The H/M ratio (H = fractions of heart isoenzymes; M = fractions of muscle isoenzymes of LDH) is decreased in the treated group: H/M = 4.06 +/- 1.13 instead of 5.30 +/- 1.80 (p less than 0.01). When the histological lesions are minimal (stage 1 or 1.5 of Billingham), the H/M ratio is not altered: 4.92 +/- 1.02. When the lesions attain or exceed stage 2, the H/M ratio is significantly decreased: 3.74 +/- 0.82. These results, which indicate an increase in anaerobic metabolism, add quantitative information to the histological study.