Measurement of the S alpha T segment as the most reliable electrocardiogram parameter for the assessment of adriamycin-induced cardiotoxicity in the rat.

A new method is described for the assessment of the early cardiotoxic effects of adriamycin and related drugs on rat electrocardiographic parameters. Evidence is presented that during repeated treatment with adriamycin, no changes occur concerning the PR and RR intervals, QTc, or R- and S-wave voltages, whereas significant changes in the QRS complex, R alpha T and alpha TP intervals, and T-wave voltage are detectable. However, the earliest and most consistent electrocardiogram alteration observed during adriamycin treatment is a progressive, irreversible widening of the S alpha T segment. The S alpha T enlargement becomes significant during the first week of treatment and may be detected in all the tracings at all the times examined. The electrocardiogram changes are accompanied by cardiac histological lesions that gradually increase in severity during the study. These results indicate that the measurement of the S alpha T segment provides a rapid, sensitive, and reliable method for the evaluation of electrocardiogram toxicity induced by adriamycin and related anthracyclines in the rat.