Evaluation of early doxorubicin-induced cardiotoxicity by means of systolic time intervals.

Systolic time intervals (PEP/LVET ratio) were used for detection of acute variations in myocardial contractility after a single dose of 30, 60, or 75 mg of doxorubicin/m2. This drug induces an acute impairment of left ventricular function (increase in the PEP/LVET ratio) detectable 1 h after doxorubicin injection. The phenomenon appears to be dose-related, with a threshold dose of 30-40 mg/m2. The decrease in myocardial contractility is fully reversible within 24 h, at least after the first dose. This kind of evaluation appears applicable to phase I studies of new anthracycline derivatives.