Introduction: Cardiotoxicity is a well-known and serious complication of antitumorous treatment. Anthracyclines represent the greatest risk. Biochemical markers of structural and functional myocardial damage have been gaining ground in cardiotoxicity diagnostics. Design: Monitoring of cardiotoxicity during induction chemotherapy in acute myeloid leukemia (AML) patients and assessment of potential for use of biochemical markers in early diagnostics of cardiotoxicity. Patients and Methods: 15 consecutive adult patients with a newly diagnosed AML (9 male and 6 female, mean age 43.7 ± 10.6 years) participated in the study. The patients received induction chemotherapy containing intermediate doses of Cytarabine (8 x 1.5 g/m2) and Idarubicin (IDA) 12 mg/m2/day intravenously on 1st 3rd and 5th day (in total 36 mg/m2 = 1/4 of the maximum cumulative dose). Serial measurements of serum NT-proBNP concentrations were performed at the baseline, the day following each IDA infusion, after 14 days and after circa 1 month, i.e. before the next chemotherapy. Cardiospecific markers (cTnT, CK-MB mass) were measured at the baseline and after the last IDA infusion. Results: The mean baseline concentration of NT-proBNP in newly diagnosed AML patients was 129.7 ± 59.6 pg/ml. The mean value of the NT-proBNP concentration increased after the first IDA infusion to 307.3 ± 171.4 pg/ml (P = 0.02). In most of the patients the second and the third IDA infusions were not associated with a further increase in the NT-proBNP value and values after 2 or 4 weeks were not significantly different from the baseline. However, in one of the patients the NT- -proBNP values were increasing after each IDA infusion (after the last one 786.2 pg/ml) and within 14 days he developed congestive heart failure due to left ventricular diastolic dysfunction as assessed by echocardiography. At that time the NTproBNP value was 1184.0 pg/ml; after diuretics it decreased significantly. In all patients plasma cTnT and CK-MB mass concentrations were within the reference interval at the baseline and after the induction chemotherapy. Conclusions: Our results show that induction chemotherapy in AML (IDA 36 mg/m2 and intermediate doses of Cytarabine): 1. does not cause detectable damage of the myocyte structure; 2. is in all patients associated with acute neurohumoral activation (transient elevation of NT-proBNP) indicating acute subclinical cardiotoxicity, 3. may lead to congestive heart failure and NT-proBNP seems to be a promising early marker and predictor of this complication.

        Key words: NT-proBNP, cardiomarkers, cardiotoxicity, anthracyclines, acute leukemia.