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Early and late arrhythmogenic effects of doxorubicin.

18587 Background: To determine the early and late arrhythmogenic effects of doxorubicin-containing chemotherapy regimens, and to identify associated risk.


METHODS
A prospective study including 29 patients who were treated with doxorubicin-containing regimens between September 2002 and September 2003. Cardiac evaluation was based on 24-hour electrocardiographic monitorization (Holter), which was performed during the first cycle of doxorubicin-containing regimens as well as after the last cycle of chemotherapy.


RESULTS
The mean age of the patients was 45.8 ± 15.1 (range 18-69) and the average dose of doxorubicin was 280.03 ± 113.50 mg/m2 (range 50-480). Holter records obtained during the first cycle of treatment revealed varying arrhythmias in 19 patients (65.5%). The most common arrhythmia was supraventricular extrasystole (n = 11, 37%). Holter records obtained after completion of therapy revealed a variety of rhythm abnormalities in 18 (62.1%) patients, with supraventricular extrasystole again being the most common arrhythmia (n = 13, 44.8%). Only 13 (44.8%) patients had arrhythmias documented in both Holter records. One patient presented with syncope during the first course of doxorubicin therapy and Mobitz type 2 atrioventricular block along with complete atrioventricular block lasting for 12 seconds were demonstrated after examination of Holter records. The patient subsequently underwent permanent pacemaker implantation. There was no correlation between the development of arrhythmia in the early and late period and sex, diagnosis, age, and previous radiotherapy history.


CONCLUSION
Doxorubicin may result in arrhythmias both in early and late periods of treatment. These arrhythmias are rarely life threatening. No significant financial relationships to disclose.