Effects of first-dose doxorubicin on cardiac rhythm as evaluated by continuous 24-hour monitoring.

Doxorubicin has been reported to cause ventricular arrhythmias and sudden death in the first 24 hours after administration. The authors placed continuous electrocardiographic recording devices on 30 patients 24 hours before, during, and 24 hours after doxorubicin administration. Nine patients experienced arrhythmias before treatment; 12 patients had posttreatment ectopy. No patient had life-threatening arrhythmias before or after treatment. Of the nine patients with pretreatment ectopy, only one experienced an increase in severity. Conversely, six patients without ectopy before treatment had arrhythmias after doxorubicin administration. The authors were unable to determine predictive factors in patients with no pretreatment ectopy who developed posttreatment premature ventricular contractions. The authors conclude that antecedent ventricular ectopy exists in the oncologic population and that this is not worsened by first-dose exposure to doxorubicin.