Comparison of the effects of bupropion and amitriptyline on cardiac conduction in depressed patients.

Tricyclic antidepressants may prolong cardiac conduction as a result of their direct cellular membrane depressant effects. These effects can be evaluated by careful quantitative assessment of the electrocardiogram (ECG). This study compared the ECG effects of bupropion and amitriptyline at therapeutically comparable doses. No significant changes were seen with bupropion in any of the ECG parameters measured (PR interval, QRS duration, QTc interval, and QRS height). Amitriptyline, however, caused a significant prolongation in PR interval (p less than .01) and QRS duration (p less than .05), as well as a decrease in QRS height (p less than .001). These results suggest that bupropion is less likely to cause cardiac conduction abnormalities in patients prone to such problems, or in those patients who overdose.