The effect of hypericum extract on cardiac conduction as seen in the electrocardiogram compared to that of imipramine

The electrocardiographic effects of high-dose hypericum extract were compared to the effects of imipramine hydrochloride on ECC recordings in a randomized, double-blind, multicenter treatment study of 209 patients suffering from depression. ECGs were recorded before and after a six-week treatment period with either hypericum extract or imipramine. At the end of the study ECGs of 84 patients treated with hypericum extract and 76 patients treated with imipramine were suitable for an analysis of conduction intervals and pathological findings. In the first ECG analysis comparing high dose hypericum extract with imipramine, a prolongation of the conduction intervals PR, QRS and QTc was found for imipramine. In contrast, a small acceleration of conduction was seen for the high-dose hypericum extract. The comparison of ECGs at the beginning and after six weeks of treatment showed a significant increase in first degree AV-blocks and abnormalities of repolarization under imipramine but a significant reduction of such pathological findings under treatment with hypericum extract. It should be emphasized that this favorable feature of safe cardiac activity was achieved with 1800 mg of hypericum extract. The reduction in pathological ECC features after treatment with hypericum extract may have resulted mainly from the change of medication, probably tricyclics, to hypericum extract. Our results indicate that for the treatment of patients with a pre-existing conductive dysfunction or elderly patients, high-dose hypericum extract is safer with regard to cardiac function than tricyclic antidepressants.