The electrocardiographic effects of high-dose hypericum extract were compared to the
effects of imipramine hydrochloride on ECG 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 ECG 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.
