Mianserin, maprotiline and intracardiac conduction.

1 High speed surface electrocardiograms were recorded in 35 patients during the baseline and after four weeks' treatment in a placebo-controlled trial of mianserin and maprotiline in primary depressive illness. 2 Measurements of the RR, PR and QT intervals, QRS width and T wave height were made blind to patient, drug and treatment interval and compared with plasma drug concentrations. The presence or absence of cardiac arrhythmias was recorded. 3 The only significant findings were an increased heart rate and PR interval and decreased QTc interval in the maprotiline group. Only one patient receiving maprotiline had a cardiac arrhythmia. There was no significant correlation between measurements of ECG parameters and plasma drug levels. 4 The results confirm the lack of cardiac effects of mianserin and show both anticholinergic activity and effects of an intracardiac conduction in the case of maprotiline. The mechanisms of these effects are discussed.