Effects of intravenous cibenzoline on ventricular vulnerability and electrophysiology in patients with sustained ventricular tachycardia in comparison to a control group.

The electrophysiologic effects of intravenous (i.v. 1.5 mg/kg) cibenzoline were investigated in 13 patients with organic heart disease and supraventricular arrhythmias (control group) and 13 patients with drug refractory sustained ventricular tachycardia (VT group). In both groups, cibenzoline increased the effective refractory period (ERP) of the right ventricle (p less than or equal to 0.05), QRS duration (p less than or equal to 0.01), and QTc duration (p less than or equal to 0.01). Cycle length of the VT was increased from 311 +/- 73 to 393 +/- 119 ms (p less than or equal to 0.05) as well. The increase in QTc duration was more pronounced (p less than or equal to 0.05) in the VT group as compared with the control group. In four patients in the VT group with the largest increase in QRS-, QTc duration and cycle length of the VT proarrhythmia was noted after i.v. cibenzoline. Cibenzoline plasma levels were not significantly different between the two study groups. In the VT group, induction of VT was prevented in 2 patients, more difficult in 2 patients, easier in 1 patient, and unchanged in 5 patients. Spontaneous occurrence of the VT or induction by atrial stimulation was noted in 4 patients. In the control group, ventricular vulnerability remained unchanged. Cibenzoline may be effective in selected patients with drug refractory VT. In such patients, the increase in QTc duration was more pronounced as compared with a control group.