Torsades de pointes in paced patients with sick sinus syndrome after disopyramide administration

Three ventricular inhibited mode (VVI) pacemaker implanted patients, all above 65 years, female and having sick sinus syndrome suffered from torsades de pointes; one patient after 2.5 years and the other two patients within a day of disopyramide therapy. All had hypopotassemia and plasma disopyramide was below the therapeutic range in two patients. Torsades de pointes was induced following ventricular paced beats and suppressed by cessation of disopyramide in all or by setting a higher pacing rate in one. In our department, permanent VVI pacemakers were implanted in 43 patients with sick sinus syndrome including 26 with bradycardia-tachycardia syndrome, nine of whom were treated by disopyramide. Torsades de pointes was observed only in those disopyramide treated bradycardia-tachycardia patients. Our report stresses the proarrhythmic nature of combined VVI pacing and antiarrhythmic agents in the presence of hypopotassemia.