Electrophysiologic drug testing in symptomatic ventricular arrhythmias after repair of tetralogy of Fallot.

Nine patients with symptomatic ventricular arrhythmias were evaluated a mean interval of 16 years after surgical repair of tetralogy of Fallot. The clinical arrhythmia was sustained ventricular tachycardia (VT) in 4 patients (group I) and premature ventricular contractions in 5 (group II). All patients underwent cardiac catheterization and electrophysiologic studies. Ventricular tachycardia was induced at electrophysiologic study in all patients in group I and in 3 patients in group II. Six patients with inducible sustained monomorphic VT underwent chronic drug testing based on electrophysiologic study. A mean of 3.3 drugs per patient was tested. Patients with right ventricular systolic hypertension did not respond to any drug tested, and underwent surgery. Five patients received drug treatment based on the results of electrophysiologic study. During a mean follow-up period of 2.2 years, no patient in either group had recurrent episodes of VT or syncope. In the postoperative patient with tetralogy of Fallot with symptomatic ventricular arrhythmias, it is concluded that electrophysiologic study is useful in reproducing clinical episodes of VT and in selecting effective antiarrhythmic medication; a small number of patients with ventricular premature complexes alone will have inducible sustained VT during electrophysiologic study; prognosis of these patients may be improved by treatment that results in prevention of VT induction; and in patients with right ventricular hypertension, VT is likely to be refractory to drug treatment.