Long-term reproducibility of electrophysiologically guided therapy with sotalol in patients with ventricular tachyarrhythmias

OBJECTIVES Goal of this study was to assess the long-term reproducibility of electrophysiologic drug testing in patients with ventricular tachyarrhythmias (VT/VF). BACKGROUND Programmed ventricular stimulation (PVS) is still widely used to guide antiarrhythmic therapy in patients with sustained ventricular tachycardia/fibrillation (VT/VF). Sotalol is considered as one of the most effective drugs for VT/VF. Because there is no proof of long-term reproducibility of successful drug test with sotalol, we investigated the long-term reproducibility of drug testing with sotalol. METHODS Thirty patients with VT/VF (age: 57 ± 11 years, 20 patients with coronary heart disease, 7 patients with no structural heart disease, 3 with others) and reproducible induction of VT/VF (28 patients VT, two patients VF) in baseline PVS, were suppressible with sotalol (mean dosage 395 ± 137 mg) in subsequent PVS. After mean follow-up of 13 ± 10 months PVS was again performed in patients, who had no evidence of progressive cardiac disease, who did not experience any arrhythmi recurrences or who were drug compliant. Irrespective of the inducibility after long-term therapy with sotalol, all patients were kept on the initial sotalol regimen. All 30 patients had stable cardiac condition, were free of VT/VF recurrences and were drug compliant. RESULTS Despite the clinical efficacy of sotalol, in 12 patients (40%) VT/VF could again be induced after 13 ± 10.2 months. Inducibility was independent of age, heart disease, ejection fraction and follow-up time. During further follow-up of 22.1 ± 10.9 months, five patients experienced nonfatal VT recurrences independently of the prior inducibility. CONCLUSIONS This study shows lacking long-term reproducibility of an initial effective PVS with sotalol. Despite an uneventful clinical follow-up, late electrophysiologic testing showed VT/VF inducibility in high portion of patients. Hence, electrophysiologic testing performed late after the initial drug test may no longer be predictive of outcome.