Radiofrequency catheter ablation of inappropriate sinus tachycardia guidedby activation mapping

OBJECTIVE The purpose of this study was to evaluate the value of activation mapping for radiofrequency modification of the sinus node and the long-ter m success rate of the procedure in a series of patients with inappropriate sinus tachycardia. BACKGROUND The results of radiofrequency ablation of inappropriate sinus ta chycardia have been reported in only a small number of patients. METHODS The subjects of this study were 29 consecutive drug-refractory pati ents who underwent catheter ablation of inappropriate sinus tachycardia. Ta rget sites were selected by activation mapping during sinus tachycardia. RESULTS The ablation procedure was successful acutely in reducing the basel ine sinus rate to <90/min and the sinus rate during isoproterenol infusion by >20% in 22 of 29 patients (76%). In 13 of 22 patients (59%) with a succe ssful acute outcome, successive applications of radiofrequency energy at th e site of earliest endocardial activation resulted in a cranial-caudal migr ation of earliest endocardial activation from the high lateral right atrium , along with a step-wise reduction in heart rate. In the other nine patient s (41%) with a successful acute outcome, the reduction in sinus rate occurr ed abruptly, unaccompanied by migration of the site of earliest activation. Symptoms due to inappropriate sinus tachycardia recurred at a mean of 4.4 +/- 3 months after the ablation procedure in 6 of 22 patients (27%). After additional procedures in three patients, symptoms:of inappropriate sinus ta chycardia ultimately were successfully eliminated over the long-term in 19 of 29 patients (66%). CONCLUSIONS In conclusion, radiofrequency ablation is at best only modestly effective for managing patients with inappropriate sinus tachycardia. The two different responses of heart rate to radiofrequency ablation may reflec t differences in the number and/or multicentricity of subsidiary sites of i mpulse generation within the sinus node and/or atrium in patients with inap propriate sinus tachycardia. (J Am Coil Cardiol 2000;35:451-7) (C) 2000 by the American College of Cardiology.