LONG-TERM FOLLOW-UP AFTER RADIOFREQUENCY MODIFICATION OF THE ATRIOVENTRICULAR NODE IN PATIENTS WITH ATRIAL-FIBRILLATION

Objectives. The purpose of this study was to describe the long term fo llow up results in 62 patients with atrial fibrillation and an uncontr olled ventricular rate, who underwent radiofrequency modification of t he atrioventricular (AV) node. Background. Previous studies in small n umbers of patients have suggested that radiofrequency modification may be effective in controlling the ventricular rate in patients with atr ial fibrillation, but long-term follow-up data have been lacking. Meth ods. The subjects of this study were 62 consecutive patients (mean age +/- SD 65 +/- 14 years; 43 with structural heart disease) who underwe nt an attempt at radiofrequency modification, of the AV node because o f symptomatic, drug-refractory atrial fibrillation with an uncontrolle d ventricular rate. The atrial fibrillation was chronic in 46 patients and paroxysmal in 16. Radiofrequency energy was applied to the poster oseptal or mid septal right atrium to lower the ventricular rate in at rial fibrillation to 120 to 130 beats/min during an infusion of 4 mu g /min of isoproterenol. Results. Short-term control of the ventricular rate was successfully achieved without the induction of pathologic AV block in 50 (81%) of 62 patients. Inadvertent high degree AV block occ urred 10 (16%) of 62 patients, with the AV block occurring at the time of the procedure in 6 patients and 36 to 72 h after the procedure in 4. During 19 +/- 8 months of follow-up (range 4 to 33), 5 (10%) of 50 patients had a symptomatic recurrence of an uncontrolled rate during a trial fibrillation. Overall, adequate rate control at rest and during exertion, without pathologic AV block, was achieved long term in 45 (7 3%) of 62 patients. Among 37 patients with a successful outcome, left ventricular ejection fraction increased from (mean +/- SD) 0.44 +/- 0. 14 to 0.51 +/- 0.10 one year later (p < 0.001). Complications other th an AV block included polymorphic ventricular tachycardia 10 to 24 h af ter the procedure in two patients who had a predisposing factor for ve ntricular tachycardia and sudden death 1 to 5 months after the procedu re in two patients with idiopathic dilated cardiomyopathy, one of whom had a pacemaker for AV block. Conclusions. In similar to 70% of prope rly selected patients with atrial fibrillation and an-uncontrolled ven tricular rate, radiofrequency modification of the AV node results in e xcellent long-term control of the ventricular rate at rest and during exertion. (C) 1997 by the American College of Cardiology