Modulation of the atrioventricular node conduction to achieve rate control in patients with atrial fibrillation: long-term results

Modulation of the AV node reduces the ventricular rate during AF, without affecting AV conduction during sinus rhythm. Acute and long-term results of AV node modulation in 75 patients with AF and severe related symptoms of heart failure are presented in this study. The procedure involved, in all cases, the selective ablation of the posterior inputs to the AV node; in a subgroup of 15 patients with poor modification of AV conduction properties, a sequential approach involving subsequent anterior input ablation was performed. The procedure caused acutely a prolongation of the Wenckebach cycle length (38 patients in sinus rhythm) from 334 +/- 88 to 470 +/- 80 ms (P < 0.01), and a reduction of the average ventricular rate (37 patients in AF) from 154 +/- 31 to 88 +/- 40 beats/min (P < 0.01); permanent complete AV block was induced in 9 of 75 patients (12%). Considering the "sequential" approach, an increase of the Wenckebach cycle length from 362 +/- 50 to 530 +/- 45 ms (P < 0.01) and a reduction of the average heart rate in patients with AF from 158 +/- 16 to 81 +/- 20 beats/min (P < 0.01) was obtained in this subgroup of patients, in whom the AH interval prolonged from 93 +/- 12 to 175 +/- 27 ms, and no complete AV block was observed. At a mean follow-up of 23 +/- 9 months (range 2-48), the mean number of hospital admissions per patient per year decreased from 4.2 to 0.2. Five of 49 patients with paroxysmal AF and 3 of 26 patients with chronic AF had high rate recurrences (1 > 120 beats/min) that caused severe palpitations; these patients were considered as late clinical failures (8/75; 11%). All patients reported a substantial subjective improvement and an increased exercise tolerance, as documented by a semiquantitative questionnaire. There were no episodes of late AV block or sudden cardiac deaths. In conclusion, modulation of the AV node--either by slow pathway ablation, or by a "sequential" posterior and anterior approach in refractory patients--allows a long-term control of the ventricular rate and prevents the recurrence of severe clinical symptoms in more than 75% of patients with drug refractory AF.