[Lausanne experience in radiofrequency percutaneous ablation of the slow pathway in nodal tachycardia].

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most frequent paroxysmal supraventricular tachycardia and results from reentry in the atrioventricular nodal region via slow and fast pathways. The curative treatment of choice consists of selective radio-frequency catheter ablation of the slow pathway. In this retrospective study we report our experience of 73 consecutive patients suffering from AVNRT treated by selective slow pathway ablation and also review some features of AVNRT. AVNRT appeared for the first time at the age of 29 +/- 15 years and lasted for 17 +/- 13 years. In 37% of the patients AVNRT recurred at least weekly, 10% presented with syncope and 15% were admitted to hospital more than 5 times. On average, 2.5+/-1.6 drugs were prescribed to 66 of the 73 patients and 83% of them were drug-refractory. Selective slow pathway ablation was successfully performed in 65 patients (89%). The procedure, although effective, was complicated by atrioventricular block in 2 patients (2.7%) and failed in 6 patients. In 5 of them, fast pathway ablation was attempted and was successful in 2 cases, resulted in atrioventricular block in one case and failed in 2 cases. The complications, apart from atrioventricular block necessitating a pacemaker in all cases, were one pulmonary embolism and 2 pneumothorax. The mean follow-up for the 70 patients for whom ablation was effective (with or without atrioventricular block) is 12.7+/-7.3 months. AVNRT relapsed in 5 patients (7%); all of them underwent a second ablation with 4 successes (slow pathway) and one atrioventricular block (fast pathway after failed slow pathway ablation). 11 patients (16%) developed palpitations: in one case they were due to atrial fibrillation and in 10 cases they remained of unknown origin. The palpitations were of short duration and well tolerated, and these patients nevertheless felt an improvement after the ablation. Therefore, at medium term, 62 patients (85%) remained free from symptoms or only slightly symptomatic and without a pacemaker, and 51 of them (70%) remained completely asymptomatic and without a pacemaker. AVNRT can result in considerable morbidity and antiarrhythmic drugs are frequently ineffective. Slow pathway ablation is a safe and effective treatment for AVNRT. In our opinion, if AVNRT or medical treatment diminish the quality of life, ablation is indicated. When AVNRT presents with hemodynamic collapse, ablation is mandatory. Fast pathway ablation after failed slow pathway ablation is associated with a high incidence of atrioventricular block and is targeted only at very symptomatic patients who accept the possibility of definitive pacemaker implantation.