Incidence and prognosis of atrioventricular block induced by radiofrequency ablation of intranodal reentrant tachycardias: a multicenter study.

The object of this study was to assess the incidence and significance of at rioventricular block (AVB) induced by radiofrequency ablation of intranodal reentrant tachycardias. The study population was 18 patients aged 44 to 83 , selected from a total population of 144 patients treated for recurrent, r efractory tachycardias. These patients developed complete AVE (9 cases), 2n d degree AVE (3 cases) and Ist degree AVE (6 cases) either immediately or i n the chronic phase after radiofrequency ablation. The outcomes were as follows: 1. in the 9 patients with complete AVE, the block regressed in a period ran ging 'from 7 seconds to 6 minutes. It recurred as complete AVE 1 to 4 days later in 2 patients, and regressed again after a maximum of 10 days. One 47 year old woman had definitive complete AVE; 2. in the 3 patients with 2nd degree AVE, the block regressed within 7 days ; 3. in the 6 cases of ist degree AVE, 2 patients developed transient complet e AVE the following day. The possible causes of AVB were : increased vagal tone in 1 case, ablation of the rapid pathway located in a postero-septal site in 8 cases and, in th e remainder, preexisting conduction defects. The authors conclude that transient complete AVE is common and usually has a good prognosis. Definitive complete AVE is a rare but possible (0.7%) com plication of radiofrequency ablation of reentrant intranodal tachycardias; other forms of AVE generally regress quickly and, although they may recur w ithin days, they carry a good prognosis in the following months. However, l ong-term follow-up remains necessary.