Focal radiofrequency ablation of narrow, slow-conducting isthmuses eliminated reentrant left atrial tachycardia in all 11 patients exhibiting significant isoelectric intervals on 12-lead ECG.
Observational (n=15)
Can focal radiofrequency ablation targeting narrow slow-conducting isthmuses eliminate reentrant left atrial tachycardias following AF ablation?
Focally ablatable narrow isthmuses of slow conduction are critical for most reentrant LATs after AF ablation and can be identified by isoelectric intervals on 12-lead ECG.
INTRODUCTION: The complete circuit of reentrant left atrial tachycardias (LATs) occurring after ablation for atrial fibrillation (AF) has not been well described. Identifying discrete isthmuses critical to these LATs may simplify their elimination by catheter ablation. METHODS AND RESULTS: Fifteen patients (all male, 56 +/- 8 years) with 15 reentrant LATs following AF ablation underwent activation and entrainment mapping. Eleven patients (11 LATs) had a single localized site with low amplitude (0.16 +/- 0.05 mV), fractionated long duration (131 +/- 23 msec) electrograms coinciding with an isoelectric interval of 106 +/- 24 msec between flutter waves on all 12 ECG leads. Three-dimensional mapping and entrainment revealed this site to be a narrow markedly slowly conducting isthmus adjacent to ablated left (n = 8) or right (n = 3) pulmonary vein (PV) ostia, and critical to nine small diameter (15 +/- 3 mm) and two large diameter (49 +/- 2 mm) circuits. One radiofrequency (RF) application on this isthmus eliminated LAT in all 11 patients. Four patients (four LATs) with large circuits around the mitral annulus and/or PV ostia lacked isoelectric ECG intervals and slow-conducting isthmuses and required multiple RF applications across anatomically wide, rapidly conducting isthmuses. CONCLUSION: Focally ablatable narrow isthmuses of slow conduction are critical for the majority of reentrant LAT occurring after ablation for AF. The role and presence of these isthmuses can be anticipated by observing significant isoelectric intervals between flutter waves on all 12-surface ECG leads. Their distinctive electrophysiological characteristics allow their identification and elimination by simple RF ablation.
Shah et al. (Wed,) conducted a observational in Reentrant left atrial tachycardias following atrial fibrillation ablation (n=15). Focal radiofrequency ablation was evaluated on Elimination of left atrial tachycardia. Focal radiofrequency ablation of narrow, slow-conducting isthmuses eliminated reentrant left atrial tachycardia in all 11 patients exhibiting significant isoelectric intervals on 12-lead ECG.