Mechanism, localization and cure of atrial arrhythmias occurring after a new intraoperative endocardial radiofrequency ablation procedure for atrial fibrillation

OBJECTIVES The purpose of this study was to test a new pattern of radiofreq uency ablation for atrial fibrillation (AFib) intended to optimize atrial a ctivation, and to demonstrate the usefulness of catheter techniques for map ping and ablation of postoperative atrial arrhythmias. BACKGROUND Linear radiofrequency lesions have been used to cure AFib, but t he optimal pattern of lesions is unknown and postoperative tachyarrhythmias are common. METHODS A radial pattern of linear radiofrequency lesions (Star) was made u sing an endocardial open surgical approach in 25 patients. Postoperative ar rhythmias were induced and characterized during electrophysiological studie s in 15 patients. RESULTS The AFib was abolished in most patients (91%), but atrial flutter ( AFlut) occurred in 96% of patients postoperatively. At postoperative electr ophysiological studies, 37 flutter morphologies were studied in 15 patients (46% spontaneous, cycle length [CL] 223 +/- 25 ms). Seven mechanisms (lesi ons discontinuity, n = 6; focal mechanism, n = 1) of AFlut were characteriz ed in six patients. In these cases, flutter was abolished using further cat heter radiofrequency ablation. In the remaining cases, flutter was usually localized to an area involving the interatrial septum, but no critical isth mus was identified for ablation. After 16 +/- 10 months, 15 patients (65%) were asymptomatic with (n = 3) or without (n = 12) antiarrhythmic medicatio ns. Eight (35%) patients had persistent arrhythmias. Postoperative atrial e lectrical activation was near physiological. CONCLUSIONS The AFib map be abolished using a radial pattern of linear endo cardial radiofrequency lesions, but postoperative AFlut is common even when lesions are made under optimal conditions. Endocardial mapping techniques can be used to characterize the flutter mechanisms, thus enabling subsequen t successful catheter ablation. (J Am Coll Cardiol 2000;35:442-50) (C) 2000 by the American College of Cardiology.