Catheter ablation of clinical intraatrial reentrant tachycardias resulting from previous atrial surgery: Localizing and transecting the critical isthmus

Objectives. We sought to evaluate the efficacy of anatomically based radiofrequency catheter ablation for the treatment of intraatrial reentrant tachycardia in patients with previous atrial surgery. Background. Intraatrial reentrant tachycardias, a common late complication of atrial surgery, are often refractory to standard medical management. Data from experimental animals and from humans indicate that anatomic barriers resulting from residual atrial scars provide a substrate for intraatrial reentry. We speculated that these tachycardias require a narrow isthmus of tissue between surgical scars and native nonconductive boundaries and that transection of this isthmus with radiofrequency ablation would therefore constitute an effective treatment. Methods. Fourteen patients with a history of atrial surgery and clinical intraatrial reentrant tachycardia underwent electrophysiologic testing. From activation mapping, putative surgical scars and patches that served as boundaries of reentrant circuits were identified. Radiofrequency lesions were then plated to transect the narrowest isthmus of conducting tissue between a surgical scar and an anatomic barrier, Catheter ablation was attempted only for tachycardias consistent with the patient's clinical arrhythmias. Results. Radiofrequency catheter ablation was attempted for 17 (55%) of 31 tachycardias identified; it successfully terminated tachycardias in 13 (93%) of 14 patients (95% confidence interval [CI] 79% to 99%). There were clinical recurrences in six patients (46%, 95% CI 19% to 73%), each of whom underwent a repeat ablation that was successful, Twelve (86%) of 14 patients (95% CI 67% to 99%) have remained free of intraatrial reentrant tachycardia for a mean of 7.5 +/- 5.3 months. Conclusions. Anatomically guided radiofrequency catheter ablation is an effective technique for definitive management of intraatrial reentrant tachycardia in patients with previous atrial surgery.