EFFICACY AND SAFETY OF RADIOFREQUENCY CATHETER ABLATION OF LEFT-SIDEDACCESSORY PATHWAYS THROUGH THE CORONARY SINUS

Radiofrequency catheter ablation of left-sided accessory pathways (APs ) with the use of an endocardial technique carries all potential risks of left heart catheterization. We analyzed the determinants of succes s, efficacy, and safety of radiofrequency catheter ablation from the c oronary sinus (CS), as a potential alternative to the endocardial tech nique in these patients. Thirteen patients (mean age 40 +/- 20 years) with 15 left-sided APs and a history of symptomatic supraventricular t achycardia were included in the study. Nine APs were localized in the left posteroseptal region, and the remaining 6 in the left free wall. Ablation from CS was attempted in 12 patients with 14 APs. In 1 patien t ablation within the CS was not deemed safe because of a small venous lumen. All 14 APs were successfully ablated using either CS ablation alone or combined with the endocardial technique. Efficacy of the CS a blation as a primary technique was 56% (5 of 9 APs). In 5 additional A Ps, ablation in the CS eliminated pathway conduction after failed endo cardial attempts. CS ablation either as a primary or a secondary techn ique eliminated conduction in 10 of 14 APs (71.4%) (group 1). In the r emaining 4 APs (group 2), the primary CS attempt was unsuccessful and APs were ablated with a subsequent endocardial approach. Determinants of success for the CS method were local AP to atrial and/or ventricula r electrogram amplitude ratios greater than or equal to 1 (p <0.05). T he success rate of CS ablation was 83% in the left posteroseptal APs a djoining the branching point of the middle cardiac vein or a CS anomal y. Radiofrequency ablation in the CS was safe at the energy levels and durations used in this study, with no evidence of major or delayed va scular complications. During follow-up of 10 +/- 7 months, there was n o recurrence of sustained tachycardia in any patient who underwent suc cessful ablation from the CS. We conclude that primary CS ablation can be an effective and safe alternative to the endocardial technique for ablation of left-sided APs with electrogram ratios greater than or eq ual to 1. These findings are frequently seen in left posteroseptal APs in proximity to the middle cardiac vein or a CS anomaly.