Efficacy and safely of radiofrequency catheter ablation of left-sided accessory 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 success, efficacy, and safety of radiofrequency catheter ablation from the coronary sinus (CS), as a potential alternative to the endocardial technique in these patients. Thirteen patients (mean age 40 ± 20 years) with 15 left-sided APs and a history of symptomatic supraventricular tachycardia 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 patient 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 ablation as a primary technique was 56% (5 of 9 APs). In 5 additional APs, oblation in the CS eliminated pathway conduction after failed endocardial attempts. CS ablation either as a primary or a secondary technique eliminated conduction in 10 of 14 APs (71.4%) (group 1). In the remaining 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 ventricular electrogram amplitude ratios ≥ 1 (p < 0.05). The success rate of CS ablation was 83% in the left posteroseptal APs adjoining the branching point of the middle cardiac vein or a CS anomaly. Radiofrequency ablation in the CS was safe at the energy levels and durations used in this study, with no evidence of major or delayed vascular complications. During follow-up of 10 ± 7 months, there was no recurrence of sustained tachycardia in any patient who underwent successful ablation from the CS. We conclude that primary CS ablation can be an effective and safe alternative to the endocardial technique for ablation of leftsided APs with electrogram ratios ≥ 1. These findings are frequently seen in left posteroseptal APs in proximity to the middle cardiac vein or a CS anomaly.