Radiofrequency ablation of a concealed left-sided accessory pathway in the mid-coronary sinus after failed conventional ablation attempts.

The case of a 71-year-old female patient with recurrent supraventricular tachycardia is reported. During the initial electrophysiological study, an orthodromic atrioventricular reentrant tachycardia utilizing a concealed left-sided accessory pathway (AP) was induced. Radiofrequency (RF) ablation via a retrograde aortic approach was unsuccessful. A second ablation attempt 6 weeks later via a transseptal approach using the EnSite Precision three-dimensional (3-D) cardiac mapping system and an irrigated-tip RF ablation catheter also failed to ablate the AP. Therefore, mapping in the coronary sinus (CS) was performed. During right ventricular pacing, the earliest retrograde atrial activation was found in the mid-CS. Irrigated-tip RF ablation for 1.8 s at this region successfully ablated the AP permanently. In complicated cases after failed conventional ablation attempts via a transfemoral or transseptal approach, CS ablation is an effective alternative to percutaneous or surgical ablation of epicardial APs. In such cases, electroanatomical mapping systems may be useful in determining the location of the AP and reducing fluoroscopy time. Furthermore, ablation with irrigated-tip RF catheters can improve the treatment success rate due to larger and deeper lesion formation.