Accessory Pathway in Left Inferoposterior Diverticulum Masquerading as Left Posterior Pathway Due to Conduction Over Coronary Sinus to Left Atrium Connection

We report the case of an accessory pathway in a left inferoposterior diverticulum. The pathway masqueraded as a true left lateral pathway due to the direction of activation over a coronary sinus to left atrium connection. The patient had undergone four prior failed ablation attempts at other institutions using both a transseptal and retrograde approach.