Case description
A 65-year-old man with a history of a circumferential PV isolation for paroxysmal atrial fibrillation (AF) and sick sinus syndrome underwent a second ablation procedure for recurrent paroxysmal AF. Twelve-lead ECG during sinus rhythm exhibited biphasic and split P-wave with a prolonged duration, which called notched P-wave (NPW, Figure 1A). Echocardiography revealed a normal LV systolic and diastolic function and an LA diameter of 31 mm. Written informed consent was obtained before the procedure. An electrophysiological study was conducted in the fasting state and under deep conscious sedation. Although the first component of the NPW was formed by the total atrial activation including that of the LA appendage, the timing of the second component of the NPW was identical to that of the coronary sinus (CS) activation (Figure 1B). Activation mapping during distal CS pacing using an electroanatomical mapping system (CARTO3, Biosense Webster Inc., Diamond Bar, CA, USA) demonstrated 2 remote earliest activation sites in the LA near the anterolateral mitral annulus and inferior mitral annulus, respectively (Figure 2A). The shortest interval between the pacing stimulation spike to the LA was 45 ms suggesting selective local capture of the CS musculature (Figure 2B). Reconnections of the left superior PV and right inferior PV were also noted. AF was spontaneously initiated by an ectopic beat and repeated immediate recurrences occurred after electrical defibrillation even after the achievement of the PV isolation. Complex fractionated atrial electrograms were recorded at the LA lateral wall, LA appendage, and CS. Therefore, additional ablation at the mitral annulus and LA lateral wall was performed, however, it did not terminate the AF. The second component of the NPW remained unchanged after the ablation. Radio-frequency applications in distal portion of CS terminated AF and eliminated the ectopic beats (Figure 3) along with the disappearance of the second component of the P-wave (Figure 1B). Eventually, sinus rhythm was maintained, and AF was no longer induced by programmed stimulation with or without isoproterenol.