Catheter Ablation of Left Atrial Posterior Wall Tachycardia Guided by Electroanatomic Mapping in a Young Patient.

Focal atrial tachycardias (ATs) arising from the left atrium (LA) most commonly originate from the ostium of the pulmonary vein, the superior mitral annulus, the body of the coronary sinus, the LA septum, and the LA appendage. Focal ATs originating from the posterior wall of the LA are extremely rare. A 34-year-old male patient presented to the cardiology outpatient clinic complaining of palpitation. Electrocardiography showed a tachycardia at a ventricular rate of 150 bpm and a narrow QRS complex. Therefore, an electrophysiological study was performed, which was consistent with an AT. The patient underwent an electrophysiological study in tachycardias with narrow QRS complexes. The diagnostic electrophysiological findings were consistent with an AT. The AT cycle length was found to be 405 ms with variability in the ventriculoatrial interval. Simultaneous LA anatomical and activation mapping was performed during the AT using a 3D electroanatomic mapping system (CARTO) and a quadripolar unidirectional irrigated tip catheter. The activation mapping revealed that the earliest endocardial activation site was at the posterior wall of the LA, where the local electrogram was 72 ms and 35 ms before the coronary sinus reference and the P-wave onset, respectively. The activation mapping also showed centrifugal spreading and mid-diastolic, fractionated signals on the posterior wall. Radiofrequency ablation was successfully performed with 30-watt power at the site of the earliest atrial activation, with a fractionated electrogram terminating the tachycardia. LA posterior ATs are a rare form of AT. The electroanatomic mapping method enables the accurate localization of the LA focal tachycardia, and a high success rate is achieved with ablation therapy.