Abstract 15694: Atrial Tachycardia Masquerading as Sinus Tachycardia - Electrophysiological Characteristics and Ablation Outcomes

Abstract

Background: Focal atrial tachycardia (AT) is typically distinguished by P wave morphology and autonomic response. AT arising close to the sinus node can be easily misdiagnosed as Inappropriate sinus tachycardia (IST). Objective: This multicenter study sought to describe the electrophysiological (EP) features and ablation outcomes of perisinus node atrial tachycardia (PNAT). Methods: Baseline as well as procedural characteristics and outcome data of 7 patients with PNAT are described. Results: Mean age of the cohort was 38±17 years (100% female). Time from symptom onset to diagnosis was12.2± 9 months with an average of 1.7 prior hospitalizations. Mean baseline HR was127.8 bpm and all patients carried a diagnosis of IST. Baseline ECG in all patients was identical to sinus tachycardia, with exception of taller P waves in lead II in 5 patients and deeper negative component of P wave in V1. At EP study, mean AT cycle length was 420 msec and significant acceleration was seen with isoproterenol, mimicking IST. Activation mapping was done using Ensite TM Balloon Array (5), Precision TM (1) and Carto TM (1). Site of origin was slightly anterolateral to sinus node in 3 and anterior, inferior and medial to sinus node in 4 (Figure). AT was successfully ablated in all patients without any phrenic injury or sinus node dysfunction. Over 2.9 years of follow-up, only 1 patient had recurrence that was successfully re-ablated. Conclusion: PNAT has similar ECG and EP characteristics and is often misdiagnosed as IST. A high index of suspicion is needed for diagnosis. Evaluation of P wave morphology during tachycardia and careful activation mapping can enable successful ablation with excellent long-term outcomes.