Focal atrial tachycardia arising from the tricuspid annulus: Electrophysiologic and electrocardiographic characteristics

Introduction: Focal right atrial tachycardia (RAT) arising from the crista terminalis, para-Hisian, and coronary sinus os regions are well described. Less information exists regarding RAT arising from the nonseptal region of the tricuspid annulus (TA), Methods and Results: From a consecutive series of 64 patients who had undergone successful radiofrequency ablation (RFA) of 67 RATs, the characteristics of 9 (13%) patients (6 men; mean age 50 +/- 20 years) with a TA focus were reviewed. The annular focus was localized to the inferoanterior TA in 7 and the superior TA in 2, Mean tachycardia cycle length was 371 +/- 66 msec, Mean activation time at the site of successful RFA in 9 of 9 patients was -43 +/- 11 msec, At 9.3 +/- 5.6 months of follow-up, 1 of 9 patients had recurrent tachycardia successfully treated with repeat RFA, In 7 of 9 patients with RAT from the inferoanterior TA, the surface ECG P wave morphology was upright in aVL, inverted in III and V-1, and either inverted or biphasic with an initial negative deflection from V-2 to V-6. Conclusion: The TA is an important site of origin of RAT. In the present study, the inferoanterior region of the TA was a preferential site of origin with resulting characteristic P wave morphology, Knowledge of this anatomic distribution and P wave morphology allows targeted mapping and may facilitate successful RFA.