Background: Atrial tachycardia (AT) originating from the non coronary cusp (NCC) has been recently described.
Objectives: To describe the clinical and electrophysiological characteristics of AT originating from the NCC and treated with radiofrequency ablation (RFA) at our center.
Methods: Files of patients (pts) with NCC - AT were retrospectively studied. Data were obtained from pts charts, ECGs, electrophysiological reports and digital recording systems.
Results: Of 101 pts with AT referred for RFA between January 2008 to October 2014 we identified 7 pts (4 females , aged 24-78 years, mean 55±19) with NCC - AT. Clinical symptoms included recurrent episodes of palpitations in 4, syncope in 2 and exercise-test induced AT in 1 pt. Mean rate of the clinical tachycardia was 172+40 bpm. Mapping the right atrium during tachycardia revealed earliest activity in the His area in 6 pts and in both the His area and the CS-ostium in 1. The left atrium was also mapped in 2 pts. Retrograde aortic approach was used for mapping the aortic cusps in all pts. Electro-anatomical mapping systems were used in 2 pts. In 2 pts ablation was attempted first in the RA and in 2 also in the LA. The earliest local atrial activation in the NCC preceded the atrial activation in the His area by 29±10 ms. In 4 pts the AT mimicked AVNRT. Since it was impossible to clearly distinguish the atrial activation pattern in 1 pt, slow pathway ablation was necessary. Ablation was carried out with regular 4-mm and irrigated 3.5 mm ablation catheters (with up to 40 watts power) in 4 and 2 pts, respectively. In our first pt, ablation was not attempted. Acute successful ablation was uncomplicated, especially no AV block was observed. During follow-up of 25±22 month, 1 pts had recurrence of AT without medications (excluding the first pt who was not ablated).
Conclusions: AT may originate from the NCC. Catheter ablation of this rare arrhythmia is safe and effective.
