PO-04-150 ATRIAL TACHYCARDIA IN PATIENTS WITH REPAIRED TETRALOGY OF FALLOT: ITS CHARACTERISTICS AND THE EFFICACY OF CATHETER ABLATION

Abstract

With advanced surgical techniques and patient care, many patients with repaired tetralogy of Fallot (TOF) have extended life expectancy. However, longevity is often complicated by tachyarrhythmias. In this study, we focused on atrial tachycardias (AT), its characteristics, and the effectiveness of catheter ablation. Seventy-seven patients with repaired TOF, who are treated and followed at the University of Tsukuba Hospital, were included. The patients were divided into patients with AT and without. Various clinical parameters were evaluated and compared between the two groups. Electrophysiological and electro-anatomic data were studied in patients who had AT and underwent catheter ablation. The mean age was 34± 12 years old, and 55% were females. Twenty-three patients had AT (30%). The patients with AT were older than those without AT (40± 12 vs 31± 11; P= 0.003), the left ventricular ejection fraction was lower (58± 6 vs 62± 5; P=0.006), the right atrial (RA) area (cm2) was larger (29± 14 vs 15± 5; P<0.001), the left atrial (LA) area (cm2) was also larger (19± 3 vs 16± 4; P<0.001), the RA to LA ratio was higher (1.5 vs 1; P<0.001), had a lower tricuspid annular plane systolic excursion (16± 4 vs 18± 4; P= 0.032), and a higher prevalence of restrictive physiology (35% vs 9%; P= 0.007), respectively. These parameters were obtained during maintained sinus rhythm in all patients. Twenty patients underwent catheter ablation, in which 30 AT were ablated. Low voltage area in RA was recognized in all patients using 3D electro-anatomic mappings. The mechanism of AT was intra-atrial reentrant tachycardia revolving around RA atriotomy scar from the previous surgery in 13 AT (43%), cavotricuspid isthmus dependent in 12 AT (40%), and focal activity in the remaining 5 AT (17%). After a median follow-up of 27 months, only three patients had AT recurrence. However, in one patient, the recurrent AT could not be suppressed by endocardial ablation and was successfully treated by surgical cryoablation done during pulmonary valve replacement. The patients with AT had biventricular dysfunction and larger bi-atrial size compared with those without AT. Additionally, regardless of AT mechanism, catheter ablation was an effective treatment modality in the majority of the patients.