Focal atrial tachycardias originating from the aorta-mitral continuity: Anatomical and electrophysiological characteristics.

BACKGROUND: The aorta-mitral annulus conjunction (AMC) is an uncommon site of origin of focal atrial tachycardias (ATs). Hence, the electrophysiological and ablation target characteristics are poorly described. OBJECTIVE: The purpose of this study was to describe the characteristics of AMC ATs in detail. METHODS: The study enrolled 650 patients with ATs, 21 (3.2%) of whom had ATs originating from the AMC. A comprehensive evaluation, including electrocardiography, electrophysiology study, computed tomography scan, and intracardiac echocardiography, was performed. RESULTS: The majority (19, 90.5%) of ATs occurred spontaneously. The mean age of this group was 48.9 ± 21.6 years, with 12 being female (57.1%). Seventeen patients had a typical biphasic P wave with a prominent positive component. The earliest activation site in the right atrium was near the His bundle, with average activation -10.3 ± 6.0 ms preceding the P wave. The successful ablation targets were distributed as follows: 1 case at 9 o'clock, 6 cases at 10 o'clock, 7 cases at 11 o'clock, 6 cases at 12 o'clock, and 1 case in the left coronary cusp. The local AMC potential differed from the commonly perceived annular potential and was characterized by a prominent A wave and a smaller V wave (atrial-to-ventricular ratio > 1). The angle of encroachment on the left atrial anterior wall, compressed by the left coronary cusp, was significantly smaller in the AMC ATs group than in the control group consisted of 40 patients who underwent coronary artery CT scans because of the chest pain but without atrial arrhythmias were randomly selected, which may have contributed to the arrhythmia substrate (141.7° ± 11.5° vs 155.2° ± 13.9°; P = .026). CONCLUSION: A new strategy for mapping AMC ATs has been introduced. The ablation target should have an atrial-to-ventricular ratio of >1.

Focal atrial tachycardias from the parahisian region: Strategies for mapping and catheter ablation.

BACKGROUND: Focal atrial tachycardias (ATs) from the parahisian region can be successfully ablated from the right atrial septum (RAS), noncoronary cusp (NCC), and right middle septum (RMS). The optimal mapping and ablation strategy for ATs from these sites remains unclear. OBJECTIVE: The purpose of this study was to investigate the electrophysiologic characteristics and optimal ablation sites of parahisian ATs from the RAS, RMS, and NCC. METHODS: A total of 362 patients with ATs undergoing radiofrequency catheter ablation of ATs were included. A detailed examination including ECG analysis and electrophysiologic study was performed. RESULTS: Overall, 91 patients had a parahisian site of AT origin, and ablation was successful in 86 (94.5%). ATs were successfully eliminated from the RAS in 23, RMS in 19, and NCC in 44. The earliest "A" potential was recorded at the distal His catheter in 69.4% of NCC ATs vs the proximal His catheter in 83.3% of RAS ATs and 86.7% of RMS ATs. Mean timing of the "A" potential of RMS ATs recorded at the His-bundle catheter was -18.25 ± 7.20 ms, which was later than ATs from the RAS (-24.59 ± 8.73 ms) or NCC (-27.08 ± 5.63 ms). For ATs originating from the RAS and RMS, an A/V ratio <1.22 predicted safe and successful ablation (sensitivity 88.4%, specificity 91.7%). CONCLUSION: For parahisian ATs, activation sequence and timing of the "A" on the His catheter can provide clues for the origin of ATs. When ablating at the RAS and RMS, an A/V ratio >1.22 identified safe and effective ablation sites.