Focal atrial tachycardias originating from the aorta-mitral continuty: Anatomic and electrophysiological characteristics

Abstract

Background

The aorta-mitral annulus conjunction (AMC) is uncommon site of origin of focal atrial tachycardias (AT). Hence, the electrophysiological and ablation target characteristics are poorly described.

Objective

To describe the characteristics of AMC AT in detail.

Methods

The study enrolled 650 patients with AT, 21 (3.2%) of whom had AT originating from AMC. A comprehensive evaluation, including electrocardiography, electrophysiologic study, CT scan, and intracardiac echocardiography (ICE) was performed.

Results

The majority (90.5%) of ATs occurred spontaneously. The average age of this group was 48.9±21.6 years, with 12 females (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 (LCC). The local AMC potential differed from the commonly perceived annular potential, and was characterized by a large A and a small V (A/V ratio >1). The angle of encroachment on the LA anterior wall, compressed by the LCC, was significantly smaller in the AMC-AT group compared to the control group, which may have contributed to the arrhythmia substrate (141.7°±11.5° vs. 155.2°±13.9°, p=0.026).

Conclusion

A new strategy for mapping AMC ATs has been introduced. The ablation target should have an A/V ratio greater than 1.