Mapping and Ablation of Paraseptal Focal Atrial Tachycardias.

BACKGROUND

Focal atrial tachycardia (AT) may arise from a range of closely related anatomical sites in the paraseptal region.

OBJECTIVES

This study sought to define the anatomical distribution and examine the electrocardiographic and electrophysiological features of paraseptal focal AT, suggest a mapping approach, and report ablation outcomes.

METHODS

This retrospective single-center study defined paraseptal ATs as originating from the following anatomical sites: right perinodal region, septal tricuspid annulus, right septum, coronary sinus (CS) ostium, left septum, septal mitral annulus, aorto-mitral continuity, and non-coronary cusp (NCC) adjacent. Early septal activation was defined when the earliest right atrial activation occurred at the His bundle region or CS ostium ≥10 milliseconds before P-wave onset.

RESULTS

Among 227 patients (mean age 54.8 ± 15.8 years; 61.7% female), foci were diverse and included: right perinodal, n = 61 (26.9%); septal tricuspid annulus, n = 23 (10.1%); right septum, n = 28 (12.3%); CS ostium, n = 43 (18.9%); left septum, n = 28 (12.3%); septal mitral annulus, n = 16 (7.1%); aorto-mitral continuity, n = 19 (8.4%); and NCC adjacent, n = 9 (4%). Ablation was attempted in 213 (93.8%) of 227 patients and was successful in 189 (88.7%) of 213 patients; there were no instances of persistent atrioventricular block. The NCC was not a common ablation site. P-wave morphology was characteristic (V1 was predominantly negative/positive, isoelectric/positive, or isoelectric, 91%) but did not distinguish between these anatomical sites. Sequential and systematic mapping was required to localize earliest activation.

CONCLUSIONS

Paraseptal focal ATs arise from diverse but closely related anatomical locations. There is no single site from which ablation is consistently successful. Although some are indeed perinodal and accessible from the NCC, others arise from adjacent structures. Nevertheless, detailed, sequential mapping facilitates safe and effective ablation in most cases.