Stabilization of unstable reentrant atrial tachycardias via fractionated continuous electrical activity ablation (CHAOS study).

Abstract

Unstable reentrant atrial tachycardias (ATs) (i.e., those with frequent circuit modification or conversion to atrial fibrillation) are challenging to ablate. We tested a strategy to achieve arrhythmia stabilization into mappable stable ATs based on the detection and ablation of rotors. All consecutive patients from May 2017 to December 2019 were included. Mapping was performed using conventional high-density mapping catheters (IntellaMap ORION, PentaRay NAV, or Advisor HD Grid). Rotors were subjectively identified as fractionated continuous (or quasi-continuous) electrograms on 1-2 adjacent bipoles, without dedicated software. In patients without detectable rotors, sites with spatiotemporal dispersion (i.e., all the cycle length comprised within the mapping catheter) plus non-continuous fractionation on single bipoles were targeted. Ablation success was defined as conversion to a stable AT or sinus rhythm. Ninety-seven patients with reentrant ATs were ablated. Of these, 18 (18.6%) presented unstable circuits. Thirteen (72%) patients had detectable rotors (median 2 [1-3] rotors per patient); focal ablation was successful in 12 (92%). In the other 5 patients, 17 sites with spatiotemporal dispersion were identified and targeted. Globally, and excluding 1 patient with spontaneous AT stabilization, ablation success was achieved in 16/17 patients (94.1%). One-year freedom from atrial arrhythmias was similar between patients with unstable and stable ATs (66.7% vs. 65.8%, p = 0.946). Most unstable reentrant ATs show detectable rotors, identified as sites with single-bipole fractionated quasi-continuous signals, or spatiotemporal dispersion plus non-continuous fractionation. Ablation of these sites is highly effective to stabilize the AT or convert it into sinus rhythm.