Stabilization of unstable reentrant atrial tachycardias via fractionated
continuous electrical activity ablation (CHAOS study).
Abstract
Introduction. Unstable reentrant atrial tachycardias (ATs) (i.e. those
with frequent circuit modification or conversion to atrial fibrillation)
are challenging to ablate. We have tested a strategy to achieve
arrhythmia stabilization into mappable stable ATs based on the detection
and ablation of rotors. Methods and Results. From May 2017 to December
2019, 97 consecutive patients with reentrant ATs were ablated. Of these,
18 (18.6%) presented unstable circuits and 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 of the mapping catheter, without dedicated
software. 13 patients (72%) had detectable rotors (median 2 [1–3]
rotors per patient); focal ablation achieved conversion into stable AT
or sinus rhythm in 12 (92%). In the other 6 patients, sites with
spatiotemporal dispersion (i.e. all the cycle length comprised within
the mapping catheter) plus non-continuous fractionation on single
bipoles were targeted. 17 sites with spatiotemporal dispersion were
detected and focally ablated. Globally, and excluding 1 patient with
spontaneous AT stabilization, ablation success to stabilize the AT 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). Conclusion. 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.