Mapping and rotor ablation
Among the 18 included patients, 14 (77.7%) presented to the ablation procedure in sinus rhythm; in 12 patients, an AT was induced but was considered not mappable due to conversion to AF (n = 10) or continuous circuit modification (n = 2); in the other 2 patients, programmed atrial stimulation directly induced AF. 3 Patients (16.7%) presented in AT; in 2 of them, conversion to AF during mapping occurred; in the other patient, after successful ablation of the index AT, programmed atrial stimulation induced AF. 1 Patient (5.6%) presented in AF.
Mapping was performed with PentaRay NAV catheter (Carto3) in 5 patients (28%), with IntellaMap ORION (Rhythmia) in 11 patients (61%), and with Advisor HD Grid (Ensite Precision) in 2 patients (11%). Contact force-sensing catheters were used for ablation in 6 patients (33.3%). In 9 patients (50%), rotor mapping and ablation was performed only in the LA; in 1 patient, only in the RA; in the other 8 patients (44.4%), both atria were mapped. Detailed rotor mapping and ablation approach is showed in Figure 2.
Rotors, defined as sites with fractionated quasi-continuous signals on 1-2 adjacent bipoles of the mapping catheter, were found in 13 patients (72%) (median 2 [1–3] rotors per patient) (Figure 3); all detected rotors showed temporal permanence after mapping and were target of ablation. Focal rotor ablation was effective in 12 of these patients (92%); in the other patient, after unsuccessful rotor ablation, 2 sites with STD and non-continuous fragmentation were detected and successfully ablated to stabilize AF into reentrant AT. In 1 patient without detectable rotors, spontaneous stabilization of AF into reentrant AT happened during mapping, and AT ablation could be successfully performed. In the other 4 patients without rotors, sites with STD and non-continuous fragmentation were detected (2, 3, 4 and 6 sites in each patient) (Figure 4); ablation of these sites resulted in arrhythmia stabilization into AT in 3 patients (75%); the other patient received electrical cardioversion. Figure 5 shows location of the detected rotors and sites with STD and non-continuous fragmentation; globally 44% were related with the pulmonary veins antra.