Ablation protocol
Radiofrequency ablation was performed using open-tip irrigated catheters
(IntellaNav MIFI, Boston Scientific Inc.; Thermocool SmartTouch,
Biosense Webster Inc.; TactiCath, Abbott Medical Inc.; or TactiCath,
Sensor Enabled, Abbott Medical Inc.). A power of 30-35 W was used for
posterior wall lesions, 35-40 W for anterior or free wall lesions, and
25-30 W inside the coronary sinus.
First, focal ablation of the identified rotors were performed with 1-4
adjacent lesions. If rotor ablation was unsuccessful, sites with STD
were targeted using the same focal approach.
Rotor ablation success was defined, for each patient, as
conversion to sinus rhythm or a stable AT using the aforementioned
strategy. If rotors were present within the pulmonary veins antra,
circumferential pulmonary vein isolation of that vein or pair of veins
was performed including the rotor within the line. If rotor ablation was
performed <1 cm from a scar or another radiofrequency
application, an ablation line between them was performed. If rotor
ablation was not successful, electrical cardioversion and empirical
pulmonary vein isolation plus CTI ablation was performed.
All stable ATs were mapped using local activation time mapping,
propagation mapping and entrainment, and subsequently ablated (focal
ablation for small reentries or focal ATs; lines for macroreentries). In
the case of conversion to another AT, the new AT was mapped and ablated.
After conversion to sinus rhythm, bidirectional block at the ablation
lines was checked with differential pacing or with activation mapping,
and absence of capture at focal ablation sites was tested. If the
patient had undergone previous ablation procedures, bidirectional block
of the previously performed lines was checked, and ablation was
performed if gaps were present. Pulmonary vein isolation was not
performed in all patients, but it was routinely completed in those with
previously documented atrial fibrillation.
Finally, programmed atrial stimulation was used to test arrhythmia
inducibility; if other sustained ATs were induced, they were mapped and
ablated. Procedural success was defined as the successful
ablation of all inducible ATs, without requiring electrical
cardioversion, with final sinus rhythm and non-inducibility at the end
of the procedure.