Targeting rotors challenged for nonparoxsymal AF

By Eleanor McDermid

Targeted ablation of electrical rotors and focal sources is not a successful strategy in patients with persistent or long-standing atrial fibrillation (AF), shows the randomised OASIS trial.

Focal impulse and rotor modulation (FIRM)-guided ablation was thought to address processes that sustain AF, making it an ideal strategy for patients with persistent arrhythmia.

However, the OASIS (Outcome of Different Ablation Strategies In Persistent and Long-Standing Persistent Atrial Fibrillation) findings show the reverse, with the FIRM-only group being terminated early for lack of efficacy.

Of the 29 patients who were randomly assigned to this group, just 14% were free of AF or atrial tachycardia at the 12-month follow-up, despite acute success in 41%.

"[W]e failed to accomplish the high acute success with rotor ablation as reported by earlier studies", say Andrea Natale (St David's Medical Center, Austin, Texas, USA) and co-researchers.

They suggest this could be because the study only included nonparoxysmal AF patients, who may need additional ablations besides rotors.

In line with this, 52% of the 42 patients who also received pulmonary vein antrum isolation (PVAI) achieved freedom from arrhythmia at 12 months. And the rate was even higher, at 76%, among another 42 patients who did not undergo FIRM-guided ablation, instead receiving PVAI plus posterior wall ablation and ablation of non-PV triggers.

All patients in this group had non-PV triggers, most commonly originating in the coronary sinus (74%), the left atrial septum (50%) and the left atrial appendage (38%).

The results indicate that "the extensive approach" used in the third group may be "the most effective ablation strategy in the nonparoxysmal AF population", writes the team in the Journal of the American College of Cardiology.

Furthermore, the procedure was quicker than those involving ablation of rotors, at 131 versus 222 to 233 minutes, taking "less procedure and fluoroscopic time than the other two strategies while offering comparable safety and better efficacy."

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