Rotor-Only Ablation Leads to Poor Outcomes in Non-Paroxysmal Atrial Fibrillation

Non-paroxysmal atrial fibrillation (AF) patients experienced poor outcomes with rotor-only ablation, according to results from the OASIS (Outcome of Different Ablation Strategies In Persistent and Long-Standing Persistent Atrial Fibrillation) trial.

In addition, the procedure time for pulmonary vein antrum isolation (PVAI) plus rotor ablation was significantly longer and had a lower efficacy than PVAI plus posterior wall (PW) plus non-PV trigger-ablation.

“PVAI is still the cornerstone for AF ablation in paroxysmal AF patients with reported success rate as high as 80%,” the trial investigators wrote in their findings, published in the Journal of the American College of Cardiology. “However, in persistent (PeAF) and long-standing persistent AF (LSPAF), the success rate is much lower even with repeat procedures.”

OASIS was a non-blinded randomized trial comparing effectiveness of 3 ablation approaches for AF treatment. Patients were randomly assigned (1:1:1) to undergo focal impulse and rotor modulation (FIRM; group 1), FIRM plus PVAI ablation (group 2), or ablation with PVAI, PW, and non-PV triggers (group 3).

The primary end point was freedom from any recurrent AF/atrial flutter/atrial tachycardia without the use of antiarrhythmic drugs after a single procedure. Recurrence was defined as atrial arrhythmia lasting more than 30 seconds off antiarrhythmic drugs at follow-up.

Secondary end points included acute procedural success and peri-procedural complications, the former defined as termination of AF or at least 10% slowing or organization into atrial tachycardia.

Of the 113 patients enrolled, 29 were placed in group 1 and 42 each in group 2 and 3. Group 1 enrollment was terminated early for futility.

Focal drivers or rotors were detected in all patients in groups 1 and 2 with a mean of 4.0 ± 1.2 and 4.2 ± 1.7 rotors per patient in each respective group (P=.55). Investigators also detected 116 AF rotors in group 1 (61% left atrium; 39% right atrium) and 117 in group 2 (68% left atrium; 33% right atrium).

Of the patients in group 1, 14% (4 of 29) were AF/atrial tachycardia-free without the use of antiarrhythmic drugs, 52.4% (22 of 42) in group 2, and 76% (32 of 42) in group 3 (log-rank P<.0001). After stratifying by AF type, a sensitivity analysis of the primary end point was performed. In patients with persistent AF, the success rate was 53% and 72% in groups 2 and 3 respectively (log-rank P=.13). In the LSP AF cohort, 50% (6 of 12) of patients in group 2 and 84.6% (11 of 13) of patients in group 3 were recurrence free (log-rank P=.06).

Procedure times in each group were as follows: 222 ± 49 minutes in group 1, 233 ± 48 minutes in group 2, and 131 ± 51 minutes in group 3. The group 3 time was significantly shorter compared to groups 1 and 2 (P<.001).

The FIRM plus PVAI ablation was associated with significantly higher risk of recurrence, compared with the PVAI, PW, and non-PV trigger ablation group (unadjusted hazard ratio: 2.37; 95% confidence interval: 1.1-5.07; P=.025).

No patients in group 1 experienced adverse events related to the procedure; however, 2 patients (1 in group 2 and 1 in group 3) had minor groin hematoma and 1 patient in group 2 had a small pericardial effusion. There were no reports of stroke, pulmonary stenosis, esophageal injury, or major bleeding events.

“Despite lengthier procedure time, we failed to accomplish the high acute success with rotor ablation as reported by earlier studies,” researchers noted. The difference between the present study and previous studies is that the latter were comprised of patients with paroxysmal and persistent AF compared with non-paroxysmal AF.

Researchers concluded that their study offers a different perspective on rotor ablation approach efficacy in these non-paroxysmal AF patients, which may lead to future investigations.

Reference

Mohanty S, Gianni C, Mohanty P, et al. Impact of rotor ablation in non-paroxysmal AF patients: results from a randomized trial (OASIS). J Am Coll Cardiol. 2016. doi:10.1016/j.jacc.2016.04.015.