Patients with longstanding persistent atrial fibrillation (AF) benefitted from empirical electrical isolation of the left atrial appendage (LAA) without any notable increases in complication rates, according to an open-label, randomized study published in the Journal of the American College of Cardiology.

The researchers, led by Andrea Natale, MD, of the Texas Cardiac Arrhythmia Institute in Austin, conducted the randomized, open-label BELIEF trial (Effect Empirical Left Atrial Appendage Isolation on Long-term Procedure Outcome in Patients With Persistent or Longstanding Persistent Atrial Fibrillation Undergoing Catheter Ablation, ClinicalTrials.gov Identifier NCT01362738) to determine if isolating the LAA could improve outcomes in patients with longstanding persistent AF.

They noted that while catheter ablation has been successful in patients with paroxysmal AF, little is known about the potential outcomes in longstanding persistent AF. Similarly, pulmonary veins have become the standard target in catheter ablation for paroxysmal AF, but controversies still exist surrounding ablation outside of the pulmonary veins.


Continue Reading

A total of 173 patients were randomly assigned to either empirical electrical LAA isolation plus standard ablation (group 1; n=85) or standard ablation alone (group 2; n=88). Patients were included if they were between the ages of 18 and 75 years old and had longstanding persistent AF refractory to antiarrhythmic drugs.

The primary end point was designated as freedom from atrial arrhythmia recurrence (defined as freedom from AF, atrial flutter, or atrial tachycardia) at 12-month post-catheter ablation. Secondary end points included 12-month post-procedure incidence of stroke, death, and hospital readmission. At the 12-month follow-up, the study was designed to detect at least a 20% difference in success rates (50% to 70%; hazard ratio [HR]: 0.515; null hazard: 0.058) at 2-sided type I error of 0.05 and 80% power.

Both groups had comparable procedural and fluoroscopy times, but the mean radiofrequency (RF) time was approximately 16 minutes shorter in group 2 (P <.001). There were no differences between the groups when comparing RF times for standard ablation, excluding the RF time for empirical electrical LAA isolation (76.0 ± 24.7 min vs 74.6 ±25.9 min in group 1 and group 2, respectively; P =.73).

In order to identify non-pulmonary vein triggers and/or pulmonary vein reconnection, the researchers performed a challenge test with isoproterenol infusion starting at 20 μg/min, titrating up to 30 μg/min for 10 to 15 minutes. In group 2, 32 patients demonstrated firing from the LAA. Additionally, a sustained arrhythmia was seen in 8 patients and the LAA was isolated in those patients according to protocol, but in the remaining 24 patients, the LAA was not isolated due to premature atrial complexes or nonsustained LAA firing.

While all of group 1 was scheduled for empirical electrical LAA isolation, 11 patients were unable to undergo the procedure because of technical difficulties (ie, a stable contact between tissue and the ablation catheter was not possible because of the LAA anatomy).

At the 12-month follow-up, 48 patients in group 1 (56%) and 25 patients in group 2 (28%) were free of recurrences after a single procedure (unadjusted HR for recurrence with standard ablation: 1.92; 95% confidence interval [CI], 1.3-2.9; log-rank P =.001). The standard ablation approach was predictive of recurrence after adjusting for sex, age, and LA size (Cox multivariable model; HR: 2.22; 95% CI, 1.29-3.81; P =.004).

At 24 months, the cumulative success rate was 65 (76%) in group 1 and 49 (56%) in group 2 (unadjusted HR: 2.24; 95% CI, 1.3-3.8; log-rank P =.003), after an average of 1.3 procedures.

None of the patients in group 1 experienced a stroke or transient ischemic attack, but 4 patients in group 2 had a stroke after standard ablation (P =.12). No deaths were reported during the study period, and hospitalization rates were similar between the groups (P =.72).

The researchers concluded that the outcomes of their study reinforced the notion that pulmonary vein isolation alone is inadequate for patients who have longstanding persistent AF. “Importantly, evidence of LAA firing was present in only 8% of patients undergoing the standard approach,” they wrote, “a finding suggesting the relevance of empirical isolation of the LAA to achieve long-term freedom from atrial arrhythmias.”  

Study Limitations

The major study limitation is that the operators who performed the empirical electrical isolation of the LAA had varying levels of experience.

Disclosures: Dr Di Biase has received speaker honoraria and travel fees from Medtronic, Atricure, EPiEP, and Biotronik, and is also a consultant for Biosense Webster, Boston Scientific Stereotaxis, and St. Jude Medical. Dr Natale has received speaker honoraria from Boston Scientific, Biosense Webster, St. Jude Medical, Biotronik, and Medtronic, and is also a consultant for Biosense Webster, St. Jude Medical, and Janssen. Dr Burkhardt is a consultant for Biosense Webster and Stereotaxis.

Reference

Di Biase L, Burkhardt JD, Mohanty P, et al. Left atrial appendage isolation in patients with longstanding persistent AF undergoing catheter ablation. BELIEF trial. J Am Coll Cardiol. 2016;68(18):1929-1940. doi:10.1016/j.jacc.2016.07.770.