Substrate and Trigger Ablation for Reduction of Atrial Fibrillation | Clinical Trial - STAR AF II

Description:

Catheter ablation for persistent atrial fibrillation is less successful than for paroxysmal atrial fibrillation. The goal of the trial was to evaluate three different ablation strategies among participants with persistent atrial fibrillation, in order to determine the optimal treatment strategy for these patients.

Contribution to the Literature: The STAR AF II trial showed that pulmonary vein isolation alone is superior to other catheter techniques in achieving freedom from atrial fibrillation.

Study Design

  • Randomized
  • Blinded
  • Parallel

Patient Populations:

  • Participants with persistent atrial fibrillation (sustained episode >7 days and <3 years) and refractory to at least one antiarrhythmic drug
  • Number of enrollees: 589
  • Duration of follow-up: 18 months
  • Mean patient age: 58 years
  • Percentage female: 22%
  • Ejection fraction: mean 55%

Exclusions:

  • Paroxysmal atrial fibrillation
  • Sustained atrial fibrillation >3 years
  • Left atrial diameter >60 mm

Primary Endpoints:

  • Atrial fibrillation lasting at least 30 seconds >30 days after ablation procedure

Secondary Endpoints:

  • Atrial fibrillation lasting at least 30 seconds after two ablation procedures
  • Any atrial arrhythmia
  • Procedure time
  • Procedure complications

Drug/Procedures Used:

Participants with persistent atrial fibrillation were randomized to pulmonary vein isolation alone (PVI; n = 67) versus PVI plus ablation of electrograms showing complex fractionated activity (PVI + electrograms; n = 263) versus PVI plus empiric linear ablation (PVI + lines; n = 259).

  1. PVI was performed by PV antral isolation with documentation of both entrance and exit block by a circular mapping catheter.
  2. PVI + electrograms were performed by PVI followed by mapping and ablation of CFEs during atrial fibrillation, identified by 3D mapping software (Ensite Velocity).
  3. PVI + lines were performed by PVI followed by a left atrial roof line and a line along the mitral valve isthmus with documentation of bidirectional block confirmed by prespecified pacing maneuvers.

Repeat procedures were allowed at 3-6 months if necessary, utilizing the same treatment assignment.

Principal Findings:

Overall, 589 patients were randomized. The median age was 58 years, 22% were women, mean ejection fraction was 55%, mean left atrial diameter was 44 mm, and 9% had diabetes.

Successful PVI occurred in 97% of all participants. Complex fractionated electrograms were eliminated in 80% of participants, and lines with block were achieved in 74% of participants.

Procedure time (fluoroscopy time) was 167 minutes (29 minutes) for PVI, 229 minutes (42 minutes) for PVI + electrograms, and 223 minutes (41 minutes) for PVI + lines.

At 18 months, freedom from atrial fibrillation occurred in 59% of the PVI group, 49% of the PVI + electrograms group, and 46% of the PVI + lines group (p = 0.15 between groups).

Freedom from atrial fibrillation after two procedures occurred in 72% of the PVI group, 60% of the PVI + electrograms group, and 58% of the PVI + lines group (p = 0.1158 between groups).

Stroke/transient ischemic attack (TIA) was 0 vs. 2 vs. 1, respectively.

Interpretation:

Among patients with persistent atrial fibrillation, freedom from recurrent atrial fibrillation was achieved in 59% of participants with PVI alone. Additional ablation of electrograms showing complex fractionated activity or lines ablation added to procedure/fluoroscopy time, without improving freedom from atrial fibrillation. This finding is counter to current guideline recommendations, which recommend additional substrate modification during PVI.

References:

Verma A, Jiang C, Betts TR, et al., on behalf of the STAR AF II Investigators. Approaches to Catheter Ablation for Persistent Atrial Fibrillation. N Engl J Med 2015;372:1812-22

Presented by Dr. Atul Verma at the European Society of Cardiology Congress, Barcelona, Spain, September 1, 2014.

Clinical Topics: Arrhythmias and Clinical EP, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Nuclear Imaging

Keywords: Atrial Fibrillation, Arrhythmias, Cardiac, Stroke, Fluoroscopy, Heart Atria, Ischemic Attack, Transient, Documentation, Pulmonary Veins, Mitral Valve, Diabetes Mellitus, ESC Congress


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