Cryoballoon Catheter Ablation in Antiarrhythmic Drug Naive Paroxysmal Atrial Fibrillation - STOP AF First

Contribution To Literature:

The STOP AF First trial showed that a first-line strategy of cryoballoon ablation was superior to antiarrhythmic drug therapy at freedom from efficacy failure. 


The goal of the trial was to evaluate a first-line strategy of cryoballoon ablation compared with antiarrhythmic drug therapy among patients with paroxysmal atrial fibrillation.

Study Design

  • Randomized
  • Parallel

Eligible patients were randomized to pulmonary vein isolation with cryoablation (n = 104) versus antiarrhythmic drug therapy (n = 99).

  • Total number of enrollees: 225
  • Total number randomized: 203
  • Duration of follow-up: 12 months
  • Mean patient age: 60 years
  • Percentage female: 39%
  • Percentage with diabetes: 14%

Inclusion criteria:

  • Patients 18-80 years of age
  • Recurrent symptomatic paroxysmal atrial fibrillation

Exclusion criteria:

  • Previous treatment with antiarrhythmic drug for ≥7 days
  • Enlarged left atrial diameter (>5 cm)
  • Previous left atrial ablation or left atrial surgical procedure

Other salient features/characteristics:

  • Time from paroxysmal atrial fibrillation onset: 1 year
  • Electrical cardioversion within the last year: 18%

Principal Findings:

The primary efficacy outcome, freedom from efficacy failure at 12 months, occurred in 75% of the cryoballoon ablation group compared with 45% of the antiarrhythmic drug therapy group (p < 0.001). Efficacy failure was defined as acute procedural failure, any subsequent atrial fibrillation surgery or ablation procedure, or any of the following after the 90-day blanking period: atrial fibrillation/flutter/tachycardia, cardioversion, or antiarrhythmic drug therapy.

The primary safety outcome at 12 months occurred in 1.9% of the cryoballoon ablation group compared with a performance goal of <12% (p < 0.0001). The primary safety outcome was defined as transient ischemic attack (TIA), stroke, major bleeding, myocardial infarction, or vascular complication within 7 days; significant pericardial effusion within 30 days; or symptomatic pulmonary vein stenosis, atrial-esophageal fistula, or unresolved phrenic nerve injury within 12 months.

Secondary outcomes:

  • Atrial fibrillation/flutter/tachycardia after 90 days: 21 in the cryoballoon ablation group compared with 35 in the antiarrhythmic drug therapy group


Among patients with paroxysmal atrial fibrillation, a first-line cryoballoon ablation strategy was superior to antiarrhythmic drug therapy. This strategy appeared to be safe with very few procedural-related adverse events. Current guidelines recommend catheter ablation after failure of antiarrhythmic drug therapy. To date, there is a paucity of data evaluating catheter ablation compared with antiarrhythmic drug therapy, with most of the studies examining radiofrequency ablation.


Wazni OM, Dandamudi G, Sood N, et al., on behalf of the STOP-AF First Trial Investigators. Cryoballoon Ablation as Initial Therapy for Atrial Fibrillation. N Engl J Med 2020;Nov 16:[Epub ahead of print].

Presented by Dr. Oussama Wazni at the European Society of Cardiology Virtual Congress, August 29, 2020.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Pericardial Disease, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias

Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Atrial Fibrillation, Atrial Flutter, Catheter Ablation, Cryosurgery, Electric Countershock, Ischemic Attack, Transient, Myocardial Infarction, Pericardial Effusion, Stroke, Tachycardia, Vascular Diseases, ESC20

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