Cardiac ablation and mapping

STOP AF trial

The STOP AF trial and STOP AF post-approval study assessed the safety and effectiveness of the Arctic Front™ and Arctic Front Advance™ cardiac cryoablation catheters.

Close-up of three healthcare professionals in scrubs and protective gear looking down intently

Study purpose and design

The Sustained Treatment of Paroxysmal Atrial Fibrillation (STOP AF) trial was designed to confirm the safety and effectiveness of the first-generation Arctic Front™ cardiac cryoablation system when used to treat patients with drug-refractory,* recurrent, symptomatic paroxysmal atrial fibrillation (PAF). Outcomes of this trial resulted in FDA approval of the cryoballoon in the U.S.1

Arctic Front™ cryoballoon encircled on a gray background

Key findings


Primary effectiveness endpoint met

The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF.


endpoint met

The first-generation cryoballoon trial showed improved safety outcomes relative to drugs. 3.1% major AF events in the ablation arm compared to the drug arm, which had 8.5% major AF events.

Study recurrence monitoring

Day 0 blanking period for AF detection

3 months

6 months

12 months

Weekly and symptom-initiated TTM

➜   ➜ ➜ 


Clinical follow-up

48-hour Holter monitor


PAS study purpose and design

The STOP AF Post Approval Study (PAS) is the largest prospective FDA multicenter study in North America to assess long-term safety and effectiveness of the Arctic Front Advance cardiac cryoablation catheter system in the treatment of patients with drug-refractory, recurrent, symptomatic paroxysmal atrial fibrillation.2 The primary objectives are effectiveness (freedom from AF) at 36 months and safety (cryoablation/procedure-related events) at 12 months.

PAS key findings

Results demonstrate Arctic Front Advance cryoballoon safety, efficacy, and suggest lesion durability in patients with drug-refractory, recurrent, symptomatic PAF. 

Primary effectiveness endpoint met

1. Freedom from AF

  • 12 months: 81.6%
  • 24 months: 73.8%
  • 36 months: 68.1%

2. Freedom from AF/AFL/AT

  • 12 months: 79.0%
  • 24 months: 70.8%
  • 36 months: 64.1%

5.8% major complication event rate, of which 3.2% (11/344) phrenic nerve injury (PNI) present post-ablation, 0.3% (1/344) persisted beyond 36 months.

Primary effectiveness
Freedom from AF recurrence at 36 months (N = 90)

Graph that illustrates the primary effectiveness of the Arctic Front cryoballoon to treat atrial fibrillation (AF)

PAS recurrence monitoring


3 months

6 months

12 months

Annual visit through 36 months


Clinical follow-up

24-hour Holter monitor




48-hour Holter monitor



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Failed one or two of the following three antiarrhythmic drugs: flecainide, propafenone, sotalol.



Packer DL, Kowal RC, Wheelan KR, et al. Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial. J Am Coll Cardiol. 2013;61(16):1713–1723.


Knight BP, Novak PG, Sangrigoli R, et al. Long-Term Outcomes After Ablation for Paroxysmal Atrial Fibrillation Using the Second-Generation Cryoballoon: Final Results From STOP AF Post-Approval Study. JACC Clin Electrophysiol. March 2019;5(3):306–314.