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    • Study purpose and design

    The STOP AF First trial1,2 is a prospective, multicenter, randomized study evaluating whether Arctic Front™ cryoballoon ablation is superior to antiarrhythmic drug (AAD) therapy as a first-line rhythm control treatment in patients with symptomatic paroxysmal atrial fibrillation (PAF).

    A total of 225 drug-naïve patients (AAD for less than 7 days) with symptomatic PAF aged 18–80 were enrolled at 24 centers in the United States. The Arctic Front Advance™ cryoballoon was used to establish pulmonary vein isolation (PVI) and the drug therapy arm received a class I or III AAD therapy.

    View trial (open in new window)

    Key findings

    Effective

    Greater than 7 out of 10 patients were free from atrial arrhythmia recurrence with cryoablation

    versus

    Less than 5 out of 10 patients with AAD therapy

    74.6% freedom from acute procedural failure or atrial arrhythmia recurrence 12 months post-ablation.

    By modified intention-to-treat analysis (which included all randomized patients who initiated therapy), freedom from primary efficacy failure was:

    74.6% in the cryoballoon arm, 45.0% in the AAD arm (p < 0.001)

    Safe

    Less than 2% serious complication rate

    Low complication rate. Primary safety events occurred in two subjects (estimated 12-month rate: 1.9%, 95% CI: 0.5–7.5%) in the cryoballoon arm. Since the upper bound of the 95% confidence interval was below the prespecified performance goal, the primary safety endpoint was met.

    Quality-of-life outcomes

    A significant improvement (p < 0.01) in subjects’ quality of life was observed at 12 months for those in the ablation group as assessed with the AFEQT and EQ-5D questionnaires. Improvements in atrial fibrillation-specific quality of life at 12 months assessed using the AFEQT were larger with Arctic Front™ cryoballoon ablation versus AAD therapy.

    Meta-analysis

    A meta-analysis of three randomized controlled trials demonstrates cryoballoon ablation, compared to AADs, as an initial first-line therapy is associated with incremental benefits, including:

    • 39% relative reduction in the risk of atrial arrhythmia recurrence3
    • 8.32 points larger improvement in AFEQT score on average3
    • 29% relative reduction in healthcare utilization3
    • 62% relative reduction in hospitalization3

    No significant difference in the rate of serious adverse events.

    Endpoint definitions

    Primary efficacy endpoint

    Treatment success at 12 months

    Treatment failure is defined as:

    • Acute procedural failure†
    • Any subsequent AF surgery or ablation in the left atrium (including those performed during the blanking period)
    • Any of the following after the 90-day blanking period:
      • Documented AF/AT/AFL
      • Cardioversion
      • Class I or III AAD use†

    Primary safety endpoint

    Composite of prespecified procedure- and system-related serious adverse events evaluated in the cryoballoon catheter ablation arm (prespecified performance goal: failure rate less than 12%)

    Primary safety events include:

    • Within 7 days:
      • Transient ischemic attack
      • Stroke
      • Major bleeding
      • Myocardial infarction
      • Vascular complication
    • Within 30 days:
      • Significant pericardial effusion
    • Within 12 months:
      • Symptomatic pulmonary vein stenosis
      • Atrial-esophageal fistula
      • Unresolved phrenic nerve injury at 12 months

    Study population

    Key inclusion criteria

    • A diagnosis of symptomatic PAF with the following documentation: 
      • Physician’s note indicating recurrent self-terminating AF or PAF
      • Any ECG-documented AF within 6 months prior to enrollment
    • Age 18–80

    Key exclusion criteria

    • History of AF treatment with class I or III AAD, including sotalol, with the intention to prevent an AF recurrence. However, patients pretreated with above AAD for less than 7 days with the intention to convert an AF episode were allowed.
    • Prior left atrial ablation or left atrial surgical procedure
    • Prior persistent AF (continuous AF greater than 7 days)
    • Left atrial diameter greater than 5.0 cm
    • NYHA class III or IV congestive heart failure and/or known left ventricular ejection fraction (LVEF) less than 45%

    Study recurrence monitoring

      Baseline 1 month 3 months 6 months 12 months
    Patient-activated ambulatory ECG (TTM; weekly and when symptomatic)     ➜ ➜ ➜
    12-lead ECG ◾ ◾ ◾ ◾ ◾
    24-hour continuous ambulatory ECG       ◾ ◾

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