ESC 2020 Congress: STOP AF First finds cryoballoon ablation safer than drug treatment for paroxysmal AF

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Oussama Wazni

Cryoballoon catheter ablation as a first line treatment for paroxysmal atrial fibrillation (AF) was found to be safer and more effective than anti arrhythmic drugs, according to a study presented at the ESC Congress 2020 (Virtual, 29 August–1 September).

 

Oussama Wazni (Cleveland Clinic, Cleveland, USA) presented the findings of the STOP AF First clinical trial during a late breaking science session at the digital congress. “Improvements in the safety and efficacy of catheter ablation have increased interest in ablation as a first line therapy,” he told attendees, adding “there are few randomised controlled trials that have evaluated first line treatment for symptomatic paroxysmal AF, particularly when considering cryoballoon catheter ablation”.

 

Previous first line trials, Wazni noted, included only radiofrequency catheter ablation, and evaluated point-by-point radiofrequency catheter ablation, revealing “modest benefits” for catheter ablation.

 

STOP AF First, Wazni explained, sought to demonstrate the superiority of cryoballoon catheter ablation versus antiarrhythmic drugs for maintaining freedom from AF, atrial tachycardia and atrial flutter in drug naive patients with symptomatic paroxysmal AF.

 

Patients were enrolled at a total of 24 US centres, the patient population was aged between 18–80, with symptomatic paroxysmal AF, and had not been on anti-arrhythmic drugs for more than seven days. Patients were randomised in a 1:1 fashion to eith pulmonary vein isolation (PVI) using the Arctic Front Advance Cryoballoon (Medtronic) or antiarrhythmic drugs (Class I or III).

 

Primary efficacy endpoint was treatment success at 12 months, with treatment failure defined as acute procedural failure, and any subsequent AF surgery or ablation in the left atrium.

 

The primary safety endpoint was a composite of pre-specified procedure and system-related adverse events, and the pre-specified performance goal was failure rate of <12%. Primary safety events include TIA within 7 days as well as stroke, major bleeding, myocardial infarction or vascular complication, significant pericardial effusion within 30 days, and symptomatic pulmonary vein stenosis, atrial esophageal fistula or unresolved phrenic nerve injury at 12 months.

 

In total, Wazni explained, 203 patients received treatment and were included in the final analysis. Of these, 102 completed the cryoballoon ablation strategy, and 91 were in the anti arrhythmic drug arm.

 

Detailing the results, Wazni noted that the primary efficacy endpoint was met with a 75% rate of freedom from primary efficacy failure in the cryoballoon ablation arm recorded. “That means 75% success rate with no recurrence of any atrial arrhythmia versus 45% in the anti arrhythmic drug arm at 12 months,” he said.

 

Additionally, the primary safety endpoint was also met, Wazni said, with only 1.9% complications, less than the performance goal of <12%. 


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