STOP AF Cryoablation for Atrial Fibrillation — Quality of Life Results and Technical Considerations

June 23, 2010 8:05 AM CT

By Peggy Noonan and Mellanie True Hills

A late-breaking study, the North American STOP AF Trial, presented at the recent Heart Rhythm 2010, the 31st Annual Scientific Sessions of the Heart Rhythm Society, was a follow up to results published earlier this year. The STOP AF (Sustained Treatment of Paroxysmal Atrial Fibrillation) clinical trial involved 245 patients at 26 centers in the U.S. and Canada who received cryoablation using the Arctic Front® Cardiac CryoAblation Catheter System.

Quality of Life and Complications Twelve Months After the Procedure

This study involved a younger (median age in the 50s) and highly-symptomatic population of paroxysmal atrial fibrillation patients. This additional analysis, which included the use of the SF-36 quality-of-life questionnaire, showed that cryoablation improved the physical and mental quality of life for patients in the study.

Overall, in this highly-symptomatic, high-burden population, 100% of patients reported afib symptoms before treatment and only 20% reported symptoms twelve months later. Patients reported improvements in six categories of debilitating symptoms when comparing before treatment to 12 months after:

  • Palpitations decreased from 86% to 25%
  • Fatigue decreased from 76% to 13%
  • Rapid heartbeat decreased from 66% to 16%
  • Difficulty breathing (dyspnea) decreased from 54% to 9%
  • Dizziness decreased from 48% to 9%
  • Fainting (syncope) decreased from 4% to 1%

The “significant reduction in AF-related symptoms” shows that cryoablation can potentially relieve suffering from symptomatic paroxysmal atrial fibrillation, said Jeremy Ruskin, MD, chair of the STOP AF trial steering committee and Director of the Cardiac Arrhythmia Service at Massachusetts General Hospital. And since the symptoms decreased from month six to month twelve, he suggested that this indicates a possible longer-lasting effect.

There were some complications—stroke, pulmonary vein stenosis (narrowing) and phrenic nerve injury—all of which can be common complications of any ablation.

“There were five strokes overall across the study population,” Dr. Ruskin said. “Only one was deemed to be ablation related” and the other four, which occurred between 30 and 260 days after ablation, were determined to be unrelated to the ablation procedure.

Pulmonary vein stenosis can be defined in different ways, but here it was defined more stringently than usual as a narrowing of the pulmonary vein by 75% or more. Seven people in the study developed pulmonary vein stenosis, but only two had symptoms and needed treatment. (One of the two declined treatment and stenosis resolved in a year and the other was treated with angioplasty with stent insertion.)

Somewhat concerning to several electrophysiologists commenting on the study at Heart Rhythm Society was that phrenic nerve palsy occurred in 29 (11.2%) of the study participants who had been treated with ablation. Most recovered in three months, on average, and after 12 months, 25 of the 29 had resolved. “Only one was still symptomatic after 12 months,” Dr. Ruskin added.

Technical Considerations

Dr. Ruskin reported that point-by-point spot ablation is quite arduous and that the balloon, which treats a larger area in an arc pattern, “may be less technically-demanding than spot-ablation.” However, he indicated that the “learning curve is quite steep”. The most experienced centers had success rates of up to 90% compared to only 56% on the first two cryoablations, but experience did not change the safety outcomes. Since even the most experienced centers in the study had only 23 cryoablations, Ruskin speculated that safety may increase with experience.

In addition, related data from the FAST-PVI study was just released last week at Cardiostim 2010, the 17th World Congress in Cardiac Electrophysiology and Cardiac Techniques. In this study, both Medtronic anatomically-shaped catheters—the cryoballoon that was used in the STOP AF study and the circular multi-electrode radiofrequency (RF) catheter—were found to speed up ablation procedures by about one-third compared to spot ablation catheters, thus decreasing ablation time and fluoroscopy exposure, and yielding high procedure success rates in stopping afib.


What does this mean to people with paroxysmal atrial fibrillation?

“Cryoablation is a highly effective technique for the prevention of recurrent paroxysmal afib in symptomatic patients who are resistant to at least one antiarrhythmic drug,” Dr. Ruskin added. “In addition, cryoablation is significantly more effective than additional trials of antiarrhythmic drug therapy in this population.”

The CryoAblation System is available in Europe and is under investigational use in the U.S.

To learn more:

Mellanie’s Comments:

As with any procedure, the amount of experience the doctor and center have with the specific procedure, device, and energy source is very important to your outcome. Ask about the success rates and adverse events for your specific doctor and center, not just overall. See Partnering with Your Doctor for more information on what to ask.


Disclaimer: Patients come first at, and we do not compromise on that. While Medtronic, the maker of the system used in the STOP AF trial, has very recently become a donor to, we believe that research findings from significant clinical trials must be reported to give patients an all-encompassing view of current and future treatment options. Therefore, we feel that it is important to report further on this study.

Peggy Noonan specializes in writing about health for consumers and medical professionals. She writes for leading national magazines and consumer publications as well as

Mellanie True Hills is founder and CEO of and an atrial fibrillation survivor.