Force-sensing SMART-AF proves safe and effective

A force-sensing ablation treatment for paroxysmal atrial fibrillation (PAF) helped to improve outcomes in the SMART-AF study, according to results published Aug. 19 in the Journal of the American College of Cardiology. But an accompanying editorial raised questions.

In this one-arm trial, 161 patients underwent PAF catheter ablation using the THERMOCOOL SMARTTOUCH system (Biosense Webster). Andrea Natale, MD, of the Texas Cardiac Arrhythmia Institute at St. David’s Medical Center in Austin, and colleagues conducted the study to evaluate whether an irrigated, contact force-sensing catheter would be safe and effective for use in treating PAF.

Patients were enrolled between June and December of 2011, with the last follow-up visit occurring at the end of January 2013.

In the seven days following the procedure, Natale et al reported four tamponade events, three pericarditis events, four vascular access complications and one heart block that occurred prior to radiofrequency application. They reported no deaths, stroke, atrioesophageal fistula, cerebrovascular accident, thromboembolism, MI or stenosis in the study period.

Analysis had freedom from atrial fibrillation/flutter or atrial tachycardia recurrence at 72.5 percent for 12 months. Outcomes were 4.25 times more likely to be successful if the force used was between the selected working ranges for 80 percent or more of the procedure. The average contact force used was 17.9 g per procedure.

Natale et al found that not only was this method safe and effective for use, but it also improved in effectiveness over an earlier ThermoCool study (72.5 percent vs 66 percent), although a direct comparison was not conducted.

However, an editorial pointed out that the tamponade rate they reported for this study, 2.48 percent, was higher than the rate reported in the earlier study, which was 1 percent.

Hugh Calkins, MD, of Johns Hopkins Hospital in Baltimore, wrote that this study did not address questions about whether the method is more or less safe and effective against second-generation cryoballoons or why the SMARTTOUCH system was not compared in a randomized trial to other force-sensing catheters. Calkins considered this to be a missed opportunity.

Meanwhile, Natale et al wrote that this trial was successful in proving safety and efficacy of the system and that future research should aim to uncover the improved success rate through stable contact force when using this or similar systems.

The study was funded by Biosense Webster.

For more on the ablation as a treatment for atrial fibrillation, see “Ablation & Afib: Zapping Barriers to Success.”