October 10th, 2011

TTOP-AF Trial Proves Efficacy of RF Ablation System, But Not Safety

A new trial demonstrates that an investigational RF ablation system is more effective than medical management in treating persistent AF, but the trial failed to meet a key predefined safety goal.

At the Venice Arrhythmias 2011 conference, Lucas Boersma presented the results of the TTOP-AF (Tailored Treatment of Persistent Atrial Fibrillation) trial, in which 210 patients with persistent AF were randomized to medical management or treatment with the Medtronic Phased RF Ablation System, which has been approved in Europe but is available only for investigational use in the U.S.

According to ClinicalTrials.gov, safety was the primary outcome measure of the trial. The acute safety event rate in the ablation arm was 12.3%, but the upper 95% confidence interval, which was 19%, exceeded the predefined 16% performance goal. A total of 21 acute safety events occurred in the ablation arm, including 4 strokes and 2 cases each of cardiac tamponade, pseudoaneurysm, and pulmonary infiltrates with fever.

The primary effectiveness endpoint, which was defined as a greater than 90% reduction in the AF and atrial flutter burden and freedom from antiarrhythmic drug therapy at 6 months, was reached in 55.8% of patients in the ablation group but only 26.4% of patients in the medical management arm, a highly significant difference (P<0.0001).

On October 27 the FDA Circulatory System Devices Panel is scheduled to discuss the PMA application for the Medtronic system.

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