Patients with AF can benefit from Medtronic Phased RF Ablation System ablation system

Medtronic, Inc. (NYSE: MDT) today announced results from its Tailored Treatment of Permanent Atrial Fibrillation (TTOP-AF) clinical trial, the first randomized study comparing ablation therapy with the Medtronic Phased RF Ablation System ablation system to traditional medical management (antiarrhythmic drugs and direct current cardioversion) in 210 patients with persistent or long-standing persistent atrial fibrillation (AF). The findings, presented today at Venice Arrhythmias 2011, the 12th International Workshop on Cardiac Arrhythmias, demonstrated that 55.8 percent of ablation management patients had an AF and atrial flutter burden reduction of greater than 90 percent and were free of antiarrhythmic drug therapy at six months compared to 26.4 percent in the traditional medical management arm (p<0.0001), thus meeting the chronic effectiveness endpoint. When including patients still on antiarrhythmic drug therapy following the procedure with the ablation system, 67.4 percent had a greater than 90 percent reduction of AF burden at six months.

While the ablation patients in the trial demonstrated a reduction in AF burden, the acute safety event rate in the trial was 12.3 percent with an upper 95 percent confidence interval of 19 percent, which did not meet the pre-defined performance goal of 16 percent. At the time the trial was designed, no benchmark for the persistent AF patient population existed, so the performance goal of 16 percent was established based on a literature review evaluating ablation procedures for right-sided and paroxysmal AF ablation procedures. In the TTOP-AF trial, 12.3 percent (17) of patients experienced one or more protocol-defined procedural and/or device-related adverse events within 7 days of the procedure. A total of 4 strokes (1.7 percent acute procedural stroke rate) occurred within the acute period after an ablation procedure. The stroke incidence was higher for the first few subjects undergoing an ablation procedure rather than for subjects enrolled later at each site, with 3 of the 4 strokes occurring during the first 5 procedures for each clinical trial center. Two of the 4 patients had complete resolution of symptoms within the 6-month follow-up period; the other 2 patients had minor residual effects from the stroke.

"Due to the advanced state of the disease and the attendant increase in the complexity of the procedure, persistent AF patients undergoing ablation have a higher risk than paroxysmal AF patients for adverse events; therefore, the acute safety findings from the TTOP-AF trial are not unexpected," said John Hummel, M.D., director of clinical electrophysiology research at The Ohio State Medical Center. "I believe these data are promising given the reduction in AF burden, and therefore this ablation technology may ultimately represent an important option for drug refractory, symptomatic, persistent AF patients who are more difficult to treat."

There is a significant unmet need for U.S. patients with symptomatic, drug refractory persistent AF. The only FDA approved AF ablation therapies are indicated for the treatment of paroxysmal AF, which is a type of AF in which irregular heartbeats in the upper chambers start and stop suddenly on their own, usually for minutes or days at a time. As the disease progresses into persistent AF (recurrent AF episodes that last more than 7 days), it becomes more complex to treat. Persistent AF patients often have increased hospitalizations and healthcare costs, and the condition is more debilitating for the patients in terms of quality of life. Additionally, persistent AF often causes structural, functional and electrical changes to the heart.

"Medtronic is fully committed to developing the most clinically advanced medical technologies to treat the millions of patients who suffer from atrial fibrillation, a condition that costs the healthcare system billions of dollars each year," said Reggie Groves, vice president and general manager of Medtronic's AF Solutions business. "We believe these data demonstrate the Medtronic Phased RF Ablation System can fill an unmet need for persistent AF patients who have few treatment options with significant limitations."