Many companies have tried and failed to get a specific labeling approval for a minimally invasive surgical system to treat atrial fibrillation (AF), a condition that affects more than 5 million people worldwide. And that includes Medtronic (Minneapolis), the latest company vying to get its Cardioblate system okayed for that prevalent condition.

The company reported that it has begun a U.S. pivotal clinical trial for the Cardioblate surgical ablation system to treat the cause of permanent AF via a different approach than it pursued in its initial foray. That effort came in 2004, with the (Cardioblate Atrial Fibrillation (CAFé) study for treatment of AF (Medical Device Daily, Dec. 17, 2004).

"The main hurdle [at that time] is that the FDA wanted a prospective, randomized trial," said Carole Bruner, a senior marketing manager at Medtronic responsible for the Cardioblate system.

"On the concomitant side," she told Medical Device Daily, "the difficulty was that the randomization was pretty much a non-starter," since surgeons wanted to provide their patients with the best possible outcomes while they had them on the operating table and wanted to use the ablation pen. Thus, it was difficult to develop a control group — a problem that MDD has recently noted in reporting on several other leading-edge technologies seeking approval.

"We kind of knew at that time that it was almost as if we were a little too far into the market in terms of acceptability . . . but the FDA wanted the randomized trial."

Now, the FDA has approved the company to conduct a prospective, non-randomized, clinical trial — Concomitant Utilization of RadioFrequency Energy for Atrial Fibrillation (CURE-AF) — which will enroll 75 patients at 10 U.S. medical centers. The primary endpoints of the trial are to evaluate the freedom from permanent AF in patients off antiarrhythmic drugs at six months, with the composite major adverse event rate at one month.

The results of the trial, if successful, will be submitted to the FDA to obtain an indication for the treatment of permanent AF in patients requiring concomitant open heart surgery.

The Cardioblate system is an irrigated radio frequency (RF) surgical ablation system used to create lesions on the heart muscle to block irregular signals of the heart, potentially reestablishing normal heart rhythm. Surgeons use irrigated RF energy from the Cardioblate system to create lesions on the heart muscle. These lesions are created to block the irregular electrical signals of the heart, which may stop the AF.

The purpose of the CURE-AF trial is to evaluate the safety and effectiveness of the Cardioblate system for reestablishing the normal heart rhythm in patients with permanent AF requiring concomitant open heart surgery utilizing the modified Cox Maze III procedure. The trial population includes patients requiring valve replacements or repairs, atrial septal defect (ASD) repairs or coronary artery bypass grafts (CABG) procedures.

"Due to the complexity and length of traditional surgical procedures for permanent AF, such as the Cox Maze III procedure, it was important for Medtronic to study potentially easier and safer techniques for the cardiac surgeon to offer to their patients suffering from permanent AF," said John Liddicoat, MD, VP of structural heart disease in the cardiac surgery business at Medtronic. "We are pleased to begin enrollment in the CURE-AF trial and hope to begin providing relief to so many patients suffering from the debilitating effects of permanent AF."

Of the more than 5 million people who suffer from AF, about one-third are categorized as suffering from permanent or chronic AF. People with AF are at increased risk of stroke, have a shorter life expectancy, and may develop symptoms such as shortness of breath. It is estimated that more than 2.5 million U.S. patients suffer from chronic AF, and the number is expected to double by 2050

The prevalence of the disease increases with age, doubling in each decade after age 50, and about 15% of all strokes occur in people with AF.

These ablation systems are particularly important to cardiac surgeons because they provide additional tools to compete with electrophysiologists who often use catheters to treat the same condition.

The Cardioblate has now gone through several generations, with the first monopolar system being cleared in February 2002 (MDD, Feb. 4, 2002) and a bipolar surgical system the following year cleared for soft tissue ablation (MDD, Aug. 11, 2003).

The company then unveiled its second-generation bipolar BP2 system, which incorporates dual linear electrodes, and its third generation bipolar LP system in 2005.

Bruner said that the irrigated RF technology between the earlier and later generations of the product has not really changed. What has changed, she said, are ease-of-use features — "like the flexible neck and the handle design and the electrode design and things like that."