Cardima Preparing For Pivotal AF Trials Of Revelation Ablation Catheter

Cardima will begin a 60-100 patient, 10-center pivotal atrial fibrillation trial of its Revelation cardiac ablation microcatheter pending FDA approval of the company's feasibility trial, according to an Oct. 23 release.

The 10-patient feasibility study was completed at Massachusetts General, Johns Hopkins and Stanford University hospitals. The firm could submit a premarketing approval application supplement as early as mid-1999. Revelation was approved via 510(k) for mapping cardiac arrhythmias in November 1997.

Atrial fibrillation may be episodic or chronic and is characterized by irregular and rapid quivering of the heart's atria. It is the most common cause of stroke in the U.S., affecting 6% of individuals over age 60.

Cardiac ablation catheters are used off-label to treat atrial fibrillation (AF) by burning a line along the wall of the heart close to the site of the electrical irregularity. The burn disrupts the energy flow across the atrium and either stops the irregular impulse or redirects it along the line of the burn.

Although Revelation uses radiofrequency technology similar to that found in other cardiac ablation catheters, it heats along the length of the device rather than at its tip.

This difference allows the cardiologist to create a single linear burn by placing the catheter along the side of the atrial wall, instead of creating a segmented line with heat from the tip, known as "drag-and-burn" or "dot-to-dot" ablation. Eight metal coils along the side of the catheter conform to the cell wall, providing close surface contact to burn at a lower heat.

The cardiologist inserts the 2.5-3 Fr microcatheter into the patient's leg or neck vein and has the option of mapping the fibrillation before performing the ablation. The microcatheter can be attached to the hospital's existing mapping system, such as an EKG, in order to pinpoint the earliest activation point of the arrhythmia. An inert switch box allows the cardiologist to switch over to radiofrequency power and ablate the atrial wall.

Acknowledging that there is some controversy over whether mapping is necessary, Chief Financial Officer Ronald Bourquin said that the device also comes with a description of the three anatomical locations most effective in treating AF. These locations may be used instead of mapping each individual patient.

Cardima will not seek a curative indication for AF with Revelation, but claims the device had an approximately 90% success rate in its European trials with the endpoint of significant reduction or complete elimination of an AF episode. Revelation received a CE mark for the AF indication in August.

While the cardiologist can test the efficacy of the ablation immediately after the procedure by attempting to pace the heart back into AF across the burn, AF may begin in another location at another time, requiring additional procedures.

The possible recurrence of AF raises the question of which method is most cost-effective and clinically successful. Anti-arrhythmic or anti-coagulant drug therapy is frequently used for milder cases, but patients may become refractive and drug therapy is expensive, particularly for chronic AF patients. At the other end of the spectrum, the Maze open-heart surgical procedure, which involves slicing and quickly re-sewing the atrial wall, cures AF but is highly invasive.

The most likely competitor with AF ablation therapy will be implantable cardioverter defibrillators (ICDs). The major device makers are all investing heavily in implantable cardiac technology. Guidant's $135 mil. purchase of InControl announced Aug. 11 was largely motivated by the acquisition of InControl's Metrix implantable atrial defibrillator ("The Gray Sheet" Aug. 17, p. 5).

The most recent entry into the $1.3 bil U.S. ICD market is St. Jude Medical's Angstrom MD and Contour MD ICDs approved by FDA Oct. 29.

It remains to be seen whether ICD implantation or ablation therapy is more cost-effective. While an ICD costs approximately $25,000 plus an additional $25,000 for implantation or battery replacement, it offers broad cardiac rhythym management. The Revelation procedure costs $10,000-15,000 per procedure, which includes $2,500-3,000 for the catheter itself, but may need to be repeated frequently.

Announcing third-quarter 1998 results on Oct. 27, Cardima reported a 105% revenue increase to $314,000 for the quarter versus the same quarter last year. Strong U.S. sales of the Revelation and Pathfinder microcatheters for diagnosis of cardiac tachyarrhythmias were cited as boosting volume.