Although the treatment of CTOs via conventional percutaneous intervention is a well-established modality with reasonably predictable results, the failure to cross using conventional guidewire technology frequently precludes subsequent repair of the lesion in the cardiac cath lab and many of these patients are ultimately managed surgically or medically. Given the high fluoroscopic times, increased use of contrast, and repetitive guidewire selection that traditionally accompanies conventional attempts to open CTOs, our staff has always thought: there must be a better way and now, there is.

Led by Dr. Charles Simonton, we recently participated in a pre-market IDE (investigational device exemption) clinical trial that compared the contemporary approach of guide wire technology to a catheter-based technique via the new Frontrunner CTO catheter (LuMend, Inc., Redwood City, CA) in the treatment of chronic total occlusions. This prospective, controlled multi-center trial included 107 patients, whose CTOs did not respond to a ten-minute guide wire attempt. The Frontrunner CTO Catheter allowed successful recanalization of 56% of CTOs not crossable with a conventional guide wire. Potential device-related study complication rates were well below established protocol limits. This trial was recently completed and the FDA subsequently granted the company clearance to market the device in the United States. Carolinas Medical Center is continuing to use the Frontrunner for patients who cannot be treated with a conventional guide wire.

The Frontrunner is one of the first FDA-cleared devices specifically indicated for coronary CTOs. Just like balloon angioplasty and stenting, the Frontrunner catheter is a minimally invasive interventional procedure.

Using the concept of controlled blunt micro-dissection, the Frontrunner enables users to gently separate and fracture atherosclerotic plaque in various tissue planes throughout the entire length of a total occlusion, without increasing the risk of perforation or Q-wave myocardial infarction. Controlled blunt micro-dissection exploits the difference in the elastic properties of the adventitia versus the inelastic properties of the fibro-calcific plaque to create a passage either through or around a chronic total occlusion.

The catheter is easily steered through the coronary vasculature to the chronic total occlusion. Once delivered to the occlusion site, the distal tip of the device is placed against the proximal cap of the CTO. The device is remotely actuated to open against the plaque and interior walls of the vessel lumen.
Repetitive actuation and steering of the catheter creates a micro channel through or around the CTO, ultimately facilitating the placement of a conventional guide wire across the occlusion and the completion of the procedure via conventional percutaneous intervention (angioplasty or stenting).

With the exception of an occasional desire to implement contra-lateral injections, the use of the Frontrunner has not markedly altered the routine patient prep and table set-up protocols we use for most PTCA/stent procedures. Average crossing times using the blunt micro-dissection technique are roughly established at 1mm/min (i.e., a 30mm CTO takes us 30 minutes to cross, as measured from the time the Frontrunner engages the proximal cap until the device exits the proximal end of the lesion). This increased predictability has greatly enhanced our ability to work CTO cases into the mainstream scheduling of procedures. (Our previous inclination was to save these cases for the end of the day).

The following case is an example of one of our early Frontrunner cases and accurately portrays what has become our treatment modality of choice when confronting CTOs at Carolinas Medical Center.

Facilitated Revascularization: Chronic Total Occlusion of an RCA
Charles A. Simonton, MD, Medical Director
Cardiovascular Research, Carolinas Heart Institute,
Charlotte, North Carolina

Case History

A 58-year-old male with a history of small inferior myocardial infarction 6 years prior to the admission who presents with a recurrent angina and positive nuclear stress test for inferior and lateral ischemia. A left heart catheterization demonstrates a chronic total occlusion (CTO) of the right coronary artery (RCA), with antegrade and retrograde collaterals (Figure 1) as well as a 70% stenosis in the mid-left circumflex artery (Cx). The left anterior descending artery (LAD) was without significant disease. Left Ventriculogram (LV) shows mild inferior hypokinesis with estimated ejection fraction of 58%.

Strategy

A two-vessel intervention was planned utilizing the Frontrunner CTO Catheter (LuMend, Inc., Redwood City, CA) to initially cross the CTO and facilitate the recanalization of the RCA. The Left Cx would be stented with a traditional approach.

Procedure

An 8 Fr JR4 guiding catheter without side-holes was advanced to the RCA. Heparin 5000 units IV was administered. A 3.0mm Frontrunner CTO Catheter was selected and advanced through the JR4 guiding catheter to the site of the proximal RCA occlusion. The nose of the Frontrunner was placed into the proximal most aspect of the occlusion just beyond the take-off of a small right ventricular branch. Four to five openings of the jaw were performed in different planes, and after the fifth opening of the jaws and subsequent closure of the jaws, the device easily advanced forward to the middle segment of the occlusion (Figure 2). There was resistance at the distal end of the occlusion and one additional jaw opening was performed, after which the device quickly popped through the distal cap and into the mid-segment of the RCA.

At this point, ReoPro (Eli Lilly & Company, Indianapolis, IN) was administered (ACT = 210 sec). The Frontrunner was removed and angiography was repeated. This revealed a long tubular lumen established through the occlusion site by the Frontrunner, and likewise illuminated a more distal 80% stenosis in the mid-segment of the RCA at the acute margin. An .014 high torque intermediate wire (Guidant Corporation, Santa Clara, CA) was then advanced and easily passed through the lumen at the site of the occlusion and across the stenosis at the acute margin, ultimately facilitating the use of a 3.0mm Crosssail pre-dilation balloon (Guidant Corporation).

The balloon was exchanged for a 3.5mm Penta stent (Guidant Corporation) deployed at the mid-segment of the RCA, followed by an additional 3.5mm Penta stent that was deployed at the site of the CTO. A 4.0 x 20mm Quantum balloon (Boston Scientific, Maple Grove, MN) was tracked to both the proximal and mid segments of the RCA, post-dilating to 14atms. This revealed a large lumen at both sites with TIMI 3 flow (Figure 3). The Cx lesion was then stented with a 3.0 x 13mm BX Velocity (Cordis Corporation, Miami, FL) without complication. The patient tolerated the procedure very well and was discharged the next day.