State of the Art of CTO Revascularization

Patient Selection and Safety David E. Kandzari, MD, Duke University Medical Center, Durham, NC, addressed patient selection by discussing results showing improvement of left ventricle (LV) function after CTO recanalization.1 In a study analyzing the potential for LV recovery after successful CTO revascularization, patients with the most severe LV dysfunction experienced the greatest increase in LV ejection fraction (25% increase over baseline; p Guidewire Techniques Martin B. Leon, MD, of Columbia University Medical Center and the Cardiovascular Research Foundation, New York, NY, described the best applications for the three major operator techniques (drilling, penetration, and sliding). Drilling, considered the workhorse technique, should be used for most CTOs with a discrete entry point after initial attempts with soft (intermediate) wires. Penetration is preferable for CTOs with a blunt entry point or for heavily calcified or resistant lesions, and can also be used as an alternative to drilling after initial soft wire failure. Sliding is best used for CTOs with microchannels, for subtotal occlusions, in-stent occlusions, and some calcified and angulated lesions. If you identify microchannels, you have a very high likelihood of success, and hydrophilic wires are entirely appropriate, Dr. Leon said. Shigeru Saito, MD, of Shonan Kamakura General Hospital, Japan, then described the standard Japanese approach to CTO revascularization using ultra-stiff guidewires. These are necessary for treating the most difficult CTO lesions those with hard, calcified plaque and those with tortuous anatomy. He emphasized the importance of tip stiffness and torque transmission: Tip stiffness decreases logarithmically with extension from a microcatheter Torque transmission is proportional to tip stiffness if the guidewire is straight Torque transmission in a tortuous artery is lower with stiffer guidewires Procedural Advances Gregory A. Braden, MD, of Cardiology Specialists of North Carolina, pointed out that 85% of unsuccessful CTO revascularization attempts fail because the guidewire is unable to cross the lesion. Recent advances may help to overcome this difficulty: New wires Dual injection/bilateral angiography Biplane imaging or multiple projections Extraluminal technique Parallel wire technique Use of small balloon (or transit catheter) for backup support Drug-eluting stents Takahiko Suzuki, MD, PhD, of the Toyohashi Heart Center, Japan, added intravascular ultrasound (IVUS)-guided wire crossing and the retrograde approach to this list. He stated that combining conventional stiff wires with new crossing techniques yielded a higher success rate in CTO revascularization. New and Emerging Technologies Researchers at the CTO Summit also discussed a host of new and emerging technologies with potential for helping recanalize chronically occluded vessels. Tornus catheter The Tornus device is a catheter made of 8 stainless steel strands woven together to enhance flexibility and strength in exchanging wires, delivering balloons, and providing support for CTO procedures. It is used after a wire has crossed a chronic occlusion, but when a conventional balloon will not cross. The catheter was developed by Asahi Intecc (Japan), and launched in the US by Abbott Vascular Devices (Redwood City, CA; visit https://www.abbottvasculardevices.com for complete device description). Masahiko Ochiai, MD, PhD, of Northern Yokohama Hospital, Kanagawa, Japan, described the advantages of using the Tornus, which was approved by the US Food and Drug Administration in September 2005. The Tornus can be advanced into the CTO by counter-clockwise rotation without strong back-up support once the tip is encroached, Dr. Ochiai said. He added that the position of the distal tip is clearly recognized by a radiopaque marker, and that the device can make a smooth channel without dissection, allowing for passage of a low profile balloon. The biggest advantage, he noted, is that once the Tornus is successfully passed through a CTO, wires ranging from very stiff to floppy can be exchanged, making for a safe procedure. There are caveats to using the Tornus catheter, Dr. Ochiai cautioned. The Tornus 2.1 Fr device should not be rotated more than 40 times continuously either in counter-clockwise or clockwise directions, he advised, or the accumulated torque would be released. And in the case of the Tornus 2.6 Fr, the limit is 20 rotations. Safecross Developed by IntraLuminal Therapeutics (Carlsbad, CA), the Safecross system uses optical coherence reflectometry (OCR) for guidance and radiofrequency (RF) energy at the wire tip for ablation. Algorithms based on absorption rates distinguish the normal artery wall from occlusive material (visit https://www.intraluminal.com/ for complete device description). Charles Simonton, MD, medical director of cardiovascular research at the Carolinas Heart Institute in Charlotte, NC, noted that the Safecross system would be appropriate for true, well-developed CTOs with presumed firm proximal and distal caps that measure

1. Werner GS, Surber R, Kuethe F, et al. Collaterals and the recovery of left ventricular function after recanalization of a chronic total coronary occlusion. Am Heart J 2005;149:129-137.