Percutaneous treatment of chronic total occlusions (CTOs) of coronary arteries represents one of the greatest technical challenges in interventional cardiology. Although CTOs are present in approximately one quarter of patients with angiographically documented coronary artery disease (CAD), these lesions represent only 15% of percutaneous interventions (PCIs) performed.<sup>1</sup> Thus, patients with CTO have historically been denied PCI in favor of either continued medical therapy or referral for coronary artery bypass graft surgery (CABG). Several studies of patients with CTO have demonstrated not only improvement in angina and a reduced need for subsequent revascularization with PCI, but also, a survival benefit.<sup>2–4</sup>
Percutaneous treatment of CTOs should be reserved for the experienced interventional cardiologist. Due to the vast array of CTO cases, patients with factors associated with a higher success rate, (occlusion age of less than 3 months, occlusion segment less than 1.5 cm, residual antegrade flow, and a “dimple” within the stump), should be identified.<sup>6</sup> Once the operator has attained the experience and knowledge of treating “simpler” CTOs, more difficult lesions may be attempted. Weisz and Moses provide an excellent review of various angiographic factors, techniques, and devices that may lead to improved patient care via successful PCI in CTOs.
In addition to the identification of lesion characteristics favorable to treatment, proper equipment selection is required for success. Advances in guidewire technology (hydrophilic coatings, stiffer tips, and tapered tips) have led to a significantly improved ability to cross CTOs when standard guidewires are not successful. Furthermore, the Safe-Cross system (<i>IntraLuminal Therapeutics, Carlsbad, California</i>), Crosser (<i>FlowCardia, Sunneyvale, California</i>) and Frontrunner (<i>LuMend, Inc., Redwood City, California</i>) are novel devices available to the operator when a guidewire will not cross the lesion. In general, registry data have demonstrated that these novel devices achieve success in > 50% of lesions in which conventional guidewires failed to cross. However, data from randomized trials on these devices are not available. In situations in which wire position distal to the lesion is attained but the profile of the balloon is too bulky to cross, the Tornus device (<i>Asahi Intecc, Aichi, Japan</i>) and the excimer laser are modalities which may be employed to create a lumen that enables balloon delivery. Finally, drug-eluting stents have demonstrated significantly improved rates of instent stenosis and the need for target vessel revascularization relative to bare-metal stents.<sup>7</sup>
In conclusion, the successful treatment of CTOs relies upon the proper selection of patients that have failed medical therapy and the identification of lesions amenable to PCI, along with an understanding of the technology available to assist the operator. As the cumulative experience of operators increase, the already promising results of percutaneous treatment of CTO will continue to improve. The article by Weisz and Moses is an excellent overview of CTOs and should serve as a reference for the interventionalist.