In Part I of this article, the definitions, prevalence, and clinical presentation of chronic total occlusions (CTOs) were reviewed, the histopathology of CTOs was examined, efforts to replicate human CTOs with experimental models were appraised, and the clinical relevance and rationale for CTO revascularization were evaluated. 1 In Part II, we summarize the technical approach to and outcomes after percutaneous coronary intervention (PCI) of occluded coronary arteries, describe the novel devices and drugs approved and undergoing investigation for CTO recanalization, and conclude with practical perspectives on managing the patient with 1 or more chronic coronary occlusions.

R emarkable progress in the percutaneous management of coronary artery disease has been achieved over the last decade. The scaffolding properties of coronary stents have resulted in percutaneous coronary intervention (PCI) becoming a predictable procedure, with reduced rates of acute closure and late restenosis compared with balloon angioplasty alone. 1,2 More recently, the site-specific delivery of antiproliferative agents from drug-eluting stents has been demonstrated to markedly attenuate vascular responses leading to neointimal hyperplasia, further reducing the occurrence of clinical and angiographic restenosis to Ͻ10% in most patients. 3,4 PCI in patients with acute coronary syndromes and acute myocardial infarction (AMI) has also been proven to save lives, reduce rates of myocardial infarction (MI), and enhance quality of life compared with alternative treatment modalities. [5][6][7] With these advances in perspective, it is often stated that successful recanalization of chronic total occlusions (CTOs) of native coronary arteries represents the "last frontier" of PCI. This statement is made in deference to the fact that CTOs represent the most technically challenging lesion subset that interventional cardiologists face, with procedural success rates considerably lower than those achieved in nonoccluded coronary vessels or acutely occluded arteries. Moreover, no consensus exists with regard to the definition of CTO, the factors related to procedural failure and/or complications, and the optimal technical approach. Indeed, until recently, the clinical benefits of PCI in CTOs had not been demonstrated.An international panel of 47 physicians from 9 countries was therefore convened in New York City for 2 days in January 2004, the purpose of which was to reach consensus on the current state of the art of CTO angioplasty (see Appendix in the online-only Data Supplement for a complete participant list). This goal was approached through a series of didactic lectures, roundtable discussions, breakout focus groups, and the performance of 14 live case demonstrations of CTO angioplasty by many of the world's most skilled operators in this subspecialty. The present report represents a synthesis of the findings from this meeting and also incorporates a literature review from the field of CTO intervention. Topics covered in Part I of this review include definitions, prevalence, and clinical presentation of CTOs; the anatomy and histopathology of coronary occlusions; experimental CTO models; and the clinical relevance and rationale for CTO revascularization. Part II will review the technical approach to and clinical outcomes after percutaneous intervention of CTOs and describe the novel devices and drugs approved and undergoing investigation for CTO recanalization.

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The influence of multiple clinical, angiographic and technical variables on the outcome of percutaneous transluminal coronary angioplasty was evaluated in a group of 76 consecutive patients with total coronary artery occlusion. Angioplasty was performed successfully in 53% of these patients. The likelihood of successful angioplasty was favorably influenced by: 1) a history of prior myocardial infarction in the distribution of the occluded arterial segment (p = 0.03); 2) an estimated maximal duration of arterial occlusion of less than 20 weeks (p less than 0.001); and 3) a length of nonvisualized arterial segment distal to the point of occlusion of less than 1.5 cm (p = 0.03). The outcome of coronary angioplasty was not significantly influenced by the vessel involved, the location of the occlusion within an involved vessel, the morphology of the occlusion (tapered versus abrupt) or the age and sex of the patient. There were no deaths and no vascular perforations. Four patients had recurrent coronary occlusion within 24 hours of the procedure; in three of these, recurrent occlusion was successfully treated with reangioplasty and in one, emergent surgical revascularization was performed. Embolic occlusion of an arterial branch distal to the point of total coronary occlusion occurred in 4 of the 40 successfully recanalized arteries. Seventy-five percent of patients having successful recanalization of an occluded coronary artery were free of the anginal symptoms that had prompted performance of the procedure at a mean follow-up period of 7.3 months. Thus, angioplasty of a total coronary artery occlusion can be performed safely and effectively, particularly in patients with a history of prior myocardial infarction, a brief estimated duration of coronary occlusion and a short nonvisualized occluded arterial segment.

The Ocelot catheter with optical coherence tomography guidance offers physicians a reliable option for crossing femoral and popliteal chronic total occlusions with low MAE rates.