ABC | Volume 110, Nº5, May 2018

Review Article Ybarra et al CTO PCI Review Arq Bras Cardiol. 2018; 110(5):476-483 Figure 2 – Hybrid Algorithm for Crossing Chronic Coronary Occlusions: The hybrid algorithm begins with double coronary injection (Item 1), which allows the evaluation of several angiographic parameters (Item 2) and selection of the type of primary approach: anterograde (Items 3 to 5) or retrograde (Item 6). Changes in strategy are performed (Item 7) depending on the evolution and progress of the procedure. 1 Double injection 2 1. Ambiguous proximal cap 2. Improper distal bed 3. Adequate collaterals for intervention NO NO YES YES 3 4 5 6 7 Strategy Exchange Retrograde Anterograde Guide wire anterograde crossing Controlled With Guide Wire Anterograde dissection and re-entry Retrograde Intralumen Retrograde Dissection and re-entry Lesion length < 20 mm The use of absorbable vascular platforms for the treatment of CTO has been evaluated in a number of studies, with promising results. 35-38 However, following the long-term results of the ABSORB III study indicating an increase in the rates of very late thrombosis, its use will probably be restricted. 39 Use of intravascular imaging methods Two intravascular imaging methods are currently available for clinical use: intravascular ultrasound (IVUS) and optical coherence tomography. Optical coherence tomography requires a fluid injection (usually contrast) to be performed, which may lead to an increase of an existing dissection plane, and therefore is not usually used in CTO ICPs. The IVUS, on the other hand, can be used in a variety of procedure situations (defining the ambiguity of the proximal cap, facilitating the re-entry into the true lumen, limiting the dissection plane and confirming the distal positioning of the guidewire in the true lumen), in addition to those in which it is used in traditional PCIs. 40-43 Results and complications The hybrid approach has allowed success rates of 85-90% in the most recent studies. 23,44-47 The occurrence of in-hospital MACE ranges from 0.5 to 2.6%. 24-27 However, these procedures are still at larger risk of complications when compared to PCIs of non-CTO lesions. 48 The incidence of peri-procedural myocardial infarction (MI) is associated with factors such as retrograde technique, moderate/severe calcification, and unsuccessful procedures. 49,50 The impact of MI peri-procedure on mid- and long-term follow-up is still not well defined. 51,52 The prevalence of bifurcation lesions in CTO interventions is 33%. The lateral branches should be considered and treated as in conventional intervention procedures. 53 The occlusion of lateral branches may affect the long and short-term outcomes of CTO PCI, being more frequent when the stent is implanted on the branch and when the technique of dissection and reentry is used. 54 CTO ICPs are at higher risk of perforations than those in non-occlusive lesions. In centers of excellence, using contemporary treatment, the incidence of perforations is approximately 1-2%. 55 The management of this complication varies with the type of perforation, and the operator should be familiar with the techniques and devices necessary for the treatment. 56 The high doses of radiation required to perform increasingly complex procedures are of concern to physicians and patients. Protocols dedicated to CTO interventions, more modern equipment and the adoption by operators of attitudes that reduce exposure to ionizing radiation have allowed these procedures to be carried out with increasingly smaller radiation doses. 57,58 The decision to interrupt the procedure should be individualized, and there is no scientific evidence to support the use of specific criteria. Five parameters are usually used (radiation, contrast, complications, futility and risk/benefit ratio), but the final decision depends heavily on the judgment of the operator. Intra- and post-hospital care should be the same as any other complex PCI, taking into account the complications that occurred during the procedure and the amounts of contrast and radiation used. Clinical benefits Successful CTO recanalization is associated with a number of clinical benefits, such as improved angina, quality of life 479