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Chronic total occlusion: a challenge for percutaneous coronary intervention

I had the privilege of chairing this interesting session with my colleague Dr C.K.Y. Wong (Hong Kong). Before starting the different talks, we made a short survey among the audience that revealed that about half of the attendees were chronic total occlusion (CTO) operators. This was reassuring regarding the educative value of the session and the interest shown in this topic by specialists and non-specialists.

The first talk by Gerald Werner (Darmstadt) focused on medical management and prognosis of CTOs. The high prevalence of CTOs was highlighted, ranging from 54% in patients with secondary revascularisation after CABG to 12% in patients with acute myocardial infarction. This latter group presents three-fold mortality at 36 months compared with patients with AMI with single vessel disease, and more than two-fold in similar presentation with concomitant multivessel disease. The presence of a CTO also influences the outcome of left main coronary artery PCI. Later in his talk, Dr Werner commented on the marked contrast between these findings and current recommendations in appropriateness criteria for revascularisation that tag CTO recanalization as “unclear or inadequate”. As an expert in the field, Dr Werner made valuable comments regarding the role of collateral support in CTOs, and negated the frequent belief that collaterals confer a protective effect on occluded vessels rendering revascularisation unnecessary.  Pivotal studies comparing medical treatment and PCI in angina included very few patents with CTOs. Likewise, Dr Werner remarked that the findings of the OAT study, including patients soon after myocardial infarction, cannot be used to infer the long-term outcome of CTOs treated medically. While there are as yet no randomised trials comparing medical treatment and PCI in patients with CTOs, data obtained in large patient cohorts have shown improved survival in those in whom CTOs were successfully opened.

Dr Soo-Teik Lim (Singapore) performed a thorough and comprehensive overview of current techniques for CTO PCI. In the first place, he gave a brief outline of the importance of adequate stratification of lesion and vessel characteristics prior to intervention to choose the most adequate approach and hardware. In this regard, he highlighted some of the markers of complexity that can be assessed with multi-detector CT (MDCT) angiography: length and calcification of the CTO, and tortuosity and shrinkage of the occluded vessel. In addition to using bilateral angiography, Dr Lim recommended the use of biplane angiography, whenever available, for CTO PCI. Following the contemporary approach to CTO recanalization, the selection of the antegrade and retrograde PCI approach, as well as the most adequate hardware for each approach, was discussed. This included issues like catheter diameter, use of microcatheters or dedicated devices (channel dilator or Tornus), performance of selective tip injections to visualise collateral paths, guidewire choice and handling techniques, mother-and-child catheter techniques, balloon anchoring, etc. Dr Lim finally made an excellent historical perspective on the sequential introduction of these techniques and developments, showing how some important developments have been superseded by newer approaches.

Dr George Sianos (Thessaloniki) addressed the potential complications of CTO PCI, as well as the long-term outcome. Overall, the complication rate in contemporary major reported CTO PCI series ranges from 1.9 to 5.3 %. Dissection of the occluded vessel is, in the view of Dr Siano, an inherent part of the procedure and, therefore, should probably not be considered a complication of CTO PCI in most cases. However, he warned about potential causes of dissection of the distal non-occluded segments of the vessel due to use of stiff guidewires used for crossing the CTO or by barotrauma caused by engaged guiding catheters without side holes. On the contrary, he highlighted the risk of vessel perforation during PCI, in most cases (88%) is caused by the guidewire. After discussing the classification of coronary perforations, the prevention and management of perforation was discussed.

A similar approach was followed to discuss aortic dissection, derived mainly from the use of guiding catheter trauma, barotrauma in wedged catheters, balloon rupture in ostial lesions, or retrograde progression (particularly in the RCA). In addition to covering the entry point with a conventional or covered stent, Dr Sianos emphasised the importance of close follow-up (including imaging screening) over the next hours after PCI to detect progression of the aortic dissection.

Contrast induced nephropathy (CIN) and radiation injury are two serious complications of PCI, facilitated in CTO patients by the complexity and length of the procedure. Adequate preparation of the patient, proper technique (use of multiple projections, collimation, etc) awareness of the risk (monitoring amount of contrast and radiation dose given), and use of IVUS contributes to reduce both complications. Finally, Dr Sianos stressed the paucity of data regarding long-term outcome after CTO PCI. In this context, his view was positive and pointed to a similar long-term outcome as in non-CTO PCI. To illustrate that with data presented during this 2012 ESC congress, he showed data presented by Del Angel et al with longitudinal optical coherence tomography follow-up in CTOs stented with DES in which the degree of stent coverage, long-term malapposition and volume of neointimal hyperplasia was found to be similar to a non-CTO group included in the study.

Dr Masahisa Yamane (Saitama) closed the session with his presentation of new technologies and future developments. In a comprehensive perspective, he analysed technological (PCI hardware, angiography and IVUS equipment, MDCT), pharmacological (DAPT) and technical (antegrade/retrograde approach, wire techniques, etc) developments in the field. Among the unsolved problems, Dr Yamane focused his talk on current solutions for vessel re-entry during CTO PCI. The audience had the privilege to attend an outstanding presentation on how angiography and IVUS images obtained during PCI can be combined to establish a connection between the false and true coronary lumen in cases of subintimal guidewire location, illustrated with cases from Dr Yamane’s experience that had been thoroughly prepared for teaching purposes.

In summary, a great ESC congress session on CTO recanalization with extremely useful teaching messages for both experts and non-experts in the field, with a very active participation of the audience.




Chronic total occlusion: a challenge for percutaneous coronary intervention

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.