Intravascular Ultrasound in Percutaneous Coronary Intervention for Chronic Total Occlusion

Background: Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is one of the most challenging procedures in interventional cardiology. New techniques and devices have made possible to face these complex procedures. Intravascular ultrasound (IVUS) reveals special features and contributes greatly to procedural success.Method: We analysed retrospectively IVUS contribution and findings in 23 cases of a total 46 CTOs PCI from February 2009 to August 2010 in our cath lab. Both true and functional CTO were included in this study. The procedure was considered successful when a TIMI III flow was reached in the occluded vessel after stent implantation with a residual stenosis less than 30%. IVUS features and contribution in CTO-PCI were analysed. All data were introduced in SPSS version 15 (SPSS Inc. Chicago, Illinois, USA). Continuous variables were described by mean ± SD and categorical variables were expressed as percentage. A P<0.05 was considered statistically significant.Results: 46 PCIs in 34 patients were performed during 19 months in our centre. The procedure was successful in 28 cases (60.9%).. IVUS was performed in 23 (82.1%) of successful procedures. IVUS revealed calcium somewhere in 17 (73.9%). Despite wire angiographic verification in true lumen distally IVUS showed subintimal wire position in part of CTO segment in 6(26.1%). In 22(95.7%) of cases IVUS allowed both the wire position verification in true lumen and the vessel measurement before stent implantation. In 1(4.3%) case a second wire was introduced into true lumen guided by IVUS after realising that the first wire was in false lumen. We could not find significant relation between calcium presence and subintimal wire penetration in CTO segment (p: 0.14) Conclusions: IVUS showed calcium in CTO segment in a high percentage of cases. It is not unusual to find wire penetration in subintimal space in part of CTO segment. IVUS has a key contribution in the step by step interpretation during PCIs of CTO. Wire position verification and more precise vessel measurement can be easily done by IVUS.