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.