The Morphological and Mechanistic Impact of an Investment Procedure on Coronary Chronic Total Occlusions.

BACKGROUND: During chronic total occlusion (CTO) percutaneous coronary intervention (PCI), a modification procedure is often performed after failure. Although this has been reported to improve subsequent procedural success, the anatomical impact and mechanism of benefit have never been systematically studied. The Invest-CTO study investigated whether a strategy of a planned 2-stage CTO PCI with upfront "investment" and staged "completion" procedure could improve procedural success and safety in high-risk CTO anatomy. In this analysis, we provide novel insights into the morphological and mechanistic impact of an upfront "investment procedure." METHODS: This Invest-CTO substudy included the first 80 consecutive patients returning for completion of CTO PCI. Angiographic characteristics at baseline prior to investment were compared with those at the start of the completion procedures. Intravascular ultrasound was performed and analyzed after wire crossing during completion to identify changes in morphology. RESULTS: At the completion procedure, the overall median (IQR) J-CTO score decreased from 4 (3-4) to 2 (1.8-3), P < .001. The vessel was open in 28.8% (n = 23). Ambiguity of the proximal cap decreased from 77.5% to 12.5% (P < .001), and ambiguity of the vessel course decreased from 76.3% to 26.3% (P < .017). Median lesion length also decreased from 28.2 mm to 15 mm (P < .001). Three distinct modification patterns were defined by intravascular ultrasound: "intraplaque true-to-true communication" (n = 30), "extraplaque with fenestration"(n = 16), and "proximal cap modification" including hematoma resolution and healing of vessel injury (n = 34). CONCLUSIONS: Performing a planned investment procedure reduced occlusion complexity, created fenestrations or facilitated intraplaque communication and wire crossing, or modified the antegrade track, facilitating subsequent dissection reentry in high-risk CTOs.