In CTO PCI, which crossing approach is used when the antegrade approach fails?

• A. Retrograde approach via collateral channels
• B. Balloon angioplasty only
• C. Direct stenting without crossing
• D. Bypass surgery

Answer: (B)

When a CTO PCI cannot be crossed with an antegrade wire, the retrograde approach through collateral channels is used. This strategy involves advancing a wire and microcatheter from a donor vessel through septal or epicardial collaterals to reach the distal true lumen of the occlusion, then crossing the lesion from distal to proximal and potentially using techniques like CART or reverse CART to connect to the proximal lumen. This approach can unlock complex occlusions that resist antegrade wiring and improves overall success rates.

Balloon angioplasty alone isn’t a crossing strategy—you need to get a wire across the occlusion first to deliver any balloon or stent. Direct stenting without crossing isn’t feasible in a CTO, and bypass surgery is a separate revascularization option outside the PCI crossing strategies.