Step-by-Step Approach to the Wire-Impenetrable Chronic Total Occlusion Proximal Cap

Wire-impenetrable chronic total occlusion (CTO) proximal caps cannot be penetrated with conventional guidewire escalation. They are often associated with severe calcification and proximal cap ambiguity. Wire-impenetrable proximal caps can be approached using a "go through" or a "go around" strategy. "Go through" involves using penetrative guidewires or other plaque-modifying equipment, such as laser and electrocautery-assisted re-entry (e-CART). The "go around" approach involves getting into the extraplaque space, through which the CTO is traversed in either the antegrade or the retrograde direction, followed by re-entry into the true lumen. Strong guide-catheter support is required for both the "go through" and "go around" approaches. We discuss the approach to wire-impenetrable CTO proximal caps, propose a step-by-step treatment algorithm, and address potential challenges and their troubleshooting.