Impact of proximal cap ambiguity on the procedural techniques and outcomes of chronic total occlusion percutaneous coronary intervention: Insights from the PROGRESS-CTO Registry

BackgroundProximal cap ambiguity is a key parameter in the global chronic total occlusion (CTO) percutaneous coronary intervention (PCI) crossing algorithm. MethodsWe examined the baseline characteristics and procedural outcomes of 9718 CTO PCIs performed in 9498 patients at 41 US and non-US centers between 2012 and 2022. ResultsProximal cap ambiguity was present in 35% of CTO lesions. Patients whose lesions had proximal cap ambiguity were more likely to have had prior coronary artery bypass graft surgery (37% vs. 24%; p < 0.001). Lesions with proximal cap ambiguity were more complex with higher J-CTO score (3.1 +/- 1.0 vs. 2.0 +/- 1.2; p < 0.001) and lower technical (79% vs. 90%; p < 0.001) and procedural (77% vs. 89%; p < 0.001) success rates compared with nonambiguous CTO lesions. The incidence of major adverse cardiovascular events (MACE) was higher in cases with proximal cap ambiguity (2.5% vs. 1.7%; p < 0.001). The retrograde approach was more commonly used among cases with ambiguous proximal cap (50% vs. 21%; p < 0.001) and was more likely to be the final successful crossing strategy (29% vs. 13%; p < 0.001). The antegrade dissection and re-entry (ADR) "move-the-cap" techniques were also more common among cases with proximal cap ambiguity. ConclusionsProximal cap ambiguity in CTO lesions is associated with higher utilization of the retrograde approach and ADR, lower technical and procedural success rates, and higher incidence of in-hospital MACE.