Retrograde CTO PCI via Epicardial Collaterals: Techniques, Tools, and Risk Mitigation.

The retrograde approach to percutaneous coronary intervention (PCI) for chronic total occlusions (CTOs) is a technically demanding strategy that requires specialized expertise and knowledge. Septal collaterals are generally considered the safest route given their intramuscular course, which can help contain blood extravasation in the event of perforation. However, when septal navigation is not feasible and no other options remain, epicardial collaterals provide a valuable alternative route to achieve successful revascularization. Although CTO PCI via epicardial collaterals is more complex and carries a higher risk of serious complications, innovations such as low-profile microcatheters and specialized low tip load guidewires have significantly enhanced both safety and technical feasibility. Consequently, retrograde CTO PCI via epicardial collaterals represents an important alternative when no other options are available and, when performed by experienced operators, allows complete revascularization even in the most challenging anatomies. Given this background, the present review provides practical guidance for interventionalists, outlining the current state of the art in terms of devices and techniques for CTO PCI via epicardial collaterals, including recommendations for complication prevention and management.