"Crossing the invisible".

Key Points Using the septal collaterals without angiographic connection during retrograde CTO PCI was associated with high collateral channel crossing rate (>80%). Two predicators for channel crossing failure were shorter posterior descending artery (less than 2/3 of the distance to cardiac apex) and well developed non‐septal collateral. Further studies focusing on retrograde channel selection could improve the success rate and safety of retrograde CTO PCI.