Retrograde CTO-PCI of Native Coronary Arteries Via Left Internal Mammary Artery Grafts: Insights from a Multicenter U.S. Registry

BACKGROUND: Retrograde percutaneous coronary intervention (PCI) of native coronary artery chronic total occlusion (CTO) via left internal mammary artery (LIMA) graft has received limited study. METHODS AND RESULTS: We compared the clinical and procedural characteristics and outcomes of retrograde CTO-PCI through LIMA grafts vs other conduits in a contemporary multicenter CTO registry. The LIMA was used as the collateral channel in 20 of 990 retrograde CTO-PCIs (2.02%) performed at 18 United States centers. The mean age of the study patients was 69 ± 7 years and 95% were men. The most common CTO target vessel was the right coronary artery (55%). The mean J-CTO score in the LIMA group was high (3.45 ± 0.76). The technical success rates were 70% for retrograde PCI via LIMA graft vs 81.05% for retrograde via other conduits (P≤.25), while procedural success rates were 70% for retrograde PCI via LIMA graft and 78.19% for retrograde via other conduits (P≤.41). The incidence of major in-hospital complications was also similar between the LIMA and non-LIMA retrograde groups (5% vs 6%; P>.99). Use of guide-catheter extensions (40% vs 28%; P≤.22), intravascular ultrasound (45% vs 31%; P≤.20), and left ventricular assist devices (24% vs 10%; P≤.08) was numerically higher in retrograde CTO-PCIs via LIMA grafts. CONCLUSIONS: Retrograde CTO-PCI is infrequently performed via LIMA grafts and is associated with similar success and major in-hospital complication rates as retrograde CTO-PCI performed via other conduits.