The impact of epicardial collateral use on the outcomes of retrograde chronic total occlusion percutaneous coronary intervention

Background: The impact of the type of collateral vessel used on the outcomes of retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study. Methods: We reviewed the baseline clinical and angiographic characteristics and procedural outcomes of 1,501 retrograde CTO PCIs performed in 1494 patients between 2012 and 2019 at 26 centres. Purpose: We sought to examine the impact of the type of collateral vessel used on the outcomes of retrograde CTO PCI. Results: Mean patient age was 65.0±10 years and 86% were men. Septal collaterals or bypass grafts were used in 66%, epicardial collaterals in 34% of lesions. Compared with cases in which only septal collaterals and bypass grafts were used, use of epicardial collaterals were associated with larger vessel diameter (3.0 [2.5; 3.0] vs. 3.0 [2.5, 3.2] mm, p=0.005), more moderate/severe tortuosity (55% vs. 42%, p\u3c0.0001), more moderate/ severe calcification (73% vs. 65%, p=0.002), and higher Japan chronic total occlusion score (3.34±1.02 vs. 3.11±1.07, p\u3c0.0001). Epicardial collateral use was associated with lower technical (76.3% vs. 80.6%, p=0.053) and procedural (71.9% vs. 77.8%, p=0.011) success rates, but similar incidence of major cardiac adverse events (4.72% vs. 4.56%, p=0.889). Epicardial collaterals were associated with more perforations (10.63% vs. 7.30%, p=0.028). Epicardial collateral use was associated with longer fluoroscopy time (82 [64, 104] 76 [(55, 102] p=0.0003) and higher contrast volume (300 [221; 414] ml vs. 270 [200; 370] ml, p\u3c0.0001). Conclusion: In a contemporary, multicenter registry epicardial collaterals were used in approximately one-third of retrograde CTO PCIs. Use of epicardial collaterals was associated with lower success but similar major complication rates