BACKGROUND: The effectiveness and safety of traditional versus dual lumen microcatheter (DLMC)-assisted parallel wiring in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study. AIMS: To compare traditional versus dual lumen microcatheter (DLMC)-assisted parallel wiring. METHODS: We compared the clinical and angiographic characteristics and outcomes of traditional versus DLMC-assisted parallel wiring after failed antegrade wiring (AW) in a large, multicenter CTO PCI registry. RESULTS: Among 1353 CTO PCIs with failed AW with a single wire, traditional parallel wiring (n = 1081) or DLMC-assisted parallel wiring (n = 272) were utilized at the operator's discretion. The baseline characteristics of patients were similar in both groups except for higher prevalence of diabetes mellitus, and lower prevalence of hypertension, prior heart failure, prior MI and cerebrovascular disease in DLMC patients. Lesions in the DLMC group were more likely to have proximal cap ambiguity, side branch at the proximal cap, blunt/no stump, moderate/severe calcification, and had higher J-CTO score (2.6 ± 1.0 vs. 2.1 ± 1.3, p <
0.001). Technical (87.1% vs. 74.3%, p <
0.001) and procedural (83.8% vs. 75.5%, p = 0.001) success and the incidence of in-hospital major cardiac adverse events (MACE) (4.8% vs. 2.0%, p = 0.020) were higher in the DLMC group. In propensity score matching analysis, DLMC-assisted wiring was associated with higher technical success (odds ratio [OR] 2.17, 95% confidence interval [CI] 1.33-3.54, p = 0.002) and no significant difference in MACE (OR 2.00, 95% CI 0.89-4.50, p = 0.093). CONCLUSIONS: In lesions that could not be crossed with AW, DLMC-assisted parallel wiring was associated with a higher likelihood of technical success, without an increased risk of MACE, compared with traditional parallel wiring.