Incidence, Predictors, and Strategies for Failure of Retrograde Microcatheter Tracking After Successful Wiring of Septal Collateral Channels in Chronic Total Occlusions

BACKGROUND: Retrograde microcatheter collateral channel (CC) tracking after successful wiring of septal CC is crucial for retrograde revascularization of coronary chronic total occlusion (CTO). However, the incidence, predictors, and strategies for failure of retrograde microcatheter CC tracking after successful wiring of septal CC remain unclear. METHODS: In total, 298 patients with CTO who underwent retrograde septal CC PCI between January 2015 and May 2019 were retrospectively analyzed. Clinical data were compared to investigate the predictors of initial microcatheter tracking failure. RESULTS: The initial and final microcatheter tracking success rates were 79.2% (236/298) and 96.6% (288/298), respectively. The procedural success rate was 94.0% (280/298). The right coronary artery-to-left anterior descending artery septal ratio (48.4% vs 33.1%, p=0.037) and CC tortuosity (34.6% vs 20.8%, p=0.045) were significantly higher in the initial microcatheter CC tracking failure group than in the successful tracking group. Multivariate logistic regression analysis revealed that severe collateral tortuosity (odds ratio [OR]: 13.241, 95% confidence interval [CI]: 3.429–27.057, p=0.038), CC entry angle of <90° (OR:4.921, 95% CI: 1.128–9.997, p=0.002), CC exit angle of <90° (OR:5.037, 95% CI: 2.237–11.182, p=0.004), use of Finecross MG as initial microcatheter (OR:1.826, 95% CI: 1.127–3.067, p=0.035), and shunning initial retrograde application of Guidezilla (OR:0.321, 95% CI: 0.267–0.915, p=0.024) were variables independently associated with initial microcatheter CC tracking failure in patients with CTO undergoing retrograde septal CC PCI. CONCLUSION: The overall initial microcatheter CC tracking failure was 20.8%. Severecollateral tortuosity, CC entry, and exit angle of <90°, use of Finecross MG as initial microcatheter, and shunning initial retrograde application of Guidezilla were variables independently associated with initial microcatheter CC tracking failure in patients with CTO undergoing retrograde septal PCI.