Table 4.

Variables associated with CTO-PCI failure in multivariate logistic regression model derived from derivation subset. Four independent predictors were identified by the forward and backward method: chronic total occlusion length ≥ 20 mm, blunt stump, bending > 45° and accumulative experience < 100 cases (n = 360). E-CTO score was derived from variables remaining in the multivariate model giving one point to each variable as the magnitude of beta coefficients was close to unit.

Predictors	Odds ratio (95% CI)	Beta coefficient	P	E-CTO score
Length	2.06 (1.13–3.7)	0.723	0.018	1
Stump	3.69 (2.0–6.69)	1.3	< 0.001	1
Tortuosity	2.67 (1.47–4.8)	0.98	0.001	1
CN	3.20 (1.61–6.3)	1.16	0.001	1

CI — confidence interval; CN — case number; E-CTO score classification: 0 = easy; 1 = intermediate; 2 = difficult; ≥ 3 = very difficult