BackgroundAlthough a chronic total occlusion (CTO) in the setting of an acute coronary syndrome is associated with higher risk, the prognosis of patients with stable CAD and CTOs remains unknown. ObjectivesTo investigate adverse event rates in patients with stable CAD with and without a CTO. MethodsIn 3597 patients with stable CAD (>50% coronary luminal stenosis) undergoing cardiac catheterization, all-cause mortality, cardiovascular mortality and the composite major adverse cardiac event (MACE) rates for cardiovascular death, myocardial infarction and heart failure hospitalization were evaluated. Cox proportional hazards and Fine and Gray sub-distribution hazard models were employed to compare event-free survival in patient subsets after adjustment for covariates. ResultsEvent rates were higher in patients with CTOs compared to those without CTOs after adjusting for demographic and clinical characteristics (cardiovascular death hazard ratio (HR) 1.29, 95% confidence interval (CI) 1.05 – 1.57, p = 0.012). Patients with CTO revascularization had lower event rates compared to those without CTO revascularization (cardiovascular death HR 0.43, CI 0.26 – 0.70, p = 0.001). Those with non-revascularized CTOs were at particularly high risk, when compared to those without CTO (cardiovascular death HR 1.52, CI 1.25 – 1.84 p < 0.001). Moreover, those with revascularized CTOs had similar event rates as patients with CAD without CTOs. ConclusionPatients with CTO have higher rates of adverse cardiovascular events compared to patients with significant CAD without CTO. This risk is greatest in individuals with non-revascularized CTO.