BackgroundLesion length is related to worse clinical outcomes following percutaneous coronary intervention (PCI) for the treatment of chronic total occlusion (CTO). However, the data to confirm the association between extremely long lesions and clinical hard endpoints have been limited. Therefore, we investigated the impact of extremely long CTO lesions (≥50 mm, treated lesion length) on the long‐term clinical outcomes following successful PCI.MethodsA total of 333 consecutive patients with CTO who underwent successful PCI with drug‐eluting stents (DESs) were allocated to either the extremely long or the short CTO group according to their CTO lesion length. The 5‐year clinical outcomes were compared between the two groups. The incidence of myocardial infarction, cardiac death (CD), revascularization, and major adverse cardiovascular events (MACE) was higher in the extremely long CTO group. The 5‐year clinical outcomes were analyzed using the Cox hazard ratio (HR) model.ResultsIn the entire study population, the extremely long CTO lesion was an independent predictor for higher rate of revascularization, MACE, CD, or mortality.ConclusionsIn our study, CTO patients with extremely long lesions (≥50 mm) who underwent successful PCI were associated with a higher risk of worse long‐term clinical outcomes, including hard clinical endpoints such as CD and mortality even in the DESs era.