The 001 DIOR study is a prospective, multicenter registry of percutaneous coronary intervention (PCI) to assess the clinical success, efficacy and safety of the Paclitaxel-eluting balloon DIOR (Eurocor GmbH, Germany) for the treatment of de novo ostial bifurcated lesions (001 of Medina classification). The DIOR balloon will be used to treat the stenotic site branch.

Inclusion Criteria:

• De novo bifurcated lesions 001 of Medina classification, with significant stenosis only in the ostium of the side branch and a reference vessel diameter is bigger or equal 2.0mm; the DIOR balloon will be used to the treat the side branch.
• The patient has clinical evidence of myocardial ischemia (stable or unstable angina, acute and non acute myocardial infarction, silent ischemia: ECG, exercise test, etz...)
• As the maximal length of the DIORTM balloon is 30 mm, all eligible lesions should be no longer than 25 mm to ensure an adequate drug elution in the treated segment, avoiding the phenomenon of "geographical miss" .
• Target lesion(s) stenosis is more or equal 50% by visual estimation.

Exclusion Criteria:

• Cardiogenic shock
• Any serious disease that might limit patient survival to less than one year
• Inability to perform clinical follow-up for a period of 1 year
• Left main bifurcation lesions: ostial left circumflex or ostial left anterior descending artery stenosis.
• Lesion length > 25 mm
• Target vessel reference diameter < 2mm
• Stenosis < 50% of the reference luminal diameter
• Severe angiographic calcification at the level of the target lesion