The aim of the study is to investigate the non-inferiority of the new sirolimus-coated balloon catheters in comparison to the paclitaxel-coated SQP with regard to acute tolerance, safety and efficacy in coronary DES in-stent restenosis.

The aim of the study is to investigate the non-inferiority of the new sirolimus-coated balloon catheters in comparison to the paclitaxel-coated SQP with regard to acute tolerance, safety and efficacy in coronary DES in-stent restenosis.

Patient population will consist of male and female adults suffering from coronary drug-eluting stent (DES) restenosis, which is to be treated by a study balloon according to the inclusion and exclusion criteria as defined below.

In Late lumen loss lesion (difference between the angiographic in-lesion MLD post procedural and at 6 months follow-up) will be evaluated by quantitative coronary angiography (QCA).

The study will be performed as a single-blind, SQP controlled study in 4 - 6 study centers in 50 patients.

Inclusion Criteria:

• 18 years of age
• Clinical evidence of stable or unstable angina (acute coronary syndrome) or a positive functional study
• Patients with ≤ 2 primary drug-eluting stent in-stent restenosis (DES-ISR) lesions (≥ 70% diameter stenosis by visual estimation or ≥ 50% and positive functional study) including margin stenosis with max 5mm distance to the stent.

Exclusion Criteria:

• Chronic renal insufficiency with serum creatinine levels > 2.0 mg per deciliter
• Known hypersensitivity or contraindications to aspirin, heparin, clopidogrel, ticlopidine or sirolimus, and sensitivity to contrast media not amenable to premedication
• Concomitant medical illness associated with a life-expectancy of less than two year
• Lesion length (ISR) > 35 mm, vessel diameter < 2.5 mm