Treatment of Coronary In-stent Restenosis (ISR) by a Sirolimus Coated or a Paclitaxel Coated Balloon

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 in-stent restenosis (ISR) lesions (≥ 70% diameter stenosis by visual estimation or ≥50% and positive functional study) including margin-stenosis with max 5 mm 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, reference vessel diameter \< 2.5 mm