This prospective, multicenter, post-market observational study aims to evaluate the safety and effectiveness of the crystalline sirolimus-coated balloon (SeQuent® Sirolimus-Coated Balloon) for the treatment of coronary artery disease in routine clinical practice. Consecutive, unselected adult patients undergoing percutaneous coronary intervention for de novo coronary lesions or in-stent restenosis will be enrolled.

The primary objective is to assess target lesion failure at 12 months, defined as the composite of target vessel myocardial infarction or ischemia-driven target lesion revascularization. Secondary objectives include angiographic procedural success, major adverse cardiovascular events, bleeding outcomes, and longer-term clinical results up to 36 months, as well as outcomes across predefined anatomical and clinical subgroups.

The study seeks to answer whether treatment with the crystalline sirolimus-coated balloon provides a safe and effective revascularization strategy in a real-world population with diverse clinical presentations and lesion characteristics.

Inclusion Criteria:

• All patients must provide written informed consent.
• Patients aged ≥18 years with coronary artery disease in whom, at the operator's discretion, treatment of a coronary stenosis in a native vessel (either de novo lesion or in-stent restenosis) or in a coronary bypass graft using the cSCB is indicated, in accordance with routine clinical practice.
• All treated lesions/segments (single or tandem) must receive cSCB therapy covering at least 3 mm beyond both edges of the lesion or pre-dilated segment to avoid geographic miss.
• In patients with multivessel coronary artery disease, all non-target vessels will be treated according to operator discretion: a) If more than one vessel is treated with the investigational device (SeQuent® SCB), all vessels will be documented and analyzed separately. b) Only one lesion per vessel will be included unless lesions are separated by ≥20 mm. c) Only one lesion per vessel will be included. d) If more than one lesion in the target vessel requires treatment, all lesions treated with a device different from the investigational procedure or with a device other than the investigational device (SeQuent® SCB) must be separated from the target lesion by ≥20 mm or considered as a single treated lesion according to this study protocol.

Exclusion Criteria:

• Explicit refusal by the patient to participate in the study.
• Known intolerance to sirolimus or to any component of the investigational device.
• Contraindication to any antiplatelet therapy.
• Life expectancy less than 12 months.
• Indication for surgical coronary revascularization.
• Pregnancy or breastfeeding.
• Clinical characteristics considered unsuitable for drug-coated balloon use at the operator's discretion, including: a) Hemorrhagic diathesis or other conditions such as gastrointestinal ulceration or cerebrovascular disorders restricting the use of antiplatelet therapy. b) Cardiogenic shock. c) Patients with left ventricular ejection fraction <30% without the use of a ventricular assist device during PCI.

Angiographic exclusion criteria

• Reference vessel diameter <2.00 mm or >4.0 mm.
• Treatment of the left main coronary artery.
• Lesions not amenable to PCI or other interventional techniques.
• Coronary artery spasm in the absence of significant stenosis.
• Target lesion not suitable for drug-coated balloon-only PCI at the operator's discretion, including: a) Aorto-ostial lesions. b) Lesions with significant persistent residual thrombotic content visible in the vessel despite thromboaspiration. c) Treatment shortly after myocardial infarction with evidence of thrombus or impaired coronary flow.

Adult patients (≥18 years) with coronary artery disease undergoing percutaneous coronary intervention in routine clinical practice, in whom treatment of a coronary stenosis in a native vessel (de novo lesion or in-stent restenosis) or in a coronary bypass graft with the SeQuent® Sirolimus-Coated Balloon is selected at the operator's discretion. Consecutive, unselected "real-world" patients will be enrolled across participating centers, including a broad range of clinical presentations and anatomical lesion substrates, provided they meet the study eligibility criteria and provide written informed consent.

Individual participant data sharing has not been planned. Data access is restricted due to confidentiality agreements, ethical approvals, and data protection regulations. Any future data sharing would require additional approvals and appropriate data anonymization.