Patient cohort is comprised of all patients who received drug coated balloon angioplasty at NNUH during the above period. Within this cohort there will be two main groups which are drug coated balloon (DCB) angioplasty for de novo coronary artery disease (CAD) and DCB angioplasty for ISR/ST. Graft cases will be reported as a small third group.

Outcomes will also be reported for three sub groups of de novo disease group, namely, dcb-only angioplasty for de novo disease, dcb-only angioplasty as primary percutaneous coronary intervention (PPCI) and dcb-only angioplasty group using a DCB with a diameter of 3mm or more in de novo disease.

Drug coated balloons are semi compliant percutaneous coronary angioplasty balloons coated with a chemotherapeutic drug such as Paclitaxel used with an excipient which allows rapid absorption to vessel wall upon balloon expansion for 30-60s. This allows coronary angioplasty without any permanent or semi- permanent stent or scaffold provided there are no vessel threatening dissections or significant acute recoil.

Death. All cause death will be defined as death due to any cause.

. Target vessel revascularisation (TVR) A TVR is defined as any repeat percutaneous intervention or surgical bypass of any segment of the target vessel. The latter is defined as the entire major coronary vessel proximal and distal to the target lesion, including upstream and downstream branches and the target lesion itself.

An MI is defined as an episode of chest pain with positive cardiac enzyme troponin as per MINAP definition (a hospital diagnosis reported as a troponin positive MI).

A TVR is defined as any repeat percutaneous intervention or surgical bypass of any segment of the target vessel. The latter is defined as the entire major coronary vessel proximal and distal to the target lesion, including upstream and downstream branches and the target lesion itself.

Acute Vessel Closure Acute vessel closure is defined as an event where a patient had to be taken back to cardiac catheterisation lab and require repeat angioplasty (during the same hospital stay) for a complete or partial occlusion of the artery due to a dissection.

TLR A TLR is defined as any repeat percutaneous intervention of the target lesion or bypass surgery of the target vessel performed for restenosis or other complication of the target lesion. The target lesion is defined as the treated segment from 5 mm proximal and 5 mm distal to the treated lesion (by visual assessment).