A Coronary angiogram is performed by an interventional cardiologist in a hospital cardiac catherisation laboratory (operating theatre). The test accurately determines if your coronary arteries which supply blood to the heart contain significant narrowings or blockages caused by cholesterol plaques or atheroma which may lead to heart attacks.
It is performed under local anaesthetic +/- IV sedation. During the procedure, a short plastic tube (sheath) is inserted into an artery in your wrist or groin. Different catheters (thin, flexible hollow tubes) are then guided through this insertion site over a wire into your heart and coronary arteries. X-ray dye (contrast) is injected through the catheters and X-ray videos are taken. We can see if any of your coronary arteries are narrowed or blocked. The left ventricle and valves are also examined for any abnormalities. After the sheath is removed, bleeding is stopped by a wristband, groin clamp device or manual pressure.
This is usually a day-only procedure.

Angiogram procedure | Angiogram | Eastern Heart Clinic (ehc.com.au)

The indications for coronary angiogram are abnormal stress test
or CTCA, chest pain.