What Does a Coronary Angiogram Reveal?

Coronary angiography is a diagnostic imaging procedure used to visualize the coronary arteries—the blood vessels that supply oxygen-rich blood to the heart muscle. During the test, a thin, flexible catheter is inserted—typically through the radial artery in the wrist or the femoral artery in the groin—and carefully advanced to the opening of the coronary arteries. A contrast dye is then injected through the catheter, and real-time X-ray imaging (fluoroscopy) captures detailed images of blood flow through the coronary vessels.

The primary purpose of coronary angiography is to detect and assess the presence, location, severity, and morphology of coronary artery stenosis or occlusion—such as narrowing caused by atherosclerotic plaque buildup. It also identifies other structural abnormalities, including coronary artery anomalies, aneurysms, dissections, or fistulas. In addition, the procedure provides critical functional information: it enables evaluation of myocardial perfusion, collateral circulation, and left ventricular systolic function when combined with left ventriculography.

This invasive test remains the clinical gold standard for definitive diagnosis of obstructive coronary artery disease and is routinely performed prior to revascularization procedures—including percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). While noninvasive alternatives like coronary computed tomography angiography (CCTA) and stress testing are valuable for initial risk stratification, coronary angiography offers unparalleled spatial resolution and hemodynamic insight, making it indispensable in guiding therapeutic decision-making for patients with suspected or known ischemic heart disease.