What is a coronary angiogram?

What is a Coronary Angiogram?

A coronary angiogram is an invasive X-ray imaging procedure that visualizes the coronary arterial system in vivo by injecting contrast dye through catheters inserted into the coronary arteries, and it has been the gold standard for depicting coronary artery anatomy and obstructive disease since the early 1960s. 1, 2

Definition and Purpose

Coronary angiography is a catheter-based selective imaging technique that provides critical anatomic information about atherosclerotic disease, including:

• Location, length, diameter, and contour of epicardial coronary arteries 2
• Presence and severity of coronary luminal obstruction 2
• Nature of the obstruction and extent of angiographically visible collateral flow 2
• Detection and quantification of coronary artery disease 3

The procedure remains the reference standard for depicting the anatomy and severity of obstructive coronary artery disease (CAD) and other coronary abnormalities, according to the American Heart Association 2. Despite newer investigative modalities like coronary CT angiography, intravascular ultrasound, and magnetic resonance coronary angiography, conventional coronary angiography has remained the gold standard for evaluating coronary artery disease 4.

How the Procedure Works

The procedure involves:

• Insertion of catheters through peripheral vessels (typically femoral or radial artery access) 1
• Selective catheterization of coronary arteries 1
• Injection of iodinated contrast media to visualize the coronary lumen 1
• Real-time X-ray fluoroscopy to capture multiple angiographic views 5

Risks and Complications

Major Adverse Events

The American Heart Association reports that coronary angiography carries measurable risks 1:

• Major adverse events (death, myocardial infarction, or stroke): 0.2% to 0.3% within 24 hours of the procedure 1
• Minor complications (primarily vascular access site problems): 1% to 2% 1
• Overall procedural complications: 1.5% incidence, including death, stroke, myocardial infarction, bleeding, infection, and contrast allergic reactions 2
• Non-fatal events: 2% risk of myocardial infarction, stroke, and emergency bypass grafting 1
• Lesser complications: 0.5% risk of bleeding, dissection, and thrombosis at the vascular access site 1

Higher Risk Populations

The American College of Cardiology identifies specific groups at increased risk 2:

• Patients >70 years old 2
• Severe left ventricular dysfunction or CAD 2
• Severe valvular disease 2
• Renal insufficiency 2
• Diabetes mellitus 2
• Bleeding disorders 2

Additional Considerations

• Patient discomfort: The procedure causes modest discomfort due to its invasive nature 1
• Radiation exposure: Approximately 10 mSv, similar to CT and equivalent to 5 years of natural background radiation 1
• Cost: Expensive due to costly equipment and the need for highly trained physicians and support personnel 1

Limitations of Coronary Angiography

Despite being the gold standard, coronary angiography has significant shortcomings 2:

• Cannot distinguish vulnerable from stable plaque 2
• Cannot assess functional significance of stenoses 2
• May underestimate disease in diffusely diseased arteries 2
• Provides information only about the coronary arterial lumen, not the vessel wall or plaque characteristics 1

Complementary Techniques

The American Heart Association recommends adjunctive techniques to overcome angiography's limitations 2:

• Fractional flow reserve (FFR): Should be used to assess hemodynamic significance of angiographically "intermediate" or "indeterminate" lesions 2
• Intravascular ultrasound and optical coherence tomography: Provide more precise information about stenosis severity and plaque morphology than angiography alone 2

Clinical Indications

The American College of Cardiology recommends angiography for 2:

• Patients with high clinical probability of CAD 2
• Those who cannot undergo diagnostic stress testing or have indeterminate/nondiagnostic stress tests 2
• Symptomatic patients with suspected stable ischemic heart disease 2
• Patients who survived sudden cardiac death or life-threatening ventricular arrhythmia 2

Noninvasive Alternatives

The American College of Radiology and American Heart Association recommend several noninvasive alternatives 2:

• CT coronary calcium scoring: Indicates atherosclerosis presence 2
• Coronary CT angiography: Provides 3-D anatomic assessment and can evaluate plaque characteristics 2, 6
• Magnetic resonance angiography (MRA): Offers visualization without ionizing radiation or iodinated contrast media 1, 7
• Carotid duplex ultrasonography: Favored for screening moderate-risk patients due to widespread availability and low cost 2