Is angiography used to diagnose atherosclerosis?

Is Angiography Used to Determine Atherosclerosis?

Yes, coronary angiography is used to determine atherosclerosis and remains the gold standard for visualizing coronary artery disease, though it has important limitations in assessing plaque characteristics and functional significance. 1

Role of Angiography in Atherosclerosis Assessment

Primary Diagnostic Capabilities

Coronary angiography provides critical anatomic information about atherosclerotic disease, including: 1

• Location, length, diameter, and contour of epicardial coronary arteries 1
• Presence and severity of coronary luminal obstruction (typically defined as ≥70% diameter reduction for significant stenosis, or ≥50% for left main disease) 1
• Nature of the obstruction and extent of angiographically visible collateral flow 1
• Coronary blood flow patterns 1

Catheter-based selective coronary angiography is considered the reference standard for depicting the anatomy and severity of obstructive CAD and other coronary abnormalities including congenital variants, coronary spasm, dissection, and vasculitis. 1

When Angiography Is Indicated for Atherosclerosis

The ACC/AHA guidelines provide clear indications: 1

• High clinical probability of CAD with clinical characteristics and noninvasive test results indicating high likelihood of severe disease 1
• Patients who cannot undergo diagnostic stress testing or have indeterminate/nondiagnostic stress tests when findings will result in important therapy changes 1
• Symptomatic patients with suspected stable ischemic heart disease whose quality of life remains unsatisfactory despite evidence-based medical therapy 1
• Patients who survived sudden cardiac death or life-threatening ventricular arrhythmia 1

Critical Limitations of Angiography

What Angiography Cannot Assess

Despite being the "gold standard," angiography has significant shortcomings that clinicians must recognize: 1

• Cannot distinguish vulnerable from stable plaque - does not identify plaques with large lipid cores, thin fibrous caps, or increased macrophages 1, 2
• Cannot assess functional significance - many stenoses appearing severe (≥70% narrowing) are not hemodynamically significant, while some "insignificant" lesions (<70%) actually restrict flow 1
• Underestimates disease in diffusely diseased arteries - requires comparison to adjacent "normal" reference segments, which may not exist 1
• Significant interobserver variability - only 70% overall agreement among readers regarding stenosis severity, reduced to 51% when restricted to vessels with any stenosis 1
• Provides only 2-D projection images rather than 3-D volumes 1

The Vulnerable Plaque Problem

Serial angiographic studies demonstrate that plaques causing acute events (unstable angina, myocardial infarction) were commonly <50% obstructive before the acute event and therefore angiographically "silent." 1 This is a critical limitation because the microscopic characteristics that make plaques dangerous—thin fibrous caps (~70 µm thick), lipid-rich necrotic cores, and intense macrophage infiltration—cannot be visualized by standard angiography. 2

Complementary Techniques to Overcome Limitations

Functional Assessment

Fractional flow reserve (FFR) should be used to assess hemodynamic significance of angiographically "intermediate" or "indeterminate" lesions, allowing clinicians to decide when PCI may be beneficial or safely deferred. 1 Studies suggest FFR-guided PCI strategy may be superior to angiography-guided strategy alone. 1

Advanced Imaging Adjuncts

• Intravascular ultrasound and optical coherence tomography provide more precise information about stenosis severity and plaque morphology than angiography alone and can be useful adjunctive tests in certain cases 1

Risk-Benefit Considerations

Procedural Complications

Angiography carries a 1.5% incidence of procedural complications according to the ACC's National Cardiovascular Data Registry. 1 Specific risks include: 1

• Death, stroke, myocardial infarction
• Bleeding, infection, contrast allergic reactions
• Vascular damage, contrast-induced nephropathy
• Arrhythmias, need for emergency revascularization

Higher risk groups include: patients >70 years old, those with severe left ventricular dysfunction or CAD, severe valvular disease, renal insufficiency, diabetes mellitus, or bleeding disorders. 1

Alternative Noninvasive Approaches

For screening and initial assessment of atherosclerosis: 1

• CT coronary calcium scoring indicates atherosclerosis presence (zero score has high negative predictive value for excluding obstructive CAD) 1
• Coronary CT angiography provides 3-D anatomic assessment and can evaluate plaque characteristics 1
• Carotid duplex ultrasonography is favored for screening moderate-risk patients due to widespread availability and low cost 1
• MR angiography can evaluate both cervical and intracranial portions of arteries 1, 3

Clinical Decision Algorithm

For suspected atherosclerosis, begin with noninvasive testing (stress testing, CT calcium scoring, or CTA) unless: 1

1. Patient has high clinical probability of severe disease requiring revascularization
2. Noninvasive testing is contraindicated, indeterminate, or nondiagnostic
3. Patient has survived sudden cardiac death or life-threatening arrhythmia
4. Symptoms persist despite optimal medical therapy

Do not perform angiography in asymptomatic patients with no evidence of ischemia on noninvasive testing. 1