What is a left anterior descending (LAD) coronary artery lesion?

What is a Left Anterior Descending (LAD) Coronary Artery Lesion?

An LAD lesion is a narrowing or blockage in the left anterior descending coronary artery—one of the major vessels supplying blood to the heart muscle—caused by atherosclerotic plaque buildup, thrombosis, or other pathology that restricts blood flow to the anterior wall and septum of the left ventricle. 1

Anatomical Definition

The LAD artery originates from the left main coronary artery and travels along the interventricular groove, typically terminating near or beyond the cardiac apex. 1, 2 The vessel is anatomically divided into segments:

• Proximal LAD (LAD1): From origin to the first septal perforating branch 3
• Mid LAD (LAD2): From first septal to first diagonal branch 3
• Distal LAD (LAD3): The remaining distal vessel 3

The LAD gives off diagonal branches that supply the anterior left ventricular wall and septal perforators that supply the interventricular septum. 1

Types of LAD Lesions

By Severity of Stenosis

Lesions are graded based on the degree of luminal narrowing:

• Mild stenosis: 25-49% diameter reduction 1
• Moderate stenosis: 50-69% diameter reduction 1
• Severe stenosis: 70-99% diameter reduction 1
• Total occlusion: 100% blockage 2

By Plaque Characteristics

• Calcified plaque: Dense calcium deposits visible on imaging 1
• Non-calcified plaque: Soft plaque with lipid-rich cores 1
• High-risk plaque (HRP): Features including low attenuation (<30 Hounsfield units), positive remodeling, napkin-ring sign, or spotty calcification 1

Clinical Significance by Location

Proximal LAD Lesions (Most Critical)

Proximal LAD stenosis carries significantly worse prognosis than distal disease because it jeopardizes blood supply to the largest territory of myocardium. 4, 5, 6

• Five-year mortality with proximal LAD plus right coronary artery lesions approaches that of left main disease (34% vs 24%) 5
• Proximal LAD stenosis ≥70% predicts 82% three-year survival compared to 94% with less severe stenosis 6
• Cardiogenic shock occurs almost exclusively with proximal LAD lesions 3

Mid and Distal LAD Lesions

These lesions affect smaller myocardial territories and generally have better prognosis, though they remain clinically significant. 7, 3

Pathophysiological Consequences

Direct Myocardial Effects

LAD occlusion causes ischemia or infarction of:

• Anterior left ventricular wall 1, 2
• Interventricular septum 1
• Cardiac apex 2
• Potentially the inferior wall in "wrap-around" LAD variants 2

Ventricular Dysfunction

• Left ventricular systolic dysfunction with reduced ejection fraction 1, 2
• Septal dysfunction affecting both left and right ventricular mechanics 8
• Right ventricular failure through ventricular interdependence mechanisms 8

Clinical Presentations

Acute Presentations

• ST-elevation myocardial infarction (STEMI): ST elevation ≥1 mm in ≥2 contiguous anterior leads (V1-V4, I, aVL) 4
• De Winter pattern: Upsloping ST-depression with tall T-waves indicating proximal LAD occlusion 2
• Unstable angina/NSTEMI: ST-depression or deep T-wave inversions in precordial leads 4

Chronic Presentations

• Stable angina with exertional chest pain 3
• Heart failure from chronic ischemic cardiomyopathy 2
• Asymptomatic in some cases despite significant stenosis 3

Diagnostic Evaluation

Coronary CT Angiography (CCTA)

Modern imaging uses the CAD-RADS classification system to standardize reporting:

• CAD-RADS 0: No plaque or stenosis 1
• CAD-RADS 1-2: Non-obstructive disease (<50% stenosis) 1
• CAD-RADS 3: Moderate stenosis (50-69%) 1
• CAD-RADS 4: Severe stenosis (70-99%) 1
• CAD-RADS 5: Total occlusion 1

Functional Assessment

• Fractional Flow Reserve (FFR): FFR ≤0.80 indicates hemodynamically significant stenosis requiring revascularization 9
• Stress testing: Identifies inducible ischemia in LAD territory 4

Management Implications

Revascularization Indications

CABG is indicated for three-vessel disease or two-vessel disease with proximal LAD involvement and reduced ejection fraction (<0.50), providing survival benefit. 1

PCI or CABG is indicated for one- or two-vessel disease with proximal LAD stenosis. 1, 4

Special Considerations

• Diabetic patients with multivessel disease involving LAD benefit more from CABG than PCI 4
• Proximal LAD stenting requires careful consideration of long-term dual antiplatelet therapy 1, 9
• Multiple stent layers in LAD should prompt consideration of surgical revascularization instead 1, 9

Common Pitfalls

Do not underestimate proximal LAD lesions even when they appear moderate (50-69%) on angiography—functional assessment with FFR is critical. 9 The presence of high-risk plaque features should prompt more aggressive management even with non-obstructive stenosis. 1

Wrap-around LAD variants can produce both anterior and inferior ECG changes, potentially causing diagnostic confusion and treatment delays. 2 Always consider this anatomical variant when ECG patterns seem atypical.

Proximal LAD disease combined with right coronary artery obstruction creates a mortality risk equivalent to left main disease and demands aggressive intervention. 5