Stenosis grading (CAD-RADS 0–5)

How CT grades stenosis severity — and why it reports ranges, not exact percentages.

The Coronary Artery Disease Reporting and Data System (CAD-RADS) standardizes the grading of stenosis severity based on the highest-grade lesion found in the coronary tree. Because CT has inherent limits in precision, grading is reported in ranges rather than exact percentages.

CatSeverityStenosisRecommendation

0 No plaque 0% Routine care

1 Minimal 1–24% FRS · preventive

2 Mild 25–49% Preventive · consider statin

3 Moderate 50–69% Functional / CT-FFR

4 Severe 70–99% ICA · revascularization eval

5 Occlusion 100% ICA · MDT review

A few category-level details worth knowing:

4 — Severe (probable flow-limiting)

4A — 70–99% stenosis in a single vessel or two vessels.
4B — > 50% in the left main, or 3-vessel obstructive disease (≥ 70%).

5 — Total occlusion

Subdivided into subtotal vs chronic total occlusion (CTO). A CTO is generally defined by > 3 months of symptoms or a lesion > 10 mm in length on CTA.

For the full system including modifiers (S / G / V / N) and management pathways, see CAD-RADS 2.0 reporting. For functional adjudication of moderate (50–69%) lesions, see CT-FFR.