Pooled Cohort Equations Place the Patient in an Intermediate Zone
Traditional risk factors alone leave many patients in an ambiguous middle category.
- 7.5–20%: PCE risk band (Intermediate 10-yr ASCVD risk)
- Uncertain: Guideline role (Statin decision not clear-cut)
- CAC scan: Next step (Class IIa recommendation)
- ~30%: Population share (Adults fall in this band)
Why intermediate risk needs more data
Risk calculators alone cannot decide statin therapy for everyone.
Non-Contrast Gated CT Captures the Coronary Tree
A quick, low-dose scan images calcium deposits along the arteries.
- ~1 mSv: Radiation dose (Low-dose gated protocol)
- <10 sec: Scan time (Single breath-hold)
- None: Contrast used (Non-contrast acquisition)
- 3 mm: Slice thickness (Standard CAC protocol)
Imaging protocol basics
ECG-gated slices freeze cardiac motion during the sweep.
Density-Weighted Plaque Area Yields the Agatston Score
Each calcified focus is scored by area and peak density.
- Area × density: Formula basis (Weighted factor 1–4)
- ≥130 HU: Threshold (Pixel calcium cutoff)
- 0–1000+: Score range (Agatston units)
- ~5 min: Reader time (Semi-automated software)
Scoring calcified lesions
Software sums weighted area across all detected plaques.
Zero Calcium Supports Stepping the Risk Category Down
A CAC of zero often means statins can be safely deferred.
- ~50%: CAC=0 prevalence (Of intermediate-risk adults)
- ~5 years: Warranty period (Low event rate window)
- Reasonable: Statin deferral (Per guideline consensus)
- High: NPV (Very low near-term events)
The power of a negative scan
Absence of calcium reclassifies many patients to low risk.
High CAC Reclassifies the Patient Upward to High Risk
A high score triggers earlier, more intensive statin therapy.
- ≥300: High CAC cutoff (Agatston units)
- ≥75th: Percentile flag (Age/sex adjusted)
- High: Statin intensity (Guideline-directed escalation)
- ↑ 2–3×: Event risk (Vs. baseline PCE estimate)
Acting on a high score
High CAC prompts high-intensity statins and closer follow-up.
CAC scoring reclassifies roughly one in three intermediate-risk patients.