When to Use Lp(a) & CAC in 1° Prevention: When Risk Is Unclear (Gray Zone)
When to Use Lp(a) & CAC in 1° Prevention: When Risk Is Unclear (Gray Zone)
Source: TCTMD
Date: March 19, 2026
When to Use CAC
• Primary prevention
• Intermediate or uncertain risk (gray zone)
• Elevated Lp(a) with unclear treatment decision
Key Findings (JACC, 2026)
• Lp(a) and CAC independently predict 15-year ASCVD risk
• Highest risk:
• Lp(a) >50 mg/dL + CAC >0 → HR ~3.0
Important Insight
• CAC = 0 → low absolute risk, even with high Lp(a); risk is slightly higher than with low Lp(a), but remains overall low.
Risk Interpretation
• Lp(a) done once in lifetime → genetic predisposition
• CAC → actual atherosclerotic burden
→ Complementary tools
Clinical Approach
(in Gray Zone)
• Start with baseline risk clinically or :
• Use 10-year risk (PREVENT / PCE)
• Classify: low / intermediate / high
• Check risk enhancers( Comorbidities):
• Elevated Lp(a)
• chronic inflammation ; hs-CRP ≥2 mg/L
• CKD (eGFR <60)
• Family history of premature ASCVD
• Metabolic syndrome
• If ≥1 enhancer AND decision remains unclear:
👉 Proceed to CAC
CAC-Guided Decision
• CAC = 0 → low short-term risk
→ consider deferring statin (selected patients)
• CAC >0 → subclinical atherosclerosis
→ initiate statin
• CAC ≥100 → high risk
→ start primary prevention or intensify therapy
Guideline Context
• Lp(a) measurement:
• Class I recommendation (once in a lifetime)
Bottom Line
• CAC clarifies risk in the gray zone
• Focus on absolute risk and plaque burden