Ischemia Rates in 25-50% Stenosis: HeartFlow Data Not Available
The provided evidence does not contain specific HeartFlow data quantifying the percentage of 25-50% stenosis lesions that demonstrate ischemia by CT-FFR analysis.
What the Evidence Shows
The 2022 CAD-RADS guidelines classify 25-49% stenosis as "mild stenosis" and generally do not recommend functional ischemia testing at this severity level 1. The guidelines focus functional assessment (including CT-FFR/HeartFlow) on moderate stenosis (50-69%) and severe stenosis (≥70%) 1.
Key Clinical Context
Anatomic stenosis severity poorly predicts functional significance: The ISCHEMIA trial demonstrated that ischemia severity was not independently associated with increased mortality or MI risk after adjusting for anatomic CAD severity 2. This underscores the discordance between anatomy and physiology.
Even moderate stenoses show low ischemia rates: While not specific to 25-50% stenosis, one study found that 47% of significant angiographic stenoses occurred without evidence of ischemia on PET imaging, and 50% of normal PET studies showed some anatomic abnormality on CCTA 1. This suggests substantial anatomy-physiology mismatch even at higher stenosis grades.
FFR-guided management focuses on hemodynamically significant lesions: The FAME trial established that FFR ≤0.80 identifies functionally significant stenoses requiring intervention, with FFR-guided PCI reducing urgent revascularization compared to medical therapy alone 3. However, this study focused on lesions considered for revascularization, not mild stenoses.
Clinical Implications for 25-50% Stenosis
Patients with 25-49% stenosis should receive guideline-directed medical therapy without routine functional testing 1. The CAD-RADS system does not recommend CT-FFR or other ischemia testing for this severity range because:
- The likelihood of hemodynamically significant ischemia is very low 1
- Medical therapy alone is the appropriate management 1
- Revascularization is not indicated regardless of ischemia presence 1
When to Consider Further Evaluation
Functional testing might be considered in 25-49% stenosis only if there are high-risk plaque features, extensive plaque burden (P3-P4), or persistent limiting symptoms despite optimal medical therapy 1. Even then, the goal is risk stratification rather than revascularization planning.
Bottom Line
No HeartFlow-specific data exists in the provided evidence to answer what percentage of 25-50% stenoses are ischemic. Based on general principles, the rate would be expected to be very low (<10-15%), but this is extrapolated from broader CAD literature rather than HeartFlow registry data. The clinical relevance is limited since this stenosis severity warrants medical therapy regardless of ischemia status 1.