Impact of Hypertension and Diabetes on CT-FFR in CTCA
Neither hypertension nor diabetes cause false negative results in CT-FFR of CTCA, as the diagnostic accuracy of CT-FFR remains high in both patient populations. 1
Understanding CT-FFR and Its Clinical Application
CT-FFR (Computed Tomography-Fractional Flow Reserve) is a non-invasive technique that simulates invasively measured FFR based on CT data to evaluate the hemodynamic significance of coronary artery stenosis. According to the Society of Cardiovascular Computed Tomography (SCCT) guidelines, CT-FFR is particularly useful for assessing coronary stenosis ranging from 50% to 90% to determine hemodynamic significance 2.
The interpretation of CT-FFR follows these thresholds:
- ≤0.75: Abnormal (I+) - indicates hemodynamically significant stenosis
- 0.76-0.80: Borderline (I+/−) - gray zone requiring clinical correlation
0.80: Normal (I-) - indicates non-hemodynamically significant stenosis 2
Diagnostic Performance in Diabetes and Hypertension
Diabetes Mellitus
Multiple studies have specifically examined the impact of diabetes on CT-FFR accuracy:
A 2022 multicenter study involving 484 patients demonstrated that machine learning-based CT-FFR maintained high diagnostic accuracy in diabetic patients compared to non-diabetic patients:
- Sensitivity: 0.79 vs. 0.82
- Specificity: 0.96 vs. 0.93
- Accuracy: 0.87 vs. 0.89
- AUC: 0.91 vs. 0.89 1
The MACHINE consortium study similarly found that the overall diagnostic accuracy of CT-FFR in diabetic patients was 83% compared to 75% in non-diabetic patients (p = 0.088), showing no statistically significant difference 3.
Hypertension
While specific data on hypertension alone is more limited, the ADVANCE registry showed that patients with hypertension had an increased likelihood of abnormal CT-FFR (OR 1.56,95%CI 1.14-2.14, p = 0.005) 4. However, this reflects the higher prevalence of functionally significant coronary disease in hypertensive patients rather than reduced diagnostic accuracy of the test itself.
Important Clinical Considerations
Microvascular Dysfunction
A potential pitfall to consider is microvascular dysfunction, which can occur in both diabetic and hypertensive patients. A study examining chronic total coronary occlusions found that microvascular dysfunction was observed more often in patients with diabetes and hypertension 5. However, this affects coronary flow reserve measurements rather than CT-FFR specifically, as CT-FFR primarily assesses the epicardial component of coronary resistance.
Interpretation in Clinical Context
When interpreting CT-FFR results:
- For values ≤0.75 (I+): Consider invasive coronary angiography for individuals likely to benefit from revascularization
- For values >0.80 (I-): Consider deferring invasive angiography and optimize medical therapy
- For values 0.76-0.80 (I+/−): Consider invasive angiography based on:
- Symptom severity
- Lesion location
- Trans-lesional pressure loss 2
Integration with Other Diagnostic Information
The 2024 ESC guidelines for chronic coronary syndromes recommend that in patients with a known intermediate coronary artery stenosis in a proximal or mid coronary segment on CCTA, CT-based FFR may be considered (Class IIb, Level B) 2.
Conclusion
CT-FFR maintains its diagnostic accuracy in both diabetic and hypertensive patients. While these conditions are associated with a higher prevalence of coronary artery disease and microvascular dysfunction, they do not compromise the ability of CT-FFR to accurately identify hemodynamically significant epicardial coronary stenosis.
When evaluating patients with diabetes or hypertension using CT-FFR, clinicians should interpret results in the context of the patient's overall clinical presentation and risk factor profile, recognizing that these conditions may increase the likelihood of finding abnormal CT-FFR values due to higher disease prevalence rather than affecting test accuracy.