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Value of FFR-CT in Patients With Extensive Coronary Calcification
Quick Takes
- Coronary CT angiography–derived fractional flow reserve (FFR-CT) has high sensitivity but limited specificity in patients with suspected coronary artery disease and severe coronary calcification.
- Co-localizing FFR-CT measurements to the site of invasive FFR measurements improves specificity but it remains low at 52%.
- FFR-CT remains useful in patients with severe coronary calcification but can result in significant false-positive results.
Study Questions:
What are the effects of extensive coronary artery calcifications on the accuracy and prognostic value of coronary computed tomography angiography–derived fractional flow reserve (FFR-CT)?
Methods:
This prospective multicenter study evaluated 260 patients with suspected coronary artery disease and a calcium score >399 Agatston units undergoing coronary CT angiography and invasive angiography. The accuracy of FFR-CT in comparison to invasive coronary angiography with invasive fractional flow reserve (FFR) when appropriate was assessed, and the relationship between FFR-CT, revascularization, and adverse events (mortality, myocardial infarction, and unstable angina hospitalization) at 90 days was evaluated. FFR-CT was assessed both with the lowest value and with co-localization to the site of invasive FFR measurement in the subset with invasive FFR.
Results:
Median age was 68.5 years and median calcium score was 895 Agatston units. An FFR-CT ≤0.80 was observed in 78% of patients. Using the lowest FFR-CT value, per-patient sensitivity and specificity were 95% and 32% compared to invasive angiography. Co-location FFR-CT was performed in 112 patients and had per-patient sensitivity and specificity of 87% and 54% compared to invasive FFR. Revascularization was performed in 85 patients and FFR-CT was ≤0.80 in 96% of these subjects. There were adverse events in three patients (1.2%) with FFR-CT ≤0.80 and no patients with higher FFR-CT values.
Conclusions:
In patients with suspected coronary artery disease and extensive coronary artery calcification, FFR-CT had high sensitivity but low specificity to identify obstructive coronary artery disease. The specificity improved when FFR-CT was co-localized to the site of the invasive FFR measurement but remained low.
Perspective:
An important element for measurement of FFR-CT is the measurement of the luminal size and contours, which can be challenging in the setting of coronary artery calcification, as it causes blooming artifact on CT and limits visualization of the lumen adjacent to the calcification. The estimation of lumen size in these lesions is a potential source of error in measuring FFR-CT. This study finds that the sensitivity of FFR-CT remains high in patients with severe coronary calcification, but even when the FFR-CT values are co-localized to the approximate site of invasive FFR measurements, the specificity remained low at 54%. The study also observed three adverse events, all in patients with low FFR-CT values, but is underpowered to detect whether this difference is statistically significant. These findings suggest that FFR-CT can still be useful in patients with severe coronary artery calcification but may result in frequent false-positive results given the low specificity.
Clinical Topics: Cardiac Surgery, Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Nuclear Imaging
Keywords: Angina, Unstable, Chest Pain, Computed Tomography Angiography, Coronary Angiography, Coronary Artery Disease, Diagnostic Imaging, Fractional Flow Reserve, Myocardial, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Plaque, Atherosclerotic, Vascular Calcification
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