Diagnostic and Clinical Value of FFR In Stable Chest Pain Patients With Extensive Coronary Calcification: The FACC Study

Background: The influence of extensive coronary calcifications on the diagnostic and prognostic value of coronary computed tomography angiography-derived fractional flow reserve (FFR) has been scantily investigated.

Objectives: The purpose of this study was to investigate the diagnostic and short-term role of FFR in chest pain patients with Agatston score (AS) >399.

Methods: This was a prospective multicenter study of 260 stable patients with suspected coronary artery disease (CAD) and AS >399. FFR was measured blinded by an independent core laboratory. All patients underwent invasive coronary angiography (ICA) and FFR if indicated. The agreement of FFR ≤0.80 with hemodynamically significant CAD on ICA/FFR (≥50% left main or ≥70% epicardial artery stenosis and/or FFR ≤0.80) was assessed. Patients undergoing FFR had colocation FFR measured, and the lowest per-patient FFR was registered in all patients. The association among per-patient FFR, coronary revascularization, and major clinical events (all-cause mortality, myocardial infarction, or unstable angina hospitalization) at 90-day follow-up was evaluated.

Results: Median age and AS were 68.5 years (IQR: 63-74 years) and 895 (IQR: 587-1,513), respectively. FFR was ≤0.80 in 204 patients (78%). Colocation FFR (n = 112) showed diagnostic accuracy, sensitivity, and specificity to identify hemodynamically significant CAD of 71%, 87%, and 54%. The area under the receiver-operating characteristics curve (AUC) was 0.75. When using the lowest FFR (n = 260), per-patient accuracy, sensitivity, and specificity were 57%, 95%, and 32%, respectively. The AUC was 0.84. A total of 85 patients underwent revascularization, and FFR was ≤0.80 in 96% of these. During follow-up, major clinical events occurred in 3 patients (1.2%), all with FFR ≤0.80.

Conclusions: Most patients with AS >399 had FFR ≤0.80. Using ICA/FFR as the reference revealed a moderate diagnostic accuracy of colocation FFR. Compared with the lowest per-patient FFR, colocation FFR measurement improved diagnostic accuracy and specificity. The 90-day follow-up was favorable with few coronary revascularizations and no major clinical events occurring in patients with FFR >0.80. (Use of FFR-CT in Stable Intermediate Chest Pain Patients With Severe Coronary Calcium Score [FACC]; NCT03548753).