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Fractional flow reserve (FFR) is widely used for physiologic assessment of intermediate coronary artery disease (CAD) lesions (30–70% diameter stenosis). We determined whether measures of CAD by coronary CT angiography (CCTA) effectively predicted lesion–specific ischemia in intermediate lesions, when compared to an FFR reference standard.
We identified 58 patients with suspected or known CAD with an intermediate stenosis by CCTA, with each stenosis interrogated by FFR (n=58). FFR ≤0.80 was considered diagnostic of lesion–specific ischemia. CCTA measures were evaluated in blinded fashion by 2 expert core laboratory readers and included: 1) diameter stenosis (DS, %), 2) area stenosis (AS, %), 3) minimal luminal diameter (MLD, mm), 4) minimal luminal area (MLA, mm2) and 5) aggregate plaque volume (APV, mm3). APV was measured by summation of contiguous plaque areas and multiplication by the slice increment (0.5 mm) from the coronary artery ostium to the distal portion of the lesion, and reported as APV% (plaque volume/vessel volume × 100). CCTA and FFR data were analyzed by independent core laboratories.
The average FFR of the study population was 0.82 ± 0.1, with 22 ischemic lesions. Significant correlations were observed between FFR and CCTA DS (r=-0.35, p=0.007), AS (r=-0.39, p=0.003), MLD (r=0.43, p=0.0009), MLA (r=0.47, p=0.0002), and APV% (r=-0.50, p<0.0001). Compared to vessels without ischemia, vessels with ischemia had greater APV% (48.9 vs. 39.3%, p<0.0001), MLD and MLA (1.3 vs. 1.7 mm, p=0.01; 2.5 vs. 3.8 mm2, p=0.01); with no significant differences in DS or AS (54.9 vs. 48.3%, p=0.07; 65.0 vs. 55.2%, p=0.05). Area under the receiver operator characteristics (ROC) curve for lesion–specific ischemia was 0.68, 0.76, 0.75, 0.78 and 0.85 for DS, AS, MLD, MLA and APV%, respectively. By ROC, APV% showed incremental prediction for lesion–specific ischemia over DS, AS and MLD (AUC 0.88 vs. 0.68, 0.88 vs. 0.66, 0.90 vs. 0.75, respectively,
As compared to individual measures of DS, AS, MLD and MLA, APV by CCTA demonstrates superior identification, discrimination and incremental value of ischemia–causing lesions.
Special Session North, Room 120
Monday, March 11, 2013, 9:00 a.m.–9:15 a.m.
Session Title: Young Investigator Awards Competition: Clinical Investigations, Congenital Heart Disease, and Cardiovascular Surgery
Abstract Category: Clinical Investigations, Congenital Heart Disease, Cardiac Surgery
Presentation Number: 408–8
- 2013 American College of Cardiology Foundation