Abstract 10376: Improved Diagnosis, Discrimination and Reclassification of Ischemia-Causing Lesions by Atherosclerotic Plaque Characteristics and Non-Invasive Fractional Flow Reserve Derived From Coronary CT Angiography
Background: Non-invasive fractional flow reserve derived from coronary CT angiography (FFRCT) is a novel method for diagnosis of ischemic coronary lesions that is superior to CT stenosis alone. Adverse plaque characteristics (APC) by coronary CT angiography (CT)–including positive remodeling (PR), low attenuation plaque (LAP) and spotty calcification (SC)–are associated with myocardial ischemia. To date, whether APCs offer additive value to FFRCT for identifying ischemia-causing lesions remains unknown.
Methods: 252 patients from 17 centers in 5 countries were prospectively enrolled. Patients underwent CT, FFRCT, invasive coronary angiography with FFR in 407 lesions. FFRCT, FFR and CT were interpreted by independent core laboratories. Lesion-specific ischemia was defined by FFR ≤0.8, while CT stenosis ≥50% was considered obstructive. APCs within coronary lesions by CT were defined as: (1) PR, remodeling index >1.10; (2) LAP, any voxel <30 HU; and (3) SC, nodular calcium <3 mm. Odds ratios (OR), area under the receiver-operating-characteristics curve (AUC) and net reclassification improvement (NRI) for lesion-specific ischemia by APCs was assessed.
Results: By FFR, ischemia was present in 151 lesions (37%). APCs were strongly associated with ischemia, with a 3-5 higher prevalence than in non-ischemic lesions for PR, LAP and SC. In multivariable analyses adjusting for stenosis and FFRCT, a dose-response relationship was observed between number of APCs and ischemia, with risk of ischemia increasing for 1 [OR 4.9, p<0.001)] and ≥2 (OR 11.2, p<0.001) APCs. Among APCs, PR (OR 5.7, p<0.001) but not LAP or SC was associated with ischemia. FFRCT provided incremental prediction for lesion-specific ischemia over CT stenosis (AUC 0.83 vs. 0.71, p<0.01). Further, APCs provided incremental prediction over CT stenosis plus FFRCT (AUC 0.87 vs. 0.83, p=0.003). PR (NRI 0.98, p<0.0001), LAP (NRI 0.91, p<0.0001) and SC (NRI 0.35, p=0.0006) enabled effective reclassification of ischemic lesions over CT stenosis and FFRCT.
Conclusions: Independent of and incremental to CT stenosis and FFRCT, atherosclerotic plaque characteristics by CT improve identification, discrimination and reclassification for coronary artery lesions that do versus do not cause ischemia.
- © 2013 by American Heart Association, Inc.