On-site assessment of computed tomography-derived fractional flow reserve in comparison with myocardial perfusion imaging and invasive fractional flow reserve.

Myocardial perfusion imaging (MPI) using Single Photon Emission Computed Tomography has been established as a standard noninvasive tool for risk stratification of coronary artery disease (CAD). We evaluated the diagnostic performance of on-site workstation-based computed tomography-derived fractional flow reserve (CT-FFR) in comparison with MPI using invasive fractional flow reserve (invasive FFR) as a gold standard. We enrolled 97 patients with suspected CAD. Diagnostic performance of CT angiography (CTA), and CT-FFR was compared in 105 lesions of 97 patients. Invasive FFR ≤ 0.8 was detected in 38 (36%) lesions. Diagnostic performance of CT-FFR was improved compared with CTA (AUC 0.83 vs. 0.60, p < 0.0001). The lesions with both CTA and MPI findings (n = 47), invasive FFR ≤ 0.8 was detected in 19 (40.4) lesions. CT-FFR (AUC 0.81, 95% CI 0.72-0.94) significantly improved diagnostic performance compared with CTA-50% (AUC 0.59, p = 0.00019) and MPI (AUC 0.64, p = 0.0082). In lesions with ≥ 50% on CTA (n = 42), diagnostic accuracy of CT-FFR (AUC 0.81) was significantly superior to MPI (AUC 0.64, p = 0.0239). In conclusions, CT-FFR improved diagnostic accuracy to detect invasive FFR ≤ 0.8 compared with luminal stenosis on CTA and ischemia on MPI. Patients with ≥ 50% stenosis on CTA would be the candidates for CT-FFR.

Ultra-High-Resolution Computed Tomography Angiography for Assessment of Coronary Artery Stenosis.

BACKGROUND: Limitations of coronary computed tomography (CTA) include false-positive stenosis at calcified lesions and assessment of in-stent patency. A prototype of ultra-high resolution computed tomography (U-HRCT: 1,792 channels and 0.25-mm slice thickness×128 rows) with improved spatial resolution was developed. We assessed the diagnostic accuracy of coronary artery stenosis using U-HRCT.Methods and Results:Seventy-nine consecutive patients who underwent CTA using U-HRCT were prospectively included. Coronary artery stenosis was graded from 0 (no plaque) to 5 (occlusion). Stenosis grading at 102 calcified lesions was compared between U-HRCT and conventional-resolution CT (CRCT: 896 channels and 0.5-mm slice thickness×320 rows). Median stenosis grading at calcified plaque was significantly improved on U-HRCT compared with CRCT (1; IQR, 1-2 vs. 2; IQR, 1-3, P<0.0001). Assessability of in-stent lumen was evaluated on U-HRCT in 79 stents. Stent strut thickness and luminal diameter were quantitatively compared between U-HRCT and CRCT. Of 79 stents, 83.5% were assessable on U-HRCT; 80% of stents with diameter 2.5 mm were regarded as assessable. On U-HRCT, stent struts were significantly thinner (median, 0.78 mm; IQR, 0.7-0.83 mm vs. 0.83 mm; IQR, 0.75-0.92 mm, P=0.0036), and in-stent lumens were significantly larger (median, 2.08 mm; IQR, 1.55-2.51 mm vs. 1.74 mm; IQR, 1.31-2.06 mm, P<0.0001) than on CRCT. CONCLUSIONS: U-HRCT with improved spatial resolution visualized calcified lesions with fewer artifacts. The in-stent lumen of stents with diameter ≥2.5 mm was assessable on U-HRCT.

Noninvasive Assessment of Stenotic Severity and Plaque Characteristics by Coronary CT Angiography in Patients Scheduled for Carotid Artery Revascularization.

AIMS: Coronary artery atherosclerosis in patients needing carotid revascularization has not been fully clarified. The aim of this study was to evaluate the stenotic severity and plaque characteristics of coronary arteries by coronary computed tomography angiography (CTA) in patients scheduled for carotid-artery stenting (CAS) or carotid endarterectomy (CEA). METHODS: We performed coronary CTA after carotid ultrasound (US) in 164 patients (81.7% male, aged 68.1± 12.2 years) from 2014 to 2016. Of all, 70 were scheduled for CAS or CEA (CAS/CEA group) and 94 were not (non-CAS/CEA group). Carotid US and coronary CTA were compared for the evaluation of stenotic severity and plaque characteristics of each vessel between CAS/CEA and non-CAS/CEA groups. RESULTS: Between the two groups, there were significant differences in the presence of significant stenosis (SS: ≥70% stenosis of coronary artery) (55.7% vs. 39.4%, P=0.038), triple-vessel disease (TVD)/left main trunk (LMT) (SS in each of three epicardial vessels and/or LMT) (24.3% vs. 7.5%, P= 0.0025), and high-risk plaque (HRP: positive remodeling and/or low attenuation) (55.7% vs. 24.5%, P＜0.0001). CAS/CEA was independently associated with TVD/LMT (OR=2.30, 95%CI: 1.14-8.59, P=0.026) and HRP (OR=3.17, 95%CI: 1.57-6.54, P=0.0012) in multivariable logistic regression analysis. Similarly, vulnerable plaque (78.6% vs. 2.1%, P＜0.0001) as well as severe stenosis of carotid artery (98.6% vs. 0%, P＜0.0001) was seen more often in CAS/CEA than in non-CAS/CEA group. CONCLUSIONS: The prevalence of TVD/LMT and HRP determined by coronary CTA is higher in patients needing CAS/CEA than in those without. Management of systemic atherosclerosis is required in the perioperative period of CAS/CEA.