Project description:Computed tomography angiography (CTA) has played a significant role in evaluation of coronary artery disease in the last decade and has demonstrated high sensitivity and negative predictive values. However, the positive predictive value as compared with invasive fractional flow reserve (FFR) is limited. CT-FFR has emerged as a disruptive noninvasive technology with higher specificity and diagnostic accuracy for detection of hemodynamically significant coronary lesions as compared with invasive FFR than conventional coronary CTA. CT-FFR has been shown to be cost-effective as a gate-keeper to invasive coronary angiography and has the potential to limit unnecessary invasive angiography studies.
Project description:Fractional flow reserve (FFR) measured during invasive coronary angiography is an independent prognosticator in patients with coronary artery disease and the gold standard for decision making in coronary revascularization. The integration of computational fluid dynamics and quantitative anatomic and physiologic modeling now enables simulation of patient-specific hemodynamic parameters including blood velocity, pressure, pressure gradients, and FFR from standard acquired coronary computed tomography (CT) datasets. In this review article, we describe the potential impact on clinical practice and the science behind noninvasive coronary computed tomography (CT) angiography derived fractional flow reserve (FFRCT) as well as future applications of this technology in treatment planning and quantifying forces on atherosclerotic plaques.
Project description:Background and objectivesFractional flow reserve (FFR) is an invasive standard method to identify ischemia-causing coronary artery disease (CAD). With the advancement of technology, FFR can be noninvasively computed from coronary computed tomography angiography (CCTA). Recently, a novel simpler method has been developed to calculate on-site CCTA-derived FFR (CT-FFR) with a commercially available workstation.MethodsA total of 319 CAD patients who underwent CCTA, invasive coronary angiography, and FFR measurement were included. The primary outcome was the accuracy of CT-FFR for defining myocardial ischemia evaluated with an invasive FFR as a reference. The presence of ischemia was defined as FFR ≤0.80. Anatomical obstructive stenosis was defined as diameter stenosis on CCTA ≥50%, and the diagnostic performance of CT-FFR and CCTA stenosis for ischemia was compared.ResultsAmong participants (mean age 64.7±9.4 years, male 77.7%), mean FFR was 0.82±0.10, and 126 (39.5%) patients had an invasive FFR value of ≤0.80. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT-FFR were 80.6% (95% confidence interval [CI], 80.5-80.7%), 88.1% (95% CI, 82.4-93.7%), 75.6% (95% CI, 69.6-81.7%), 70.3% (95% CI, 63.1-77.4%), and 90.7% (95% CI, 86.2-95.2%), respectively. CT-FFR had higher diagnostic accuracy (80.6% vs. 59.1%, p<0.001) and discriminant ability (area under the curve from receiver operating characteristic curve 0.86 vs. 0.64, p<0.001), compared with anatomical obstructive stenosis on CCTA.ConclusionsThis novel CT-FFR obtained from an on-site workstation demonstrated clinically acceptable diagnostic performance and provided better diagnostic accuracy and discriminant ability for identifying hemodynamically significant lesions than CCTA alone.
Project description:BackgroundNitroglycerin administration prior to examination improves stenosis assessment of coronary computed tomography (CT) angiography (CCTA). However, whether nitroglycerin influences CT-derived fractional flow reserve (FFR, CT-FFR) evaluation remains unclear. This study aimed to investigate the effect of nitroglycerin on diagnostic performance of CT-FFR.MethodsIn this single-center retrospective study, 107 consecutive patients suspected of coronary artery disease (CAD) with nitroglycerin administration prior to CCTA in 2019 were matched to 107 patients without nitroglycerin in 2016 from Fuwai Hospital. All patients underwent CCTA and invasive FFR in a month. Vessel-based and patient-based accuracy and diagnostic performance of CT-FFR were compared between the two groups, as well as image quality, coronary artery diameter and evaluability. Quantitative variables were compared by Kruskal-Wallis H test. Categorical variables and rates were compared by χ2 test or Fisher exact test.ResultsA total of 214 patients (56.1±8.9 years, 155 male) with 237 target lesion vessels were analyzed, including 120 vessels in nitroglycerin and 117 vessels in non-nitroglycerin group. Per-vessel based accuracy of CT-FFR was higher in nitroglycerin group {80.0% [95% confidence interval (CI): 71.7-86.7%] vs. 68.4% (59.1-76.7%), P=0.041}. On a per-patient basis, nitroglycerin administration improved the accuracy [83.2% (74.7-89.7%) vs. 68.2% (58.5-76.9%), P=0.01], specificity [82.7% (69.7-91.8%) vs. 61.9% (48.8-73.9%), P=0.01], positive predictive value (PPV) [83.6% (73.6-90.4%) vs. 58.6% (50.0-66.9%), P=0.004], and area under the curve (AUC) [0.83 (0.75-0.89) vs. 0.71 (0.61-0.79), P=0.03] of CT-FFR. Vessel diameters (left main arteries: 4.3 vs. 3.8 mm, P<0.001; left anterior descending arteries: 3.1 vs. 2.9 mm, P=0.001; left circumflex arteries: 2.9 vs. 2.7 mm, P=0.01; right coronary arteries: 3.7 vs. 3.4 mm, P=0.001) and number of evaluable coronary arteries (11.0 vs. 8.0, P<0.001) were larger in nitroglycerin group.ConclusionsNitroglycerin administration prior to CCTA has positive effects on diagnostic performance of CT-FFR.
Project description:AimsCoronary plaque characteristics are associated with ischaemia. Differences in plaque volumes and composition may explain the discordance between coronary stenosis severity and ischaemia. We evaluated the association between coronary stenosis severity, plaque characteristics, coronary computed tomography angiography (CTA)-derived fractional flow reserve (FFRCT), and lesion-specific ischaemia identified by FFR in a substudy of the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps).Methods and resultsCoronary CTA stenosis, plaque volumes, FFRCT, and FFR were assessed in 484 vessels from 254 patients. Stenosis >50% was considered obstructive. Plaque volumes (non-calcified plaque [NCP], low-density NCP [LD-NCP], and calcified plaque [CP]) were quantified using semi-automated software. Optimal thresholds of quantitative plaque variables were defined by area under the receiver-operating characteristics curve (AUC) analysis. Ischaemia was defined by FFR or FFRCT ≤0.80. Plaque volumes were inversely related to FFR irrespective of stenosis severity. Relative risk (95% confidence interval) for prediction of ischaemia for stenosis >50%, NCP ≥185 mm(3), LD-NCP ≥30 mm(3), CP ≥9 mm(3), and FFRCT ≤0.80 were 5.0 (3.0-8.3), 3.7 (2.4-5.6), 4.6 (2.9-7.4), 1.4 (1.0-2.0), and 13.6 (8.4-21.9), respectively. Low-density NCP predicted ischaemia independent of other plaque characteristics. Low-density NCP and FFRCT yielded diagnostic improvement over stenosis assessment with AUCs increasing from 0.71 by stenosis >50% to 0.79 and 0.90 when adding LD-NCP ≥30 mm(3) and LD-NCP ≥30 mm(3) + FFRCT ≤0.80, respectively.ConclusionStenosis severity, plaque characteristics, and FFRCT predict lesion-specific ischaemia. Plaque assessment and FFRCT provide improved discrimination of ischaemia compared with stenosis assessment alone.
Project description:Recent advances in image-based modeling and computational fluid dynamics permit the calculation of coronary artery pressure and flow from typically acquired coronary computed tomography (CT) scans. Computed fractional flow reserve is the ratio of mean coronary artery pressure divided by mean aortic pressure under conditions of simulated maximal coronary hyperemia, thus providing a noninvasive estimate of fractional flow reserve (FFRCT) at every point in the coronary tree. Prospective multicenter clinical trials have shown that computed FFRCT improves diagnostic accuracy and discrimination compared to CT stenosis alone for the diagnosis of hemodynamically significant coronary artery disease (CAD), when compared to invasive FFR as the reference gold standard. This promising new technology provides a combined anatomic and physiologic assessment of CAD in a single noninvasive test that can help select patients for invasive angiography and revascularization or best medical therapy. Further evaluation of the clinical effectiveness and economic implications of noninvasive FFRCT are now being explored.
Project description:BackgroundA pathophysiological interplay exists between plaque morphology and coronary physiology. Machine learning (ML) is increasingly being applied to coronary computed tomography angiography (CCTA) for cardiovascular risk stratification. We sought to assess the performance of a ML score integrating CCTA-based quantitative plaque features for predicting vessel-specific ischemia by invasive fractional flow reserve (FFR) and impaired myocardial blood flow (MBF) by positron emission tomography (PET).MethodsThis post-hoc analysis of the PACIFIC trial (Prospective Comparison of Cardiac Positron Emission Tomography/Computed Tomography [CT]' Single Photon Emission Computed Tomography/CT Perfusion Imaging and CT Coronary Angiography with Invasive Coronary Angiography) included 208 patients with suspected coronary artery disease who prospectively underwent CCTA' [15O]H2O PET, and invasive FFR. Plaque quantification from CCTA was performed using semiautomated software. An ML algorithm trained on the prospective NXT trial (484 vessels) was used to develop a ML score for the prediction of ischemia (FFR≤0.80), which was then evaluated in 581 vessels from the PACIFIC trial. Thereafter, the ML score was applied for predicting impaired hyperemic MBF (≤2.30 mL/min per g) from corresponding PET scans. The performance of the ML score was compared with CCTA reads and noninvasive FFR derived from CCTA (FFRCT).ResultsOne hundred thirty-nine (23.9%) vessels had FFR-defined ischemia, and 195 (33.6%) vessels had impaired hyperemic MBF. For the prediction of FFR-defined ischemia, the ML score yielded an area under the receiver-operating characteristic curve of 0.92, which was significantly higher than that of visual stenosis grade (0.84; P<0.001) and comparable with that of FFRCT (0.93; P=0.34). Quantitative percent diameter stenosis and low-density noncalcified plaque volume had the greatest ML feature importance for predicting FFR-defined ischemia. When applied for impaired MBF prediction, the ML score exhibited an area under the receiver-operating characteristic curve of 0.80; significantly higher than visual stenosis grade (area under the receiver-operating characteristic curve 0.74; P=0.02) and comparable with FFRCT (area under the receiver-operating characteristic curve 0.77; P=0.16).ConclusionsAn externally validated ML score integrating CCTA-based quantitative plaque features accurately predicts FFR-defined ischemia and impaired MBF by PET, performing superiorly to standard CCTA stenosis evaluation and comparably to FFRCT.
Project description:BackgroundDistinct sex-related differences exist in coronary artery plaque burden and distribution. We aimed to explore sex differences in quantitative plaque burden by coronary CT angiography (CCTA) in relation to ischemia by invasive fractional flow reserve (FFR).MethodsThis post-hoc analysis of the PACIFIC trial included 581 vessels in 203 patients (mean age 58.1 ± 8.7 years, 63.5% male) who underwent CCTA and per-vessel invasive FFR. Quantitative assessment of total, calcified, non-calcified, and low-density non-calcified plaque burden were performed using semiautomated software. Significant ischemia was defined as invasive FFR ≤0.8.ResultsThe per-vessel frequency of ischemia was higher in men than women (33.5% vs. 7.5%, p < 0.001). Women had a smaller burden of all plaque subtypes (all p < 0.01). There was no sex difference on total, calcified, or non-calcified plaque burdens in vessels with ischemia; only low-density non-calcified plaque burden was significantly lower in women (beta: -0.183, p = 0.035). The burdens of all plaque subtypes were independently associated with ischemia in both men and women (For total plaque burden (5% increase): Men, OR: 1.15, 95%CI: 1.06-1.24, p = 0.001; Women, OR: 1.96, 95%CI: 1.11-3.46, p = 0.02). No significant interaction existed between sex and total plaque burden for predicting ischemia (interaction p = 0.108). The addition of quantitative plaque burdens to stenosis severity and adverse plaque characteristics improved the discrimination of ischemia in both men and women.ConclusionsIn symptomatic patients with suspected CAD, women have a lower CCTA-derived burden of all plaque subtypes compared to men. Quantitative plaque burden provides independent and incremental predictive value for ischemia, irrespective of sex.
Project description:BackgroundCoronary computed tomography angiography (CTA) and optical coherence tomography (OCT) provide additional functional information beyond the anatomy by applying computational fluid dynamics (CFD). This study sought to evaluate a novel approach for estimating computational fractional flow reserve (FFR) from coronary CTA-OCT fusion images.MethodsAmong patients who underwent coronary CTA, 148 patients who underwent both pressure wire-based FFR measurement and OCT during angiography to evaluate intermediate stenosis in the left anterior descending artery were included from the prospective registry. Coronary CTA-OCT fusion images were created, and CFD was applied to estimate computational FFR. Based on pressure wire-based FFR as a reference, the diagnostic performance of Fusion-FFR was compared with that of CT-FFR and OCT-FFR.ResultsFusion-FFR was strongly correlated with FFR (r = 0.836, P < 0.001). Correlation between FFR and Fusion-FFR was stronger than that between FFR and CT-FFR (r = 0.682, P < 0.001; z statistic, 5.42, P < 0.001) and between FFR and OCT-FFR (r = 0.705, P < 0.001; z statistic, 4.38, P < 0.001). Area under the receiver operating characteristics curve to assess functionally significant stenosis was higher for Fusion-FFR than for CT-FFR (0.90 vs. 0.83, P = 0.024) and OCT-FFR (0.90 vs. 0.83, P = 0.043). Fusion-FFR exhibited 84.5% accuracy, 84.6% sensitivity, 84.3% specificity, 80.9% positive predictive value, and 87.5% negative predictive value. Especially accuracy, specificity, and positive predictive value were superior for Fusion-FFR than for CT-FFR (73.0%, P = 0.007; 61.4%, P < 0.001; 64.0%, P < 0.001) and OCT-FFR (75.7%, P = 0.021; 73.5%, P = 0.020; 69.9%, P = 0.012).ConclusionCFD-based computational FFR from coronary CTA-OCT fusion images provided more accurate functional information than coronary CTA or OCT alone.Clinical trial registration[www.ClinicalTrials.gov], identifier [NCT03298282].
Project description:In the United States, the real-world feasibility and outcome of using fractional flow reserve from coronary computed tomography angiography (FFRCT) is unknown. We sought to determine whether a strategy that combined coronary computed tomography angiography (CTA) and FFRCT could safely reduce the need for invasive coronary angiography (ICA), as compared to coronary CTA alone. The study included 387 consecutive patients with suspected CAD referred for coronary CTA with selective FFRCT and 44 control patients who underwent CTA alone. Lesions with 30-90% diameter stenoses were considered of indeterminate hemodynamic significance and underwent FFRCT. Nadir FFRCT ≤ 0.80 was positive. The rate of patients having ICA, revascularization and major adverse cardiac events were recorded. Using coronary CTA and selective FFRCT, 121 patients (32%) had at least one vessel with ≥50% diameter stenosis; 67/121 (55%) patients had at least one vessel with FFRCT ≤ 0.80; 55/121 (45%) underwent ICA; and 34 were revascularized. The proportion of ICA patients undergoing revascularization was 62% (34 of 55). The number of patients with vessels with 30-50% diameter of stenosis was 90 (23%); 28/90 (31%) patients had at least one vessel with FFRCT ≤ 0.80; 8/90 (9%) underwent ICA; and five were revascularized. In our institutional practice, compared to coronary CTA alone, coronary CTA with selective FFRCT reduced the rates of ICA (45% vs. 80%) for those with obstructive CAD. Using coronary CTA with selective FFRCT, no major adverse cardiac events occurred over a mean follow-up of 440 days. FFRCT safely deferred ICA in patients with CAD of indeterminate hemodynamic significance. A high proportion of those who underwent ICA were revascularized.