Aims To test the hypothesis that virtual functional assessment index (vFAI) is related with regional flow parameters derived by quantitative positron emission tomography (PET) and can be used to... Show moreAims To test the hypothesis that virtual functional assessment index (vFAI) is related with regional flow parameters derived by quantitative positron emission tomography (PET) and can be used to assess abnormal vasodilating capability in coronary vessels with stenotic lesions at coronary computed tomography angiography (CCTA).Methods and results vFAI, stress myocardial blood flow (MBF), and myocardial flow reserve (MFR) were assessed in 78 patients (mean age 62.2 +/- 7.7 years) with intermediate pre-test likelihood of coronary artery disease (CAD). Coronary stenoses >= 50% were considered angiographically significant. PET was considered positive for significant CAD, when more than one contiguous segments showed stress MBF <= 2.3 mL/g/min for O-15-water or <1.79 mL/g/min for N-13-ammonia. MFR thresholds were <= 2.5 and <= 2.0, respectively. vFAI was lower in vessels with abnormal stress MBF (0.76 +/- 0.10 vs. 0.89 +/- 0.07, P < 0.001) or MFR (0.80 +/- 0.10 vs. 0.89 +/- 0.07, P < 0.001). vFAI had an accuracy of 78.6% and 75% in unmasking abnormal stress MBF and MFR in O-15-water and 82.7% and 71.2% in N-13-ammonia studies, respectively. Addition of vFAI to anatomical CCTA data increased the ability for predicting abnormal stress MBF and MFR in O-15-water studies [AUC(ccta+vfai) = 0.866, 95% confidence interval (CI) 0.783-0.949; P = 0.013 and AUC(ccta+vfai) = 0.737, 95% CI 0.648-0.825; P = 0.007, respectively]. An incremental value was also demonstrated for prediction of stress MBF (AUC(ccta+vfai) = 0.887, 95% CI 0.799-0.974; P = 0.001) in N-13-ammonia studies. A similar trend was recorded for MFR (AUC(ccta+vfai) = 0.780, 95% CI 0.632-0.929; P = 0.13).Conclusion vFAI identifies accurately the presence of impaired vasodilating capability. In combination with anatomical data, vFAI enhances the diagnostic performance of CCTA. Show less
OBJECTIVETo determine whether coronary computed tomography angiography (CTA) should be performed in patients with any clinical probability of coronary artery disease (CAD), and whether the... Show moreOBJECTIVETo determine whether coronary computed tomography angiography (CTA) should be performed in patients with any clinical probability of coronary artery disease (CAD), and whether the diagnostic performance differs between subgroups of patients.DESIGNProspectively designed meta-analysis of individual patient data from prospective diagnostic accuracy studies.DATA SOURCESMedline, Embase, and Web of Science for published studies. Unpublished studies were identified via direct contact with participating investigators.ELIGIBILITY CRITERIA FOR SELECTING STUDIESProspective diagnostic accuracy studies that compared coronary CTA with coronary angiography as the reference standard, using at least a 50% diameter reduction as a cutoff value for obstructive CAD. All patients needed to have a clinical indication for coronary angiography due to suspected CAD, and both tests had to be performed in all patients. Results had to be provided using 2x2 or 3x2 cross tabulations for the comparison of CTA with coronary angiography. Primary outcomes were the positive and negative predictive values of CTA as a function of clinical pretest probability of obstructive CAD, analysed by a generalised linear mixed model; calculations were performed including and excluding non-diagnostic CTA results. The no-treat/treat threshold model was used to determine the range of appropriate pretest probabilities for CTA. The threshold model was based on obtained post-test probabilities of less than 15% in case of negative CTA and above 50% in case of positive CTA. Sex, angina pectoris type, age, and number of computed tomography detector rows were used as clinical variables to analyse the diagnostic performance in relevant subgroups.RESULTSIndividual patient data from 5332 patients from 65 prospective diagnostic accuracy studies were retrieved. For a pretest probability range of 7-67%, the treat threshold of more than 50% and the no-treat threshold of less than 15% post-test probability were obtained using CTA. At a pretest probability of 7%, the positive predictive value of CTA was 50.9% (95% confidence interval 43.3% to 57.7%) and the negative predictive value of CTA was 97.8% (96.4% to 98.7%); corresponding values at a pretest probability of 67% were 82.7% (78.3% to 86.2%) and 85.0% (80.2% to 88.9%), respectively. The overall sensitivity of CTA was 95.2% (92.6% to 96.9%) and the specificity was 79.2% (74.9% to 82.9%). CTA using more than 64 detector rows was associated with a higher empirical sensitivity than CTA using up to 64 rows (93.4% v 86.5%, P=0.002) and specificity (84.4% v 72.6%, P<0.001). The area under the receiver-operating-characteristic curve for CTA was 0.897 (0.889 to 0.906), and the diagnostic performance of CTA was slightly lower in women than in with men (area under the curve 0.874 (0.858 to 0.890) v 0.907 (0.897 to 0.916), P<0.001). The diagnostic performance of CTA was slightly lower in patients older than 75 (0.864 (0.834 to 0.894), P=0.018 v all other age groups) and was not significantly influenced by angina pectoris type (typical angina 0.895 (0.873 to 0.917), atypical angina 0.898 (0.884 to 0.913), non-anginal chest pain 0.884 (0.870 to 0.899), other chest discomfort 0.915 (0.897 to 0.934)).CONCLUSIONSIn a no-treat/treat threshold model, the diagnosis of obstructive CAD using coronary CTA in patients with stable chest pain was most accurate when the clinical pretest probability was between 7% and 67%. Performance of CTA was not influenced by the angina pectoris type and was slightly higher in men and lower in older patients. Show less
ObjectivesApplication of computational fluid dynamics (CFD) to three-dimensional CTCA datasets has been shown to provide accurate assessment of the hemodynamic significance of a coronary lesion. We... Show moreObjectivesApplication of computational fluid dynamics (CFD) to three-dimensional CTCA datasets has been shown to provide accurate assessment of the hemodynamic significance of a coronary lesion. We aim to test the feasibility of calculating a novel CTCA-based virtual functional assessment index (vFAI) of coronary stenoses >30% and 90% by using an automated in-house-developed software and to evaluate its efficacy as compared to the invasively measured fractional flow reserve (FFR).Methods and resultsIn 63 patients with chest pain symptoms and intermediate (20-90%) pre-test likelihood of coronary artery disease undergoing CTCA and invasive coronary angiography with FFR measurement, vFAI calculations were performed after 3D reconstruction of the coronary vessels and flow simulations using the finite element method. A total of 74 vessels were analyzed. Mean CTCA processing time was 25(10)min. There was a strong correlation between vFAI and FFR, (R=0.93, p<0.001) and a very good agreement between the two parameters by the Bland-Altman method of analysis. The mean difference of measurements from the two methods was 0.03 (SD=0.033), indicating a small systematic overestimation of the FFR by vFAI. Using a receiver-operating characteristic curve analysis, the optimal vFAI cutoff value for identifying an FFR threshold of 0.8 was 0.82 (95% CI 0.81 to 0.88).ConclusionsvFAI can be effectively derived from the application of computational fluid dynamics to three-dimensional CTCA datasets. In patients with coronary stenosis severity >30% and 90%, vFAI performs well against FFR and may efficiently distinguish between hemodynamically significant from non-significant lesions.Key PointsVirtual functional assessment index (vFAI) can be effectively derived from 3D CTCA datasets.In patients with coronary stenoses severity >30% and 90%, vFAI performs well against FFR. vFAI may efficiently distinguish between functionally significant from non-significant lesions. Show less
