Computed tomographic coronary angiography (CTCA) has been proposed as a noninvasive test for significant coronary artery disease (CAD), but only limited data are available from prospective ...multicenter trials. The goal of this study was to establish the diagnostic accuracy of CTCA compared to coronary angiography (CA) in a large population of symptomatic patients with clinical indications for coronary imaging. This national, multicenter study was designed to prospectively evaluate stable patients able to undergo CTCA followed by conventional CA. Data from CTCA and CA were analyzed in a blinded fashion at central core laboratories. The main outcome was the evaluation of patient-, vessel-, and segment-based diagnostic performance of CTCA to detect or rule out significant CAD (≥50% luminal diameter reduction). Of 757 patients enrolled, 746 (mean age 61 ± 12 years, 71% men) were analyzed. They underwent CTCA followed by CA 1.7 ± 0.8 days later using a 64-detector scanner. The prevalence of significant CAD in native coronary vessels by CA was 54%. The rate of nonassessable segments by CTCA was 6%. In a patient-based analysis, sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios of CTCA were 91%, 50%, 68%, 83%, 1.82, and 0.18, respectively. The strongest predictors of false-negative results on CTCA were high estimated pretest probability of CAD (odds ratio OR 1.97, p <0.001), male gender (OR 1.5, p <0.002), diabetes (OR 1.5, p <0.0001), and age (OR 1.2, p <0.0001). In conclusion, in this large multicenter study, CTCA identified significant CAD with high sensitivity. However, in routine clinical practice, each patient should be individually evaluated, and the pretest probability of obstructive CAD should be taken into account when deciding which method, CTCA or CA, to use to diagnose its presence and severity.
Obesity and Cardiovascular Disease Mousseaux, Elie, MD, PhD
Journal of the American College of Cardiology,
08/2009, Volume:
54, Issue:
8
Journal Article
Recently several methods have been proposed as tools to measure aortic pulse wave velocity (aPWV). The carotid-femoral pulse wave velocity (cf-PWV), the current clinical gold standard method for the ...noninvasive assessment of aPWV, uses the carotid–femoral pulse transit time (cf-PTT) to derive cf-PWV. The heart-ankle PWV (ha-PWV), brachial-ankle PWV (ba-PWV) and finger-toe (ft-PWV) are also methods presuming to approximate aPWV based on time delays between physiological signals at two locations (~heart-ankle PTT, ha-PTT; ~brachial-ankle PTT, ba-PTT; ~finger-toe PTT, ft-PTT). To test the validity of these methods, we used a 1D arterial network model (143 segments) including the foot and hand circulation.
The arterial tree dimensions and properties were taken from the literature and completed with CT-scans data. We calculated PTT’s with all the methods above.
The calculated PTT’s were compared with the aortic PTT (aPTT), considered as the absolute reference method in this study. The correlation between methods and aPTT was good and significant, cf-PTT (R
2
= 0.97; P < 0.001; mean difference 5 ± 2 ms), ha- PTT (R
2
= 0.96; P < 0.001; 150 ± 23 ms), ba-PTT (R
2
= 0.96; P < 0.001; 70 ± 13 ms) and ft-PTT (R
2
= 0.95; P < 0.001; 14 ± 10 ms). Consequently, good correlation was also observed for the PWV values derived with the tested methods, but absolute values differed because of different path lengths used. In conclusion, our computer model based analyses demonstrate that for PWV methods based on peripheral signals, PTT’s closely correlate with the aPTT, supporting the use of these methods in clinical practice.
Purpose
Understanding and prediction of ascending thoracic aortic aneurysms (ATAA) progression are not well established yet and aortic dissection is frequently occurring on normally sized and mildly ...dilated aortas. Despite known theoretical associations between pressures and blood flow patterns there are no studies focusing on their simultaneous evaluation. Our aim was to propose a comprehensive and quantitative evaluation of pressure-flow-wall interplay from 4D flow MRI in the setting of aortic dilation.
Methods
We studied 12 patients with ATAA (67 ± 14 years, 7 males) and 12 healthy subjects (63 ± 12 years, 8 males) who underwent 4D flow MRI. The segmented velocity fields were used to estimate: 1) local ascending aorta (AA) pressure changes from Navier-Stokes-derived relative pressure maps (AADP, mmHg), 2) AA wall shear stress (AAWSS, Pa) by estimating local velocity derivatives at the aortic borders, 3) aortic flow vorticity using the λ2 method (AAV, s-1).
Results
AA local pressure change (AADP) was significantly associated with both AAV (
r
= 0.55,
p
= 0.006) and AAWSS (
r
= 0.69,
p
< 0.001) and both associations remained significant after adjustment for diameter, age and BSA (
p
= 0.007 and
p
= 0.003 respectively). Such positive associations indicate that local pressure variations affect local blood flow, generating flow current from high to low pressures and subsequently vortices with the underlying stress exerted on the AA wall.
Conclusion
Local variations in aortic pressures, measured using 4D flow MRI, are associated with flow disorganization as quantified by vorticity and with the increase in the stress exerted on the aortic wall, as quantified by wall shear stress.
Purpose
Referral to surgery in thoracic aortic aneurysms (TAA) is based on maximal diameter (Dmax) measured from imaging, which is known to have a high diagnosis failure rate. In addition to ...geometry, 4D flow MRI provides a comprehensive time-resolved flow imaging. Thus, our aim was to evaluate the ability of 4D flow MRI-derived quantitative flow indices to characterize TAA.
Methods
We studied 20 patients with TAA and tricuspid valve (TAVd, Dmax = 43 ± 5 mm, Age = 66 ± 14 years) and 56 healthy controls (YC: 30 subjects, Age = 36 ± 9 years ≤50 years, OC: 26 subjects, Age = 65 ± 9 years > 50 years). All underwent 4D flow MRI. After aortic segmentation, ascending aorta (AA) backward flow volume (VBF) was calculated in addition to maximal velocity jet angle and eccentricity (Ecc). Receiver operating characteristic analysis was performed to assess the ability of flow indices to characterize AA = dilation.
Results
While AA Dmax was 1.4-fold higher in TAVd than OC, VBF increased by 6.5 folds and Ecc and Angle varied by 1.3 to 1.7 folds between the two groups. Moreover, VBF changed by 12.7 folds between the aneurysmal AA as compared to TAVd descending aorta. Finally, VBF increased consistently with age in all controls and was able to detect AA dilation with a 0.98 accuracy.
Conclusion
AA backward flow quantified from 4D flow MRI outperformed the previously described indices such as flow eccentricity and angle in the characterization of thoracic aortic aneurysms.
Purpose
To provide a comprehensive assessment of aortic stiffness, through both local and regional distensibility and pulse wave velocity (PWV), in patients with either a tricuspid (TAV) or bicuspid ...(BAV) aortic valve and/or aortic dilation using MRI.
Methods
We included 18 patients with TAV and dilated ascending aorta (DTAV, 65 ± 14 years, 11 males), 19 patients with a non-stenotic BAV without severe regurgitation (55 ± 15 years, 17 males), both paired for age, gender and pressures to control groups. All subjects underwent thoracic aortic axial 2D+t and sagittal 3D+t velocity-encoded MRI and carotid applanation tonometry. Local ascending (AA) and descending (DA) aortic distensibility as well as aortic arch PWV were automatically measured from 2D+t data
1
, while regional AA and DA PWV were calculated from 3D+t data
2
.
Results
As expected, both DTAV and BAV groups showed significantly increased maximal aortic diameters when compared to their respective control group: 47 ± 5 vs 31 ± 3 mm and 44 ± 4 vs 31 ± 4 mm, respectively (
p
< 0.001). However, no significant changes were found in local and regional aortic stiffness indices between both patient groups and their matched controls (
p
≥ 0.05).
Conclusion
2D or 3D data-derived distensibility or PWV concomitantly and unexpectedly indicate that aortic stiffness was unchanged in patients with aortopathy when compared to matched healthy controls. Since fundamental laminal flow conditions and elastic properties driving Moens-Korteweg models are not reached in highly dilated aortas, the associated turbulent flow, local flow disorganization, changes in derived pressure gradients and flow-wall forces might be more suitable for an early discrimination of patients with valve/aneurismal disease.
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