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Characterization of endothelial shear stress (ESS) may allow for prediction of the progression of atherosclerosis. The aim of this investigation was to develop a non-invasive approach for in vivo assessment of ESS by coronary computed tomography angiography (CTA) and to compare it with ESS derived from invasive coronary angiography (ICA). A total of 41 patients with mild or intermediate coronary stenoses who underwent both CTA and ICA were included in the analysis. Two geometrical models of the interrogated vessels were reconstructed separately from CTA and ICA images. Subsequently, computational fluid dynamics were applied to calculate the ESS, from which ESS CTA and ESS ICA were derived, respectively. Comparisons between ESS CTA and ESS ICA were performed on 163 segments of 57 vessels in the CTA and ICA models. ESS CTA and ESS ICA were similar: mean ESS: 4.97 (4.37-5.57) Pascal versus 4.86 (4.27-5.44) Pascal, p = 0.58; minimal ESS: 0.86 (0.67-1.05) Pascal versus 0.79 (0.63-0.95) Pascal, p = 0.37; and maximal ESS: 14.50 (12.62-16.38) Pascal versus 13.76 (11.44-16.08) Pascal, p = 0.44. Good correlations between the ESS CTA and the ESS ICA were observed for the mean (r = 0.75, p < 0.001), minimal (r = 0.61, p < 0.001), and maximal (r = 0.62, p < 0.001) ESS values. In conclusion, geometrical reconstruction by CTA yields similar results to ICA in terms of segment-based ESS calculation in patients with low and intermediate stenoses. Thus, it has the potential of allowing combined local hemodynamic and plaque morphologic information for risk stratification in patients with coronary artery disease.

Calculation of fractional flow reserve (FFR) based on computational fluid dynamics (CFD) requires reconstruction of patient-specific coronary geometry and estimation of hyperemic flow rate. Coronary computed tomography angiography (CCTA) and invasive coronary angiography (ICA) are two dominating imaging modalities used for the geometrical reconstruction. Our aim was to investigate the impact of image resolution as inherently associated with these two imaging modalities on geometrical reconstruction and subsequent FFR calculation. Patients with mild or intermediate coronary stenoses who underwent both CCTA and ICA were included. CCTA images were acquired either by 320-row area detector CT or by 128-slice dual-source CT. Two geometrical models were reconstructed separately from CCTA and ICA, from which FFRCTA and FFRQCA were subsequently calculated using CFD simulations, applying the same hyperemic flow rate derived from the ICA images at the inlet boundaries. A total of 57 vessels in 41 patients were analyzed. Average diameter stenosis was 43.4 ± 10.8 % by 3D QCA. Reasonably good correlation between FFRCTA and FFRQCA was observed (r = 0.71, p < 0.001). The difference between FFRCTA and FFRQCA was correlated with the deviation between minimal lumen areas by CCTA and by ICA (ρ = 0.34, p = 0.01), but not with plaque volume (ρ = -0.09, p = 0.51) or calcified plaque volume (ρ = 0.01, p = 0.95). Applying the cutoff value of ≤0.8 to both FFRCTA and FFRQCA, the agreement between FFRCTA and FFRQCA in discriminating functional significant stenoses was moderate (kappa 0.47, p < 0.001). Disagreement was found in 10 (17.5 %) vessels. Acceptable correlation between FFRCTA and FFRQCA was observed, while their agreement in distinguishing functional significant stenosis was moderate. Our results suggest that image resolution has a significant impact on FFR computation.

The evolution of the oxidative metabolism of (11)C acetate parallels the recovery of left ventricular(LV) contraction following acute myocardial infarction(AMI). This study was designed to unravel, for the first time, the impact of the global washout rate(WR) of (123)I-beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) on the recovery of LV function followingAMI, as evidenced from conventional echocardiography.Twenty consecutive patients (age: 58 +/- 13 years; 16 males and 4 females) with ST-segment elevation myocardial infarction (STEMI) were enrolled and all of them underwent successful percutaneous coronary intervention (PCI). (123)I-BMIPP cardiac scintigraphy was performed at 7 +/- 3 days after admission. The WR was calculated from the polar map and the regional BMIPP defect score was calculated using a 17 segment model. Echocardiography was performed within 24 h of admission and at 3 months to record the ejection fraction (EF), the wall motion score index (WMSI), the ratio of the mitralinflow velocity to the early diastolic velocity (E/E0)and the myocardial performance index (MPI). The mean global WR of the BMIPP was 22.12 +/- 7.22%, and it was significantly correlated with the improvement of the WMSI (r = 0.61, P\0.004). However,the relative changes of the EF, E/E0 and MPI were not correlated with the WR. The BMIPP defect score (18 +/- 10) was significantly correlated with the WMSI on admission (r = 0.74, P = 0.0002), but the defect score was not correlated with the relative changes of any of the echocardiographic parameters. We proved that the WR of the BMIPP is a promising indicator of improvement of the LV wall motion (WMSI) following ST-segment elevation myocardial infarction and successful reperfusion.

(123)I-beta-methyl-iodophenyl pentadecanoic acid (BMIPP) and (99m)Tc-Tetrofosmin (TF) mismatch designated as stunned myocardium having both systolic and diastolic components. The degree of mismatch might reflect subsequent functional improvement, and this study was designed to unravel the impact of mismatched defect score (MMDS) on recovery of both systolic and diastolic function following acute myocardial infarction (AMI). Forty patients with recent AMI were recruited, and all of them underwent emergency percutaneous coronary intervention. Echocardiography and BMIPP and TF cardiac scintigraphy were performed on 7 +/- 3 days of admission. Follow up echocardiography was performed after 3 months. MMDS were compared with the systolic [ejection fraction (EF) and wall motion score index (WMSI)] and diastolic [peak velocity of early diastolic filling of mitral inflow/peak early diastolic velocity of the mitral annulus(E/E') and left atrial volume index(LAVI)] parameters. BMIPP defect score was significantly higher than the TF defect score and there was a strong positive correlation between them (r = 0.90, P < 0.00001). Thirty-two (80%) patients showed mismatched defect and rest 8(20%) showed matched defect. Of 32 patients 24(75%), 22(69%), 19(59%), and 20(62.5%) showed improved EF, WMSI, E/E' and LAVI respectively. Conversely out of 8 only 2(25%), 1(12.5%), and 2(25%) patients showed improvement of EF, WMSI and LAVI, respectively. E/E' was not improved in patients with matched defect. MMDS were significantly correlated with the improvement of EF (r = -0.46, P = 0.002), WMSI (r = 0.41, P = 0.007), E/E' (r = 0.56, P < 0.0002), and LAVI (r = 0.44, P = 0.004). Mismatched defect score could predict the approximate amount of viable dysfunctional myocardium, and the degree of mismatch showed a significant correlation with the improvement of both systolic and diastolic function.