Atherosclerotic plaque characterization by CT angiography for identification of high-risk coronary artery lesions: a comparison to optical coherence tomography.

AIMS: Adverse plaque characteristics (APCs) by coronary computed tomography (CT) angiography (CTA) are associated with myocardial ischaemia and future acute coronary syndromes. The overall objective was to determine whether APCs on non-invasive CTA are associated with vulnerable plaque features by invasive optical coherence tomography (OCT). METHODS AND RESULTS: Sixty-eight coronary plaques in 45 patients were evaluated by CTA and OCT. APCs by CTA were: positive remodelling (PR), remodelling index ≥1.10; low attenuation plaque (LAP), any intraplaque voxel <30 Hounsfield units; spotty calcification (SC), intraplaque calcification ≤3 mm; and 'napkin-ring' sign, low intraplaque attenuation surrounded by a higher attenuation rim. OCT evaluated plaques for thin-cap fibroatheroma (TCFA, ≤65 µm, lipid arch >90°) and macrophage infiltration. Increasing plaque vulnerability was graded by OCT as having no TCFA, TCFA without macrophage infiltration, and TCFA with macrophage infiltration. OCT lesions included those with no TCFA (n = 44), TCFA without macrophage infiltration (n = 7), and TCFA with macrophage infiltration (n = 17). Increasing plaque vulnerability grade by OCT was associated with higher diameter stenosis (43.6 vs. 40.7 vs. 57.3%, P = 0.01), and greater prevalence of PR (11 vs. 43 vs. 71%, P < 0.001), LAP (11 vs. 29 vs. 59%, P = 0.001), and SC (2 vs. 29 vs. 18%, P = 0.02), but not for napkin-ring sign (P = 0.18). In multivariable analysis, PR [odds ratio (OR) 16.9, 95% confidence interval (CI) 3.9-73.3, P < 0.001] and LAP (OR 11.2, 95% CI 2.8-44.3, P = 0.001) predicted TCFA with macrophage infiltration, whereas SC and napkin-ring sign did not. CONCLUSION: Plaques demonstrating PR and LAP by CTA are associated with TCFA with macrophage infiltration by OCT.

Utility of right ventricular free wall speckle-tracking strain for evaluation of right ventricular performance in patients with pulmonary hypertension.

BACKGROUND: The objectives of this study were to test the utility of right ventricular (RV) speckle-tracking strain as an assessment tool for RV function in patients with pulmonary hypertension (PH) compared with conventional echocardiographic parameters and to investigate the relationship of the findings obtained with RV speckle-tracking strain with the hemodynamic parameters of RV performance. METHODS: Forty-five prospective consecutive patients with PH were studied. RV free wall longitudinal speckle-tracking strain (RV-free) and RV septal wall longitudinal speckle-tracking strain (RV-septal) were calculated by averaging each of three regional peak systolic strains along the entire right ventricle. The conventional echocardiographic parameters-RV fractional area change, RV myocardial performance index, tricuspid annular plane systolic excursion, and tricuspid annular peak systolic velocity-were also studied. For comparison, 22 age-matched volunteers with normal ejection fractions were studied. RESULTS: RV-free in patients with PH was significantly lower than that in normal controls, but RV-septal in the two groups was similar. Importantly, multivariate analysis revealed that RV-free was an independent echocardiographic predictor of hemodynamic RV performance items, including mean pulmonary artery pressure (ß = -0.844, P = .001) and pulmonary vascular resistance (ß = -0.045, P < .001). RV-free was also correlated with RV ejection fraction and RV end-systolic volume measured by cardiac magnetic resonance imaging and with 6-min walking distance (r = 0.60, r = 0.56, and r = 0.49, respectively, P < .05). Furthermore, the improvement in RV-free 5 ± 3 months after adding medical treatment was significantly correlated with that in 6-min walking distance (r = 0.68, P < .0001). CONCLUSIONS: RV-free has the potential to allow for noninvasive follow-up of patients with PH.

Circadian expression of clock genes in human peripheral leukocytes.

In mammals, behavioral and physiological processes display 24-h rhythms that are regulated by a circadian system. In the present study, we investigated the possibility that the expression of clock genes in peripheral leukocytes can be used to assess the circadian clock system. We found that Per1 and Per2 exhibit circadian oscillations in mRNA expression in mouse peripheral leukocytes. Furthermore, the rhythms of Per1 and Per2 mRNA expression in peripheral leukocytes are severely blunted in homozygous Cry1/2 double-deficient mice that are known to have an abolished biological clock. We have examined the circadian expression of clock genes in human leukocytes and found that Per1 mRNA exhibits a robust circadian expression while Per2 and Bmal1 mRNA showed weak rhythm. These observations suggest that monitoring Per1 mRNA expression in human leukocytes may be useful for investigating the function of the circadian system in physiological and pathophysiological states.

Alterations of circadian expressions of clock genes in Dahl salt-sensitive rats fed a high-salt diet.

In mammals, behavioral and physiologic processes display 24-hour rhythms that are regulated by a circadian system consisting of central and peripheral oscillators. Because various cardiovascular functions show diurnal variations and abnormal patterns of circadian blood pressure variation carry a high risk of cardiovascular complications, we investigated whether the expression of clock genes is altered in an animal model of hypertension. In Dahl salt-sensitive rats fed a high-salt (4% NaCl) diet for 6 weeks (DS-H), radiotelemetry monitoring showed increased amplitude of circadian variations in blood pressure. The ratio of heart weight to body weight and the ratio of kidney weight to body weight were higher in DS-H. Echocardiographic data showed that the wall thickness of the left ventricle was greater in DS-H. Northern blot analysis and single cosinor analysis revealed that the amplitudes of circadian expression changes of the clock genes (mPer2, Bmal1, and dbp) in the heart, liver, and kidney were significantly decreased in DS-H rats compared with a normal-salt-diet group, except for Bmal1 in the liver. The circadian expression changes of plasminogen activator inhibitor-1, a clock-regulated gene, were attenuated in the hearts of DS-H. The present results demonstrate that DS-H show altered circadian expression of peripheral clock genes. Detailed analyses of the relation between circadian expression of clock genes and blood pressure regulation might reveal a role for chronologic therapy of cardiovascular disease.