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Background: While it is widely assumed that coronary CT angiography permits detection and quantification of 'positive remodelling' of coronary atherosclerotic lesions, there is a paucity of data comparing CT with established reference methods., Objective: To assess the accuracy of dual-source CT for detecting positive versus absent or negative coronary artery remodelling of coronary atherosclerotic lesions as compared with intravascular ultrasound (IVUS)., Methods: The datasets were evaluated of 38 patients referred for invasive coronary angiography and in whom an IVUS study of one coronary vessel was performed. Coronary CT angiography was performed within 24 h before invasive coronary angiography. Using dual-source CT (Siemens Healthcare, Forchheim, Germany), a contrast-enhanced volume dataset was acquired (120 kV, 400 mA/rot, collimation 2×64×0.6 mm, 60-80 ml contrast agent, intravenous). IVUS was performed using a 40 MHz IVUS catheter (Atlantis, Boston Scientific Corporation, Natick, Massachusetts, USA) and motorised pullback at 0.5 mm/s. 48 corresponding non-calcified and partially calcified plaques within the coronary artery system were identified in both CT and IVUS using bifurcation points as fiducial markers. In CT datasets, multiplanar reconstructions orthogonal to the centre line of the coronary artery were rendered and cross-sectional vessel area was measured at the site of maximal narrowing as well as at a reference segment proximal to the lesion for each of the 48 plaques. The remodelling index (RI) was calculated by dividing the vessel area at the site of maximal narrowing by the area of the reference segment. Corresponding vessel areas and RIs were also determined in IVUS., Results: CT classified 41 plaques as positively remodelled (RI≥1.05) and seven as having either absent or negative remodelling (RI<1.05). In IVUS 29 plaques demonstrated positive remodelling, while 19 did not. Mean cross-sectional vessel areas measured by CT at the lesion and at the reference segment were 19±5 mm(2) and 17± 5 mm(2), respectively, versus 18±5 mm(2) and 17±5 mm(2) for IVUS (mean difference 1±2 mm(2) and -0.2±1 mm(2), p<0.0001 and 0.8, respectively). The mean RI in CT was significantly larger than in IVUS (1.2±0.2 vs 1.1±0.2, p<0.0001). Correlation between CT and IVUS was higher for vessel area measurements (r>0.9, p<0.0001) than for remodelling indices (r=0.7, p<0.0001) with Bland-Altman analysis showing a systematic overestimation of vessel areas and RI in CT. Interobserver agreement was moderate for CT and IVUS measurements. Receiver operating characteristic curve analysis showed that a RI of 1.1 in CT identified positively remodelled plaques in IVUS with a sensitivity of 83% and a specificity of 78% (area under the curve=0.8, 95% CI 0.7 to 1.0). Using the standard cut-off point of 1.05 to identify positively remodelled plaques in CT resulted in a sensitivity of 100%, and a specificity of 45%., Conclusion: Coronary CT angiography allows analysis of coronary artery remodelling. The degree of positive remodelling is typically overestimated by CT. A threshold of 1.1 for the RI may be optimal to classify plaques as 'positively remodelled' in coronary CT angiography.

Background: The quantification of non-calcified coronary plaques using multidetector computed tomography has not been extensively investigated., Objective: To evaluate the ability of dual-source computed tomography (DSCT) to quantify non-calcified plaque volumes using intravascular ultrasound (IVUS) as the standard of reference., Methods: The datasets of 70 patients with suspected or known coronary artery disease who underwent DSCT (330 ms gantry rotation, 2 x 64 x 0.6 mm collimation, 60-90 ml contrast agent) were analysed before invasive coronary angiography, with IVUS performed as part of the diagnostic procedure. 100 individual non-calcified coronary atherosclerotic plaques (one to three plaques per patient) with suitable fiducial markers were matched and selected for plaque volume measurements using manual segmentation. Only DSCT datasets with good or excellent image quality were considered for analysis., Results: Intra and interobserver variability for plaque volume measurements by DSCT were 6+/-5% and 11+/-7%, respectively. Mean total plaque volume by DSCT was 89+/-66 mm(3) (range 14-400 mm(3)). Mean total plaque volume by IVUS was 90+/-73 mm(3) (range 16-409 mm(3)). The mean difference between DSCT and IVUS was 1+/-34 mm(3) (range -131-85 mm(3)). Despite the good correlation for plaque volume measurements (r=0.89, p<0.001), agreement between the two methods was only modest (Bland-Altman limits of agreement -67 to +65 mm(3)). CONCLUSIONS ; Non-calcified plaque volumes as determined by DSCT yielded good correlation but only modest agreement in comparison with IVUS.

Background: Multidetector CT allows detection of coronary artery calcium and, after contrast injection, visualisation of the coronary artery lumen. It is commonly assumed that the absence of coronary calcification makes the presence of obstructive coronary lesions highly unlikely. This study evaluates the clinical characteristics of patients with at least one symptomatic, high-grade coronary artery stenosis in both computed tomography and invasive angiography but absence of any coronary calcification and compares the results with patients with stenoses in the setting of detectable coronary calcium, Patients and Methods: The study retrospectively identified 21 consecutive patients with symptoms in whom a high-grade coronary artery stenosis had been identified in 64-slice or dual-source CT coronary angiography (Siemens Sensation 64 or Siemens Definition, 120 kV, 50 to 85 ml of intravenous contrast at 5 ml/s) in the absence of coronary calcium and in whom that finding had been confirmed by invasive coronary angiography. Clinical presentation ("unstable": all forms of acute coronary syndrome versus "stable": stable chest pain or dyspnoea on exertion) and standard cardiovascular risk factors were assessed, and the results were compared with 42 consecutive patients with symptoms in whom both coronary calcium and coronary stenoses had been identified in computed tomography and invasive coronary angiography., Results: The majority of patients with coronary stenoses in the absence of coronary calcium presented with "unstable" symptoms (non-ST-segment elevation myocardial infarction (NSTEMI) or unstable angina), significantly more frequently than patients with detectable calcification (71% vs 26%, p = 0.001). The age range of patients without calcium was 33 to 76 years, their mean age was younger (53 (SD 13) vs 63 (8) years, p<0.001), but none of the risk factors showed any significant difference compared with patients with calcification., Conclusion: The presence of significant coronary artery stenosis in the absence of coronary calcium is possible. It is more likely in the setting of unstable angina or NSTEMI than in stable chest pain and occurs more frequently in younger patients.

Background: Increasing scientific data suggest a role for inflammation in chronic heart failure (CHF), but up to now the exact mechanisms are still not clear. Recently, platelets were identified as inducing inflammation partly by releasing cytokines. This new aspect necessitates further studies about the contribution of platelets for the inflammatory setting of CHF., Methods: 50 CHF patients (mean 66.9 (SD 12.6) years, mean EF 22.1% (SD 9.1)) and 25 healthy controls (mean 63.6 (SD 10.2) years) were examined. MCP-1 serum levels were measured via EIA, expression of platelet CD154 by flow cytometry. In in-vitro experiments activated platelets were cocultured with human umbilical vein endothelial cells (HUVEC) in the presence and absence of anti-CD154 antibodies. MCP-1 in the supernatants was measured by EIA., Results: CHF patients showed significantly enhanced MCP-1 levels (median: 191.8; 25th centile: 153.7; 75th centile: 227.1 pg/ml vs median: 101.0; 25th centile: 86.7; 75th centile: 117.5 pg/ml, p<0.001). MCP-1 levels positively correlated with severity of CHF. In the cell coculture model activated platelets were able to significantly induce MCP-1 release from HUVEC in a CD154-dependent manner. Furthermore, CHF patients showed enhanced platelet CD154 expression with a positive correlation with MCP-1 levels. Aspirin therapy had no influence on either CD154 expression or MCP-1 levels., Conclusions: Platelets can contribute to enhanced MCP-1 levels in CHF. MCP-1 is markedly elevated in serum of CHF patients showing a direct correlation with the severity of symptoms and the degree of left ventricular dysfunction. Further studies are required to test whether MCP-1 blocking or sophisticated anti-platelet strategies may represent new therapeutic options in CHF.

Objective: To compare the presence and extent of coronary calcifications in young patients with first, unheralded acute myocardial infarction with matched controls without a history of coronary artery disease., Methods: In 102 patients under 60 years of age (19-59 years, mean 41 years; 88% male), electron beam tomography was done 1-14 days after acute myocardial infarction, before any coronary intervention. Coronary calcifications were quantified using the Agatston score. Age related calcium centiles were determined based on the Mayo Clinic "epidemiology of coronary calcification" study, and results were compared with a group of 102 controls without coronary artery disease, matched for sex, age, and risk factors., Results: Calcifications were present in 95.1% of patients with acute myocardial infarction and in 59.1% of controls (p = 0.008). The mean (SD) Agatston score was 529 (901) in the infarct patients versus 119 (213) in the controls (p < 0.001). An Agatston score above the 50th centile was present in 87.2% of infarct patients and 47.0% of controls (p = 0.006), and above the 90th centile in 60.7% of infarct patients and only 5.8% of controls (p = 0.001)., Conclusions: In young patients with their first, unheralded acute myocardial infarction, the presence and extent of coronary calcium are significantly greater than in matched controls.

Objective: To investigate whether CD40L/CD154 on platelets and soluble CD40L/CD154 may play a role in the inflammatory process of acute coronary syndromes., Design and Setting: Observational study in a university hospital., Patients: 15 patients with acute myocardial infarction, 25 patients with unstable angina, 15 patients with stable angina, and 12 controls., Main Outcome Measures: CD40L/CD154 on platelets, P-selectin/CD62P on platelets, soluble CD40L/CD154 serum concentrations., Results: Mean (SD) CD40L/CD154 expression on platelets was 6.2 (2.8) MFI (mean fluorescence intensity) in the infarct group, 11 (3.3) MFI in the unstable angina group (p < 0.001 v infarction), 3.6 (0.9) MFI in the stable angina group (p < 0.01 v infarction; p < 0.001 v unstable angina), and 3.2 (1.0) MFI in the controls (p < 0.01 v infarction; p < 0.001 v unstable angina; NS v stable angina). Soluble CD40L/CD154 concentration was 5.2 (1.1) ng/ml in the infarct group, 4.2 (0.7) ng/ml in the unstable angina group (p < 0.001 v infarction), 2.9 (1.0) ng/ml in stable angina group (p < 0.001 v infarction and unstable angina), and 3.0 (0.5) ng/ml in the controls (p < 0.001 v infarction and unstable angina; NS v stable angina). At a six months follow up, there was lower expression of CD40L/CD154 on platelets in patients with unstable angina (12.3 (3.6) v 3.8 (1.2) MFI, p < 0.0001) and acute myocardial infarction (6.2 (2.8) v 3.5 (0.8) MFI, p < 0.01) compared with their admission values six months earlier. Patients with unstable angina who needed redo coronary angioplasty (PTCA) or who had recurrence of angina were characterised by increased CD40L/CD154 expression on platelets compared with the remainder of the study group (recurrence of angina: 12.7 (3.2) v 9.7 (1.6) MFI, p < 0.05; re-do PTCA: 14.3 (4.2) v 10.3 (2.1) MFI, p < 0.05)., Conclusions: Both CD40L/CD154 on platelets and soluble CD40L/CD154 are raised in patients with unstable angina and myocardial infarction. These findings suggest that CD40-CD40L/CD154 interactions may play a pathogenic role in triggering and propagation of acute coronary syndromes.

Objective: To evaluate the accuracy of contrast enhanced electron beam computed tomography (EBCT) after acute myocardial infarction in determining patency of the infarct related artery and detecting high grade stenoses and occlusions in the coronary vessels., Design: Case study using blinded comparison with invasive coronary angiography., Patients: 36 patients (mean age 53 years) 4-70 days after acute myocardial infarction., Interventions: The patients were studied by EBCT and invasive coronary angiography. For EBCT, 50 axial images of the heart (3 mm slice thickness) were acquired. They were triggered by the ECG during breath holding, after intravenous injection of contrast agent. The original images, surface reconstructions, and maximum intensity projections were evaluated for the presence of high grade stenoses and occlusions of the coronary arteries., Main Outcome Measures: EBCT results were compared with invasive coronary angiography., Results: Of a total of 144 coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery in 36 patients), 29 (20%) were unevaluable by EBCT. In the remaining arteries, 33 of 36 high grade lesions were correctly detected (92% sensitivity). Specificity was also 92% (73/79). Patency of the infarct related artery was correctly detected in 15 of 16 cases (94%). Five of the 14 occluded infarct related arteries (35%) were mistaken as stenotic but patent, and six could not be assessed., Conclusions: EBCT is very accurate in detecting significant coronary artery lesions in patients after acute myocardial infarction, but differentiation between occluded and patent infarct related arteries is currently unreliable.