CT Attenuation of Pericoronary Adipose Tissue in Normal Versus Atherosclerotic Coronary Segments as Defined by Intravascular Ultrasound.

BACKGROUND: The factors influencing genesis of atherosclerosis at specific regions within the coronary arterial system are currently uncertain. Local mechanical factors such as shear stress as well as metabolic factors, including inflammatory mediators released from epicardial fat, have been proposed. We analyzed computed tomographic (CT) attenuation of pericoronary adipose tissue in normal versus atherosclerotic coronary segments as defined by intravascular ultrasound (IVUS). PATIENTS AND METHODS: We evaluated the data sets of 29 patients who were referred for invasive coronary angiography and in whom IVUS of 1 coronary vessel was performed for clinical reasons. Coronary CT angiography was performed within 24 hours from invasive coronary angiography. Computed tomographic angiography was performed using dual-source CT (Siemens Healthcare; Forchheim, Germany). A contrast-enhanced volume data set was acquired (120 kV, 400 mA/rot, collimation 2 × 64 × 0.6 mm, 60-80 mL intravenous contrast agent). Intravascular ultrasound was performed using a 40-MHz IVUS catheter (Atlantis; Boston Scientific Corporation, Natick, Mass) and motorized pullback at 0.5 mm/s. Sixty corresponding coronary artery segments within the coronary artery system were identified in both dual source computed tomography and IVUS using bifurcation points as fiducial markers. In dual source computed tomography data sets, 8 serial parallel cross sections (2-mm slice thickness) were rendered orthogonal to the center line of the coronary artery for each segment. For each cross section, pericoronary adipose tissue within a radius of 3 mm from the coronary artery and enclosed within the epicardium (excluding coronary veins and myocardium) was manually traced and mean CT attenuation values were obtained. Intravascular ultrasound was used to define coronary segments as follows: presence of predominantly fibrous atherosclerotic plaque (hyperechoic), presence of predominantly lipid-rich atherosclerotic plaque (hypoechoic), and absence of atherosclerotic plaque. RESULTS: In IVUS, 20 coronary segments with fibrous plaque, 20 segments with lipid-rich plaque, and 20 coronary segments without plaque were identified. The mean CT attenuation of pericoronary adipose tissue for segments with any coronary atherosclerotic plaque was -34 ± 14 Hounsfield units (HU), as compared with -56 ± 16 HU for segments without plaque (P = 0.005). The density of pericoronary fat in segments with fibrous versus lipid-rich plaque as defined by IVUS was not significantly different (-35 ± 19 HU vs -36 ± 16 HU, P = 0.8). CONCLUSIONS: Mean CT attenuation of pericoronary adipose tissue is significantly lower for normal versus atherosclerotic coronary segments. This supports a hypothesis of different types of pericoronary adipose tissue, the more metabolically active of which might exert local effects on the coronary vessels, thus contributing to atherogenesis.

Reproducibility of aortic annulus measurements by computed tomography.

OBJECTIVES: To evaluate a systematic approach for measurement of aortic annulus dimensions by cardiac computed tomography. METHODS: CT data sets of 64 patients were evaluated. An oblique cross-section aligned with the aortic root was created by systematically identifying the caudal insertion points of the three aortic cusps and sequentially aligning them in a double oblique plane. Aortic annulus dimensions, distances of coronary ostia and a suitable fluoroscopic projection angle were independently determined by two observers. RESULTS: Interobserver intraclass correlation coefficients (ICC) for aortic annulus diameters were excellent (ICC 0.89-0.93). Agreement for prosthesis size selection was excellent (ĸ = 0.86 for mean, ĸ = 0.84 for area-derived and ĸ = 0.91 for circumference-derived diameter). Mean distances of the left/right coronary ostium were 13.4 ± 2.4/14.4 ± 2.8 mm for observer 1 and 13.2 ± 2.7/13.5 ± 3.2 mm for observer 2 (p = 0.30 and p = 0.0001, respectively; ICC 0.76/0.77 for left/right coronary artery). A difference of less than 10° for fluoroscopic projection angle was achieved in 84.3% of patients. CONCLUSIONS: A systematic approach to generate a double oblique imaging plane exactly aligned with the aortic annulus demonstrates high interobserver and intraobserver agreements for derived measurements which are not influenced by aortic root calcification. KEY POINTS: • Systematic approach to generate a double oblique imaging plane for TAVI evaluation. • This method is straightforward and software independent. • An approach with high reproducibility, not influenced by aortic root calcification.

Accuracy of automated software-guided detection of significant coronary artery stenosis by CT angiography: comparison with invasive catheterisation.

PURPOSE: True automated detection of coronary artery stenoses might be useful whenever expert evaluation is not available, or as a "second reader" to enhance diagnostic confidence. We evaluated the accuracy of a PC-based stenosis detection tool alone and combined with expert interpretation. METHODS: One hundred coronary CT angiography datasets were evaluated with the automated software alone, by manual interpretation (axial images, multiplanar reformations and maximum intensity projections in free double-oblique planes), and by expert interpretation aware of the automated findings. Stenoses ≥ 50 % were noted per-vessel and per-patient, and compared with invasive angiography. RESULTS: Automated post-processing was successful in 90 % of patients (88 % of vessels). When excluding uninterpretable datasets, per-patient sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 89 %, 79 %, 74 % and 92 % (per-vessel: 82 %, 85 %, 48 % and 96 %). All 100 datasets were evaluable by expert interpretation. Per-patient sensitivity, specificity, PPV and NPV were 95 %, 95 %, 93 % and 97 % (per-vessel: 89 %,98 %, 88 % and 98 %). Knowing the results of automated interpretation did not improve the performance of expert readers. CONCLUSION: Automated off-line post-processing of coronary CT angiography shows adequate sensitivity, but relatively low specificity in coronary stenosis detection. It does not increase accuracy of expert interpretation. Failure of post-processing in 10 % of all patients necessitates additional manual image work-up. KEY POINTS: • Coronary CT angiography is increasingly used for detection of coronary artery stenosis • Computer assisted diagnosis might facilitate and speed up interpretation • Performance in properly segmented cases compared favourably with manual image interpretation • However, automated segmentation failed in about 10 % of cases • Manual reading is still mandatory; computer assisted diagnosis can provide a useful second read.

Image quality of ultra-low radiation exposure coronary CT angiography with an effective dose <0.1 mSv using high-pitch spiral acquisition and raw data-based iterative reconstruction.

OBJECTIVES: We evaluated the potential of prospectively ECG-triggered high-pitch spiral acquisition with low tube voltage and current in combination with iterative reconstruction to achieve coronary CT angiography with sufficient image quality at an effective dose below 0.1 mSv. METHODS: Contrast-enhanced coronary dual source CT angiography (2 × 128 × 0.6 mm, 80 kV, 50 mAs) in prospectively ECG-triggered high-pitch spiral acquisition mode was performed in 21 consecutive individuals (body weight <100 kg, heart rate ≤60/min). Images were reconstructed with raw data-based filtered back projection (FBP) and iterative reconstruction (IR). Image quality was assessed on a 4-point scale (1 = no artefacts, 4 = unevaluable). RESULTS: Mean effective dose was 0.06 ± 0.01 mSv. Image noise was significantly reduced in IR (128.9 ± 46.6 vs. 158.2 ± 44.7 HU). The mean image quality score was lower for IR (1.9 ± 1.1 vs. 2.2 ± 1.0, P < 0.0001). Of 292 coronary segments, 55 in FBP and 40 in IR (P = 0.12) were graded "unevaluable". In patients with a body weight ≤75 kg, both in FBP and in IR, the rates of fully evaluable segments were significantly higher in comparison to patients >75 kg. CONCLUSIONS: Coronary CT angiography with an estimated effective dose <0.1 mSv may provide sufficient image quality in selected patients through the combination of high-pitch spiral acquisition and raw data-based iterative reconstruction.

Coronary vessel and luminal area measurement using dual-source computed tomography in comparison with intravascular ultrasound: effect of window settings on measurement accuracy.

BACKGROUND: Image display settings (window and level) have a substantial impact on measurements of coronary artery and plaque dimensions in computed tomography (CT), and their influence on measurement accuracy has not been systematically evaluated. We analyzed the influence of window width/level settings on the accuracy for determining cross-sectional lumen and outer vessel diameters in contrast-enhanced CT angiography compared with intravascular ultrasound (IVUS). METHODS: We evaluated the data sets of 35 patients. Coronary CT angiography was performed as part of a research protocol before invasive coronary angiography. A contrast-enhanced volume data set was acquired using a dual-source CT (DSCT) scanner (Siemens Healthcare, Forchheim, Germany). Intravascular ultrasound was performed using a 40-MHz IVUS catheter (Atlantis, Boston Scientific Corporation, Natick, Mass) and motorized pullback at 0.5 mm/s. One hundred exactly corresponding sites within the coronary artery system were identified in both DSCT and IVUS using bifurcation points as fiducial markers. In DSCT data sets, multiplanar reconstructions (0.75-mm slice thickness) were rendered orthogonally to the centerline of the coronary artery at each of the 100 sites. Computed tomographic images were displayed using 4 previously published settings (700/200, 700/140, and 500/150 Hounsfield units [HU], and 1 HU/65% of the mean luminal intensity [HU] and 155%/65% of the mean luminal intensity [HU] for window width/level) as well as with a visually adjusted setting for subjectively optimal lumen and outer vessel area measurement. Coronary lumen and cross-sectional vessel areas were manually traced using all 5 display settings and compared with IVUS measurements. RESULTS: Concerning cross-sectional vessel area measurements, correlation was close and significant compared with IVUS using all settings (r ≥ 0.93, P = 0.01 for all settings). Bland-Altman analysis revealed a good agreement between both modalities with a systematic bias toward overestimation in CT. Least bias was demonstrated using the setting 155%/65% of the mean luminal intensity for window width/level, with a mean (SD) difference of 0.2 (1.73) mm2. For the measurement of the luminal area, the window setting using a width of 1 HU and a level of 65% of the mean luminal intensity showed the lowest correlation to IVUS (r = 0.85), with a systematic bias toward underestimation of the lumen in CT. Bland-Altman analysis revealed a moderate agreement with a mean (SD) difference of -2.1 (1.6) mm2. For all other settings, a very close correlation was observed (r > 0.9, P = 0.01), and Bland-Altman analysis revealed a slight trend toward lumen underestimation in CT, yet with a good agreement. The least bias was demonstrated using the setting 700/200 HU for window width/level with a mean (SD) difference of -0.1 (0.9) mm2. CONCLUSION: Previously published window settings and visually adjusted window setting correlate very well with IVUS measurements regarding coronary artery cross-sectional and luminal area, with a better agreement for luminal area measurements. A systematic bias toward overestimation of vessel area in CT was observed as well as a slight trend toward lumen underestimation. This bias was least for vessel area measurement using 155%/65% of the mean luminal intensity (HU) for window width/level, whereas for luminal area measurement, the setting 700/200 HU for window width/level yielded the least bias.

Accuracy of dual-source computed tomography to identify significant coronary artery disease in patients with atrial fibrillation: comparison with coronary angiography.

AIMS: It has been previously reported that the sensitivity and specificity of multislice computed tomography (CT) for detecting significant coronary artery disease (CAD) is high. However, regular sinus rhythm has been considered a prerequisite for an adequate examination, even though atrial fibrillation (AF) is common among patients evaluated for the presence of coronary heart disease. In this study, we investigated the sensitivity and specificity of dual-source CT (DSCT) to detect and rule out significant coronary stenoses in patients with AF referred for invasive coronary angiography. METHODS AND RESULTS: One hundred and ten consecutive patients with AF who were admitted for a first diagnostic coronary angiogram were screened for participation. Out of these, 50 patients were excluded either due to renal insufficiency, inability to maintain an adequate breath hold or due to rapid AF non-responsive to ß-blocker therapy (heart rate > 100 b.p.m.). Sixty remaining patients (mean age 71 ± 7 years) were included and subjected to CT angiography using DSCT within 24 h before invasive coronary angiography. A contrast-enhanced volume data set was acquired (330 ms gantry rotation, collimation 2 × 64 × 0.6 mm, retrospective electrocardiogram gating). Data sets were evaluated concerning the presence or absence of significant coronary stenoses and validated against invasive coronary angiography. A significant stenosis was assumed if the diameter reduction was ≥50%. Mean heart rate during CT was 70 ± 15 b.p.m. (range 32-107 b.p.m.). On a per-patient basis, the sensitivity and specificity for DSCT to detect significant coronary stenoses in vessels >1.5 mm diameter was 100% [14/14, 95% confidence interval (CI) 77-100] and 85% (39/46, 95% CI 71-94), respectively, with a negative predictive value (NPV) of 100% (39/39, 95% CI 91-100) and a positive predictive value (PPV) of 67% (14/21, 95% CI 43-85). On a per-artery basis, 240 vessels were evaluated (left main, left anterior descending, left circumflex, and right coronary artery in 60 patients, with 3 non-assessable vessels due to either severe calcification or motion artefacts which were considered positive for stenoses) with a sensitivity of 95% (21/22, 95% CI 77-100) and specificity of 94% (204/218, 95% CI 89-97); NPV was 99% (204/205, 95% CI 96-100), and PPV was 60% (21/35, 95% CI 38-80). CONCLUSION: Our study demonstrates high sensitivity, specificity, and NPV of DSCT to detect significant CAD in selected patients with rate controlled AF.

Coronary computed tomography angiography with a consistent dose below 1 mSv using prospectively electrocardiogram-triggered high-pitch spiral acquisition.

AIMS: We evaluated the feasibility and image quality of a new scan mode for coronary computed tomography angiography (CTA) with an effective dose of less than 1 mSv. METHODS AND RESULTS: In 50 consecutive patients (body weight

Prevalence of first-pass myocardial perfusion defects detected by contrast-enhanced dual-source CT in patients with non-ST segment elevation acute coronary syndromes.

OBJECTIVE: To investigate the prevalence and diagnostic value of first-pass myocardial perfusion defects (PD) visualised by contrast-enhanced multidetector computed tomography (MDCT) in patients admitted for a first acute coronary syndrome (ACS). METHODS: Thirty-eight patients with non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (UA) and scheduled for percutaneous coronary intervention underwent dual-source CT immediately before catheterisation. CT images were analysed for the presence of any PD by using a 17-segment model. Results were compared with peak cardiac troponin-I (cTnI) and angiography findings. RESULTS: PD were seen in 21 of the 24 patients with NSTEMI (median peak cTnI level 7.07 ng/mL; range 0.72-37.07 ng/mL) and in 2 of 14 patients with UA. PD corresponded with the territory of the infarct-related artery in 20 out of 22 patients. In a patient-based analysis, sensitivity, specificity, negative and positive predictive values of any PD for predicting NSTEMI were 88%, 86%, 80% and 91%. Per culprit artery, the respective values were 86%, 75%, 80% and 83%. CONCLUSION: In patients with non-ST segment elevation ACS, first-pass myocardial PD in contrast-enhanced MDCT correlate closely with the presence of myocardial necrosis, as determined by increases in cTnI levels.

Radiation exposure and image quality in staged low-dose protocols for coronary dual-source CT angiography: a randomized comparison.

OBJECTIVE: To evaluate staged low-dose approaches for coronary CT angiography (CTA) in which a standard sequence was added if the low-dose sequence did not allow reliable rule-out of coronary stenosis. PATIENTS AND METHODS: A total of 176 consecutive patients referred for dual-source CTA were randomized to three protocols: group 1 using prospective ECG-triggering (100 kV, 330 mAs), group 2 a retrospectively gated "MinDose" sequence (100 kV, 330 mAs) and group 3 a standard spiral sequence (120 kV, 400 mAs). If image quality in low-dose groups 1 or 2 was non-diagnostic, an additional standard CT examination (as in group 3) was performed. RESULTS: Non-diagnostic image quality was found in 11/56, 4/55, and 2/65 patients (46/896, 4/880 and 3/1,040 coronary segments) in groups 1, 2 and 3, respectively. Median (interquartile ranges) volumes of contrast material, CTDI(vol), DLP and effective dose for low-dose groups 1 and 2 and for standard group 3 were 92.5 (11.3), 75.0 (2.5) and 75.0 (9.0) ml; 8.0 (1.4), 16.8 (4.8) and 48.1 (14.2) mGy; 108.0 (27.3), 246.0 (93.0) and 701.0 (207.8) mGy cm; and 1.5 (0.4), 3.4 (1.3) and 9.8 (2.9) mSv, respectively. CONCLUSION: A staged coronary CTA protocol with an initial low-dose approach and addition of a standard sequence--should image quality be too low--can lead to a substantial reduction in radiation exposure.

Prospectively ECG-triggered high-pitch spiral acquisition for coronary CT angiography using dual source CT: technique and initial experience.

OBJECTIVE: We evaluated radiation exposure and image quality of a new coronary CT angiography protocol, high-pitch spiral acquisition, using dual source CT (DSCT). MATERIAL AND METHODS: Coronary CTAwas performed in 25 consecutive patients with a stable heart rate of 60 bpm or less after premedication, using 2 x 128 0.6-mm sections, 38.4-mm collimation width and 0.28-s rotation time. Tube settings were 100 kV/320 mAs and 120 kV/400 mAs for patients below and above 100-kg weight, respectively. Data acquisition was prospectively ECG-triggered at 60% of the R-R interval using a pitch of 3.2 (3.4 for the last 10 patients). Images were reconstructed with 75-ms temporal resolution, 0.6-mm slice thickness and 0.3-mm increment. Image quality was evaluated using a four-point scale (1 = excellent, 4 = unevaluable). RESULTS: Mean range of data acquisition was 113 +/- 22 mm, mean duration was 268 +/- 23 ms. Of 363 coronary artery segments, 327 had an image quality score of 1, and only 2 segments were rated as "unevaluable". Mean dose-length product (DLP) was 71 +/- 23 mGy cm, mean effective dose was 1.0 +/- 0.3 mSv (range 0.78-2.1 mSv). For 21 patients with a body weight below 100 kg, mean DLP was 63 +/- 5 mGy cm (0.88 +/- 0.07 mSv; range 0.78-0.97 mSv). CONCLUSION: Prospectively ECGtriggered high-pitch spiral CT acquisition provides high and stable image quality at very low radiation dose.

Image quality in a low radiation exposure protocol for retrospectively ECG-gated coronary CT angiography.

OBJECTIVE: The purpose of our study was to systematically compare the image quality of dual-source CT coronary angiography using 100 kV instead of 120 kV. SUBJECTS AND METHODS: One hundred patients with a body weight

Technical note: raw data-based approach to identify the optimal reconstruction phase in coronary computed tomography angiography.

For coronary computed tomography (CT) angiography, the reconstruction phase finally used has to be iteratively adapted to the patient-specific heart motion to provide optimal image quality and therewith to improve the diagnostic value. The purpose was to provide an automatically raw data-based identification of the patient-specific optimal reconstruction phase for cardiac computed tomography imaging. We validated our method by a visual assessment of 65 patient data sets. In 52% of all cases, the highest correlation of the computed and the visually identified optimal reconstruction phase was ensured. In 30% of the cases, our method provided a higher image quality compared with the results obtained in routine clinical work. Our identification of the optimal reconstruction phase is a reliable method and can improve the medical workflow by providing optimal image quality with the initial image reconstruction, making multiple time-consuming image reconstructions obsolete.

Real-time determination of the optimal reconstruction phase to control ECG pulsing in spiral cardiac CT.

The reconstruction phase providing optimal image quality in coronary CT angiography is dependent on the heart rate but additionally displays substantial patient-dependent variation. The purpose of this study was to provide online identification of the patient-specific optimal reconstruction phase during CT coronary angiography data acquisition and to allow adaptation of tube current modulation for the individual patient. A raw data-based cardiac motion signal (kymogram) was used for the detection of the optimal reconstruction phase. The individual motion curve of each patient was correlated with dedicated template curves to reduce signal noise. Data sets of 90 consecutive patients were used for validation purposes. The reliability of our approach increased with scan time and provided highest correlation with the visually identified optimal reconstruction phase already after half of the total scan time indicated by a difference value of 13.2% and 8.2%, respectively. A high correlation of the computed and the visually identified optimal reconstruction phase was assured in most cases providing a dose reduction of 36% compared to conventional TCM application for a confidence interval of 80%. Our method is a fully automatic computer-assisted approach identifying the optimal reconstruction phase with high reliability while online capability can be ensured. We conclude that our method can identify cardiac phases providing highest image quality already during CT scanning. Reduction of the tube current by a patient-specific optimization providing a minimal dose level is the major benefit for the patients.

Lipoprotein apheresis in Germany - Still more commonly indicated than implemented. How can patients in need access therapy?

BACKGROUND: Although lipid-lowering drugs, especially statins, and recently also PCSK9 inhibitors can reduce LDL cholesterol (LDL-C) and decrease the risk for cardiovascular disease (CVD) including coronary artery disease (CAD) events most efficiently, only 5-10% of high-risk cardiovascular patients reach the target values recommended by international guidelines. In patients who cannot be treated adequately by drugs it is possible to reduce increased LDL-C and/or lipoprotein(a) (Lp(a)) values by the use of lipoprotein apheresis (LA) with the potential to decrease severe CVD events in the range of 70%->80%. Even in Germany, a country with well-established reimbursement guidelines for LA, knowledge about this life-saving therapy is unsatisfactory in medical disciplines treating patients with CVD. Starting in 1996 our aim was to offer LA treatment following current guidelines for all patients in the entire region of our clinic as standard of care. METHODS: Based on the experience of our large apheresis competence center overlooking now nearly 80,000 LA treatments in the last two decades, we depict the necessary structure for identification of patients, defining indication, referral, implementation and standardisation of therapy as well as for reimbursement. LA is unfamiliar for most patients and even for many practitioners and consultants. Therefore nephrologists performing more than 90% of LA in Germany have to form a network for referral and ongoing medical education, comprising all regional care-givers, general practitioners as well as the respective specialists and insurances or other cost bearing parties for offering a scientifically approved therapeutic regimen and comprehensive care. The German Lipid Association (Lipid-Liga) has implemented the certification of a lipidological competence center as an appropriate way to realize such a network structure. RESULTS: Working as a lipidological and apheresis competence center in a region of 400,000 to 500,000 inhabitants, today we treat 160 patients in the chronic LA program. In spite of the availability of PCSK9 inhibitors since 2015, LA has remained as an indispensable therapeutic option for targeted lipid lowering treatment. An analysis of nearly 37,000 LA treatments in our own center documented a >80% reduction of cardiovascular events in patients treated by regular LA when comparing with the situation before the start of the LA therapy. We have implemented the concept of an apheresis competence center characterised by ongoing medical education with a focus on lipidological and cardiovascular aspects, interdisciplinary networking and referral. CONCLUSIONS: Incidence and prevalence of LA patients in our region demonstrate that based on our ongoing patient-centered approach the access of patients in need to LA is substantially above the German average, thus contributing to an extraordinary reduction of cardiovascular events in the population we in particular feel responsible for.

Assessment of changes in non-calcified atherosclerotic plaque volume in the left main and left anterior descending coronary arteries over time by 64-slice computed tomography.

Multidetector computed tomography (MDCT) permits the visualization of the coronary arteries and of coronary atherosclerotic plaques. The natural course of noncalcified plaque is not known. This study was conducted to measure the change in noncalcified coronary plaque volume in the left main coronary artery and in the proximal left anterior descending coronary artery over time using 64-slice MDCT. Fifty patients in whom noncalcified lesions had been detected on baseline MDCT received follow-up scans after an interval of 17 +/- 6 months. Plaque areas were traced manually in serial multiplanar reconstructions to determine overall volume. The mean plaque volumes were 92 +/- 81 mm(3) on baseline MDCT and 115 +/- 110 mm(3) on follow-up MDCT (p <0.001). The mean annualized volume change was 22% (95% confidence interval 14.7% to 29.7%). A weak but significant correlation with low-density lipoprotein cholesterol level was observed for the amount of baseline plaque volume (r = 0.37, p <0.001). In conclusion, the quantification of noncalcified plaque volume is possible on repeated 64-slice MDCT. A significant increase of the amount of noncalcified plaque was observed over a mean interval of 17 months. Contrast-enhanced MDCT may therefore be a tool to study the progression of coronary atherosclerosis.

Diagnostic accuracy of noninvasive coronary angiography in patients after bypass surgery using 64-slice spiral computed tomography with 330-ms gantry rotation.

BACKGROUND: Multidetector computed tomographic angiography (MDCT) has been shown to allow detection of coronary artery bypass graft (CABG) occlusions and stenoses. However, the assessment of native coronary arteries in addition to CABG has thus far not been sufficiently validated. METHODS AND RESULTS: Fifty patients with a total of 138 CABG (34 mammary grafts, 3 radial grafts, 101 venous grafts) were investigated by MDCT (0.6-mm collimation, 32 detector rows, 2 focal points, 330-ms rotation) 9 to 252 months (mean, 106 months) after surgery. CABG and all native coronary arteries with a diameter of > 1.5 mm were evaluated for the presence of significant stenoses (> or = 50% diameter reduction). Results were compared with quantitative coronary angiography. By MDCT, all CABG were evaluable and were correctly classified as occluded (n=38) or patent (n=100). Sensitivity for stenosis detection in patent grafts was 100% (16/16) with a specificity of 94% (79/84). For the per-segment evaluation of native coronary arteries and distal runoff vessels, sensitivity in evaluable segments (91%) was 86% (87/101) with a specificity of 76% (354/465). If evaluation was restricted to nongrafted arteries and distal runoff vessels, sensitivity was 86% (38/44) with a specificity of 90% (302/334). On a per-patient basis, classifying patients with at least 1 detected stenosis in a CABG, a distal runoff vessel, or a nongrafted artery or with at least 1 unevaluable segment as "positive," MDCT yielded a sensitivity of 97% (35/36) and specificity of 86% (12/14). CONCLUSIONS: We found that 64-slice MDCT permits the evaluation of bypass grafts and the assessment of the native coronary arteries for the presence of stenosis.

Influence of Cardiovascular Risk Factors on the Prevalence of Coronary Atherosclerosis in Patients with Angiographically Normal Coronary Arteries.

RATIONALE AND OBJECTIVES: Cardiovascular (CV) disease is predominately influenced by CV risk factors and coronary computed tomography angiography (CTA) is capable of detecting early-stage coronary artery disease. We sought to determine the influence of CV risk factors on the prevalence of nonobstructive atherosclerosis in patients with normal-appearing coronary arteries in invasive coronary angiography (ICA). MATERIALS AND METHODS: In this retrospective analysis, we included 60 consecutive symptomatic patients, having undergone ICA and coronary CTA. Coronary dual source CTA was performed using electrocardiogram-triggered retrospective gated image acquisition at 40%-70% of RR interval (tube voltage 100-120 kV, tube current time product 320-440 mAs, 60 mL contrast, and flow rate 6 mL/s). RESULTS: Out of 60 patients (32 men, mean age 61 ± 11 years) with a normal coronary artery appearance in ICA, 45 (75%) patients showed atherosclerotic plaque in CTA. Plaque was present in 14 of 60 (23%) left main, 41 of 60 (68%) left anterior descending, 21 of 60 (35%) circumflex coronary arteries, and 24 of 60 (40%) right coronary arteries. More than 15% of all coronary artery segments showed detectable plaques. Interobserver agreement ranged from good to very good on a per-patient, per-vessel, and per-segment level. Patients with presence of plaque were significantly older (P = 0.005) and showed higher incidence of arterial hypertension (P = 0.019) as compared to individuals without coronary plaque in dual source computed tomography. CONCLUSIONS: The prevalence of coronary atherosclerosis by CTA is substantial in symptomatic patients with normal invasive coronary angiogram. Hypertension and older age significantly influence the prevalence of atherosclerotic plaque and highlight the importance of risk-modifying therapy.

Lipidological competence centres and networks: Future perspectives to improve healthcare of patients with disorders of lipid metabolism.

BACKGROUND: Numerous healthcare studies have shown that more than 90% of all patients with dyslipidaemia are not treated adequately. OBJECTIVES: The "Deutsche Gesellschaft zur Bekämpfung von Fettstoffwechselstörungen und ihren Folgeerkrankungen (DGFF)" [German Society of Lipidology], a non-profit professional membership organization, has already made a series of efforts to improve the care of patients suffering from dyslipidaemia. A recent outcome is the nationwide implementation and certification of Lipidological Competence Centres and Networks (LCCNs). METHODS AND RESULTS: By involving numerous external medical cooperation partners and combining the detailed work of different in-house medical specialists, the Medical Care Centre Kempten-Allgäu was able to improve both the diagnosis and treatment of patients exhibiting disorders of lipid metabolism (DLM). This local lipidological network is so successful, that it may serve as a nationwide standard model for outpatient lipidological care. Detailed organizational structures for improved lipidological care which are suitable to provide a template for future guidelines for the certification of LCCNs have been developed by the Medical Care Centre Kempten-Allgäu. Stringent requirements of implementation with respect to medical staff, content and structure, staff training, patient education and public relations as well as to documentation, quality assurance and quality improvement must be fulfilled both by the lipidological competence centre (LCC) and the cooperation partners within the lipidological network (LN). Finally, members of the health care system (e.g. health policy and health insurances) should be involved in this attempt and convinced of financial support. CONCLUSION: The implementation and certification of national LCCNs supported by DGFF could contribute to a comprehensive improvement in the care of patients with dyslipidaemia, resulting in prevention of cardiovascular diseases and reduction of cardiovascular sequelae.

Measurement of coronary artery bifurcation angles by multidetector computed tomography.

OBJECTIVE: Optimal stent deployment in coronary artery bifurcations requires information about the angle between main vessel and side branch. We evaluated the accuracy and interobserver variability of bifurcation angle measurements by contrast-enhanced 16-slice multidetector computed tomography (MDCT) in comparison with invasive angiography and examined the average angles of 4 main coronary bifurcations. METHODS: To determine the accuracy of MDCT for measurement of bifurcation angles, we scanned a coronary artery phantom containing 6 bifurcations (2-mm metal rods with angles between 25 degrees and 90 degrees ) using MDCT, and angles determined in the MDCT data set were compared with the true values. To assess interobserver variability of angle measurements in comparison to invasive angiography, the angles of 3 bifurcation sites (left anterior descending and left circumflex coronary artery [LAD/LCX], LAD and first diagonal branch [LAD/Diag 1], and posterior descending coronary artery and right posterolateral branch [PDA/Rpld]) were determined in 15 patients both in 16-detector row MDCT data sets and invasive coronary angiograms by 2 independent observers each. To assess the natural distribution of the 4 main coronary artery bifurcation angles (LAD and LCX, LAD and Diag 1, LCX and OM1, PDA and Rpld), the average angles of these bifurcations were determined in 16-slice MDCT data sets acquired for coronary artery visalization in a group of 100 consecutive patients with suspected coronary artery disease. RESULTS: The phantom study revealed a mean difference between measured and true angles of 0.7 +/- 0.5 degrees . In the comparison MDCT versus invasive angiography, the 45 angles were significantly lager in MDCT (mean: 66 +/- 20 degrees vs. 56 +/- 24 degrees , P = 0.027). Interobserver variability was significantly lower in MDCT (r = 0.91) than invasive angiography (r = 0.62). Analysis of the natural distribution of bifurcation angles by MDCT revealed average values of 80 +/- 27 degrees (LAD/LCX), 46 +/- 19 degrees (LAD/Diag1), 48 +/- 24 degrees (LCX/OM1), and 53 +/- 27 degrees (PDA/Rpld), respectively. CONCLUSION: MDCT allows assessment of coronary bifurcation angles with high accuracy, which may be of future potential for planning interventional treatment.

Efficacy, safety, and tolerability of long-term lipoprotein apheresis in patients with LDL- or Lp(a) hyperlipoproteinemia: Findings gathered from more than 36,000 treatments at one center in Germany.

LDL cholesterol (LDL-C) and lipoprotein(a) (Lp(a)) are main risk factors for cardiovascular disease (CVD). Efficacy, safety, and tolerability of lipoprotein apheresis (LA) were investigated in 36,745 LA treatments of 118 patients with CVD in a retrospective, monocentric study. Indications were severe hypercholesterolemia (n = 83) or isolated Lp(a) hyperlipoproteinemia (n = 35). Average age of patients at start of LA treatment was 58.1 years for males and 62.5 years for females. Medium interval between the first cardiovascular event and LA treatment was 6.4 ± 5.6 years and the average LA treatment period was 6.8 ± 4.9 years. On average treatments were performed once a week, via peripheral venous access in 79.3% of non-hemodialysis patients. In patients with hypercholesterolemia initial pre-LA LDL-C was lowered from 176.4 ± 67.0 mg/dL by 66.7 ± 10.8% per session, achieving a long-term interval mean value of 119.8 ± 34.7 mg/dL, i.e. reduction by 32.1 ± 19.6% (p < 0.0001). In patients with isolated elevated Lp(a) initial pre-LA Lp(a) was lowered from 127.2 ± 67.3 mg/dL by 66.8 ± 5.8% per session, achieving a long-term interval mean value of 60.0 ± 19.5 mg/dL, i.e. reduction by 52.8 ± 23.0% (p < 0.0001). After start of LA the average annual rate of major adverse coronary events (MACE) of all patients declined by 79.7% (p < 0.0001). Subgroup analysis showed decline by 73.7% (p < 0.0001) in patients with severe hypercholesterolemia, and by 90.4% (p < 0.0001) in patients with isolated elevated Lp(a). Adverse events (AE) occurred in 1.1% of treatments. LA treatment of patients with high risk for CVD due to LDL and/or Lp(a) hyperlipoproteinemia was effective, safe, and well tolerated. The number of cardiovascular events, at least during a six-year period, declined by 80%.