ISSN 1671-5411 CN 11-5329/R

2006 Vol. 3, No. 1

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Assessment of left ventricular ejection fraction: comparison of two dimensional echocardiography, cardiac magnetic resonance imaging and 64-row multi-detector computed tomography
Chee Khoon LIEW, Tiong Kiam ONG, Sze Piaw CHIN, Yean Yip FONG, Wei Ling CHAN, Choon Kiat ANG, Houng Bang LIEW, Kui Hian SIM, Rapaee ANNUAR, Tobias Seyfarth
2006, 3(1): 2-8.
Objectives To compare left ventricular ejection fraction (LVEF) determined from 64-row multi-detector computed tomography (64-row MDCT) with those determined from two dimensional echocardiography (2D echo) and cardiac magnetic resonance imaging (CMR). Methods Thirty-two patients with coronary artery disease underwent trans-thoracic 2D echo, CMR and contrast-enhanced 64-row MDCT for assessment of LVEF within 48 hours of each other. 64-row MDCT LVEF was derived using the Syngo Circulation software, CMR LVEF was by Area Length Ejection Fraction (ALEF) and Simpson method and 2D echo LVEF by Simpson method. Results The LVEF was 49.13 ± 15.91% by 2D echo, 50.72 ± 16.55% (ALEF method) and 47.65 ± 16.58%(Simpson method) by CMR and 50.00 ± 15.93% by 64-row MDCT. LVEF measurements by 64-row MDCT correlated well with LVEF measured with CMR using either the ALEF method (Pearson correlation r = 0.94, P <0.01) or Simpson method (r = 0.92, P<0.01). It also correlated well with LVEF measured using 2D echo (r = 0.80, P < 0.01). Conclusion LVEF measurements by 64-row MDCT correlated well with LVEF measured by CMR and 2D echo. The correlation between 64-row MDCT and CMR was better than the correlation between 2D echo with CMR. Standard data set from a 64-row MDCT coronary study can be reliably used to calculate the LVEF.
Feasibility and accuracy of coronary imaging in elderly patients using the 64-row multi-detector computed tomography: a correlation study with conventional coronary angiography
Wei Ling CHAN, Chee Khoon LIEW, Sze Piaw CHIN, Tiong Kiam ONG, Yean Yip FONG, Choon Kiat ANG, Houng Bang LIEW, Kui Hian SIM, Seyfarth Tobias, Rapaee ANNUAR
2006, 3(1): 9-14.
Background Elderly patients generally have higher occurrence of coronary calcification, increased heart rate and difficulty with prolonged breath-holding. The aim of our study was to investigate the feasibility and accuracy of using 64-row multi-detector com-puted tomography (MDCT) in the assessment of coronary artery stenoses in elderly patients. Methods One hundred and fifty two patients with suspected or known coronary artery disease were divided into 4 groups according to their age (Group A: 40-49 years, n=34, Group B: 50-59 years, n=57; Group C: 60-69 years, n=48; Group D: 70 years and above; n=13). Coronary CT angiography (CTA) using a 64-row MDCT was performed and the findings were compared with that of conventional coronary angiography (CCA). Using axial images, multi-planar reconstructions (MPR) and maximum intensity projections (MIP), coronary segments of lumen diameter = 1.5mm were analyzed for the presence of significant stenosis (= 50% ). Results Percentages of poor image quality from coronary CTA preventing reliable correlations with CCA were 21%, 14%, 19% and 62% in Groups A to D respectively. Patients in Group D had significantly higher calcium scores compared with the other groups (P<0.001). In patients where CTA images were of acceptable quality, percentages of accurate correlations with CCA were 89.8%, 93.4%, 86.6% and 78.0% for Groups A to D respectively. There were no significant difference in serum creatinine. heart rate and contrast volume between the 4 groups. Conclusions The 64-row MDCT coronary angiography was less accurate and feasible for patients aged 70 years or above due to heavy coronary calcifica-tion and inability to perform a satisfactory breath-hold. However, a high diagnostic accuracy with the MDCT is possible in patients aged less than 70 years.
Calcified plaque: the Achilles' Heel of present computed tomography coronary angiography for the elderly?
Gianluca Rigatelli
2006, 3(1): 15-16.
Nine percent to 27% of cardiac catheterizations today showed either angiographic normal coronary arteries or minimal atherosclerosis. '?2 Given the expense of cardiac catheterization and the desire to use this valuable resource for therapeutic rather than diagnostic purpose, there is a strong impetus to develop non-invasive means of accurately detecting significant coronary artery stenosis. Although echocardiography is the most common non-invasive cardiac procedure, nuclear cardiology, more recently cardiac computed tomography angiography (CTA) and cardiac magnetic resonance (CMR) play more important roles in detecting significant coronary artery disease. While CMR had great promise as a radiation-free and contrast-free 'one-stop' procedure, its technology currently lags behind CTA in the non-invasive imaging of coronary artery.
High-resolution computed tomography in patients with atypi-cal 'cardiac' chest pain: a study investigating patients at 10-year cardiovascular risks defined by the Framingham and PROCAM scores
Choon Kiat ANG, Alan Yean Yip FONG, Sze Piaw CHIN, Tiong Kiam ONG, Wei Ling CHAN, Chee Khoon LIEW, Houng Bang LIEW, Kui Hian SIM, Seyfarth M Tobias, Rapaee ANNUAR
2006, 3(1): 17-21.
Background and objective Atypical 'cardiac' chest pain (ACCP) is not usually caused by myocardial ischaemia. Current non-invasive investigations for these symptoms arc not yet as accurate as invasive coronary angiography. The latest 64-row multi-detector computed tomography (MDCT) technology is non-invasive, has high specificity and negative predictive values for the detection of significant coronary disease. Our aim was to investigate if this modality can provide more information in the assessment of outpatients with ACCP in addition to established cardiovascular risk scores. Methods Seventy consecutive patients presenting to the outpatient clinic with ACCP underwent 64-row MDCT scan of the coronary arteries. They were categorized into low. medium or high risk groups based upon the Framingham and PROCAM scores. We defined a clinically abnormal MDCT scan as coronary stenosis =50% or calcium score >400 Agatston. Results Fifty-three (75.7%) patients did not have clinically abnormal scans. Framingham score classi-fied 43 patients as low-risk while PROCAM classified 59 patients as low-risk. MDCT scans were abnormal for 18.6% and 22.0% of the respective low-risk group of patients. For patients with mcdium-to-high risk. 33.3% and 36.4% of Framingham and PROCAM patient groups respectively had abnormal MDCT scans. Conclusion MDCT adds valuable information in the assessment of patients with ACCP by identifying a significant proportion of patients categorized as low-risk to have underlying significant coronary stenosis and coronary calcification by established cardiovascular risk scores.
A new Screening Tool for Detecting Early Atheroslerosis
Charlie W. Shaeffer, Palm Spring CA, Thach Nguyen
2006, 3(1): 22-23.
In a study published in the current issue of the Journal of Geriatric Cardiology. Ang and co-investigators used the high-resolution 64-slice CT coronary angiography to detect coro-nary lesions in a group of patients with atypical angina.1 The clinical data of these patients were also used to calculate their risk according the Framingham and PROCAM scoring system. --1 As the cohort is composed with a majority of low risk pa-tients with atypical angina, only a small minority of the pa-tients were classified as having medium and high risk. The results showed that MDCT uncovered 18% either significant lesions (>50% stenosis) or calcifications (>400Agatston units) in the low risk patients and 33% in the medium and high risk subgroups.
Comparison of 16 slice multi-detector computed tomography and breath hold 3D magnetic resonance angiography in the detection of coronary stenosis
Xin LIU, Zulong CAI, Youquan CAI, Shaohong ZHAO, Ningyu AN, Yuangui GAO
2006, 3(1): 24-28.
Objective To compare 16-slice multi-detector spiral computed tomography (MDCT) and breathhold 3D magnetic resonance (MR) coronary angiography in the visualization of coronary arteries and the accuracy of detecting significant (> 50%) coronary stenoses in patients with suspected coronary artery disease. Methods Forty patients were examined by 16-slice CT (GE, Lightspecdl6) and MR (GE.Twinspeed) within 3 days: 31 of them underwent conventional coronary angiography (CAG) within 2 weeks after CT and MR scan. CT was performed with 16x 1.25 mm detector collimation, 0.5 s rotation time and images were reconstructed at 60%-75% of the cardiac cycle. MR was performed with breath hold 3D FIESTA (TR4.0 ms, TE1.7 ms, flip angle 65, slice thickness 3 mm, FOV 280 mm, matrix 256x 192) . Mean heart rate was 63 ± 5.8 bpm and (3-blocker was used in 24 patients. MR and CT image quality was evaluated in 9 coronary segments (RCA1. RCA2. RCA3, LM, LAD1, LAD2, LAD3, LCX1. LCX2) using a four-point grading scale. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated for detection of significant stenosis using CAG as the gold standard. Results 16-slice CT showed higher image quality in most coronary segments except RCA2. Forty-three segments were diagnosed as significant stenosis by CAG, 36 and 27 of these were correctly detected by CT and MR respectively. Sensitivity, specificity, positive predictive value, and negative predictive value of 16-slice CT and MR for detecting significant stenosis were 83%, 84%, 49%, 97% and 63%, 90%, 55%, 93%, respectively. Conclusion Sixteen-slice CT showed higher image quality in most coronary segments cxccpted for middle RCA. 16-slice CT had higher sensitivity than MR for detection of coronary significant stenosis, whereas MR had higher specificity than CT. Both CT and MR showed high negative predictive value, which is useful for excluding coronary stenosis in symptomatic patients.
64-row multi-dector computed tomography coronary image from a center with early experience: first illustration of learning curve
Sze Piaw CHIN, Tiong Kiam ONG, Wei Ling CHAN, Chee Khoon LIEW, Fong Yean Yip ALAN, Houng Bang LIEW, Kui Hian SIM, M. Tobias Seyfarth
2006, 3(1): 29-34.
Background and objectives The recent joint ACCF/AHA clinical competence statement on cardiac imaging with multi-detector computed tomography recommended a minimum of 6 months training and 300 contrast examinations, of which the candidate must be directly involved in at least 100 studies. Whether this is adequate to become proficient in interpretation of coronary computed tomog-raphy angiography (CTA) is not known. The aim of our study was to plot the 'learning curve' for CTA assessment of haemodynamically significant coronary stenosis in a center with 1 year's experience using a 64-row scanner. Methods A total of 778 patients underwent contrast-enhanced CTA between January and December 2005. Out of these patients, 301 patients also underwent contrast-enhanced conventional coronary angiography (CCA). These patients were divided into 4 groups according to the time the examination was underwent. Group Ql: first quarter of the year (n=20). Group Q2: second quarter (n=l28), Group Q3: third quarter ( n= 134), and Group Q4: fourth quarter ( n=19). For Group Q4 patients we used a 'test-bolus' protocol instead of 'bolus-tracking' for contrast-enhancement. Results The sensitivity, specificity, positive, and negative predictive values were Ql - 64%, 89%, 49% and 94%, respectively, Q2 -79%, 96%, 74% and 97%, respectively, Q3 - 78%, 96%, 74%, 97%, respectively, and Q4 - 100% for all. Conclusions In a center with formal training and high caseload, our accuracy in CTA analysis reached a plateau after 6 months experience. Test-bolus protocols produce better image quality and can improve accuracy. New centers embarking on CTA will need to overcome an initial 6-month learning curve depending upon the caseload during which time they should consider correlation with CCA.
The coronary computed tomography angiogram: from the basics to advanced interpretation
Tiong Kiam ONG, Stephan Achenbach
2006, 3(1): 35-44.
According to the WHO's World Health Report 2003, cardiovascular disease was responsible for 16.7 million deaths annually. As a result, it is now the leading cause of death in developed countries and in many developing countries. De-tecting and preventing the progression of coronary artery dis-ease is the target of many pharmaceutical, technological and other scientific programs today. Presently, the main diagnos-tic tool for evaluating coronary arteries is the conventional coronary angiogram (CCA). In the U.S. alone, between 1979 and 2000, the number of cardiac catheterizations increased by 341 % with more than 2 million cases performed in 2000 alone. However, other than the cost associated with the procedure, conventional coronary angiography is invasive and is associ-ated with a complication rate of around 2%.
Increased ostial pulmonary vein diameter in congestive heart failure: a multi-slice computed tomography angiography evaluation
Lei GAO, Caiyi LU, Ming YIN, Yuxiao ZHANG, Yi WEN, Shiwen WANG, Xihai ZHAO, Xin LIU
2006, 3(1): 45-50.
Background and Objectives The relationship between left atrial (LA) size and congestive heart failure (CHF) is well recognized; however, there is little information on the association of pulmonary vein (PV) diameter and CHF.The purpose of this study was to investigate the changes of PV and LA sizes in CHF patients by multislice computed tomography (MSCT) angiography using a new 64-slice scanner. Methods and Results We assessed diameters of PVs ostium and LA by 64-slice MSCT with three-dimensional recon-struction in 25 CHF patients and in 26 age- and sex-matched non-CHF controls. Compared with controls, CHF patients showed significant greater diameters of left superior pulmonary vein (LSPV) and right inferior pulmonary vein (RIPV) in both anterior-posterior(AP) and superior-inferior (SI) directions (/><().01), significant dilation of right superior pulmonary vein (RSPV) in AP direc-tion (P<0.05), as well as significant increase of LA transverse, AP, and SI diameters (P<0.01). Conclusion Significant dilation of PVs with simultaneous LA enlargement was demonstrated in CHF patients. This anatomic and geometric changes may participate in the perpetuation of AF.
The egg or the chicken?
Vuong DuThinh
2006, 3(1): 51-51.
In this issue of the Journal of Geriatric Cardiology, Gao et al.,1 in a report of increased ostial pulmonary vein diameter by multislice CT angiography reported a statistically signifi-cant enlargement of the pulmonary veins in patients with con-gestive heart failure (CHF). This finding alone should not be of any surprise as anatomic remodeling and general dilation of the cardiac chambers are well described in patients with CHF. What is thought provoking is the conjecture that pulmonary vein ostial dilation may play a role in the genesis and mainte-nance of atrial fibrillation. Multiple theories of the mechanism of atrial fibrillation exist, but it is safe to assume that disper-sion of refractoriness in the left atrium is a necessary condi-tion to maintain atrial fibrillation. Whether the mere anatomi-cal change of the pulmonary vein ostia in CHF is sufficient to create this dispersion of refractoriness is a matter of hot debate. This report by Gao et al. however, is important in the implica-tion of the use of this novel imaging technique for the purpose of identifying and visualizing the pulmonary vein ostia for atrial fibrillation ablation.
Multi-detector CT angiography for the assessment of anterior spinal artery and artery of Adamkiewicz patency in patients suspected of having thoracic aortic pathology
Shaohong ZHAO, Laura Logan, Pamela Schraedley, Geoffrey D. Rubin
2006, 3(1): 52-56.
Objective To evaluate the visualization of the anterior spinal artery (ASA) and the artery of Adamkiewicz (AKA) as well as the affecting factors for the detection rate using multidetector row CT (MDCT). Methods Ninety-nine consecutive patients (3 1 women and 68 men; age range. 25-90 years; average age 61.3 years) with suspicion for thoracic aortic lesions necessitating surgical interven-tion (31 aortic aneurysm, 45 dissection, 5 intramural hematoma. and 18 normal), underwent 16-slice MDCT angiography from the aortic arch to the aortic bifurcation. Transverse sections, multiplanar reformations (MPR) and thin maximum intensity projections (MIP) were used to assess the ASA and AKA. The level of the ASA and AKA origins and CT acquisition parameters were recorded. The contrast-to-noise ratio (CNR) of the image, an index of the mass of the Tl I body (vertebral mass index), the subcutaneous fat thickness, and the CT value within the aortic arch and at the Tl 1 level were measured. The detection of the ASA and AKA was evaluated relative to the acquisition parameters, scan characteristics, and aortic lesion type. Differences were assessed with Wilcoxon rank-sum and t tests. Results The ASA was visualized in 51 patients (52%) and the AKA in 18 patients (18%). The ASA was identified in 36/67 (54%) patients with 1.25 mm thickness and in 15/32 (47%) patients with 2.5-3.0 mm thickness. This difference did not achieve significance (P=0.13). The detection rate of the ASA and the AKA was influenced by vertebral mass index and the CNR (F<0.05). The amount of subcutaneous fat affected the detection rate of the ASA (P<0.05) but not the AKA. In CT scans with ASA detection, the mean CT values in the aorta at the arch and at Tl 1 were 360 and 358 HU, respectively; whereas in CT scans without ASA detection, the CT values in the aorta at the arch and at Tl 1 were lower (297 and 317 HU, respectively; both P<0.05). Conclusion The ASA and AKA were less frequently detected in our cohorts than previous reports. The visualization of the ASA and AKA was significantly affected by aortic enhancement, the "vertebral mass index", and the CNR.
Is it time for elective left main percutaneous coronary inter-vention to become 'main stream'?
Joshua Cohen, Andrew D. Michaels
2006, 3(1): 57-58.
Left main (LM) stenting is considered by many to be one of the last frontiers of interventional cardiology. Begin-ning with the VA cooperative study published in 1976 demon-strating a mortality benefit for patients undergoing coronary artery bypass grafting (CABG), ' the standard of care for treat-ment of left main coronary artery disease has been surgical. The most recent 2005 update of the ACC/AHA/SCAI Practice Guidelines on PCI2 again notes that "CABG using IMA graft-ing is the 'gold standard' for treatment of unprotected left main disease and has proven benefit on long-term outcomes."
Obesity, hypertension and the metabolic syndrome
Matthew J. Sorrentino
2006, 3(1): 59-60.
The prevalence of obesity in both developed and devel-oping countries has increased dramatically in recent years. Many people who are obese develop metabolic changes that increase the risk of diabetes mellitus and adverse cardiovascu-lar outcomes. Obesity leads to the development of insulin resistance, lipid abnormalities and increased blood pressure. The metabolic syndrome was designated as a way to easily identify individuals that tend to have a clustering of cardio-vascular risk factors. Central obesity is one of the main deter-minants of the metabolic syndrome and is essential for the defi-nition of metabolic syndrome according to the recent Interna-tional Diabetes Federation worldwide definition of metabolic syndrome.
Different treatments for different mechanisms in vasovagal syncope
Quan FANG, Kangan CHENG, Hua DENG, Ning WU
2006, 3(1): 61-64.
The treatment of vasovagal syncope has been by far unsatisfactory. Beta-blockers may prevent vasovagal syncope, but they exacerbates heart asystole. Cardiac pacing prevents syncope but notpresyncope. The frequent, serious vasovagal syncope attacks of a 63- year-old woman patient were completely prevented by administration of 100 mg metoprolol (b.i.d) for 3 months until the patient experienced a complete heart block. A ODD pacemaker implantation abolished syncope but not the presyncope, which was eventually prevented in a follow-up period of 24 months by adding 75 mg atenalol twice a day. This case suggests a different mecha-nism involved in vasovagal syncope.