Tamar Gaspar

Usefulness of 64-Slice Cardiac Computed Tomographic Angiography for Diagnosing Acute Coronary Syndromes and Predicting Clinical Outcome in Emergency Department Patients With Chest Pain of Uncertain Origin

Background— Multidetector computed tomography (MDCT) has high diagnostic value for detecting or excluding coronary artery stenosis. We examined performance characteristics of MDCT for diagnosing or excluding an acute coronary syndrome in patients presenting to the emergency department (ED) with possible ischemic chest pain and examined relation to clinical outcome during a 15-month follow-up period. Methods and Results— We prospectively studied 58 patients (56±10 years of age, 36% female) with chest pain possibly ischemic in origin and no new ECG changes or elevated biomarkers. The patients underwent 64-slice contrast-enhanced MDCT, which showed normal coronary vessels (no or trivial atheroma) in 15 patients, nonobstructive plaque in 20 (MDCT-negative patients), and obstructive coronary disease (≥50% luminal narrowing) in 23 (MDCT-positive group). By further investigation (new elevation of cardiac biomarkers, abnormal myocardial perfusion scintigraphy and/or invasive angiography), acute coronary syndrome was diagnosed in 20 of the 23 MDCT-positive patients (ED MDCT sensitivity 100% [20/20], specificity 92% [35/38], positive predictive value 87% [20/23], negative predictive value 100% [35/35]). During a 15-month follow-up period, no deaths or myocardial infarctions occurred in the 35 patients discharged from the ED after initial triage and MDCT findings. One patient underwent late percutaneous coronary intervention (late major adverse cardiovascular events rate, 2.8%). Overall, ED MDCT sensitivity for predicting major adverse cardiovascular events (death, myocardial infarction, or revascularization) during hospitalization and follow-up was 92% (12/13), specificity was 76% (34/45), positive predictive value was 52% (12/23), and negative predictive value was 97% (34/35). Conclusions— We found that 64-slice cardiac MDCT is a potentially valuable diagnostic tool in ED patients with chest pain of uncertain origin, providing early direct noninvasive visualization of coronary anatomy. ED MDCT had high positive predictive value for diagnosing acute coronary syndrome, whereas a negative MDCT study predicted a low rate of major adverse cardiovascular events and favorable outcome during follow-up.

Three-Dimensional Imaging of the Left Ventricular Outflow Tract: Impact on Aortic Valve Area Estimation by the Continuity Equation

BACKGROUND Measurement of left ventricular outflow tract (LVOT) area for estimation of aortic valve area (AVA) using two-dimensional (2D) transthoracic echocardiography (TTE) and the continuity equation assumes a round LVOT. The aim of this study was to compare measurements of LVOT area and AVA using 2D and three-dimensional (3D) TTE and cardiac computed tomographic angiography (CCTA) in an attempt to improve the accuracy of AVA estimation using TTE. METHODS Fifty patients were prospectively studied, 25 with aortic stenosis and 25 without aortic stenosis (group 1). LVOT area and AVA were estimated using 2D TTE, and LVOT area and diameters were measured using 256-slice CCTA and 3D TTE. AVA was also planimetered using CCTA in midsystole. LVOT area and AVA estimated by 2D TTE were correlated with measurements by 3D TTE and CCTA. Findings from group 1 were then validated in 38 additional patients with aortic stenosis (group 2). RESULTS LVOTs were oval in 96% of the patients in group 1, with a mean eccentricity index (diameter 2/diameter 1) of 1.26 ± 0.09 by CCTA. Compared with CCTA, 2D TTE systematically underestimated LVOT area (and therefore AVA) by 17 ± 16%. The correlation between CCTA and 3D TTE LVOT area was only moderate (r = 0.63), because of inadequate 3D transthoracic echocardiographic image quality. Mean AVA was 0.92 ± 0.44 cm(2) by 2D TTE and 1.14 ± 0.68 cm(2) by CCTA (P = .0015). After correcting AVA on 2D TTE by a factor of 1.17 (accounting for LVOT area ovality), there was no difference between 2D TTE and CCTA (0.06 ± 26 cm(2), P = .20, r = 0.86). In group 2, 2D TTE underestimated LVOT area and AVA by 16 ± 11%, similar to group 1, and AVA by TTE was 0.75 ± 0.14 cm(2) compared with 0.88 ± 0.21 cm(2) by CCTA (P < .0001). When the correction factor was applied to the group 2 results, the corrected AVA by 2D TTE (×1.17) was 0.87 ± 0.17 cm(2), similar to AVA by CCTA (P = .70). CONCLUSIONS Three-dimensional imaging revealed oval LVOTs in most patients, resulting in underestimation of LVOT area and AVA on 2D TTE by 17%. This accounted for the difference in AVA between 2D TTE and CCTA. Current 3D TTE is inadequate to accurately measure LVOT area.

Noninvasive evaluation of arterial grafts with newly released multidetector computed tomography

BACKGROUND High-quality postoperative imaging of bypass conduits is essential when evaluating different types of conduits, anastomoses, and surgical techniques. We investigated the potential value of the newest generation of multidetector-row computer tomographic scanners in assessing bypass grafts. METHODS From June to September 2002, 14 patients underwent scanning with a newly released 16-slice computed tomographic scanner (Mx8000 IDT; Philips Medical Systems) after coronary artery bypass grafting. Four patients had had minimally invasive direct coronary artery bypass grafting and 3, redo coronary artery revascularization. Contrast-enhanced computed tomographic angiography was performed using retrospective electrocardiographic gating. Scan length was 22 to 30 cm, and total scan time was 27 to 37 seconds. RESULTS Of the 14 patients, 8 were scanned within 1 week after operation and 6, 1 month to 12 months postoperatively. Average heart rate during the scan was 82 beats per minute (range, 60 to 97 beats per minute), and all patients were able to hold their breath for the required time. Thirty conduits were studied: 26 arterial (18 in situ left and right internal mammary artery grafts, five free right internal mammary and radial artery grafts, and three in situ right gastroepiploic artery grafts) and four vein grafts. Excellent visualization of all 30 grafts was achieved. Thirty-four of the 35 distal anastomoses were patent; one vein graft was occluded. CONCLUSIONS This new technology is a promising noninvasive measure to evaluate patency of bypass conduits, including the gastroepiploic artery where catheterization is usually difficult. The ability to display the vessel wall as well as its lumen might distinguish radial artery spasm from intimal hyperplasia. The superb resolution and increased scan length required to cover the entire internal mammary artery grafts-from origin to distal anastomoses-can be achieved easily in a single breath-holding owing to the increased number of slices per rotation and shortening of the gantry rotation time.

Combined Assessment of Coronary Anatomy and Myocardial Perfusion Using Multidetector Computed Tomography for the Evaluation of Coronary Artery Disease

Multidetector computed tomography (MDCT) is increasingly used as an alternative to invasive coronary angiography. Although computed tomographic coronary angiography (CTCA) has been validated against invasive coronary angiography and nuclear myocardial perfusion imaging, the potential of MDCT to evaluate perfusion has not been fully explored. We sought to (1) develop a new technique for quantitative assessment of myocardial enhancement based on analysis of MDCT images acquired for CTCA, (2) identify the underlying causes of myocardial hypoenhancement detected by MDCT, and (3) determine the added diagnostic value of the MDCT perfusion index when combined with CTCA. We studied 84 patients undergoing clinical CTCA (64 patients with invasive coronary angiogram and a control group of 20 patients). MDCT perfusion index was calculated from x-ray attenuation measured in 16 myocardial segments. Hypoenhancement was automatically detected using comparisons with the normal range obtained in the control group, and its added value was determined against invasive coronary angiographic findings combined with known previous myocardial infarction. Myocardial hypoenhancement was detected in 29 of 64 patients in 47 vascular territories, of which 36 (77%) were abnormal by the reference technique. Of these 36 abnormalities, 10 (28%) were associated with previous myocardial infarction, whereas 26 (72%) corresponded to significant coronary stenosis. The addition of MDCT perfusion index to CTCA improved its diagnostic accuracy (sensitivity 0.87 to 0.96, accuracy 0.84 to 0.88, despite a decrease in specificity 0.79 to 0.68). In conclusion, myocardial hypoenhancement is a potentially valuable addition to MDCT evaluation of coronary artery disease without additional cost in radiation dose or contrast load.

Cardiac computed tomographic angiography for risk stratification and prediction of late cardiovascular outcome events in patients with a chest pain syndrome

BACKGROUND Contrast-enhanced multidetector cardiac computed tomographic angiography (CCTA) has high sensitivity and specificity for diagnosing anatomic coronary stenoses, but its role in predicting late clinical outcome events has not been well studied. METHODS We examined predictive value of CCTA for late major adverse cardiovascular (CV) outcome events (MACE)(CV death, myocardial infarction, myocardial revascularization) (follow-up 18.2+/-6.3, range 9-30 months) in 545 consecutive symptomatic patients (368 (68%) men, 177 (32%) women) with clinical suspicion, but without previously diagnosed, coronary artery disease (CAD) who underwent 40- or 64-channel CCTA. RESULTS MACE occurred in 53/545 (9.7%) patients (early 30 day CCTA-driven events excluded): CV death/myocardial infarction in 3/327 (0.9%) patients with no coronary luminal narrowing >25% (group 1), in 3/127 (2.4%) with >or=1 luminal narrowing(s) of 26-69% (group 2) and in 9/91 (9.9%) with >or=1 coronary luminal narrowing(s) of >or=70% (group 3) (p<0.0001). CV death/myocardial infarction/revascularization occurred in 5/327 (1.5%) group 1 patients, 19/127 (14.9%) group 2 and 29/91 (31.9%) group 3 (p<0.0001). Multivariate analysis (adjusting for age, gender, coronary risk factors and coronary calcium score) identified CCTA stenosis (>25%) as a powerful independent predictor of MACE (HR 10.9, 95%CI 4.1-29.0, p<0.0001). CONCLUSIONS CCTA was useful to predict late clinical outcome events in patients undergoing evaluation of a chest pain syndrome.

Value of multidetector computed tomography evaluation of myocardial perfusion in the assessment of ischemic heart disease: comparison with nuclear perfusion imaging

MDCT-derived myocardial perfusion has not yet been validated against accepted standards. We developed a technique for quantification of myocardial perfusion from MDCT images and studied its diagnostic value against SPECT myocardial perfusion imaging (MPI). Ninety-eight patients were studied. Abnormal perfusion was detected by comparing normalized segmental x-ray attenuation against values obtained in 20 control subjects. Disagreement with resting MPI was investigated in relationship to MDCT image quality, severity of MPI abnormalities, and stress MPI findings. Resting MPI detected mild or worse abnormalities in 20/78 patients. MDCT detected abnormalities in 15/20 patients (sensitivity of 0.75). Most abnormalities missed by MDCT analysis were graded as mild on MPI. Additional abnormalities found in 16/78 patients were not confirmed on resting MPI (specificity of 0.72). However, 8 of these 16 apparently false positive MDCT perfusion tests had abnormal stress MPI; of these 8 patients, 7 had optimal MDCT image quality, while in 6/8 remaining patients, image quality was suboptimal. When compared with resting MPI, MDCT detected perfusion abnormalities with high accuracy. Moreover, half of MDCT perfusion abnormalities not confirmed by resting MPI were associated with abnormal stress MPI. Importantly, this information can be obtained without additional radiation dose or contrast agent.

Visceral abdominal adipose tissue and coronary atherosclerosis in asymptomatic diabetics

BACKGROUND Visceral abdominal adipose tissue (VAT) may play an active role in the progression of coronary atherosclerosis. We examined the relation between VAT, non-alcoholic fatty liver disease and extent of coronary atheroma in patients with type 2 diabetes mellitus but no known coronary artery disease. METHODS Coronary artery calcium and area, distribution and thickness of upper abdominal fat were measured in selected axial cross-sections from non-enhanced computed tomography (CT) scans of the chest. Coronary atheroma was assessed visually on a per vessel basis from 64 slice CT angiography using axial views and multi-format reconstructions. Fatty liver was diagnosed when liver density was <40 Hounsfield units (HU) or ≥10 HU below spleen density. RESULTS The area of VAT was increased in patients with versus without multi-vessel coronary artery plaque (237.0 ± 101.4 vs 179.2 ± 79.4 mm(2), p<0.001). Waist circumference (101.6 ± 12.3 versus 95.3 ± 13.8 cm) and internal abdominal diameter (218.7 ± 33.0 vs 194.6 ± 25.7 mm) (both p<0.001) were increased in patients with multi-vessel plaque whereas subcutaneous fat was unrelated to coronary plaque. Presence of fatty liver (93/318 patients, 29.2%) did not correlate with presence or extent of coronary plaque. The correlation of VAT with multi-vessel plaque although nominally independent of the metabolic syndrome (p=0.04) was not independent of waist circumference. CONCLUSION In asymptomatic subjects with DM and no history of CAD area of VAT correlated with the presence and extent of coronary atheroma but as a risk predictor added little independent information to that obtained by more readily obtainable measures of adiposity-waist circumference and internal abdominal diameter.

Uses and Limitations of 40 Slice Multi-Detector Row Spiral Computed Tomography for Diagnosing Coronary Lesions in Unselected Patients Referred for Routine Invasive Coronary Angiography

Background and Aims: The value of multi-detector row computed tomography (MDCT) in routine cardiology practice is uncertain. We examined the applicability of MDCT imaging for the diagnosis of obstructive coronary artery disease in a routine clinical setting. Methods: MDCT scanning (40 slice) was performed in 111 unselected patients referred for invasive coronary angiography (ICA) and findings were compared to an independent quantitative assessment of the ICA on a segmental, vessel and patient basis. Results: Sensitivity and positive predictive value for segmental disease (72.2 and 70.9% respectively, overall) were higher in patients aged ≧60 years and history of disease ≧1 year, whereas specificity and negative predictive value were high in all groups. In the patient-based analysis, sensitivity and positive predictive value (84.7 and 87.8%, respectively) were higher, the latter in keeping with the high-patient prevalence of disease, but specificity and negative predictive value (61.5 and 55.2%) were low. Conclusions: Usefulness of MDCT was significantly influenced by age, duration of coronary artery disease and female gender, and on a patient-based analysis its diagnostic accuracy was not sufficient to replace ICA in a routine clinical setting.

Long-term prognosis and outcome in patients with a chest pain syndrome and myocardial bridging: A 64-slice coronary computed tomography angiography study

BACKGROUND Small case series have associated coronary myocardial bridging (MB) with adverse cardiac events. However, the clinical significance of MB in unselected patients with chest pain remains unclear. The purpose of this study was to explore the relation between the presence of isolated MB and subsequent adverse cardiac events in symptomatic patients referred for coronary computed tomography angiography (CCTA). METHODS AND RESULTS Three hundred and thirty-four consecutive patients (age 57 ± 13 years, 43% female) with chest pain and no prior history of coronary artery disease (CAD) who underwent 64-slice CCTA and had no obstructive CAD (≥ 50% coronary luminal obstruction) were included. Patients were followed for cardiac events [cardiovascular (CV) death or non-fatal myocardial infarction (MI)] over 6.1 ± 1 years. Outcomes were compared between patients with MB vs. those without MB using the Cox models. MB was present in 117 out of 334 (35%) patients on CCTA and 80% of MB involved the mid-distal left anterior descending coronary artery. During a mean follow-up duration of 6.1 ± 1 years, cardiac events occurred in 6 out of 117 (5.1%) patients with, and 7 out of 217 (3.2%) patients without MB (P = 0.40). Univariate predictors of cardiac events were hypertension [hazards ratio (HR) = 10.6, P = 0.002], diabetes mellitus (HR = 4.8, P = 0.01), and older age (HR = 1.1, P = 0.0004). The association of hypertension and age with adverse cardiac events remained statistically significant after adjusting for other variables. Neither the presence nor the extent of MB was associated with an increased risk of cardiac events. CONCLUSION MB is a common finding on CCTA among patients presenting with chest pain but no obstructive CAD. No association was evident between MB and the risk of CV death or MI.

Validation of remote dielectric sensing (ReDS™) technology for quantification of lung fluid status: Comparison to high resolution chest computed tomography in patients with and without acute heart failure

BACKGROUND Pulmonary congestion is a common presentation of acute decompensated heart failure (ADHF). The ability to quantify increased pulmonary parenchymal water content in chest computed tomography (CCT) is well known. However, availability and radiation limitations make it unsuitable for serial assessment of lung fluid content. The ReDS™ technology allows quantification of lung fluid content. OBJECTIVE The objective of this work was to validate the ability of the ReDS™ technology to quantify total lung fluid when compared with CCT in ADHF and non-ADHF patients. METHODS Following CCT, ReDS measurements were obtained from consented subjects. ReDS measurements were then compared to the CCT using lung density analysis software. CCT results were converted from Hounsfield Units to percentage units, allowing comparison with the ReDS readings. The analyses, performed on 16 ADHF and 15 non-ADHF patients, were conducted by an independent observer blinded to ReDS outcomes. RESULTS The fluid content averages and standard deviations for the non-ADHF group were 28.7±5.9% and 27.3±6.6% and for the ADHF patients 40.7±8.8% and 39.8±6.8% (CCT and ReDS respectively). Intraclass correlation was found to be 0.90, 95% CI [0.8-0.95]. Regression analysis yielded a slope of 0.94 (95% confidence interval [0.77-1.12]) and intercept 3.10 (95% confidence interval of [-3.02-9.21]). The absolute mean difference between the quantification of the two methods was 3.75 [%] with SD of 2.22 [%]. CONCLUSION Current findings show high correlation between the ReDS noninvasive system and CCT in both ADHF and non-ADHF patients. Remote patient monitoring using ReDS™ based system may help in the management of patients with heart failure.