The effect of aortic area measurement site on the energy loss coefficient: a comparison between echocardiography and cardiac computed tomography angiography in patients with aortic stenosis.

AIM: The energy loss coefficient (ELCo) has been suggested as a more accurate indicator of aortic stenosis (AS) severity as compared to transthoracic echocardiography (TTE) aortic valve area (AVA). There are little data regarding the optimal location for aortic area (Aa) measurement needed for ELCo calculation and the agreement of ELCo with direct anatomical AVA measurement. The aim of this study was to determine the optimal site of Aa measurement for calculation of the ELCo, using cardiac computed tomography angiography (CCTA) AVA planimetry as the reference standard. METHODS: We analyzed 69 patients with AS who underwent both CCTA and TTE. ELCo and CCTA planimetry AVA were compared using multiple sites for CCTA Aa measurement (sinus, sinotubular junction, or ascending aorta). RESULTS: CCTA AVA was 0.96±0.46 cm2 . ELCo was 0.95±0.43 cm2 using sinotubular junction Aa, 0.92±0.41 cm2 using sinus Aa, and 0.91±0.4 cm2 using the ascending aorta (P=.84, P=.13, and P=.08 compared to CCTA AVA). There was good agreement between CCTA AVA and ELCo using all Aa locations (0.89-0.90). On subgroup analysis of 16 patients most likely to be affected by pressure recovery (aortic diameter<3 cm and AVA ≥1 cm2 ), ELCo using the sinotubular junction Aa showed the best agreement with CCTA AVA as compared to the other Aa locations (0.84 vs 0.75-0.77). CONCLUSIONS: ELCo using Aa measurement at the sinotubular junction showed the best agreement with CCTA AVA. We therefore recommend using the sinotubular junction Aa for ELCo calculation.

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.

Automated Computer-Assisted Diagnosis of Obstructive Coronary Artery Disease in Emergency Department Patients Undergoing 256-Slice Coronary Computed Tomography Angiography for Acute Chest Pain.

A 256-slice coronary computed tomography angiography (CCTA) is an accurate method for detection and exclusion of obstructive coronary artery disease (OBS-CAD). However, accurate image interpretation requires expertise and may not be available at all hours. The purpose of this study was to evaluate the usefulness of a fully automated computer-assisted diagnosis (COMP-DIAG) tool for exclusion of OBS-CAD in patients in the emergency department (ED) presenting with chest pain. Three hundred sixty-nine patients in ED without known coronary disease underwent 256-slice CCTA as part of the assessment of chest pain of uncertain origin. COMP-DIAG (CorAnalyzer II) automatically reported presence or exclusion of OBS-CAD (>50% stenosis, ≥1 vessel). Performance characteristics of COMP-DIAG for exclusion and detection of OBS-CAD were determined using expert reading as the reference standard. Seventeen (5%) studies were unassessable by COMP-DIAG software, and 352 patients (1,056 vessels) were therefore available for analysis. COMP-DIAG identified 33% of assessable studies as having OBS-CAD, but the prevalence of OBS-CAD on CCTA was only 18% (66 of 352 patients) by standard expert reading. However, COMP-DIAG correctly identified 61 of the 66 patients (93%) with OBS-CAD with 21 vessels (2%) with OBS-CAD misclassified as negative. In conclusion, compared to expert reading, automated computer-assisted diagnosis using the CorAnalyzer showed high sensitivity but only moderate specificity for detection of obstructive coronary disease in patients in ED who underwent 256-slice CCTA. The high negative predictive value of this computer-assisted algorithm may be useful in the ED setting.

Low cardiorespiratory fitness and coronary artery calcification: Complementary cardiovascular risk predictors in asymptomatic type 2 diabetics.

BACKGROUND: Despite its well-established prognostic value, cardiorespiratory fitness (CRF) is not incorporated routinely in risk assessment tools. Whether low CRF provides additional predictive information in asymptomatic type 2 diabetics beyond conventional risk scores and coronary artery calcification (CAC) is unclear. METHODS: We studied 600 type 2 diabetics aged 55-74 years without known coronary heart disease. CRF was quantified in metabolic equivalents (METs) by maximal treadmill testing and categorized as tertiles of percent predicted METs (ppMETs) achieved. CAC was calculated by non-enhanced computed tomography scans. The individual and joint association of both measures with an outcome event of all-cause mortality, myocardial infarction or stroke, was determined over a mean follow-up period of 80 ± 16 months. RESULTS: There were 72 (12%) events during follow-up. Low CRF was independently associated with event risk after adjustment for traditional risk factors and CAC (HR 2.25, 95% CI 1.41-3.57, p = 0.001). CRF (unfit/fit) allowed further outcome discrimination both amongst diabetics with low CAC scores (9.5% versus 2.0% event rate), and amongst diabetics with high CAC scores (23.5% versus 12.4% event rate), p < 0.001. The addition of CRF to a model comprising UKPDS and CAC scores improved the area under the curve for event prediction from 0.66 to 0.71, p = 0.03, with a positive continuous net reclassification improvement (NRI) of 0.451, p = 0.002. CONCLUSIONS: CRF, quantified by ppMETs, provided independent prognostic information which was additive to CAC. Low CRF may identify asymptomatic diabetic subjects at higher risk for all-cause mortality, myocardial infarction or stroke, despite low CAC.

Prognostic impact of abdominal fat distribution and cardiorespiratory fitness in asymptomatic type 2 diabetics.

BACKGROUND: Impaired cardiorespiratory fitness (CRF) is a potent risk factor for mortality in diabetes, and may modify the relation between adiposity and mortality. We evaluated the interaction between CRF and abdominal adiposity distribution with all-cause mortality, myocardial infarction or stroke in patients with diabetes. METHODS: We studied 294 type 2 diabetics without known coronary artery disease. CRF was quantified in metabolic equivalents by maximal treadmill testing, and categorized as low CRF (first tertile) or high CRF (second and third tertiles). Abdominal fat was quantified as subcutaneous or visceral adipose tissue from non-enhanced computed tomography scans. Association of CRF, adiposity distribution and their interaction with all-cause mortality, myocardial infarction or stroke was assessed by Cox proportional-hazard models. RESULTS: There were 31 (11%) events during 62 ± 12 months. Low CRF was significantly associated with event risk before and after adjustment for each measure of adiposity (hazard ratio 3.79, 95% confidence interval 1.79-8.01, p < 0.001). CRF level was inversely correlated with subcutaneous (r = -0.44, p < 0.001) but not visceral adipose tissue (r = -0.06, p = 0.31). Absolute event rates increased progressively across visceral adipose tissue tertiles, but decreased across subcutaneous tertiles. However, within each tertile of both adiposity measures, increased events were observed in the low compared with the high CRF group; this trend was also observed in an adjusted multivariate proportional hazards model. CONCLUSIONS: Although subcutaneous and visceral adipose tissues differed in their association with CRF levels and absolute event rates, lower baseline CRF in type 2 diabetics was significantly associated with higher risk of all-cause mortality, myocardial infarction or stroke, regardless of abdominal adiposity pattern.

Automatic assessment of coronary artery calcium score from contrast-enhanced 256-row coronary computed tomography angiography.

The coronary artery calcium score (CS), an independent predictor of cardiovascular events, can be obtained from a stand-alone nonenhanced computed tomography (CT) scan (CSCT) or as an additional nonenhanced procedure before contrast-enhanced coronary CT angiography (CCTA). We evaluated the accuracy of a novel fully automatic tool for computing CS from the CCTA examination. One hundred thirty-six consecutive symptomatic patients (aged 59 ± 11 years, 40% female) without known coronary artery disease who underwent both 256-row CSCT and CCTA were studied. Original scan reconstruction (slice thickness) was maintained (3 mm for CSCT and 0.67 mm for CCTA). CS was computed from CCTA by an automatic tool (COR Analyzer, rcadia Medical Imaging, Haifa, Israel) and compared with CS results obtained by standard assessment of nonenhanced CSCT (HeartBeat CS, Philips, Cleveland, Ohio). We also compared both methods for classification into 5 commonly used CS categories (0, 1 to 10, 11 to 100, 101 to 400, >400 Agatston units). All scans were of diagnostic quality. CS obtained by the COR Analyzer from CCTA classified 111 of 136 (82%) of patients into identical categories as CS by CSCT and 24 of remaining 25 into an adjacent category. Overall, CS values from CCTA showed high correlation with CS values from CSCT (Spearman rank correlation = 0.95, p <0.0001). In conclusion, CS values automatically computed from 256-row CCTA correlated highly with standard CS values obtained from nonenhanced CSCT. CS obtained directly from CCTA may obviate the need for an additional scan and attendant radiation.

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.

Diagnostic accuracy of 256-row computed tomographic angiography for detection of obstructive coronary artery disease using invasive quantitative coronary angiography as reference standard.

We assessed the performance of a new-generation, 256-row computed tomography (CT) scanner for detection of obstructive coronary artery disease (CAD) compared to invasive quantitative coronary angiography. A total 121 consecutive symptomatic patients without known CAD referred for invasive coronary angiography (age 59 ± 12 years, 37% women) underwent clinically driven 256-row coronary computed tomographic angiography (CCTA) before the invasive procedure. Obstructive CAD (>50% diameter stenosis) was assessed visually on CCTA by 2 independent observers using the 18-segment society of cardiovascular CT model and on invasive angiograms using quantitative coronary angiography (the reference standard). Observers were unaware of the findings from the alternate modality. Nonassessable coronary computed tomographic angiographic segments were considered obstructive for the purpose of analysis. Quantitative coronary angiography demonstrated obstructive CAD in 145 segments in 82 of 121 patients (68%). Overall, 1,677 coronary segments were available for comparative analysis, of which 39 (2.3%) were nonassessable by CCTA, mostly because of heavy calcification. Patient-based and segment-based analysis showed a sensitivity of 100% and 97% (95% confidence interval 95% to 100%) and specificity of 69% (95% confidence interval 55% to 84%) and 97% (confidence interval 96% to 98%), respectively. Four segments with obstructive CAD in 4 patients were not detected by CCTA. All 4 patients had additional coronary obstructions identified by CCTA. The predictive accuracy was 90% (range 85% to 95%) for patient based and 97% (96% to 98%) for segment based analysis. In conclusion, 256-row CCTA showed high sensitivity and high predictive accuracy for detection of obstructive CAD in patients without previously known disease. Although coronary calcification might still interfere with analysis, the rate of nonassessable segments was low.

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.

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.

Image quality in obese patients undergoing 256-row computed tomography coronary angiography.

To evaluate, objectively and subjectively, the feasibility of 256-row computed tomography coronary angiography (CTCA) in obese patients. 256-row CTCA was performed in 68 symptomatic patients (age 61 ± 10 years, 37 females), 39 obese (body mass index-BMI > 30 kg/m(2)) and 29 non-obese. Retrospective analysis was performed by two observers who assessed the image quality of each coronary segment using a 4-point subjective scale (1 excellent to 4 non-diagnostic), and another blinded observer measured objective image parameters. BMI in the obese group was 35 ± 5 (32-65) Kg/m(2), and 24 ± 3 (16-29) Kg/m(2) in the non-obese (P = 0.004). Average subjective image quality was similar in obese (1.41 ± 0.40) and non-obese (1.34 ± 0.40) patients, P = 0.17. Proportion of coronary artery segments with non-diagnostic image quality was low in both groups (0.7% in obese and 0.2% in non-obese, P = 0.31). Signal to noise and contrast to noise ratios were not significantly lower in obese than in non-obese patients (9.4 ± 3 vs. 12 ± 2.5, P = 0.16 and 11.1 ± 3.8 vs. 13.7 ± 2.9, P = 0.07 respectively). However, dose length product (1167 ± 567 vs. 827 ± 375 mGy × cm, P = 0.014) and image noise (44 ± 13 vs. 35 ± 5 HU, P < 0.001) were higher in the obese patient group. Image quality was preserved in obese patients undergoing 256-row CTCA at the cost of increased radiation exposure and image noise.

[Appropriateness criteria for the use of cardiac computed tomography: position paper of the Israeli Heart Society and the Israeli Society of Radiology].

Cardiac computed tomography (CCT) is a relatively new imaging modality which allows high quality imaging of the coronary vessels and various cardiac structures. Together with the advances in scanner technology and the more frequent use of the technology in clinical practice, there is a need to better define the appropriate indications for the use of CCT. This review summarizes the appropriateness criteria for the use of CCT as were defined by a joint committee of the Israeli Heart Society and the Israeli Society of Radiology.

Heart rate recovery after exercise and coronary atheroma in asymptomatic individuals with type 2 diabetes mellitus: a study using 64-slice coronary CT angiography.

Impaired heart rate recovery after exercise (HRR) is a marker of autonomic dysfunction and a predictor of long-term mortality either directly or due to associated cardiovascular disease. In a cohort of 552 asymptomatic type 2 diabetics (age 63.2 ± 5.4 yr, 54.9% women) participating in a long-term prospective outcomes study, we examined the hypothesis that cardiac autonomic dysfunction, as demonstrated by HRR in the first minute after exercise, is an independent correlate of multivessel coronary artery atheroma. HRR1 was reduced in patients with any coronary plaque (p = 0.012), multivessel coronary plaque (p = 0.006), and coronary stenosis (p = 0.027). However, the association was not independent of the United Kingdom Prospective Diabetes Study risk score thus it appears to be related to the adverse risk profile of these patients.

Pulse pressure and coronary atherosclerosis in asymptomatic type 2 diabetes mellitus: a 64 channel cardiac computed tomography analysis.

BACKGROUND: Identification of high risk sub-groups for early initiation of preventive medical therapy requires widespread population screening using simple, inexpensive tests. High pulse pressure has been shown to predict adverse coronary events. We examined if this correlation was related to a greater coronary plaque burden in patients with high pulse pressure using 64 channel coronary computed tomographic angiography (CCTA) in patients with type 2 diabetes mellitus. METHODS: The study included 427 consecutive asymptomatic diabetic patients with no history of coronary disease, (age 55-74 years, 58% women), undergoing CCTA as part of a prospective outcomes study. RESULTS: Coronary atheroma was present in 76.6% of patients, multivessel coronary atheroma in 55.1% and luminal stenosis (>or=50% of diameter) in 22.9%. Pulse pressure (adjusted for age, gender, mean blood pressure and heart rate) correlated with number of coronary arteries with atheroma (p=0.005) and with multivessel coronary atheroma (odds ratio 1.24 95%CI 1.06-1.43 for each 10 mm Hg pulse pressure, p=0.009). The correlation was independent of Framingham and United Kingdom Prospective Diabetic Study risk scores (p=0.027 and p=0.036 respectively). Adjusted pulse pressure also correlated with quartiles of coronary artery calcium score (p=0.009). CONCLUSION: Elevated pulse pressure was a useful independent marker of presence and extent of pre-clinical coronary artery disease in an asymptomatic diabetic population.

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.