Probability Of Coronary Artery Disease Research Articles

Overestimation of pretest probability of coronary artery disease by Duke clinical score in patients undergoing coronary CT angiography in a Japanese population

BackgroundThe Duke clinical score (DCS) is commonly used to estimate the pretest probability of coronary artery disease (CAD). However, the criterion was developed in a population undergoing catheter angiography. ObjectiveTo test the hypothesis that DCS overestimates the CAD probability when applied to patients evaluated with coronary CT angiography (CCTA). A second objective is to compute an adjustment of the calculated DCS to apply to this population. MethodsThe DCS was calculated for the 3996 consecutive CCTA studies (February 2009 to April 2013) performed for symptomatic patients with no known CAD. Performance of the DCS for the detection of CAD was evaluated by the area under the receiver operating characteristic curve. Using the training cohort (n = 2789), a linear regression line between the calculated probability and the observed prevalence of CAD identified a modified DCS cutoff for a better risk categorization; this was internally validated by a separate cohort (n = 1207). ResultsThe DCS showed a good discrimination (area under the receiver operating characteristic curve = 0.71) for the detection of CAD (prevalence = 23.3%). The calibration analysis showed an overall 2.4-fold overestimation by DCS with a DCS < 23% corresponding to the low-risk category (ie, observed prevalence of CAD < 10%). There was no appropriate DCS cutoff to define high-risk category (ie, prevalence > 90%). The validation cohort showed a prevalence of 9.4% when DCS < 23% was used to define low risk. ConclusionAmong patients who underwent CCTA, DCS overestimated the pretest probability by at least 2-fold; the DCS < 23% should define the lower risk probability. The DCS poorly identifies high-risk population and thus development of new CCTA-based criteria is warranted.

The association between pretest probability of coronary artery disease and stress test utilization and outcomes in a chest pain observation unit.

Cardiology consensus guidelines recommend use of the Diamond and Forrester (D&F) score to augment the decision to pursue stress testing. However, recent work has reported no association between pretest probability of coronary artery disease (CAD) as measured by D&F and physician discretion in stress test utilization for inpatients. The author hypothesized that D&F pretest probability would predict the likelihood of acute coronary syndrome (ACS) and a positive stress test and that there would be limited yield to diagnostic testing of patients categorized as low pretest probability by D&F score who are admitted to a chest pain observation unit (CPU). This was a prospective observational cohort study of consecutively admitted CPU patients in a large-volume academic urban emergency department (ED). Cardiologists rounded on all patients and stress test utilization was driven by their recommendations. Inclusion criteria were as follows: age>18 years, American Heart Association (AHA) low/intermediate risk, nondynamic electrocardiograms (ECGs), and normal initial troponin I. Exclusion criteria were as follows: age older than 75 years with a history of CAD. A D&F score for likelihood of CAD was calculated on each patient independent of patient care. Based on the D&F score, patients were assigned a priori to low-, intermediate-, and high-risk groups (<10, 10 to 90, and >90%, respectively). ACS was defined by ischemia on stress test, coronary artery occlusion of ≥70% in at least one vessel, or elevations in troponin I consistent with consensus guidelines. A true-positive stress test was defined by evidence of reversible ischemia and subsequent angiographic evidence of critical stenosis or a discharge diagnosis of ACS. An estimated 3,500 patients would be necessary to have 1% precision around a potential 0.3% event rate in low-pretest-probability patients. Categorical comparisons were made using Pearson chi-square testing. A total of 3,552 patients with index visits were enrolled over a 29-month period. The mean (±standard deviation [SD]) age was 51.3 (±9.3) years. Forty-nine percent of patients received stress testing. Pretest probability based on D&F score was associated with stress test utilization (p<0.01), risk of ACS (p<0.01), and true-positive stress tests (p=0.03). No patients with low pretest probability were subsequently diagnosed with ACS (95% CI=0 to 0.66%) or had a true-positive stress test (95% CI=0 to 1.6%). Physician discretionary decision-making regarding stress test use is associated with pretest probability of CAD. However, based on the D&F score, low-pretest-probability patients who meet CPU admission criteria are very unlikely to have a true-positive stress test or eventually receive a diagnosis of ACS, such that observation and stress test utilization may be obviated.

Diagnostic role of coronary calcium scoring in the rapid access chest pain clinic: prospective evaluation of NICE guidance

Coronary artery calcium (CAC) imaging by unenhanced computed X-ray tomography (CT) is recommended as an initial diagnostic test for patients with stable chest pain symptoms but a low likelihood (10-29%) of underlying obstructive coronary artery disease (CAD) after clinical assessment. The recommendation has not previously been tested prospectively in a rapid access chest pain clinic (RACPC). We recruited 300 consecutive patients presenting with stable chest pain to the RACPC of three hospitals. All patients underwent CAC imaging, followed by invasive coronary angiography (ICA) in patients with CAC ≥ 1000 Agatston units (Au) and CT coronary angiography (CTCA) in those with CAC <1000. Patients with 50-70% stenosis on CTCA underwent myocardial perfusion scintigraphy (MPS) while those with ≥ 70% stenosis underwent ICA. Obstructive CAD was defined as ≥ 70% stenosis on ICA or the presence of inducible ischaemia on MPS. Patients were followed up clinically for a mean of 17 (SD 6) months. The mean patient age was 60.6 (SD 9.6) years and 48% were males. Obstructive CAD was found in 56 (19%) patients, of whom 42 (14%) underwent revascularization. CAC was zero in 131 (44%) patients, of whom two (1.5%) had obstructive CAD and one (0.8%) underwent revascularization. The sensitivity, specificity, negative predictive value, and positive predictive value of CAC ≥ 1 for detection of obstructive CAD were 96, 53, 32, and 98%, respectively. None of the 57 patients with low pre-test probability of CAD and zero CAC had obstructive CAD or suffered a cardiovascular event during the follow-up. Patients with stable chest pain symptoms but a low likelihood of CAD can safely be diagnosed as not having obstructive CAD in the absence of detectable coronary calcification by unenhanced CT. Patients with CAC >400 Au have a high prevalence of obstructive CAD and further investigation with ICA or functional imaging may be warranted rather than CTCA. These findings support NICE guidance for the investigation of stable chest pain. ClinicalTrials gov identifier: NCT01464203.

The diagnostic performance of coronary artery angiography with 64-MSCT and post 64-MSCT: systematic review and meta-analysis.

PurposeTo comprehensively investigate the diagnostic performance of coronary artery angiography with 64-MDCT and post 64-MDCT.Materials and MethodsPubMed was searched for all published studies that evaluated coronary arteries with 64-MDCT and post 64-MDCT. The clinical diagnostic role was evaluated by applying the likelihood ratios (LRs) to calculate the post-test probability based on Bayes' theorem.Results91 studies that met our inclusion criteria were ultimately included in the analysis. The pooled positive and negative LRs at patient level were 8.91 (95% CI, 7.53, 10.54) and 0.02 (CI, 0.01, 0.03), respectively. For studies that did not claim that non-evaluable segments were included, the pooled positive and negative LRs were 11.16 (CI, 8.90, 14.00) and 0.01 (CI, 0.01, 0.03), respectively. For studies including uninterruptable results, the diagnostic performance decreased, with the pooled positive LR 7.40 (CI, 6.00, 9.13) and negative LR 0.02 (CI, 0.01, 0.03). The areas under the summary ROC curve were 0.98 (CI, 0.97 to 0.99) for 64-MDCT and 0.96 (CI, 0.94 to 0.98) for post 64-MDCT, respectively. For references explicitly stating that the non-assessable segments were included during analysis, a post-test probability of negative results >95% and a positive post-test probability <95% could be obtained for patients with a pre-test probability of <73% for coronary artery disease (CAD). On the other hand, when the pre-test probability of CAD was >73%, the diagnostic role was reversed, with a positive post-test probability of CAD >95% and a negative post-test probability of CAD <95%.ConclusionThe diagnostic performance of post 64-MDCT does not increase as compared with 64-MDCT. CTA, overall, is a test of exclusion for patients with a pre-test probability of CAD<73%, while for patients with a pre-test probability of CAD>73%, CTA is a test used to confirm the presence of CAD.

Computed tomography coronary angiography: Is radiation a concern for the gold standard test for anomalous coronary arteries?

Multi-detector computed tomography is now an established modality for the investigation of coronary artery disease.1,2^ 64-Slice multi-detector computed tomography is the standard requirement by the British society of cardiac imaging and can image the whole heart in four heart beats. The 320 slice multi-detector computed tomography can image the heart in one heart beat, but both technologies depend on B-blockers to slow the patient’s heart rate to 60 beats per minute to ensure excellent image quality and low radiation dose. The faster dual source multi-detector computed tomography is less dependent on B-blockers. The availability and ease of use of multi-detector computed tomography has meant that it is increasingly used in younger patients to rule out coronary artery disease or rule out anomalous coronary arteries. We consider the radiation associated with computed tomography coronary angiography and the available dose reduction techniques.

Characterization of Coronary Artery Diseases Using 256 Multi Detectors CT Scanners

Coronary heart disease is the most common cause of death in the general population. Multi detector Computed Tomography (MDCT) is noninvasive technique and can study the entire coronary-artery tree during a single imaging session. The aims of this study were to characterize coronary arteries in patients who were clinically diagnosed to have coronary artery disease (CAD) using (MDCT) 256 slices, and to compare the findings with other cardiac examinations outcome. The study was done at King Fahad Specialist Hospital-Alqaseem- KSA during the period from January to May 2013 .A total of 102 patients, 63(61.76%) males, and 39 (38.24 %) females were included. All patients with pre-test probability of CAD underwent coronary CT angiography with beta-blockers were administered prior to the scan, and other cardiac investigations were obtained. Patient’s age, gender, BMI, weight, Cholesterol level, Hypertension, Diabetes Mellitus, chest pain types, Calcium scoring, were evaluated and correlated with the CT findings and other cardiac investigation results. The evaluated arteries were Left Main Artery (LMA), Left Anterior Descending artery (LAD), Right Coronary Artery (RCA), and Left Circumference Artery (LCA) and were observed for plaques characterization, occlusion or stenosis. A significant association was detected between the CT plaques morphology and BMI, Hyper tension and calcium score at P-value < 0.05. Patients with normal findings in ECG 53 (57.6%) , Echocardiography 58.0(76.3%) and Myocardial Perfusion Imaging (MPI) 2(25.0%) were found to have positive cardiac disease in CTA. Echocardiography is able to characterize Atrial filibration, Heart failure, Ventricle diseases, Valve stenoses and has significant association with gender P-value 0.022 and BMI P-value 0.042.Myocardial Perfusion Imaging results showed the cardiac function and ejection fraction. No significant association was found between CT findings in coronary arteries and MPI results at P-value 0.789.Coronary CTA disclose diseases in arteries (98.5%), heart anomalies or valve disease 3(3%) ,plaques with significant stenosis 4(4%) , plaque without significant stenosis 11(10.9%) ,stenosis without plaques 14 (14%) and total occlusion 1(1%). In relation to other cardiac tests; cardiac ischemic changes can be detected in ECG, MPI and Echocardiography. Association between CT Plaque Characteristics and Invasive Coronary Arteries results were significant for LAD and RCA at P-value 0.05. Coronary CTA is a promising non-invasive technique and is highly recommended for characterization of Coronary Arteries and diagnosis the CAD; it could be of great value prior to invasive coronary angiography, although ECG, Echocardiography and MPI(SPECT) are better in studying function.

A new risk score model to predict the presence of significant coronary artery disease in renal transplant candidates.

BackgroundRenal transplant candidates are at high risk of coronary artery disease (CAD). We sought to develop a new risk score model to determine the pre-test probability of the occurrence of significant CAD in renal transplant candidates.MethodsA total of 1,060 renal transplant candidates underwent a comprehensive cardiovascular risk evaluation. Patients considered at high risk of CAD (age ≥50 years, with either diabetes mellitus (DM) or cardiovascular disease (CVD)), or having noninvasive testing suggestive of CAD were referred for coronary angiography (n = 524). Significant CAD was defined by the presence of luminal stenosis ≥70%. A binary logistic regression model was built, and the resulting logistic regression coefficient B for each variable was multiplied by 10 and rounded to the next whole number. For each patient, a corresponding risk score was calculated and the receiver operating characteristic (ROC) curve was constructed.ResultsThe final equation for the model was risk score = (age × 0.4) + (DM × 9) + (CVD × 14) and for the probability of CAD (%) = (risk score × 2) – 23. The corresponding ROC for the accuracy of the diagnosis of CAD was 0.75 (P <0.0001) in the developmental model.ConclusionsWe developed a simple clinical risk score to determine the pre-test probability of significant CAD in renal transplant candidates. This model may help those directly involved in the care of patients with end-stage renal disease being considered for transplantation in an attempt to reduce the rate of cardiovascular events that presently hampers the long-term prognosis of such patients.

Combined anatomical and functional CT imaging for the detection of coronary artery disease

In recent years coronary CT angiography (CTA) has become an important non-invasive method for anatomic detection of coronary artery disease (CAD). The technique is robust and allows the assessment of coronary stenosis and plaques with acceptable radiation dose.1 The multi-centre studies have demonstrated very high negative predictive value for the identification of >50% coronary artery stenoses making CTA an excellent tool for exclusion of CAD. The recent ESC guidelines for stable CAD2 suggest the use of CTA especially in symptomatic patients with lower range of intermediate pre-test probability of CAD. Cardiac imaging is used not only to confirm the diagnosis of CAD but also to document ischaemia, assess the risk and guide selection of treatment options.2 Therefore, the evaluation of the haemodynamic significance of stenosis is important and the functional tests have an important role in the current clinical guidelines on stable CAD.2 Angiographic severity of coronary lesion has been found to be a poor predictor of its' haemodynamic significance. Both coronary anatomy and the functional consequences of the coronary lesions are possible to study using non-invasive techniques and it has become attractive to combine two imaging methods either in the same imaging session using hybrid imaging or combining two separate …

The new Vancouver Chest Pain Rule using troponin as the only biomarker: an external validation study

ObjectivesTo externally evaluate the accuracy of the new Vancouver Chest Pain Rule and to assess the diagnostic accuracy using either sensitive or highly sensitive troponin assays. MethodsProspectively collected data from 2 emergency departments (EDs) in Australia and New Zealand were analysed. Based on the new Vancouver Chest Pain Rule, low-risk patients were identified using electrocardiogram results, cardiac history, nitrate use, age, pain characteristics and troponin results at 2 hours after presentation. The primary outcome was 30-day diagnosis of acute coronary syndrome (ACS), including acute myocardial infarction, and unstable angina. Sensitivity, specificity, positive predictive values and negative predictive values were calculated to assess the accuracy of the new Vancouver Chest Pain Rule using either sensitive or highly sensitive troponin assay results. ResultsOf the 1635 patients, 20.4% had an ACS diagnosis at 30 days. Using the highly sensitive troponin assay, 212 (13.0%) patients were eligible for early discharge with 3 patients (1.4%) diagnosed with ACS. Sensitivity was 99.1% (95% CI 97.4-99.7), specificity was 16.1 (95% CI 14.2-18.2), positive predictive values was 23.3 (95% CI 21.1-25.5) and negative predictive values was 98.6 (95% CI 95.9-99.5). The diagnostic accuracy of the rule was similar using the sensitive troponin assay. ConclusionsThe new Vancouver Chest Pain Rule should be used for the identification of low risk patients presenting to EDs with symptoms of possible ACS, and will reduce the proportion of patients requiring lengthy assessment; however we recommend further outpatient investigation for coronary artery disease in patients identified as low risk.

Concordance and diagnostic accuracy of vasodilator stress cardiac MRI and 320-detector row coronary CTA

Vasodilator stress cardiac magnetic resonance (CMR) detects ischemia whereas coronary CT angiography (CTA) detects atherosclerosis. The purpose of this study was to determine concordance and accuracy of vasodilator stress CMR and coronary CTA in the same subjects. We studied 151 consecutive subjects referred to detect or exclude suspected obstructive coronary artery disease (CAD) in patients without known disease or recurrent stenosis or ischemia in patients with previously treated CAD. Vasodilator stress CMR was performed on a 1.5 T scanner. CTA was performed on a 320-detector row system. Subjects were followed for cardiovascular events and downstream diagnostic testing. Subjects averaged 56 ± 12 years (60 % male), and 62 % had intermediate pre-test probability for obstructive CAD. Follow-up averaged 450 ± 115 days and was 100 % complete. CMR and CTA agreed in 92 % of cases (κ 0.81, p < 0.001). The event-free survival was 97 % for non-ischemic and 39 % for ischemic CMR (p < 0.0001). The event-free survival was 99 % for non-obstructive and 36 % for obstructive CTA (p < 0.0001). Using a reference standard including quantitative invasive angiography or major cardiovascular events, CMR and CTA had respective sensitivities of 93 and 98 %; specificities of 96 and 96 %; positive predictive values of 91 and 91 %; negative predictive values of 97 and 99 %; and accuracies of 95 and 97 %. Non-ischemic vasodilator stress CMR or non-obstructive coronary CTA were highly concordant and each confer an excellent prognosis. CMR and CTA are both accurate for assessment of obstructive CAD in a predominantly intermediate risk population.

Cost-effectiveness of 64-slice CT angiography compared to conventional coronary angiography based on a coverage with evidence development study in Ontario

Conventional coronary angiography (CCA) is the standard diagnostic for coronary artery disease (CAD), but multi-detector computed tomography coronary angiography (CTCA) is a non-invasive alternative. Methods: A multi-center coverage with evidence development study was undertaken and combined with an economic model to estimate the cost–effectiveness of CTCA followed by CCA vs CCA alone. Alternative assumptions were tested in patient scenario and sensitivity analyses. Results: CCA was found to dominate CTCA, however, CTCA was relatively more cost-effective in females, in advancing age, in patients with lower pre-test probabilities of CAD, the higher the sensitivity of CTCA and the lower the probability of undergoing a confirmatory CCA following a positive CTCA. Conclusions: Results were very sensitive to alternative patient populations and modeling assumptions. Careful consideration of patient characteristics, procedures to improve the diagnostic yield of CTCA and selective use of CCA following CTCA will impact whether CTCA is cost-effective or dominates CCA.

Novel predictive model of obstructive coronary artery disease combining clinical and biohumoral data

Background: The probability of coronary artery disease (CAD) is currently estimated by the analysis of symptoms characteristics, age, sex, cardiovascular risk factors and stress tests. We sought to investigate the incremental diagnostic value of circulating biomarkers in reclassifying the probability of CAD. Methods: A total of 449 patients (60±9 years, 61% males) with angina-like chest pain or equivalent symptoms, enrolled in the EVINCI study, underwent clinical examination, exercise electrocardiogram, biohumoral characterization (36 biomarkers associated with atherosclerosis) and invasive coronary angiography. Primary end point was obstructive CAD, defined as >70% coronary stenosis in at least one major epicardial vessel, or 30-70% stenosis with fractional flow reserve ≤0.8. Diamond & Forrester (D&F) predictive model, including age, sex, type of symptoms and exercise ECG, was used as reference. A new model was built-up adding biohumoral variables selected by multivariate logistic regression to D&F variables. Diagnostic performance was assessed by the area under the Receiver Operating Characteristics curve (AUC) and the clinical utility by estimating net reclassification improvement (NRI), using 50% probability of CAD as cut-off. Results: The probability of obstructive CAD was 65% \[34-78%] by D&F model while the actual prevalence of the disease was 30%. High-density lipoprotein cholesterol, aspartate transaminase, homeostasis model assessment index, interleukin-6 and osteopontin were independent predictors of obstructive CAD at multivariate logistic regression. The addition of these biomarkers to D&F variables determined a significant increase of diagnostic accuracy [AUC from 0.72 (SE 0.03) to 0.82 (SE 0.03)\] (p <0.001). The integrated model allowed a correct reclassification of 18% of patients [NRI=18% (SE 0.05), p=0.001]. Conclusions: The D&F model overestimates the probability of obstructive CAD. Updating the model to a contemporary European population and adding biohumoral markers improves the predictive accuracy and correctly reclassifies a significant number of patients.

Stress echocardiography has superior accuracy and is more cost effective for predicting coronary artery disease in patients with suspected angina compared to exercise ECG

Purpose: Exercise ECG (ExECG) is widely used to assess patients with suspected coronary artery disease (CAD). However stress echocardiography (SE) is a well-established alternative technique for the assessment of these patients. We hypothesised that SE, due to its greater accuracy and feasibility, may be superior to ExECG, in terms of positive predictive value and cost effectiveness, when used as the initial test for the assessment of patients with no previous history of CAD presenting with suspected stable angina. Methods: Patients referred with recent onset chest pain during 2011, with no known history of CAD and with a pre-test likelihood of CAD greater than 10%, who underwent first line ExECG or SE were identified. The tests were classified as positive, negative or inconclusive for ischaemia. Coronary angiography (CA) was performed, with the knowledge of the functional test results, as indicated clinically. CAD was defined as the presence of >50% stenosis in at least one major epicardial vessel on CA. Cost to diagnosis of CAD was determined for each functional test by adding the initial cost, of the test to the cost of subsequent tests leading to and including CA. Follow up data on hard events, cardiac death and acute myocardial infarction (AMI), were collected on all patients for a period up to one year after the presentation of the last study patient. Results: We identified 457 patients who underwent ExECG (225 (49%) negative, 94 (21%) positive, 138 (30%) inconclusive) and 257 who underwent SE (213 (83%) negative, 38 (15%) positive, 6 (2%) inconclusive) as first line. The mean pre-test probability of CAD was 43±26% vs 51±28% respectively. Of 74 patients referred for CA on the basis of ExECG, CAD was present in 35 (47%) which was significantly (p=0.04) lower than in the SE group which predicted CAD in 28 out of 42 patients referred for CA (67%). The mean cost to diagnosis was £460 for the ExECG versus £385 for the SE group (p=0.02). No cardiac deaths were found in either group. There was no difference in event rate, (p=0.8 by log rank test) of AMI in patients who were discharged on the basis of a negative ExECG (4 (2%)) versus those with a negative SE (4 (2%)) over a period of 18±6 months. Conclusions: In a population with intermediate pre-test probability of CAD, SE was more accurate and more cost effective for predicting the presence of CAD compared to ExECG. This study suggests that SE rather than ExECG should be the initial test for the assessment of suspected stable angina in this population.

Improved accuracy of myocardial perfusion SPECT for detection of coronary artery disease by machine learning in a large population

ObjectiveWe aimed to improve the diagnostic accuracy of myocardial perfusion SPECT (MPS) by integrating clinical data and quantitative image features with machine learning (ML) algorithms. Methods1,181 rest 201Tl/stress 99mTc-sestamibi dual-isotope MPS studies [713 consecutive cases with correlating invasive coronary angiography (ICA) and suspected coronary artery disease (CAD) and 468 with low likelihood (LLk) of CAD <5%] were considered. Cases with stenosis <70% by ICA and LLk of CAD were considered normal. Total stress perfusion deficit (TPD) for supine/prone data, stress/rest perfusion change, and transient ischemic dilatation were derived by automated perfusion quantification software and were combined with age, sex, and post-electrocardiogram CAD probability by a boosted ensemble ML algorithm (LogitBoost). The diagnostic accuracy of the model for prediction of obstructive CAD ≥70% was compared to standard prone/supine quantification and to visual analysis by two experienced readers utilizing all imaging, quantitative, and clinical data. Tenfold stratified cross-validation was performed. ResultsThe diagnostic accuracy of ML (87.3% ± 2.1%) was similar to Expert 1 (86.0% ± 2.1%), but superior to combined supine/prone TPD (82.8% ± 2.2%) and Expert 2 (82.1% ± 2.2%) (P < .01). The receiver operator characteristic areas under curve for ML algorithm (0.94 ± 0.01) were higher than those for TPD and both visual readers (P < .001). The sensitivity of ML algorithm (78.9% ± 4.2%) was similar to TPD (75.6% ± 4.4%) and Expert 1 (76.3% ± 4.3%), but higher than that of Expert 2 (71.1% ± 4.6%), (P < .01). The specificity of ML algorithm (92.1% ± 2.2%) was similar to Expert 1 (91.4% ± 2.2%) and Expert 2 (88.3% ± 2.5%), but higher than TPD (86.8% ± 2.6%), (P < .01). ConclusionML significantly improves diagnostic performance of MPS by computational integration of quantitative perfusion and clinical data to the level rivaling expert analysis.

Prevalence and Extent of Obstructive Coronary Artery Disease Among Patients Undergoing Elective Coronary Catheterization in New York State and Ontario

Prior studies have shown that physicians in New York State (New York) perform twice as many cardiac catheterizations per capita as those in Ontario for stable patients. However, the role of patient selection in these findings and their implications for detection of obstructive coronary artery disease (CAD) are largely unknown. To evaluate the extent of obstructive CAD and to compare the probability of detecting obstructive CAD for patients undergoing cardiac catheterization. An observational study was conducted involving patients without a history of cardiac disease who underwent elective cardiac catheterization between October 1, 2008, and September 30, 2011. Obstructive CAD was defined as diameter stenosis of 50% or more in the left main coronary artery or stenosis of 70% or more in a major epicardial vessel. Observed rates and predicted probabilities of obstructive CAD. Predicted probabilities were estimated using logistic regression models. A total of 18,114 patients from New York and 54,933 from Ontario were included. The observed rate of obstructive CAD was significantly lower in New York at 30.4% (95% CI, 29.7%-31.0%) than in Ontario at 44.8% (95% CI, 44.4%-45.3%; P < .001). The percentage of patients with left main or 3-vessel CAD was also significantly lower in New York than in Ontario (7.0% [95% CI, 6.6%-7.3%] vs 13.0% [95% CI, 12.8%-13.3%]; P < .001). In New York, a substantially higher percentage of patients with low predicted probability of obstructive CAD underwent cardiac catheterization; for example, only 19.3% (95% CI, 18.7%-19.9%) of patients undergoing cardiac catheterization in New York had a greater than 50% predicted probability of having obstructive CAD than those in Ontario at 41% (95% CI, 40.6%-41.4%; P < .001). At 30 days, crude mortality for patients undergoing cardiac catheterization was slightly higher in New York at 0.65% (90 of 13,824; 95% CI, 0.51%-0.78%) than in Ontario at 0.38% (153 of 40,794; 95% CI, 0.32%-0.43%; P < .001). In Ontario compared with New York State, patients undergoing elective cardiac catheterization were significantly more likely to have obstructive CAD. This appears to be related to a higher percentage of patients in New York with low predicted probability of CAD undergoing cardiac catheterization.

Comparison of different cardiac risk scores for coronary artery disease in symptomatic women: do female-specific risk factors matter?

Cardiovascular diseases remain the leading cause of death in women and there is a need for more accurate risk assessment scores. The aims of our study were to compare the accuracy of several widely used cardiac risk assessment scores in predicting the likelihood of obstructive coronary artery disease (CAD) on CT coronary angiography (CTCA) in symptomatic women and to explore which female-specific risk factors were independent predictors of obstructive CAD on CTCA and whether adding these risk factors to pre-test probability scores would improve their predictive value. Data were obtained from a cohort of 228 consecutively included symptomatic women undergoing evaluation for CAD and referred for CTCA. Obstructive CAD was defined as ≥50% luminal stenosis on CTCA. Pre-test probability for CAD was calculated according to the Diamond and Forrester score, New score, Duke clinical score, and an updated Diamond and Forrester score. Female-specific factors were obtained by a written questionnaire. Pre-test probability scores were compared with ROC analysis and showed that only the New score and the updated Diamond and Forrester score were significant predictive scores for obstructive CAD on CTCA (area under the curve, AUC, 0.67, p < 0.01; AUC 0.61, p = 0.04, respectively). Multivariable logistic regression analysis identified that gestational diabetes mellitus (GDM) and oestrogen status were independent predictors of obstructive CAD when adjusted for the pre-test probability scores. The updated Diamond and Forrester score was used for net reclassification improvement (NRI) analysis, since the New score already accounts for oestrogen status. Adding GDM and oestrogen status to the updated Diamond and Forrester score resulted in a significant NRI (p = 0.04). There is a large variability in prediction of obstructive CAD using different pre-test probability risk scores in symptomatic women. Logistic regression analysis revealed that oestrogen status and GDM were independently associated with the occurrence of obstructive stenosis on CTCA. The predictive ability of cardiac pre-test probability scores improved significantly with the addition of oestrogen status and GDM.

Restriction of the referral of patients with stable angina for CT coronary angiography by clinical evaluation and calcium score: impact on clinical decision making

To investigate the value of the calcium score (CaSc) plus clinical evaluation to restrict referral for CT coronary angiography (CTCA) by reducing the number of patients with an intermediate probability of coronary artery disease (CAD). We retrospectively included 1,975 symptomatic stable patients who underwent clinical evaluation and CaSc calculation and CTCA or invasive coronary coronary angiography (ICA). The outcome was obstructive CAD (≥50 % diameter narrowing) assessed by ICA or CTCA in the absence of ICA. We investigated two models: (1) clinical evaluation consisting of chest pain typicality, gender, age, risk factors and ECG and (2) clinical evaluation with CaSc. Discrimination of the two models was compared. The stepwise reclassification of patients with an intermediate probability of CAD (10-90 %) after clinical evaluation followed by clinical evaluation with CaSc was assessed by clinical net reclassification improvement (NRI). Discrimination of CAD was significantly improved by adding CaSc to the clinical evaluation (AUC: 0.80 vs. 0.89, P < 0.001). CaSc and CTCA could be avoided in 9 % using model 1 and an additional 29 % of CTCAs could be avoided using model 2. Clinical NRI was 57 %. CaSc plus clinical evaluation may be useful in restricting further referral for CTCA by 38 % in symptomatic stable patients with suspected CAD. • CT calcium scores (CaSc) could proiritise referrals for CT coronary angiography (CTCA) • CaSc provides an incremental discriminatory value of CAD compared with clinical evaluation • Risk stratification is better when clinical evaluation is combined with CaSc • Appropriate use of clinical evaluation and CaSc helps avoid unnecessary CTCA referrals.

Automated tissue characterization of in vivo atherosclerotic plaques by intravascular optical coherence tomography images

Intravascular optical coherence tomography (IVOCT) is rapidly becoming the method of choice for the in vivo investigation of coronary artery disease. While IVOCT visualizes atherosclerotic plaques with a resolution <20µm, image analysis in terms of tissue composition is currently performed by a time-consuming manual procedure based on the qualitative interpretation of image features. We illustrate an algorithm for the automated and systematic characterization of IVOCT atherosclerotic tissue. The proposed method consists in a supervised classification of image pixels according to textural features combined with the estimated value of the optical attenuation coefficient. IVOCT images of 64 plaques, from 49 in vivo IVOCT data sets, constituted the algorithm’s training and testing data sets. Validation was obtained by comparing automated analysis results to the manual assessment of atherosclerotic plaques. An overall pixel-wise accuracy of 81.5% with a classification feasibility of 76.5% and per-class accuracy of 89.5%, 72.1% and 79.5% for fibrotic, calcified and lipid-rich tissue respectively, was found. Moreover, measured optical properties were in agreement with previous results reported in literature. As such, an algorithm for automated tissue characterization was developed and validated using in vivo human data, suggesting that it can be applied to clinical IVOCT data. This might be an important step towards the integration of IVOCT in cardiovascular research and routine clinical practice.

113 CORONARY CT ANGIOGRAPHY: A USEFUL DIAGNOSTIC MODALITY IN THE ELDERLY?

<h3>Objective</h3> To establish for the first time whether CT coronary angiography (CTCA) is a useful screening investigation for coronary artery disease in the elderly. <h3>Background</h3> CTCA is an effective diagnostic tool as reflected by its inclusion in consensus guidelines (1). Elderly patients present a significant proportion of those screened for coronary artery disease and this is set to increase (2). However, due to the greater burden of coronary calcification with advancing age (3), there is often reluctance amongst clinicians to select this modality for elderly patients due to the perception that images are likely to be non-diagnostic. Our study aims to determine whether the exclusion of elderly patients from CTCA is justifiable by establishing its diagnostic utility in this demographic. <h3>Method</h3> Patients aged over 70 years and screened for coronary artery disease using 320-detector CT at our institution between 2009 and 2012 were analysed retrospectively. CTCA examinations performed for other purposes and those with previously documented coronary artery disease were excluded from analysis. Studies were designated as either showing obstructive coronary artery disease, non-obstructive atheroma or normal arteries if reported without uncertainty at the time of imaging. Individuals who then underwent invasive coronary angiography were followed to confirm the positive predictive value of CTCA in the population studied. <h3>Results</h3> Of the 886 CTCA examinations in the elderly conducted over the analysis period, 321 studies met the inclusion criteria. The median patient age was 74 years and atrial fibrillation was present in 10% of subjects at the time of imaging. 83% of studies were diagnostic, with obstructive atheroma excluded in 59% patients. The positive predictive value of obstructive atheroma was 89% when compared with invasive angiography. With non-diagnostic studies included in this group, the positive predictive value of a non-negative test was 74%. <h3>Conclusions</h3> CTCA is a useful diagnostic test in the elderly. Obstructive atheroma was excluded in the majority of patients screened for coronary artery disease with an acceptable positive predictive value. Concerns that extensive calcification precludes use of this technique in the elderly are therefore unfounded and CTCA should be considered as an option when selecting an appropriate screening test for coronary artery disease in elderly patients.

Coronary computed tomography angiography-adapted Leaman score as a tool to noninvasively quantify total coronary atherosclerotic burden

To describe a coronary computed tomography angiography (CCTA)-adapted Leaman score (CT-LeSc) as a tool to quantify total coronary atherosclerotic burden with information regarding localization, type of plaque and degree of stenosis and to identify clinical predictors of a high coronary atherosclerotic burden as assessed by the CT-LeSc. Single center prospective registry including a total of 772 consecutive patients undergoing CCTA (Dual-source CT) from April 2011 to March 2012. For the purpose of this study, 581 stable patients referred for suspected coronary artery disease (CAD) without previous myocardial infarction or revascularization procedures were included. Pre-test CAD probability was determined using both the Diamond-Forrester extended CAD consortium method (DF-CAD consortium model) and the Morise score. Cardiovascular risk was assessed with the HeartScore. The cut-off for the 3rd tercile (CT-LeSc ≥8.3) was used to define a population with a high coronary atherosclerotic burden. The median CT-LeSc in this population (n = 581, 8,136 coronary segments evaluated; mean age 57.6 ± 11.1; 55.8 % males; 14.6 % with diabetes) was 2.2 (IQR 0-6.8). In patients with CAD (n = 341), the median CT-LeSc was 5.8 (IQR 3.2-9.6). Among patients with nonobstructive CAD, most were classified in the lowest terciles (T1, 43.0 %; T2, 36.1 %), but 20.9 % were in the highest tercile (T3). The majority of the patients with obstructive CAD were classified in T3 (78.2 %), but 21.8 % had a CT-LeSc in lower terciles (T1 or T2). The independent predictors of a high CT-LeSc were: Male sex (OR 1.73; 95 % CI 1.04-2.90) diabetes (OR 2.91; 95 % CI 1.61-5.23), hypertension (OR 2.54; 95 % CI 1.40-4.63), Morise score ≥ 16 (OR 1.97; 95 % CI 1.06-3.67) and HeartScore ≥ 5 (OR 2.42; 95 % CI 1.41-4.14). We described a cardiac CT adapted Leaman score as a tool to quantify total (obstructive and nonobstructive) coronary atherosclerotic burden, reflecting the comprehensive information about localization, degree of stenosis and type of plaque provided by CCTA. Male sex, hypertension, diabetes, a HeartScore ≥5 % and a Morise score ≥ 16 were associated with a high coronary atherosclerotic burden, as assessed by the CT-LeSc. About one fifth of the patients with nonobstructive CAD had a CT-LeSc in the highest tercile, and this could potentially lead to a reclassification of the risk profile of this subset of patients identified by CCTA, once the prognostic value of the CT-LeSc is validated.