Added value of hybrid myocardial perfusion SPECT and CT coronary angiography in the diagnosis of coronary artery disease.

AIMS: Hybrid single photon emission computed tomography (SPECT)/coronary computed tomography angiography (CCTA) has only been evaluated for its diagnostic accuracy as a single test in patients suspected of significant coronary artery disease (CAD). Added value of hybrid SPECT/CCTA beyond usual clinical work-up, or use of each of these tests separately, remains unclear. We evaluated the added value of hybrid myocardial perfusion SPECT (SPECT) and CCTA, beyond pre-test likelihood and exercise stress ECG (X-ECG), in the diagnosis of CAD. METHODS AND RESULTS: Two hundred and five patients with stable angina pectoris and intermediate-to-high pre-test likelihood were prospectively included. All patients underwent clinical history and examination, X-ECG, stress and rest SPECT, coronary calcium scoring (CCS) and CCTA. Fractional flow reserve measurement <0.80 or a lesion >50% on coronary angiography (CA) served as reference standard for significant CAD. Multiple imputation was used to correct for missing test results (17-20%). Added value of hybrid SPECT/CCTA to the basic model of pre-test likelihood plus X-ECG was quantified using logistic regression analysis. Model differences were then assessed using differences in C-index and in net reclassification improvement (NRI). The basic model had a C-index of 0.73 (95%CI 0.66-0.80). This significantly increased to 0.85 (95%CI 0.80-0.91) by addition of only SPECT, to 0.90 (95%CI 0.85-0.94) when adding only CCTA, and to 0.96 (95%CI 0.92-0.99) when adding hybrid SPECT/CCTA. The accompanying NRIs were 0.82 (95%CI 0.62-1.02), 0.86 (95%CI 0.66-1.06) and 1.57 (95%CI 1.11-1.59) respectively. CONCLUSION: Current analysis resembles clinical routine of layered testing and shows that hybrid SPECT/CCTA imaging has a substantially higher yield than standalone SPECT or CCTA in the diagnostic workup of patients suspected of significant CAD.

Quantitative computed tomographic coronary angiography: does it predict functionally significant coronary stenoses?

BACKGROUND: Coronary lesions with a diameter narrowing ≥50% on visual computed tomographic coronary angiography (CTCA) are generally considered for referral to invasive coronary angiography. However, similar to invasive coronary angiography, visual CTCA is often inaccurate in detecting functionally significant coronary lesions. We sought to compare the diagnostic performance of quantitative CTCA with visual CTCA for the detection of functionally significant coronary lesions using fractional flow reserve (FFR) as the reference standard. METHODS AND RESULTS: CTCA and FFR measurements were obtained in 99 symptomatic patients. In total, 144 coronary lesions detected on CTCA were visually graded for stenosis severity. Quantitative CTCA measurements included lesion length, minimal area diameter, % area stenosis, minimal lumen diameter, % diameter stenosis, and plaque burden [(vessel area-lumen area)/vessel area×100]. Optimal cutoff values of CTCA-derived parameters were determined, and their diagnostic accuracy for the detection of flow-limiting coronary lesions (FFR≤0.80) was compared with visual CTCA. FFR was ≤0.80 in 54 of 144 (38%) coronary lesions. Optimal cutoff values to predict flow-limiting coronary lesion were 10 mm for lesion length, 1.8 mm2 for minimal area diameter, 73% for % area stenosis, 1.5 mm for minimal lumen diameter, 48% for % diameter stenosis, and 76% for plaque burden. No significant difference in sensitivity was found between visual CTCA and quantitative CTCA parameters (P>0.05). The specificity of visual CTCA (42%; 95% confidence interval [CI], 31%-54%) was lower than that of minimal area diameter (68%; 95% CI, 57%-77%; P=0.001), % area stenosis (76%; 95% CI, 65%-84%; P<0.001), minimal lumen diameter (67%; 95% CI, 55%-76%; P=0.001), % diameter stenosis (72%; 95% CI, 62%-80%; P<0.001), and plaque burden (63%; 95% CI, 52%-73%; P=0.004). The specificity of lesion length was comparable with that of visual CTCA. CONCLUSIONS: Quantitative CTCA improves the prediction of functionally significant coronary lesions compared with visual CTCA assessment but remains insufficient. Functional assessment is still required in lesions of moderate stenosis to accurately detect impaired FFR.

Diagnostic performance of computed tomography coronary angiography to detect and exclude left main and/or three-vessel coronary artery disease.

OBJECTIVES: To determine the diagnostic performance of CT coronary angiography (CTCA) in detecting and excluding left main (LM) and/or three-vessel CAD ("high-risk" CAD) in symptomatic patients and to compare its discriminatory value with the Duke risk score and calcium score. MATERIALS AND METHODS: Between 2004 and 2011, a total of 1,159 symptomatic patients (61 ± 11 years, 31 % women) with stable angina, without prior revascularisation underwent both invasive coronary angiography (ICA) and CTCA. All patients gave written informed consent for the additional CTCA. High-risk CAD was defined as LM and/or three-vessel obstructive CAD (≥50 % diameter stenosis). RESULTS: A total of 197 (17 %) patients had high-risk CAD as determined by ICA. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios of CTCA were 95 % (95 % CI 91-97 %), 83 % (80-85 %), 53 % (48-58 %), 99 % (98-99 %), 5.47 and 0.06, respectively. CTCA provided incremental value (AUC 0.90, P < 0.001) in the discrimination of high-risk CAD compared with the Duke risk score and calcium score. CONCLUSIONS: CTCA accurately excludes high-risk CAD in symptomatic patients. The detection of high-risk CAD is suboptimal owing to the high percentage (47 %) of overestimation of high-risk CAD. CTCA provides incremental value in the discrimination of high-risk CAD compared with the Duke risk score and calcium score. KEY POINTS: • Computed tomography coronary angiography (CTCA) accurately excludes high-risk coronary artery disease. • CTCA overestimates high-risk coronary artery disease in 47 %. • CTCA discriminates high-risk CAD better than clinical evaluation and coronary calcification.

Computed tomography coronary imaging as a gatekeeper for invasive coronary angiography in patients with newly diagnosed heart failure of unknown aetiology.

AIMS: To evaluate the accuracy of cardiac computed tomography (CT) in distinguishing CAD and non-CAD heart failure (HF) and its effectiveness as a gatekeeper for invasive coronary angiography (ICA). METHODS AND RESULTS: We prospectively included 93 symptomatic patients with newly diagnosed HF of unknown aetiology (59 men; mean age 53 ± 13) and EF <45%, and/or fractional shortening <25%, and/or end-diastolic LV diameter >60 mm (men) or >55 mm (women). In all patients, the CT calcium score (CTCS) was determined. CTCS = 0 excluded CAD HF. Additional CT coronary angiography (CTCA) was performed if CTCS >0. ICA was used as the gold standard for distinguishing between CAD and non-CAD HF in patients with >20% luminal diameter narrowing on CTCA. CAD HF was defined as >50% luminal diameter narrowing in either (i) the left main coronary artery or proximal left anterior descending coronary artery or (ii) in multiple coronary arteries. Diagnostic accuracy and follow-up data (20 ± 16 months) were collected for all patients. CTCS = 0 ruled out CAD HF in 43 patients (46%). The CT algorithm had 100% sensitivity, 95% specificity, 67% positive predictive value, and 100% negative predictive value for detecting CAD HF. Patients with CTCS = 0 or non-CAD HF on CTCA had no coronary events during follow-up, and ICA could have been safely avoided in 76 out of 93 patients (82%). CONCLUSION: In patients with HF of unknown aetiology, cardiac CT combining CTCS and CTCA has high accuracy for detecting CAD HF and can be used effectively as a gatekeeper for ICA.

Incremental diagnostic accuracy of hybrid SPECT/CT coronary angiography in a population with an intermediate to high pre-test likelihood of coronary artery disease.

AIMS: Hybrid myocardial perfusion imaging with single photon emission computed tomography (SPECT) and CT coronary angiography (CCTA) has the potential to play a major role in patients with non-conclusive SPECT or CCTA results. We evaluated the performance of hybrid SPECT/CCTA vs. standalone SPECT and CCTA for the diagnosis of significant coronary artery disease (CAD) in patients with an intermediate to high pre-test likelihood of CAD. METHODS AND RESULTS: In total, 98 patients (mean age 62.5 ± 10.1 years, 68.4% male) with stable anginal complaints and a median pre-test likelihood of 87% (range 22-95%) were prospectively included in this study. Hybrid SPECT/CCTA was performed prior to conventional coronary angiography (CA) including fractional flow reserve (FFR) measurements. Hybrid analysis was performed by combined interpretation of SPECT and CCTA images. The sensitivity, specificity, positive (PPV), and negative (NPV) predictive values were calculated for standalone SPECT, CCTA, and hybrid SPECT/CCTA on per patient level, using an FFR <0.80 as a reference for significant CAD. Significant CAD was demonstrated in 56 patients (57.9%). Non-conclusive SPECT or CCTA results were found in 32 (32.7%) patients. SPECT had a sensitivity of 93%, specificity 79%, PPV 85%, and NPV 89%. CCTA had a sensitivity of 98%, specificity 62%, PPV 77%, and NPV 96%. Hybrid analysis of SPECT and CCTA improved the overall performance: sensitivity, specificity, PPV, and NPV for the presence of significant CAD to 96, 95, 96, and 95%, respectively. CONCLUSIONS: In > 40% of the patients with a high pre-test likelihood no significant CAD was demonstrated, emphasizing the value of accurate pre-treatment cardiovascular imaging. Hybrid SPECT/CCTA was able to accurately diagnose and exclude significant CAD surpassing standalone myocardial SPECT and CCTA, vs. a reference standard of FFR measurements.

Hybrid myocardial perfusion SPECT/CT coronary angiography and invasive coronary angiography in patients with stable angina pectoris lead to similar treatment decisions.

OBJECTIVES: To evaluate to what extent treatment decisions for patients with stable angina pectoris can be made based on hybrid myocardial perfusion single-photon emission CT (SPECT) and CT coronary angiography (CCTA). It has been shown that hybrid SPECT/CCTA has good performance in the diagnosis of significant coronary artery disease (CAD). The question remains whether these imaging results lead to similar treatment decisions as compared to standalone SPECT and invasive coronary angiography (CA). METHODS: We prospectively included 107 patients (mean age 62.8±10.0 years, 69% male) with stable anginal complaints and an intermediate to high pre-test likelihood for CAD. Hybrid SPECT/CCTA was performed prior to CA in all patients. The study outcome was the treatment decision categorised as: no revascularisation, percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Treatment decisions were made by two interventional cardiologists and one cardiothoracic surgeon in two steps: first, based on the results of hybrid SPECT/CCTA; second, based on SPECT and CA. RESULTS: Revascularisation (PCI or CABG) was indicated in 54 (50%) patients based on SPECT and CA. Percentage agreement of treatment decisions in all patients based on hybrid SPECT/CCTA versus SPECT and CA on the necessity of revascularisation was 92%. Percentage agreement of treatment decisions in patients with matched, unmatched and normal hybrid SPECT/CCTA findings was 95%, 84% and 100%, respectively. CONCLUSIONS: Panel evaluation shows that patients could be accurately indicated for and deferred from revascularisation based on hybrid SPECT/CCTA.

Computed tomography coronary angiography accuracy in women and men at low to intermediate risk of coronary artery disease.

OBJECTIVES: To investigate the diagnostic accuracy of CT coronary angiography (CTCA) in women at low to intermediate pre-test probability of coronary artery disease (CAD) compared with men. METHODS: In this retrospective study we included symptomatic patients with low to intermediate risk who underwent both invasive coronary angiography and CTCA. Exclusion criteria were previous revascularisation or myocardial infarction. The pre-test probability of CAD was estimated using the Duke risk score. Thresholds of less than 30 % and 30-90 % were used for determining low and intermediate risk, respectively. The diagnostic accuracy of CTCA in detecting obstructive CAD (≥50 % lumen diameter narrowing) was calculated on patient level. P < 0.05 was considered significant. RESULTS: A total of 570 patients (46 % women [262/570]) were included and stratified as low (women 73 % [80/109]) and intermediate risk (women 39 % [182/461]). Sensitivity, specificity, PPV and NPV were not significantly different in and between women and men at low and intermediate risk. For women vs. men at low risk they were 97 % vs. 100 %, 79 % vs. 90 %, 80 % vs. 80 % and 97 % vs. 100 %, respectively. For intermediate risk they were 99 % vs. 99 %, 72 % vs. 83 %, 88 % vs. 93 % and 98 % vs. 99 %, respectively. CONCLUSION: CTCA has similar diagnostic accuracy in women and men at low and intermediate risk. KEY POINTS : • Coronary artery disease (CAD) is increasingly investigated by computed tomography angiography (CTCA). • CAD detection or exclusion by CTCA is not different between sexes. • CTCA diagnostic accuracy was similar between low and intermediate risk sex-specific-groups. • CTCA rarely misses obstructive CAD in low-intermediate risk women and men. • CAD yield by invasive coronary angiography after positive CTCA is similar between sex-risk-specific groups.

A clinical prediction rule for the diagnosis of coronary artery disease: validation, updating, and extension.

AIMS: The aim was to validate, update, and extend the Diamond-Forrester model for estimating the probability of obstructive coronary artery disease (CAD) in a contemporary cohort. METHODS AND RESULTS: Prospectively collected data from 14 hospitals on patients with chest pain without a history of CAD and referred for conventional coronary angiography (CCA) were used. Primary outcome was obstructive CAD, defined as ≥ 50% stenosis in one or more vessels on CCA. The validity of the Diamond-Forrester model was assessed using calibration plots, calibration-in-the-large, and recalibration in logistic regression. The model was subsequently updated and extended by revising the predictive value of age, sex, and type of chest pain. Diagnostic performance was assessed by calculating the area under the receiver operating characteristic curve (c-statistic) and reclassification was determined. We included 2260 patients, of whom 1319 had obstructive CAD on CCA. Validation demonstrated an overestimation of the CAD probability, especially in women. The updated and extended models demonstrated a c-statistic of 0.79 (95% CI 0.77-0.81) and 0.82 (95% CI 0.80-0.84), respectively. Sixteen per cent of men and 64% of women were correctly reclassified. The predicted probability of obstructive CAD ranged from 10% for 50-year-old females with non-specific chest pain to 91% for 80-year-old males with typical chest pain. Predictions varied across hospitals due to differences in disease prevalence. CONCLUSION: Our results suggest that the Diamond-Forrester model overestimates the probability of CAD especially in women. We updated the predictive effects of age, sex, type of chest pain, and hospital setting which improved model performance and we extended it to include patients of 70 years and older.

Incremental value of the CT coronary calcium score for the prediction of coronary artery disease.

OBJECTIVES: To validate published prediction models for the presence of obstructive coronary artery disease (CAD) in patients with new onset stable typical or atypical angina pectoris and to assess the incremental value of the CT coronary calcium score (CTCS). METHODS: We searched the literature for clinical prediction rules for the diagnosis of obstructive CAD, defined as ≥50% stenosis in at least one vessel on conventional coronary angiography. Significant variables were re-analysed in our dataset of 254 patients with logistic regression. CTCS was subsequently included in the models. The area under the receiver operating characteristic curve (AUC) was calculated to assess diagnostic performance. RESULTS: Re-analysing the variables used by Diamond & Forrester yielded an AUC of 0.798, which increased to 0.890 by adding CTCS. For Pryor, Morise 1994, Morise 1997 and Shaw the AUC increased from 0.838 to 0.901, 0.831 to 0.899, 0.840 to 0.898 and 0.833 to 0.899. CTCS significantly improved model performance in each model. CONCLUSIONS: Validation demonstrated good diagnostic performance across all models. CTCS improves the prediction of the presence of obstructive CAD, independent of clinical predictors, and should be considered in its diagnostic work-up.

Diagnostic accuracy and clinical utility of noninvasive testing for coronary artery disease.

BACKGROUND: Computed tomography coronary angiography (CTCA) has become a popular noninvasive test for diagnosing coronary artery disease. OBJECTIVE: To compare the accuracy and clinical utility of stress testing and CTCA for identifying patients who require invasive coronary angiography (ICA). DESIGN: Observational study. SETTING: University medical center in Rotterdam, the Netherlands. PATIENTS: 517 patients referred by their treating physicians for evaluation of chest symptoms by using stress testing or ICA. INTERVENTION: Stress testing and CTCA in all patients. MEASUREMENTS: Diagnostic accuracy of stress testing and CTCA compared with ICA; pretest probabilities of disease by Duke clinical score; and clinical utility of noninvasive testing, defined as a pretest or posttest probability that suggests how to proceed with testing (no further testing if < or =5%, proceed with ICA if between 5% and 90%, and refer directly for ICA if > or =90%). RESULTS: Stress testing was not as accurate as CTCA; CTCA sensitivity approached 100%. In patients with a low (<20%) pretest probability of disease, negative stress test or CTCA results suggested no need for ICA. In patients with an intermediate (20% to 80%) pretest probability, a positive CTCA result suggested need to proceed with ICA (posttest probability, 93% [95% CI, 92% to 93%]) and a negative result suggested no need for further testing (posttest probability, 1% [CI, 1% to 1%]). Physicians could proceed directly with ICA in patients with a high (>80%) pretest probability (91% [CI, 90% to 92%]). LIMITATIONS: Referral and verification bias might have influenced findings. Stress testing provides functional information that may add value to that from anatomical (CTCA or ICA) imaging. CONCLUSION: Computed tomography coronary angiography seems most valuable in patients with intermediate pretest probability of disease, because the test can distinguish which of these patients need invasive angiography. These findings need to be confirmed before CTCA can be routinely recommended for these patients.

Does slice thickness affect diagnostic performance of 64-slice CT coronary angiography in stable and unstable angina patients with a positive calcium score?

BACKGROUND: Coronary calcification can lead to over-estimation of the degree of coronary stenosis. PURPOSE: To evaluate whether thinner reconstruction thickness improves the diagnostic performance of 64-slice CT coronary angiography (CTCA) in angina patients with a positive calcium score. MATERIAL AND METHODS: We selected 20 scans from a clinical study comparing CTCA to conventional coronary angiography (CCA) in stable and unstable angina patients based on a low number of motion artifacts and a positive calcium score. All images were acquired at 64 x 0.625 mm and each CTCA scan was reconstructed at slice thickness/increment 0.67 mm/0.33 mm, 0.9 mm/0.45 mm, and 1.4 mm/0.7 mm. Two reviewers blinded for CCA results independently evaluated the scans for the presence of significant coronary artery disease (CAD) in three randomly composed series, with > or =2 weeks in between series. The diagnostic performance of CTCA was compared for the different slice thicknesses using a pooled analysis of both reviewers. Significant CAD was defined as >50% diameter narrowing on quantitative CCA. Image noise (standard deviation of CT numbers) was measured in all scans. Inter-observer variability was assessed with kappa. RESULTS: Significant CAD was present in 8% of 304 available segments. Median total Agatston calcium score was 181.8 (interquartile range 34.9-815.6). Sensitivity at 0.67 mm, 0.9 mm, and 1.4 mm slice thickness was 70% (95% confidence interval 57-83%), 74% (62-86%), and 70% (57-83%), respectively. Specificity was 85% (82-88%), 84% (81-87%), and 84% (81-87%), respectively. The positive predictive value was 30 (21-38%), 29 (21-37%), and 28 (20-36%), respectively. The negative predictive value was 97% (95-98%), 97% (96-99%), and 97% (96-99%), respectively. Kappa for inter-observer agreement was 0.56, 0.58, and 0.59. Noise decreased from 32.9 HU at 0.67 mm, to 23.2 HU at 1.4 mm (P<0.001). CONCLUSION: Diagnostic performance of CTCA in angina patients with a positive calcium score was not markedly affected by modest variations in reconstruction slice thickness.

CT coronary angiography in patients suspected of having coronary artery disease: decision making from various perspectives in the face of uncertainty.

PURPOSE: To determine the cost-effectiveness of computed tomographic (CT) coronary angiography as a triage test, performed prior to conventional coronary angiography, by using a Markov model. MATERIALS AND METHODS: A Markov model was used to analyze the cost-effectiveness of CT coronary angiography performed as a triage test prior to conventional coronary angiography from the perspective of the patient, physician, hospital, health care system, and society by using recommendations from the United Kingdom, the United States, and the Netherlands for cost-effectiveness analyses. For CT coronary angiography, a range of sensitivities (79%-100%) and specificities (63%-94%) were used to help diagnose significant coronary artery disease (CAD). Optimization criteria (ie, outcomes considered) were: revised posttest probability of CAD, life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs). Extensive sensitivity analysis was performed. RESULTS: For a prior probability of CAD of less than 40%, the probability of CAD after CT coronary angiography with negative results was less than 1%. The Markov model calculations from the patient/physician perspective suggest that CT coronary angiography maximizes life-years respectively in 60-year-old men and women at a prior probability of less than 38% and 24% and maximizes QALYs at a prior probability of less than 17% and 11%. From the hospital/health care perspective, CT coronary angiography helps reduce health care and direct nonhealth care-related costs (according to UK/U.S. recommendations), regardless of prior probability, and lowers all costs, including production losses (Netherlands recommendations) at a prior probability of less than 87%-92%. Analysis performed from a societal perspective by using a willingness-to-pay threshold level of euro 80,000/QALY suggests that CT coronary angiography is cost-effective when the prior probability is lower than 44% and 37% in men and women, respectively. Sensitivity analyses showed that results changed across the reported range of sensitivity of CT coronary angiography. CONCLUSION: The optimal diagnostic work-up depends on the optimization criterion, prior probability of CAD, and the diagnostic performance of CT coronary angiography.

Is there a role for CT coronary angiography in patients with symptomatic angina? Effect of coronary calcium score on identification of stenosis.

Present guidelines discourage the use of CT coronary angiography (CTCA) in symptomatic angina patients. We examined the relation between coronary calcium score (CS) and the performance of CTCA in patients with stable and unstable angina in order to understand under which conditions CTCA might be a gate-keeper to conventional coronary angiography (CCA) in such patients. We included 360 patients between 50 and 70 years old with stable and unstable angina who were clinically referred for CCA irrespective of CS. Patients received CS and CCTA on 64-slice scanners in a multicenter cross-sectional trial. The institutional review board approved the study. Diagnostic performance of CTCA to detect or rule out significant coronary artery disease was calculated on a per patient level in pre-defined CS categories. The prevalence of significant coronary artery disease strongly increased with CS. Negative CTCA were associated with a negative likelihood ratio of <0.1 independent of CS. Positive CTCA was associated with a high positive likelihood ratio of 9.4 if CS was <10. However, for higher CS the positive likelihood ratio never exceeded 3.0 and for CS >400 it decreased to 1.3. In the 62 (17%) patients with CS <10, CTCA reliably identified the 42 (68%) of these patients without significant CAD, at no false negative CTCA scans. In symptomatic angina patients, a negative CTCA reliably excludes significant CAD but the additional value of CTCA decreases sharply with CS >10 and especially with CS >400. In patients with CS <10, CTCA provides excellent diagnostic performance.

Comparison of frequency of calcified versus non-calcified coronary lesions by computed tomographic angiography in patients with stable versus unstable angina pectoris.

Computed tomographic coronary angiography (CTCA) can noninvasively identify calcified and noncalcified coronary plaques. The aim of this study was to compare the phenotypes of all plaques and of culprit plaques between patients with unstable angina pectoris (UAP) and those with stable angina pectoris (SAP), because plaque characteristics may differ between these patients. In 110 patients with UAP and 189 with SAP from a multicenter study comparing 64-slice CTCA with conventional coronary angiography, the number and phenotypes (noncalcified, mixed, and calcified) of coronary plaques were compared. In a subanalysis in 50 patients with UAP and 64 with SAP, culprit plaque characteristics, including culprit plaque cross-sectional area relative to total vessel cross-sectional area, culprit plaque length, remodeling index, and spotty calcification, were determined. Odds ratios for the presence of UAP, adjusted for clinical variables and the total number of plaques, were calculated for plaque characteristics on CTCA. Although the number of plaques was similar for patients with UAP and those with SAP, plaques in patients with UAP were more frequently noncalcified than in patients with SAP. The odds ratio for UAP was 1.3 (95% confidence interval [CI] 1.1 to 1.5) per noncalcified plaque. In the culprit plaque subanalysis, odds ratios for UAP were 0.99 (95% CI 0.96 to 1.01) per millimeter culprit plaque length, 2.7 (95% CI 1.2 to 6.4) for noncalcified culprit plaque, and 1.06 (95% CI 0.99 to 1.13) per percentage relative culprit plaque cross-sectional area. No significant relation was found between remodeling index or spotty calcification and UAP. In conclusion, noncalcified plaques and large noncalcified culprit plaques are more frequently found in patients with UAP than in those with SAP.

Diagnostic accuracy of computed tomography angiography in patients after bypass grafting: comparison with invasive coronary angiography.

OBJECTIVES: We sought to evaluate the contribution of noninvasive dual-source computed tomography angiography (CTA) in the comprehensive assessment of symptomatic patients after coronary artery bypass grafting (CABG). BACKGROUND: Assessment of bypass grafts and distal runoffs by invasive coronary angiography is cumbersome and often requires extra procedure time, contrast load, and radiation exposure. METHODS: Dual-source CTA was performed in 52 (41 men, mean age 66.6 +/- 13.2 years) symptomatic post-CABG patients scheduled for invasive coronary angiography. No oral or intravenous beta blockers or sedation were administered before the scan. Mean interval between CABG surgery and CTA was 9.6 +/- 7.2 (range 0 to 20) years. Mean heart rate during scanning was 64.5 +/- 13.2 (range 48 to 92) beats/min. Seventy-five percent of patients had both arterial and venous grafts. A total of 152 graft segments and 142 distal runoffs vessels were analyzed. Native coronary segments were divided into nongrafted (n = 118) and grafted segments (n = 289). A significant stenosis was defined as >or=50% lumen diameter reduction, and quantitative coronary angiography served as reference standard. RESULTS: The diagnostic accuracy of CTA for the detection or exclusion of significant stenosis in arterial and venous grafts on a segment-by-segment analysis was 100%. Sensitivity, specificity, positive predictive value, and negative predictive value to detect significant stenosis were 95% (95% confidence interval [CI]: 73% to 100%), 100% (95% CI: 96% to 100%), 100% (95% CI: 79% to 100%), 99% (95% CI: 95% to 100%) in distal runoffs respectively; 100% (95% CI: 97% to 100%), 96% (95% CI: 90% to 98%), 97% (95% CI: 93% to 99%), 100% (95% CI: 95% to 100%) in grafted native coronary arteries respectively; and 97% (95% CI: 83% to 100%), 92% (95% CI: 83% to 96%), 83% (95% CI: 67% to 92%), 99% (95% CI: 92% to 100%) in nongrafted native coronary arteries, respectively. CONCLUSIONS: Noninvasive CTA is successful for evaluating bypass grafts in symptomatic post-CABG patients, whereas invasive coronary angiography is still required for the assessment of significant stenosis in distal runoffs and native coronary arteries.

Diagnostic accuracy of 64-slice computed tomography coronary angiography: a prospective, multicenter, multivendor study.

OBJECTIVES: This study sought to determine the diagnostic accuracy of 64-slice computed tomographic coronary angiography (CTCA) to detect or rule out significant coronary artery disease (CAD). BACKGROUND: CTCA is emerging as a noninvasive technique to detect coronary atherosclerosis. METHODS: We conducted a prospective, multicenter, multivendor study involving 360 symptomatic patients with acute and stable anginal syndromes who were between 50 and 70 years of age and were referred for diagnostic conventional coronary angiography (CCA) from September 2004 through June 2006. All patients underwent a nonenhanced calcium scan and a CTCA, which was compared with CCA. No patients or segments were excluded because of impaired image quality attributable to either coronary motion or calcifications. Patient-, vessel-, and segment-based sensitivities and specificities were calculated to detect or rule out significant CAD, defined as >or=50% lumen diameter reduction. RESULTS: The prevalence among patients of having at least 1 significant stenosis was 68%. In a patient-based analysis, the sensitivity for detecting patients with significant CAD was 99% (95% confidence interval [CI]: 98% to 100%), specificity was 64% (95% CI: 55% to 73%), positive predictive value was 86% (95% CI: 82% to 90%), and negative predictive value was 97% (95% CI: 94% to 100%). In a segment-based analysis, the sensitivity was 88% (95% CI: 85% to 91%), specificity was 90% (95% CI: 89% to 92%), positive predictive value was 47% (95% CI: 44% to 51%), and negative predictive value was 99% (95% CI: 98% to 99%). CONCLUSIONS: Among patients in whom a decision had already been made to obtain CCA, 64-slice CTCA was reliable for ruling out significant CAD in patients with stable and unstable anginal syndromes. A positive 64-slice CTCA scan often overestimates the severity of atherosclerotic obstructions and requires further testing to guide patient management.

Comprehensive assessment of coronary artery stenoses: computed tomography coronary angiography versus conventional coronary angiography and correlation with fractional flow reserve in patients with stable angina.

OBJECTIVES: We sought to determine the diagnostic accuracy of noninvasive visual (computed tomography coronary angiography [CTCA]) and quantitative computed tomography coronary angiography (QCT) to predict the hemodynamic significance of a coronary stenosis, using intracoronary fractional flow reserve (FFR) as the reference standard. BACKGROUND: It has been demonstrated that CTCA provides excellent diagnostic sensitivity for identifying coronary stenoses, but may lack accurate delineation of the hemodynamic significance. METHODS: We investigated 79 patients with stable angina pectoris who underwent both 64-slice or dual-source CTCA and FFR measurement of discrete coronary stenoses. CTCA and conventional coronary angiography (CCA), and QCT and quantitative coronary angiography (QCA), were performed to determine the severity of a stenosis that was compared with FFR measurements. A significant anatomical or functional stenosis was defined as >/=50% diameter stenosis or an FFR <0.75. Stented segments and bypass grafts were not included in the analysis. RESULTS: A total of 89 stenoses were evaluated of which 18% (16 of 89) had an FFR <0.75. The diagnostic accuracy of CTCA, QCT, CCA, and QCA to detect a hemodynamically significant coronary lesion was 49%, 71%, 61%, and 67%, respectively. Correlation between QCT and QCA with FFR measurement was weak (R values of -0.32 and -0.30, respectively). Correlation between QCT and QCA was significant, but only moderate (R = 0.53; p < 0.0001). CONCLUSIONS: The anatomical assessment of the hemodynamic significance of coronary stenoses determined by visual CTCA, CCA, or QCT or QCA does not correlate well with the functional assessment of FFR. Determining the hemodynamic significance of an angiographically intermediate stenosis remains relevant before referral for revascularization treatment.

Comparison of diagnostic accuracy of 64-slice computed tomography coronary angiography in women versus men with angina pectoris.

We compared the diagnostic accuracy of 64-slice computed tomographic (CT) coronary angiography to detect significant coronary artery disease (CAD) in women and men. The 64-slice CT coronary angiography was performed in 402 symptomatic patients, 123 women and 279 men, with CAD prevalence of 51% and 68%, respectively. Significant CAD, defined as > or =50% coronary stenosis on quantitative coronary angiography, was evaluated on a patient, vessel, and segment level. The sensitivity and negative predictive value to detect significant CAD was very good, both for women and men (100% vs 99%, p = NS; 100% vs 98%, p = NS), whereas diagnostic accuracy (88% vs 96%; p <0.01), specificity (75% vs 90%, p <0.05), and positive predictive value (81% vs 95%, p <0.001) were lower in women. The per-segment analysis demonstrated lower sensitivity in women compared with men (82% vs 93%, p <0.001). The sensitivity in women did not show a difference in proximal and midsegments, but was significantly lower in distal segments (56% vs 85%, p <0.05) and side branches (54% vs 89%, p <0.001). In conclusion, CT coronary angiography reliably rules out the presence of obstructive CAD in both men and women. Specificity and positive predictive value of CT coronary angiography were lower in women. The sensitivity to detect stenosis in small coronary branches was lower in women compared with men.

64-slice computed tomography coronary angiography in patients with high, intermediate, or low pretest probability of significant coronary artery disease.

OBJECTIVES: We assessed the usefulness of 64-slice computed tomography coronary angiography (CTCA) to detect or rule out coronary artery disease (CAD) in patients with various estimated pretest probabilities of CAD. BACKGROUND: The pretest probability of the presence of CAD may impact the diagnostic performance of CTCA. METHODS: Sixty-four-slice CTCA (Sensation 64, Siemens, Forchheim, Germany) was performed in 254 symptomatic patients. Patients with heart rates > or =65 beats/min received beta-blockers before CTCA. The pretest probability for significant CAD was estimated by type of chest discomfort, age, gender, and traditional risk factors and defined as high (> or =71%), intermediate (31% to 70%), and low (< or =30%). Significant CAD was defined as the presence of at least 1 > or =50% coronary stenosis on quantitative coronary angiography, which was the standard of reference. No coronary segments were excluded from analysis. RESULTS: The estimated pretest probability of CAD in the high (n = 105), intermediate (n = 83), and low (n = 66) groups was 87%, 53%, and 13%, respectively. The diagnostic performance of the computed tomography (CT) scan was different in the 3 subgroups. The estimated post-test probability of the presence of significant CAD after a negative CT scan was 17%, 0%, and 0% and after a positive CT scan was 96%, 88%, and 68%, respectively. CONCLUSIONS: Computed tomography coronary angiography is useful in symptomatic patients with a low or intermediate estimated pretest probability of having significant CAD, and a negative CT scan reliably rules out the presence of significant CAD. Computed tomography coronary angiography does not provide additional relevant diagnostic information in symptomatic patients with a high estimated pretest probability of CAD.