Dual-energy computed tomography for detection of coronary artery disease

Recent technological advances in computed tomography (CT) technology have fulfilled the prerequisites for the cardiac application of dual-energy CT (DECT) imaging. By exploiting the unique characteristics of materials when exposed to two different x-ray energies, DECT holds great promise for the diagnosis and management of coronary artery disease. It allows for the assessment of myocardial perfusion to discern the hemodynamic significance of coronary disease and possesses high accuracy for the detection and characterization of coronary plaques, while facilitating reductions in radiation dose. As such, DECT enabled cardiac CT to advance beyond the mere detection of coronary stenosis expanding its role in the evaluation and management of coronary atherosclerosis.     

Cost-effective applications of cardiac computed tomography in coronary artery disease

Computed tomography has been introduced as a noninvasive imaging modality used for coronary artery calcium scoring in asymptomatic individuals and contrast-enhanced coronary angiography in symptomatic individuals. As the rising costs of healthcare reflect, in part, the development of these types of new expensive technologies for cardiac diagnosis, the economic considerations that surround them should be of interest to clinicians and payers alike. In this review, we discuss basic principles underlying economic efficiency analyses of medical products, using computed tomography in coronary artery disease as a case in point.     

Erectile dysfunction and coronary artery disease prediction: evidence‐based guidance and consensus

• ? A significant proportion of men with erectile dysfunction (ED) exhibit early signs of coronary artery disease (CAD), and this group may develop more severe CAD than men without ED (Level 1, Grade A).
• ? The time interval among the onset of ED symptoms and the occurrence of CAD symptoms and cardiovascular events is estimated at 2–3 years and 3–5 years respectively; this interval allows for risk factor reduction (Level 2, Grade B).
• ? ED is associated with increased all‐cause mortality primarily due to increased cardiovascular mortality (Level 1, Grade A).
• ? All men with ED should undergo a thorough medical assessment, including testosterone, fasting lipids, fasting glucose and blood pressure measurement. Following assessment, patients should be stratified according to the risk of future cardiovascular events. Those at high risk of cardiovascular disease should be evaluated by stress testing with selective use of computed tomography (CT) or coronary angiography (Level 1, Grade A).
• ? Improvement in cardiovascular risk factors such as weight loss and increased physical activity has been reported to improve erectile function (Level 1, Grade A).
• ? In men with ED, hypertension, diabetes and hyperlipidaemia should be treated aggressively, bearing in mind the potential side effects (Level 1, Grade A).
• ? Management of ED is secondary to stabilising cardiovascular function, and controlling cardiovascular symptoms and exercise tolerance should be established prior to initiation of ED therapy (Level 1, Grade A).
• ? Clinical evidence supports the use of phosphodiesterase 5 (PDE5) inhibitors as first‐line therapy in men with CAD and comorbid ED and those with diabetes and ED (Level 1, Grade A).
• ? Total testosterone and selectively free testosterone levels should be measured in all men with ED in accordance with contemporary guidelines and particularly in those who fail to respond to PDE5 inhibitors or have a chronic illness associated with low testosterone (Level 1, Grade A).
• ? Testosterone replacement therapy may lead to symptomatic improvement (improved wellbeing) and enhance the effectiveness of PDE5 inhibitors (Level 1, Grade A).
• ? Review of cardiovascular status and response to ED therapy should be performed at regular intervals (Level 1, Grade A).

     

Functional assessment of coronary artery disease by cardiac computed tomography

Introduction: Rapid technological advances in computed tomography (CT) have allowed CT coronary angiography (CTCA) to be delivered at low radiation dose and high diagnostic accuracy. Due to its high negative predictive value for coronary artery disease, it has become a gatekeeper for the assessment of patients with chest pain of recent onset. Second line functional assessment of a detected coronary stenosis relies mostly on other imaging modalities. Functional assessment of coronary artery disease by CT is therefore an attractive addition to CTCA.

Areas covered: This review will discuss the current evidence base and future development for CT perfusion imaging. Furthermore, this review will discuss CT-derived fractional flow reserve and CT coronary plaque characteristics as alternative approaches for functional evaluation of coronary artery disease. Finally, combining coronary anatomy and functional assessment of coronary flow with myocardial tissue characterization by CT may be attractive allowing triple assessment by CT.

Expert commentary: The combined use of CTCA and functional assessment of coronary artery stenosis by CT perfusion or CT-derived fractional flow reserve is an attractive diagnostic pathway that requires further evaluation.     

Coronary artery fistula in a patient with coronary artery disease: evaluation by coronary angiography and multidetector computed tomography

A 54-year-old man with acute miyocardial infarction was successfully treated with coronary artery stenting. Coronary angiography is the preferred diagnostic method for imaging the coronary arteries, but coronary artery fistulas origin and course may not be apparent. New tomographic cardiovascular imaging tests such as, multidetector computed tomography (MDCT) can be used to precise delineation of coronary fistulas. An erratum to this article can be found at     

Five-year mortality and coronary heart disease development after normal coronary angiogram

BACKGROUND:

Previous studies depict low cardiac event and mortality rates in patients with angiographically normal coronary arteries. These studies, however, are limited by small sample sizes, short follow-up intervals, and selection biases. This study was undertaken to determine the natural five-year course of a diverse cohort of subjects with documented normal coronary arteries with respect to coronary heart disease development, revascularization need, and all-cause mortality.

METHODS:

Consecutive adult patients with angiographically normal coronary arteries were followed up for 5 years through medical record review. Patients with any degree of angiographic abnormality, including minimal luminal irregularity or non-critical stenosis, were excluded. Patients were not excluded based on age, co-morbidities (except cardiac transplant and structural heart disease), indication for angiogram, or initial hospitalization status.

RESULTS:

Normal coronary arteries were found in 182 (31.3%) of 582 patients; 129 met all inclusion criteria. The mean age was (49.1±12.5) years; 47 (36.7%) were male and 75 (58.1%) were caucasian. The most common indication for angiography was cumulative risk factors (60.5%). Within 5 years of a normal angiogram, 13 of 129 patients died (10.1%; 95 CI 5.7%-16.9%). Six (40%; 95 CI 19.8% to 64.3%) of 15 patients undergoing repeat angiogram within five years developed new coronary heart disease, with one requiring revascularization. Of traditional risk factors of coronary heart disease, only diabetes was associated with a higher risk of death.

CONCLUSION:

The natural five-year course of a diverse cohort of patients with documented normal coronary arteries suggests that there is significant risk for death and development of coronary heart disease.KEY WORDS: Angiography, Coronary disease, Mortality, Prognosis     

64排螺旋CT检测冠状动脉病变与同型半胱氨酸水平的相关性研究

目的 探讨64排螺旋CT(MSCT)检测冠状动脉病变与同型半胱氨酸水平的相关性.方法 入选研究对象87例,均未接受叶酸和(或)维生素B12等治疗,分为急性冠状动脉综合征(ACS)组33例、稳定型心绞痛(SAP)组29例和正常对照组25例,均行冠状动脉MSCT成像检查,根据CT值进一步将ACS和SAP患者分为易损斑块组26例,混合斑块组19例,钙化斑块组17例;对所有研究对象检测血清同型半胱氨酸(Hcy)浓度.结果 3组间血清Hcy浓度按ACS组(16.44±5.48) μmol/L、SAP组(13.06±5.80) μmol/L、正常对照组(9.94±4.23) μmol/L顺序递减(均P＜0.01);易损斑块组和混合斑块组血清Hcy浓度均高于钙化斑块组,为(16.50±5.24) μmol/L、(15.51±6.24) μmol/L vs(11.63±5.21) μmol/L(均P＜0.01);ACS组与SAP组斑块构成比不同(x2=7.628,P＜0.05);ACS组易损斑块检出率(42.4％)高于SAP组(17.2％),ACS组钙化斑块检出率(18.2％)低于SAP组(48.3％)(均P＜0.05);斑块的不同性质与血清Hcy浓度间存在相关关系(rs=0.467,P＜0.01).结论 冠状动脉MSCT联合血清Hcy化验检查可作为诊断冠心病并预测其严重程度的无创方法在临床上得以应用.     

冠状动脉计算机断层扫描血管造影价值的认识

自1995年首次报道用增强计算机断层扫描血管造影(CTA)进行无创性冠状动脉(冠脉)病变检测以来,CTA已成为诊断冠心病常用的无创性方法[1]。近年来,随着心电图门控多排螺旋CTA的广泛应用,特别是64排或以上的CT硬件系统发     

Prognostic value of absence or presence of coronary artery disease determined by 64-slice computed tomography coronary angiography A systematic review and meta-analysis

To determine via a meta-analysis the prognostic value of 64-slice computed tomography angiography (CTA) by quantifying risk of major adverse cardiac events (MACE) in different patient groups classified according to CT angiographic findings. A systematic literature search and meta-analyses was conducted on 10 studies examining stable, symptomatic and intermediate risk patients by 64-slice CTA. Patients were followed up for a mean of 21 month. Patient groups with CT-angiographic non-obstructive (stenosis <50% of luminal narrowing) or obstructive (stenosis ≥50% of luminal narrowing) CAD were compared to those having normal angiography without CAD. MACE (cardiac death, non-fatal myocardial infarction and revascularization) numbers were used to calculate odds ratios (OR) with 95% confidence interval (CI) in each group. Ten studies including 5,675 patients were eligible for meta-analysis. The cumulative MACE rate over 21 months were 0.5% in patients with normal CTA, 3.5% in non-obstructive CAD and 16% in obstructive CAD. Compared to normal CTA, non-obstructive CAD was associated with significant increased risk of MACE with OR = 6.68 (3.01–14.82 CI 95%), P = 0.0001. Obstructive CAD was associated with further significant increased risk of MACE with OR = 41.19 (22.56–75.18, CI 95%), P = 0.0001. The studies were homogenous, P-value >0.05 for heterogeneity. 64-slice CTA is able to differentiate low-risk from high-risk patients with suspected or known CAD. Absence of CAD predicts excellent prognosis, while obstructive CAD is associated with markedly increased risk of MACE.     

Abnormal electron beam computed tomography results: the value of repeating myocardial perfusion single-photon emission computed tomography in the ongoing assessment of coronary artery disease

OBJECTIVE: To determine whether asymptomatic patients with atherosclerosis, indicated by the presence of coronary artery calcium on electron beam computed tomography, are at enough risk for progression of disease to justify a repeated stress single-photon emission computed tomography (SPECT) examination after an initial normal to low-risk perfusion study. PATIENTS AND METHODS: We retrospectively identified patients who had abnormal results on electron beam computed tomography (coronary artery calcium score > 0) and normal to low-risk results on SPECT (defined as a summed stress score of 0-3) within a 3-month period from January 1, 1995, to October 31, 2002. Of the 504 identified patients, 285 remained after exclusion criteria were applied. Of the 285 patients, 69 (mean +/- SD age, 58.2 +/- 7.6 years; 91% male) underwent at least 1 repeated myocardial perfusion SPECT imaging study within 4 years of their initial assessment as normal or at low risk without recurrence of symptoms. The value of repeated SPECT imaging was assessed by detection of a substantial change in the repeated SPECT study and by documentation of a clinical event (death, nonfatal myocardial infarction, or revascularization). Follow-up was 100% complete at a mean of 4.3 +/- 1.6 years. RESULTS: Only 4 patients (6%) had a substantial progression in their SPECT risk category; substantial changes on the SPECT scans occurred only in patients with a coronary artery calcium score greater than 100. Three patients underwent revascularization, yielding a 5-year rate for survival free of revascularization of 94% (95% confidence interval, 88%-100%). No deaths or nonfatal myocardial infarctions were reported. CONCLUSION: The principal findings of this study indicate that asymptomatic patients with initial normal or low-risk results from stress SPECT performed because of abnormal coronary artery calcium scores who remain asymptomatic are at low risk of death, myocardial infarction, or coronary revascularization. Three patients underwent revascularization by percutaneous coronary intervention despite the absence of symptoms. A substantial change in SPECT results (defined as progression from normal or low-risk summed stress score to intermediate- or high-risk summed stress score) affected 6% of patients and was not associated with any adverse hard events (nonfatal myocardial infarction or death).     

螺旋CT评价冠状动脉钙化积分和预测冠心病事件的可靠性

目的:应用螺旋CT评价冠状动脉钙化积分和预测冠心病事件发生的可能性。方法:既往有冠心病史或经心电图负荷试验和/或冠状动脉造影,临床确诊为冠心病患者87例(冠心病组)和非冠心病患者125例(对照组),分别进行螺旋CT检查,记录年龄、钙化率、钙化积分、冠状动脉钙化的部位及支数。结果:两组均随年龄的增长钙化率逐渐增高,70岁以上钙化率达90%以上。冠心病组与对照组的冠状动脉钙化积分有显著性差异(t=-26.83～-9.93,P<0.01),也随年龄的增长而增加,钙化血管支数与钙化积分呈正相关,以左前降支钙化发生率最高,为72%。结论:应用螺旋CT检测冠状动脉钙化,对可疑冠心病患者,提供早期诊断的依据。对冠状动脉狭窄程度的追踪观察是一种可靠、无创、可反复进行的有效方法。     

Multislice computed tomography for determination of coronary artery disease in a symptomatic patient population

Background Multislice computed tomography (MSCT) has started to replace Electron beam CT for quantitation of coronary artery calcium. However no study has evaluated the diagnostic accuracy of MSCT for prediction of coronary artery disease (CAD) in a symptomatic patient population using the volume score. Methods and Results 1347 symptomatic subjects (male = 803, mean age = 62 years) with suspected CAD underwent MSCT studies 1 ± 2 days before the coronary angiogram. The Agatston (ACS) and Volumetric calcium score (VCS) were calculated using a proprietary workstation. Statistical analyses included the Pearson’s correlation coefficient and the nonparametric Mann–Whitney U-test to compare the calcium score in different age groups and between men and women. Sensitivity, specificity and predictive accuracy were calculated for different calcium thresholds for prediction of CAD. ROC curve analyses were used to establish relations between the coronary calcium score and presence or absence of CAD. In 720 (53%) subjects (male = 419) angiography revealed a minimal lumen diameter stenosis greater than 50%. Patients with significant CAD had significantly higher total calcium score values than patients without CAD (P = 0.001). ACS and VCS demonstrate a close correlation for the whole study group, r = 0.99. The overall sensitivity of any calcium to predict stenosis was 99%, specificity = 32%. Exclusion of calcium was highly accurate for exclusion of CAD in subjects older than 50 years (predictive accuracy = 98%). An absolute cutoff >100 and an age and sex specific threshold (score over 75th percentile) were identified as the cutoff levels with the highest sensitivities (86–89%) and lowest false positive rates (20–22%). ROC analyses revealed MSCT calcium scanning as a good clinical test which can be performed with similar accuracy in all age groups with an area under the curve of 0.84. Conclusion Determination of coronary calcium with MSCT is an accurate imaging modality for prediction of significant CAD in a patient population with intermediate likelihood of CAD. Exclusion of any calcium provided strong evidence that patients older than 50 years did not have obstructive CAD. ACS and VCS show an equivalent diagnostic accuracy.     

Association of atherosclerosis in the descending thoracic aorta with coronary artery disease on multi detector row computed tomography coronary angiography in patients with suspected coronary artery disease

The association between atherosclerosis in the descending thoracic aorta (DTA) visualized on computed tomography coronary angiography (CTA) and coronary artery disease (CAD) has not been extensively explored. Therefore, a comprehensive analysis of DTA atherosclerosis on CTA was performed and the association of DTA atherosclerosis with CAD was evaluated in patients with suspected CAD. A total of 344 patients (54 ± 12 years, 54 % men) with suspected CAD underwent CTA. CTA were classified based on CAD severity in no signs of atherosclerosis or minor wall-irregularities <30 %, non-significant CAD 30–50 %, or significant CAD ≥50 % stenosis. The DTA was divided in segments according the posterior intercostal arteries. Per segment the presence of atherosclerotic plaque (defined as ≥2 mm wall thickness) was determined and maximal wall thickness was measured. Plaque composition was scored as non-calcified or mixed and the percentage of DTA segments with atherosclerosis was calculated. Significant CAD was present in 152 (44 %) patients and 278 (81 %) had DTA atherosclerotic plaque. DTA maximal wall thickness and percentage of DTA segments with atherosclerosis were 2.7 ± 1 mm and 49 ± 36 %. The presence, severity and extent of DTA atherosclerosis significantly increased with increasing CAD severity. Multivariate logistic regression analysis corrected for age and other risk factors demonstrated independent associations of DTA plaque (OR 6.56, 95 % CI 1.78–24.19, p = 0.005) and maximal DTA wall thickness (OR 2.00, 95 % CI 1.28–3.12, p = 0.002) with significant CAD. The presence and severity of DTA atherosclerosis were independently related with significant CAD on CTA in patients with suspected CAD.     

Prevalence of left main coronary artery disease among patients referred to multislice computed tomography coronary examinations

We have evaluated the prevalence of left main coronary artery disease (LMCAD) among patients referred to multislice computed tomography (MSCT) coronary angiography examinations. The study Group comprised of 1,000 consecutive patients (750 male and 250 female; mean age 53±12 years) who underwent successful 64-slice MSCT examinations. Left main coronary artery (LMCA) was classified into three Groups: normal LMCA; nonsignificant LMCAD with coronary plaques resulting in obstructions ≤50%; and significant LMCAD corresponding to obstructions >50%. We have found that 24 patients (2.4%) had significant LMCAD. Additional 200 patients (20%) had nonsignificant LMCAD. Univariate analysis revealed that LMCAD was associated with age, male gender, diabetes, hypertension, hyperlipidemia, typical symptoms, history of previous myocardial infarction and previous percutaneous coronary intervention. Only age and male gender were found as independent predictors for LMCAD in multivariate analysis (P < 0.001 and P = 0.001, respectively,). Angiographic follow-up was avaliable for the 24 patients with significant LMCAD, and conventional coronary angiography confirmed the presence of significant LMCAD in all of these patients. Significant LMCAD was found in 2.4% of the 1,000 patients referred to 64-slice MSCT examinations. Age and male gender were the independent predictors for LMCAD.     

Value of coronary artery calcium scanning by computed tomography for predicting coronary heart disease in diabetic subjects

OBJECTIVE: The South Bay Heart Watch is a cohort study designed to determine the significance of coronary calcium in high-risk asymptomatic patients. This is a report of the relative risk (RR) for outcomes of coronary artery calcium in diabetic and nondiabetic subjects. RESEARCH DESIGN AND METHODS: A total of 1312 diabetic and nondiabetic subjects underwent risk factor screening and computed tomography testing for coronary calcium at baseline and were followed clinically for 6.3 +/- 1.4 years. End points were either 1). hard events of nonfatal myocardial infarction (MI) or coronary death or 2). any cardiovascular event (nonfatal MI, coronary death, coronary revascularization, or stroke). RESULTS: The incidence rates of a hard event and any cardiovascular event for diabetic and nondiabetic subjects were 14.5 and 6.1% and 23.8 and 12.2%, respectively (P < 0.001). Cox regression analyses of the combined risk relationship of diabetes status and calcium score demonstrated that relative to nondiabetic subjects with low calcium scores (<2.8), diabetic subjects with calcium scores >or=2.8 exhibited at least a fourfold increase in the risk of either a hard or any cardiovascular event (P < 0.001). Cox regression analyses conducted separately for nondiabetic and diabetic subjects revealed that coronary calcium score risk groups were significantly associated with events in nondiabetic subjects (RR >or= 2.6, P 0.05). CONCLUSIONS: The risk of coronary heart disease increases with increasing calcium scores and diabetes status. Calcium scores have less prognostic value in diabetic subjects.