Coronary multidetector computed tomography in the assessment of patients with acute chest pain

Assessment of cardiac ischaemia and viability: role of cardiovascular magnetic resonance

Over the past years, cardiovascular magnetic resonance (CMR) has proven its efficacy in large clinical trials, and consequently, the assessment of function, viability, and ischaemia by CMR is now an integrated part of the diagnostic armamentarium in cardiology. By combining these CMR applications, coronary artery disease (CAD) can be detected in its early stages and this allows for interventions with the goal to reduce complications of CAD such as infarcts and subsequently chronic heart failure (CHF). As the CMR examinations are robust and reproducible and do not expose patients to radiation, they are ideally suited for repetitive studies without harm to the patients. Since CAD is a chronic disease, the option to monitor CAD regularly by CMR over many decades is highly valuable. Cardiovascular magnetic resonance also progressed recently in the setting of acute coronary syndromes. In this situation, CMR allows for important differential diagnoses. Cardiovascular magnetic resonance also delineates precisely the different tissue components in acute myocardial infarction such as necrosis, microvascular obstruction (MVO), haemorrhage, and oedema, i.e. area at risk. With these features, CMR might also become the preferred tool to investigate novel treatment strategies in clinical research. Finally, in CHF patients, the versatility of CMR to assess function, flow, perfusion, and viability and to characterize tissue is helpful to narrow the differential diagnosis and to monitor treatment.

Cardiac CT in the emergency department: convincing evidence, but cautious implementation

In clinical practice, assessment of chest pain patients presenting to the emergency department is difficult and the work-up can be lengthy and costly. There is growing evidence supporting the use of coronary computed tomography angiography (CTA) in early assessment of patients presenting with acute chest pain to the emergency department. CTA appears to be a faster and more accurate way to diagnosis or rule out coronary stenosis, leading to reduced hospital admissions, decreased time in the ED and lower costs. The focus of this article is to review the current literature of the use of Coronary CTA and "triple rule out" protocols in the emergency department setting and to provide a chest pain algorithm, showing how Coronary CTA can be implemented effectively in clinical practice. Potential pitfalls and requirements for implementation will also be discussed.

Comparative diagnostic yield and 3-month outcomes of "triple rule-out" and standard protocol coronary CT angiography in the evaluation of acute chest pain

BACKGROUND

"Triple rule-out" CT angiography simultaneously evaluates coronary artery disease, pulmonary embolism, and aortic dissection in a single imaging examination. However, the clinical outcomes of this approach are unknown.

OBJECTIVE

Using standard cardiac CT angiography as a reference, this study was performed to describe the diagnostic yield and clinical outcomes of patients undergoing triple rule-out in clinical practice.

METHODS

We identified consecutive patients at 2 institutions undergoing triple rule-out or cardiac CT angiography for acute chest pain. The primary outcome was a composite diagnostic yield consisting of coronary artery diameter stenosis >50%, pulmonary embolism, and aortic dissection. Other reported outcomes included radiation dose, downstream resource use, and 90-day clinical outcomes.

RESULTS

Among 2068 patients (272 triple rule-out and 1796 cardiac CT angiograms), the composite diagnostic yield was 14.3% with triple rule-out and 16.3% with cardiac CT (P = 0.41) and was driven by the diagnosis of obstructive coronary artery disease (13.2% triple rule-out versus 16.1% cardiac CT, P = 0.22). The diagnostic yield for pulmonary embolism was low (1.1% triple rule-out and 0.2% cardiac CT, P = 0.052) and no aortic dissections were found in either group. Compared with cardiac CT, the triple rule-out approach was associated with higher radiation exposure (12.0 ± 5.6 mSv versus 8.2 ± 4.0 mSv, P < 0.0001), a greater incidence of subsequent emergency center cardiac evaluations (5.9% versus 2.5%, P = 0.0017), and more downstream pulmonary embolism-protocol CT angiography (3.3% versus 0.9%, P = 0.0034).

CONCLUSIONS

Among patients with acute chest pain, a triple rule-out approach resulted in higher radiation exposure compared with cardiac CT, but was not associated with improved diagnostic yield, reduced clinical events, or diminished downstream resource use.

The diagnostic performance of multi-slice coronary computed tomographic angiography: a systematic review

BACKGROUND

The use of coronary computed tomographic angiography (CCTA) for evaluation of patients with suspected coronary artery disease (CAD) is growing rapidly, yet questions remain regarding its diagnostic accuracy and its impact on clinical decision-making and patient outcomes.

METHODS

A systematic literature review was conducted to identify studies examining (a) CCTA's diagnostic accuracy; and (b) the impact of CCTA on clinical decision-making and/or patient outcomes. Diagnostic accuracy estimates were limited to patient-based analyses of occlusion; outcome studies were eligible for inclusion if they involved patients at low-to-intermediate risk of CAD. Pooled accuracy estimates were derived using bivariate random effects models; non-diagnostic CCTA results were conservatively assumed to be false positives.

RESULTS

A total of 42 diagnostic accuracy studies and 11 patient outcome studies were identified. The pooled mean sensitivity for CCTA in primary analyses was 98% (95% CI: 96%, 99%); specificity was 85% (81%, 89%). A small number of outcome studies set primarily in the emergency department found triage of low-risk patients using CCTA produced no serious adverse outcomes and was time-saving relative to standard triage care. Outcome studies in the outpatient setting were limited to four case series that did not directly compare patient care or outcomes with those of contemporaneous patients evaluated without CCTA.

CONCLUSIONS

CCTA appears to have high diagnostic accuracy in patients with suspected CAD, but its potential impact on clinical decision-making and patient outcomes is less well-understood, particularly in non-emergent settings.

Features of Disrupted Plaques by Coronary Computed Tomographic Angiography

Background—

This study was designed as a “proof-of-concept” to establish whether coronary computed tomographic angiography (CTA) has the capability to identify morphological features of plaque disruption.

Methods and Results—

In patients with unstable angina undergoing CTA and invasive coronary angiography within 30 days, quantitative CTA analysis was performed on all plaques for percent stenosis, volume, remodeling index, and volume of low-attenuation plaque (<50 Hounsfield units). Plaques with >25% stenosis were evaluated for CTA features of disruption, including ulceration and intraplaque dye penetration. Using invasive coronary angiography complex plaque as the reference standard for disruption, the sensitivity and specificity of ulceration and intraplaque dye penetration by CTA were determined. In 60 patients, 294 plaques were identified by CTA, of which 109 (37%) had features of disruption, including ulceration in 53 (18%) lesions and intraplaque dye penetration in 80 (27%). Compared with nondisrupted lesions, plaques with ulceration or intraplaque dye penetration by CTA were more voluminous (313±356 mm 3 versus 118±93 mm 3 P <0.0001), more often positively remodeled (94.5% versus 44.3%, P <0.0001), contained more low-attenuation plaque (99±161 mm 3 versus 19±18 mm 3 , P <0.0001), and were more often complex by ICA (57.8% versus 8.1%, P <0.0001). CTA features of disruption demonstrated modest to good sensitivity (53% to 81%) and good specificity (82% to 95%) for complex plaque by invasive coronary angiography.

Conclusions—

In this highly selected group of patients with unstable angina, CTA can delineate features of plaque disruption, including ulceration and intraplaque dye penetration, which are specific markers of invasively identified complex plaque. Further studies are needed to confirm the generalizability of the results and to explore the clinical and prognostic implications of these findings.

Utility of nonspecific resting electrocardiographic features for detection of coronary artery stenosis by computed tomography in acute chest pain patients: from the ROMICAT trial

Twelve-lead surface electrocardiography (ECG) and computed tomography (CT) are used to evaluate for myocardial ischemia and coronary artery disease (CAD), respectively. We aimed to determine features on resting ECG that predict coronary artery stenosis by cardiac CT. In 309 acute chest pain patients, we compared the initial triage resting ECG to contrast-enhanced 64-slice cardiac CT angiography. We assessed for 6 quantitative (QT interval, QTc interval, QTc > 440 ms, gender-specific QTc, QT dispersion and QRS duration) and 4 qualitative ECG parameters (ST depression >0.05 to ≤0.1 mV, T wave inversion ≥0.1 mV, T wave flattening, and any T wave abnormalities) and for the presence of coronary stenosis by CT (>50% luminal narrowing). Specificities of these ECG parameters were excellent (83.6-97.0%) while sensitivities were poor (12.2-29.3%). For coronary stenosis detection, the ECG features with the greatest performance were the presence of ST depression (positive likelihood ratio [LR+] 4.09) and T wave inversion (LR+ 4.58). In multivariable analyses, the risk for coronary stenosis increased by 33-41% for every 20 ms prolongation of the QTc interval after adjusting for age, gender, and cardiac risk factors or adjustment for Framingham risk score. Similarly, there was an increase of fourfold with the presence of ST depression >0.05 to ≤0.1 mV or T wave inversion ≥0.1 mV. In acute chest pain patients, resting ECG features of QTc interval prolongation, mild ST depression, and T wave inversion are independently associated with the presence of CT coronary stenosis and their presence suggests an increase risk of CAD.

Clinical perspective of coronary computed tomographic angiography in diagnosis of coronary artery disease

Since a 4-detector row coronary computed tomographic angiography (CCTA) was launched in 1998, CCTA has experienced rapid improvement of imaging qualities with the ongoing evolution of computed tomography (CT) technology. The diagnostic accuracy of CCTA to detect coronary artery stenosis is well established, whereas improvements are still needed to reduce the overestimation of coronary artery disease (CAD) and assess plaque composition. CCTA has been used to evaluate CAD in various clinical settings. For example, CCTA could be an efficient initial triage tool at emergency departments for patients with acute chest pain with low-to-intermediate risk because of its high negative predictive value. In patients with suspected CAD, CCTA could be a cost-effective alternative to myocardial perfusion imaging and exercise electrocardiogram for the initial coronary evaluation of patients with intermediate pre-test likelihood suspected CAD. However, in asymptomatic populations, there is a lack of studies that show an improved prognostic power of CCTA over other modalities. Therefore, the clinical use of CCTA to detect CAD for purposes of risk stratification in asymptomatic individuals should be discouraged. As CT technology evolves, CCTA will provide better quality coronary imaging and non-coronary information with lower radiation exposure. Future studies should cover these ongoing technical improvements and evaluate the prognostic power of CCTA in various clinical settings of CAD in large, well-designed, randomized trials.

Differential associations between blood biomarkers of inflammation, oxidation, and lipid metabolism with varying forms of coronary atherosclerotic plaque as quantified by coronary CT angiography

Although epidemiologic data link biomarkers of cardiovascular risk with incident and prevalent coronary artery disease, exact anatomic relationships between biomarkers and coronary atherosclerosis as measured by coronary CT angiography remain unclear. Patients with acute chest pain who ultimately had no evidence of acute coronary syndrome underwent contrast-enhanced 64-slice coronary CT angiography to determine presence, extent and composition of coronary atherosclerotic plaque. We determined the differences in levels of blood biomarkers measured at the time of the CT scan between different CT-based atherosclerotic plaque groups. Among 313 patients (mean age: 51.6 ± 11 years, 62% male) high-sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase-2 were associated with the extent of calcified plaque (P = 0.03 and P < 0.001), while hs-CRP and apolipoprotein A1 were associated with the extent of non-calcified plaque (P = 0.03 and P = 0.004; respectively). Despite a generally lower risk profile, subjects with exclusively non-calcified plaque had significantly higher levels of hs-CRP and oxidized low-density lipoprotein (P = 0.01 and P = 0.03; respectively) and lower levels of adiponectin (P = 0.03) when compared to subjects with calcified plaque (n = 130, 42%). Biomarkers reflecting inflammation, vascular remodeling, oxidation, and lipoprotein metabolism maybe associated with different patterns of coronary atherosclerosis as quantified by coronary CT angiography.

Progress and Current State of Coronary CT

The recent appearance of multislice computed tomography (CT) has enabled noninvasive imaging of the coronary artery. Particularly, the appearance of 64-row CT has rapidly promoted its spread into routine medical practice. In this report, progress and current state of coronary CT employing multislice CT are outlined.

Myocardial hypoenhancement in a case of acute coronary syndrome with normal coronary arteries: demonstration by 64-slice multidetector computed tomography

A 48-year-old man presented with severe chest pain that had started 2 h before and ST elevation on the electrocardiogram. Cardiac computed tomography (CT) was performed using a 64-slice multidetector scanner (MDCT) to assess coronary artery stenosis at 3 h after the onset. Coronary CT angiography showed no significant stenosis at the coronary arteries, but CT myocardial images at systole demonstrated predominantly subendocardial hypoenhancement in the anterior wall. Cardiac CT that combined coronary angiography and myocardial imaging demonstrated myocardial hypoenhancement in a case of acute coronary syndrome with normal coronary arteries, which may be related to microvascular dysfunction caused by vasospastic angina or microvascular angina.

320-row CT coronary angiography: effect of 100-kV tube voltages on image quality, contrast volume, and radiation dose

To prospectively evaluate image quality parameters, contrast volume and radiation dose at the 100-kilovolt (kV) setting during coronary computed tomographic angiography (CCTA) on a 320-row computed tomography scanner. We enrolled 107 consecutive patients with a heart rate <65 beats per minute (bpm) undergoing prospective electrocardiogram (ECG)-triggered CCTA. Forty patients with a body mass index (BMI) <25 kg/m(2) were scanned using 100-kV tube voltage settings, while 67 patients were scanned using 120-kV protocols. Image quality was assessed by two readers unaware of patient information and scan parameters. Attenuation in the aorta and perivascular fat tissue and image noise were measured. Contrast-to-noise ratios (CNRs) and contrast material volumes were calculated. The effective radiation doses were estimated using a chest conversion coefficient (0.017). Diagnostic image quality was achieved in 98.2% of coronary segments with 100-kV CCTA and 98.6% of coronary segments with 120-kV CCTA, with no significant differences in image quality scores for each coronary segment. Vessel attenuation, image noise, and CNR were not significantly different between the 100- and 120-kV protocols. Mean contrast injection rate and mean material volume were significantly lower for the 100-kV CCTA (4.35 ± 0.28 ml/s and 53.13 ± 3.77 ml, respectively) than for the 120-kV CCTA (5.16 ± 0.21 ml/s and 62.40 ± 3.66 ml respectively; P < 0.001). The effective radiation dose was 2.12 ± 0.19 mSv for 100-kV CCTA, a reduction of 54% compared to 4.61 ± 0.82 mSv for 120-kV CCTA. A 100-kV CCTA can be implemented in patients with a BMI < 25 kg/m(2). The 100-kV setting allows significant reductions in contrast material volume and effective radiation dose while maintaining adequate diagnostic image quality.

Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association

The management of low-risk patients presenting to emergency departments is a common and challenging clinical problem entailing 8 million emergency department visits annually. Although a majority of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent treatment of a serious problem and those with more benign entities who do not require admission. Inadvertent discharge of patients with acute coronary syndrome from the emergency department is associated with increased mortality and liability, whereas inappropriate admission of patients without serious disease is neither indicated nor cost-effective. Clinical judgment and basic clinical tools (history, physical examination, and electrocardiogram) remain primary in meeting this challenge and affording early identification of low-risk patients with chest pain. Additionally, established and newer diagnostic methods have extended clinicians' diagnostic capacity in this setting. Low-risk patients presenting with chest pain are increasingly managed in chest pain units in which accelerated diagnostic protocols are performed, comprising serial electrocardiograms and cardiac injury markers to exclude acute coronary syndrome. Patients with negative findings usually complete the accelerated diagnostic protocol with a confirmatory test to exclude ischemia. This is typically an exercise treadmill test or a cardiac imaging study if the exercise treadmill test is not applicable. Rest myocardial perfusion imaging has assumed an important role in this setting. Computed tomography coronary angiography has also shown promise in this setting. A negative accelerated diagnostic protocol evaluation allows discharge, whereas patients with positive findings are admitted. This approach has been found to be safe, accurate, and cost-effective in low-risk patients presenting with chest pain.

Pictorial review: computed tomography features of cardiovascular emergencies and associated imminent decompensation

Multi-detector computed tomography (MDCT) scanner is available in most hospitals and is increasingly being used as the first line imaging in trauma and suspected cardiovascular emergencies, such as acute coronary syndrome, pulmonary artery thrombo-embolism, abdominal aortic aneurysm and acute haemorrhage (Ryan et al. Clin Radiol 60:599-607, 2005). A significant number of these patients are haemodynamically unstable and can rapidly progress into shock and death. Recognition of computed tomography (CT) signs of imminent cardiovascular decompensation will alert the clinical radiologist to the presence of shock. In this review, the imaging findings of cardiovascular emergencies in both acute traumatic and non-traumatic settings with associated signs of imminent decompensation will be described and illustrated.

Cardiac PET imaging for the detection and monitoring of coronary artery disease and microvascular health

Positron emission tomography (PET) myocardial perfusion imaging in concert with tracer-kinetic modeling affords the assessment of regional myocardial blood flow (MBF) of the left ventricle in absolute terms (milliliters per gram per minute). Assessment of MBF both at rest and during various forms of vasomotor stress provides insight into early and subclinical abnormalities in coronary arterial vascular function and/or structure, noninvasively. The noninvasive evaluation and quantification of MBF and myocardial flow reserve (MFR) extend the scope of conventional myocardial perfusion imaging from detection of end-stage, advanced, and flow-limiting, epicardial coronary artery disease (CAD) to early stages of atherosclerosis or microvascular dysfunction. Recent studies have shown that impaired hyperemic MBF or MFR with PET, with or without accompanying CAD, is predictive of increased relative risk of death or progression of heart failure. Quantitative approaches that measure MBF with PET identify multivessel CAD and offer the opportunity to monitor responses to lifestyle and/or risk factor modification and to therapeutic interventions. Whether improvement or normalization of hyperemic MBF and/or the MFR will translate to improvement in long-term cardiovascular outcome remains clinically untested. In the meantime, absolute measures of MBF with PET can be used as a surrogate marker for coronary vascular health, and to monitor therapeutic interventions. Although the assessment of myocardial perfusion with PET has become an indispensable tool in cardiac research, it remains underutilized in clinical practice. Individualized, image-guided cardiovascular therapy may likely change this paradigm in the near future.

Usefulness of computed tomographic coronary angiography in patients with acute chest pain with and without high-risk features

The accuracy of 64-slice computed tomographic coronary angiography (CTA) and its ability to direct revascularization in patients with acute chest pain syndrome (ACPS) was investigated. A total of 107 patients with ACPS presenting to the emergency department and referred to cardiology were prospectively enrolled and underwent CTA. From the clinical features, the patients were categorized as having high-risk acute coronary syndrome features or no high-risk features. At the treating physician's discretion, the patients underwent risk stratification with either invasive coronary angiography (ICA) or technetium-99m single photon emission computed tomography. All tests were interpreted by experts unaware of the clinical information. All 52 patients with high-risk acute coronary syndrome features underwent ICA. Of the 55 patients with no high-risk features, 36 underwent single photon emission computed tomography and 19 underwent ICA. The patients were followed up until a decision regarding revascularization was made. Compared with ICA, the operating characteristics of CTA (per-patient analysis) were excellent, with a sensitivity of 98% (95% confidence interval [CI] 87% to 100%), specificity of 100% (95% CI 85% to 100%), positive predictive value of 100% (95% CI 90% to 100%), and negative predictive value of 97% (95% CI 80% to 100%). The agreement between CTA and routine testing (single photon emission computed tomography or ICA) was very good (kappa = 0.94). CTA correctly identified 40 patients (100%) who underwent revascularization and 61 (91.0%) who were treated medically (kappa = 0.88, 95% CI 0.79 to 0.97). In conclusion, CTA might represent a single modality that could be used to triage a wide spectrum of patients with ACPS and could have the potential to rule out coronary disease and identify those who might require revascularization.

Evaluation of the patient with acute chest pain

The past decade has brought rapid advances in CT technology, which allows increasingly precise application to the study of coronary arteries and acute chest pain. The literature has expanded to lend quantifiable justification to the intuitive appeal of a rapid, reproducible, 3D study of the heart and vasculature. More complete analysis of efficacy and costs on broader populations will further refine our understanding of how best to implement what may become the new gold standard. Meanwhile, evolving technology promises to further challenge radiologists and clinicians to optimize approach and diagnosis to acute chest pain.

An organized system of emergency care for patients with myocardial infarction: a reality?

An organized system of emergency care is an essential requirement for the modern treatment of ST-elevation acute myocardial infarction. There is a strong need to deliver reperfusion therapy as soon as possible, with primary percutaneous coronary intervention being the preferred option if performed in a timely manner and thrombolytic therapy, particularly in the prehospital setting, being a good alternative if the primary percutaneous coronary intervention-related delay exceeds the equipoise. In this situation, emergency medical services have a primary role in rescuing patients from cardiac arrest, performing prehospital diagnosis, triage and treatment and safely transporting them to the most appropriate cardiological center, including interhospital transfer. A complete reorganization of the healthcare systems in different countries is frequently needed to build an ST-elevation acute myocardial infarction system of care, focusing on fast transport, use of telemedicine and diversion protocols to skip the unsuited centers.

Coronary computed tomographic angiography (CCTA) in community hospitals: "current and emerging role"

Coronary computed tomographic angiography (CCTA) is a rapidly evolving test for diagnosis of coronary artery disease. Although invasive coronary angiography is the gold standard for coronary artery disease (CAD), CCTA is an excellent noninvasive tool for evaluation of chest pain. There is ample evidence to support the cost-effective use of CCTA in the early triage process of patients presenting with chest pain in the emergency room. CCTA plays a critical role in the diagnosis of chest pain etiology as one of potentially fatal conditions, aortic dissection, pulmonary embolism, and myocardial infarction. This 'triple rule out' protocol is becoming an increasingly practicable and popular diagnostic tool in ERs across the country. In addition to a quick triage of chest pain patients, it may improve quality of care, decrease cost, and prevent medico-legal risk for missing potentially lethal conditions presenting as chest pain. CCTA is also helpful in the detection of subclinical and vulnerable coronary plaques. The major limitations for wide spread acceptance of this test include radiation exposure, motion artifacts, and its suboptimal imaging with increased body mass index.

Incremental diagnostic value of regional left ventricular function over coronary assessment by cardiac computed tomography for the detection of acute coronary syndrome in patients with acute chest pain: from the ROMICAT trial

BACKGROUND

The incremental value of regional left ventricular function (LVF) over coronary assessment to detect acute coronary syndrome (ACS) is uncertain.

METHODS AND RESULTS

We analyzed 356 patients (mean age, 53+/-12 years; 62% men) with acute chest pain and inconclusive initial emergency department evaluation. Patients underwent 64-slice contrast-enhanced cardiac computed tomography before hospital admission. Caregivers and patients remained blinded to the results. Regional LVF and presence of coronary atherosclerotic plaque and significant stenosis (>50%) were separately assessed by 2 independent readers. Incremental value of regional LVF to predict ACS was determined in the entire cohort and in subgroups of patients with nonobstructive coronary artery disease, inconclusive assessment for stenosis (defined as inability to exclude significant stenosis due to calcium or motion), and significant stenosis. During their index hospitalization, 31 patients were ultimately diagnosed with ACS (8 myocardial infarction, 22 unstable angina), of which 74% (23 patients) had regional LV dysfunction. Adding regional LVF resulted in a 10% increase in sensitivity to detect ACS by cardiac computed tomography (87%; 95% confidence interval, 70% to 96%) and significantly improved the overall accuracy (c-statistic: 0.88 versus 0.94 and 0.79 versus 0.88, for extent of plaque and presence of stenosis, respectively; both P<0.03). The diagnostic accuracy of regional LVF for detection of ACS has 89% sensitivity and 86% specificity in patients with significant stenosis (n=33) and 60% sensitivity and 86% specificity in patients with inconclusive coronary computed tomographic angiography (n=33).

CONCLUSIONS

Regional LVF assessment at rest improves diagnostic accuracy for ACS in patients with acute chest pain, especially in those with coronary artery disease and thus may be helpful to guide further management in patients at intermediate risk for ACS.

Computed tomographic coronary artery calcium assessment for evaluating chest pain in the emergency department: long-term outcome of a prospective blind study

OBJECTIVE

To determine the long-term outcome of computed tomographic (CT) quantification of coronary artery calcium (CAC) used as a triage tool for patients presenting with chest pain to an emergency department (ED).

PATIENTS AND METHODS

Patients (men aged 30-62 years and women aged 30-65 years) with chest pain and low-to-moderate probability of coronary artery disease underwent both conventional ED chest pain evaluation and CT CAC assessment prospectively. Patients' physicians were blinded to the CAC results. The results of the conventional evaluation were compared with CAC findings on CT, and the long-term outcome in patients undergoing CT CAC assessment was established. Primary end points (acute coronary syndrome, death, fatal or nonfatal non-ST-segment elevation myocardial infarction, fatal or nonfatal ST-segment elevation myocardial infarction) and secondary outcomes (coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, coronary stenting, or a combination thereof) were obtained when the patient was dismissed from the ED or hospital and then at 30 days, 1 year, and 5 years.

RESULTS

Of the 263 study patients, 133 (51%) had a CAC score of zero. This absence of CAC correlated strongly with the likelihood of noncardiac chest pain. Among 133 patients with a CAC score of zero, only 1 (<1%) had cardiac chest pain. Conversely, of the 31 patients shown to have cardiac chest pain, 30 (97%) had evidence of CAC on CT. When a CAC cutoff score of 36 was used, as suggested by receiver operating characteristic analysis, sensitivity was 90%; specificity, 85%; positive predictive value, 44%; and negative predictive value, 99%. During long-term follow-up, patients without CAC experienced no cardiac events at 30 days, 1 year, and 5 years.

CONCLUSION

Findings suggest that CT CAC assessment is a powerful adjunct in chest pain evaluation for the population at low-to-intermediate risk. Absent or minimal CAC in this population makes cardiac chest pain extremely unlikely. The absence of CAC suggests an excellent long-term (5-year) prognosis, with no primary or secondary cardiac outcomes occurring in study patients at 5-year follow-up.

Feasibility of noninvasive assessment of thin-cap fibroatheroma by multidetector computed tomography

OBJECTIVES

The purpose of this study was to investigate whether multidetector computed tomography (MDCT) can noninvasively help assess thin-cap fibroatheroma (TCFA).

BACKGROUND

Plaque rupture and thrombus formation play key roles in the onset of acute coronary syndrome. TCFA is recognized as a precursor lesion for plaque rupture, and MDCT angiography can potentially help identify plaques prone to rupture.

METHODS

We enrolled 105 patients with coronary artery disease (acute coronary syndromes, n = 31; stable angina pectoris, n = 74). Culprit lesions were assessed by both MDCT and optical coherence tomography (OCT). Patients were divided into a TCFA and a non-TCFA group according to OCT findings; clinical and MDCT observations were compared for 2 groups.

RESULTS

There were no differences in patients' characteristics between the 2 groups. OCT revealed 25 TCFAs at the culprit site in 105 patients. Acute coronary syndrome was more frequent in the TCFA group than in the non-TCFA group (52% vs. 23%, p = 0.01). High-sensitive C-reactive protein was higher in the TCFA group (0.32 +/- 0.32 mg/dl vs. 0.17 +/- 0.16 mg/dl, p < 0.001). Positive remodeling identified by MDCT was observed more frequently in the TCFA group than in the non-TCFA group (76% vs. 31%, p < 0.001). Computed tomography attenuation value of the culprit plaque in the TCFA group was lower than that in the non-TCFA group (35.1 +/- 32.3 HU vs. 62.0 +/- 33.6 HU, p < 0.001). The frequency of ring-like enhancement in the TCFA group was higher than in the non-TCFA group (44% vs. 4%, p < 0.0001). The sensitivity, specificity, positive predictive value, and negative predictive value of ring-like enhancement for detecting TCFA are 44%, 96%, 79%, and 85%, respectively. By stepwise regression, the ring-like enhancement, high-sensitive C-reactive protein, and diagnosis of acute events were associated with the presence of TCFA at the culprit site.

CONCLUSIONS

MDCT can identify differences in plaque morphologies between TCFA and non-TCFA. From our results, MDCT may provide for the noninvasive assessment of vulnerable plaque.

Efficacy and safety of the computed tomography coronary angiography based approach for patients with acute chest pain at an emergency department: one month clinical follow-up study

To evaluate the safety and efficacy of the computed tomography coronary angiography (CTCA) for evaluation of acute chest pain in real world population, we prospectively enrolled 296 patients with acute chest pain at emergency department (ED) from November 2005 to February 2007. The patients were grouped based on the clinical information and CTCA result. The patients with a low risk profile and no significant coronary stenosis (>50%) in CTCA were discharged immediately (Group 1, n=103). On the other hand, the patients with an intermediate risk profile without significant stenosis were observed in ED for 24 hr (Group 2, n=104). The patients with significant stenosis underwent further coronary evaluation and management accordingly (Group 3, n=89). While no false negative case was found in Group 1, seven cases (6.73%) were found in Group 2, mostly during the observation period. In Group 3, there were 54 (60.67%) cases of acute coronary syndrome including 10 myocardial infarctions. The overall accuracy of CTCA for acute coronary syndrome was 88.5% (sensitivity), 85.1% (specificity), 60.7% (positive predictive value) and 96.6% (negative predictive value). In conclusion, clinical decision based on CTCA is safe and effective for low risk patients. Further validation is needed in patients with intermediate risk profile.

Prevalence of first-pass myocardial perfusion defects detected by contrast-enhanced dual-source CT in patients with non-ST segment elevation acute coronary syndromes

OBJECTIVE

To investigate the prevalence and diagnostic value of first-pass myocardial perfusion defects (PD) visualised by contrast-enhanced multidetector computed tomography (MDCT) in patients admitted for a first acute coronary syndrome (ACS).

METHODS

Thirty-eight patients with non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (UA) and scheduled for percutaneous coronary intervention underwent dual-source CT immediately before catheterisation. CT images were analysed for the presence of any PD by using a 17-segment model. Results were compared with peak cardiac troponin-I (cTnI) and angiography findings.

RESULTS

PD were seen in 21 of the 24 patients with NSTEMI (median peak cTnI level 7.07 ng/mL; range 0.72-37.07 ng/mL) and in 2 of 14 patients with UA. PD corresponded with the territory of the infarct-related artery in 20 out of 22 patients. In a patient-based analysis, sensitivity, specificity, negative and positive predictive values of any PD for predicting NSTEMI were 88%, 86%, 80% and 91%. Per culprit artery, the respective values were 86%, 75%, 80% and 83%.

CONCLUSION

In patients with non-ST segment elevation ACS, first-pass myocardial PD in contrast-enhanced MDCT correlate closely with the presence of myocardial necrosis, as determined by increases in cTnI levels.

The prognostic value of cardiac computed tomographic angiography

With advancements in temporal and spatial resolution, CT has excellent diagnostic characteristics for non-invasive evaluation of coronary artery disease in appropriate patients. Nevertheless, clinical usefulness of diagnostic testing requires not only high diagnostic accuracy but also risk stratification for patient management. Current guidelines for risk stratification of patients with coronary artery disease rely primarily upon functional testing; alternatively, anatomic risk stratification may also be performed with invasive coronary angiography. This article reviews current and emerging concepts in the prognostic value of cardiac CT angiography.

High-risk chief complaints I: chest pain--the big three

Chest pain is one of the most frequently seen chief complaints in patients presenting to emergency departments, and is considered to be a "high-risk" chief complaint. The differential diagnosis for chest pain is broad, and potential causes range from the benign to the immediately life-threatening. Although many (if not most) emergency department patients with chest pain do not have an immediately life-threatening condition, correct diagnoses can be difficult to make, incorrect diagnoses may lead to catastrophic therapies, and failure to make a timely diagnosis may contribute to significant morbidity and mortality. Several atraumatic "high-risk" causes of chest pain are discussed in this article, including myocardial infarction and ischemia, thoracic aortic dissection, and pulmonary embolism. Also included are brief discussions of tension pneumothorax, esophageal perforation, and cardiac tamponade.

Role of 64-slice cardiac computed tomography in the evaluation of patients with non-ST-elevation acute coronary syndrome

PURPOSE

This study was done to evaluate the feasibility, sensitivity and specificity of 64-slice computed tomography (CT) in identifying haemodynamically significant (>50%) coronary artery stenoses in patients with suspected acute coronary syndrome (ACS) by correlating the CT findings with the clinical event and data provided by conventional coronary angiography (CCA).

MATERIALS AND METHODS

Sixty-four patients (38 men and 26 women; mean age 65 years; range+/-10 years) presenting to our hospital's emergency department with a clinical suspicion of ACS were studied with 64-slice CT followed by CCA within 24 h of arrival.

RESULTS

Two patients (3.1%) were excluded from the analysis due to artefacts. Per-patient analysis in the remaining 62 patients identified 24 cases (38.7%) of negative CT findings (no stenoses or stenoses <50%), 35 cases of positive CT findings (56.4%) with identification of the culprit lesion, two cases in which the culprit lesion was not identified and one patient with unconfirmed stenosis. Sensitivity and specificity were 94.6% and 96%, respectively. Per-vessel analysis (186 vessels) revealed 17 non-evaluable vessels (9.1%) due to motion artefacts, 61 vessels (32.8%) with stenosis >50%, seven overestimated vessels (3.7%) due to extensive calcifications, three vessels (1.6%) with underestimated stenosis and 98 vessels (52.6%) without stenosis. Sensitivity and specificity were 95.3% and 93.3%, respectively.

CONCLUSIONS

In this type of emergency, coronary CT angiography could lead to considerably lower healthcare costs by identifying patients without coronary disease and allowing immediate discharge without any need for further diagnostic procedures.

Multislice computed tomography for comprehensive assessment of the heart in acute chest pain: a case report

Introduction

Over the last decade cardiac computed tomography emerged as a non-invasive imaging modality for the assessment of the heart and the coronary arteries. Only recently its use for patient management in the emergency department was suggested.

Case Presentation

We present an 84-year old male patient with concomitant early in-stent restenosis after coronary artery stent placement, myocardial infarction, left and right ventricular thrombi and aortic valve stenosis. Diagnoses were made on emergency cardiac computed tomography. All findings were confirmed by catheter coronary angiography, echocardiography and cardiac magnetic resonce imaging.

Conclusion

The comprehensive emergency work-up by cardiac computed tomography, illustrates the potential value of cardiac computed tomography in the emergency setting.

CT of coronary artery disease

Technical innovation is rapidly improving the clinical utility of cardiac computed tomography (CT) and will increasingly address current technical limitations, especially the association of this test with relatively high levels of radiation. Guidelines for appropriate indications are in place and are evolving, with an increasing evidence base to ensure the appropriate use of this modality. New technologies and new applications, such as myocardial perfusion imaging and dual-energy CT, are being explored and are widening the scope of coronary CT angiography from mere coronary artery assessment to the integrative analysis of cardiac morphology, function, perfusion, and viability. The scientific evaluation of coronary CT angiography has left the stage of feasibility testing and increasingly, evidence-based data are accumulating on outcomes, prognosis, and cost-effectiveness. In this review, these developments will be discussed in the context of current pivotal transitions in cardiovascular disease management and their potential influence on the current role and future fate of coronary CT angiography will be examined.

Automated computer-aided stenosis detection at coronary CT angiography: initial experience

OBJECTIVE

To evaluate the performance of a computer-aided algorithm for automated stenosis detection at coronary CT angiography (cCTA).

METHODS

We investigated 59 patients (38 men, mean age 58 +/- 12 years) who underwent cCTA and quantitative coronary angiography (QCA). All cCTA data sets were analyzed using a software algorithm for automated, without human interaction, detection of coronary artery stenosis. The performance of the algorithm for detection of stenosis of 50% or more was compared with QCA.

RESULTS

QCA revealed a total of 38 stenoses of 50% or more of which the algorithm correctly identified 28 (74%). Overall, the automated detection algorithm had 74%/100% sensitivity, 83%/65% specificity, 46%/58% positive predictive value, and 94%/100% negative predictive value for diagnosing stenosis of 50% or more on per-vessel/per-patient analysis, respectively. There were 33 false positive detection marks (average 0.56/patient), of which 19 were associated with stenotic lesions of less than 50% on QCA and 14 were not associated with an atherosclerotic surrogate.

CONCLUSION

Compared with QCA, the automated detection algorithm evaluated has relatively high accuracy for diagnosing significant coronary artery stenosis at cCTA. If used as a second reader, the high negative predictive value may further enhance the confidence of excluding significant stenosis based on a normal or near-normal cCTA study.

Usefulness of age and gender in the early triage of patients with acute chest pain having cardiac computed tomographic angiography

To identify the age- and gender-specific subpopulations of patients with acute chest pain in whom coronary computed tomographic angiography (CTA) will yield the greatest diagnostic benefit. Subjects with acute chest pain and an inconclusive initial evaluation (nondiagnostic electrocardiograhic findings, negative cardiac biomarkers) underwent contrast-enhanced 64-slice coronary CTA as a part of an observational cohort study. Independent investigators determined the presence of significant coronary stenosis (>50% luminal narrowing) and the occurrence of acute coronary syndrome (ACS) during the index hospitalization. We determined the diagnostic accuracy and effect on pretest probability of ACS using Bayes' theorem by age and gender. Of 368 patients (age 52.7 +/- 12 years, 61% men), 8% had ACS. The presence of significant coronary stenosis on CTA and the occurrence of ACS increased with age for both men and women (p <0.001). Cardiac CTA was highly sensitive and specific in women <65 years of age (sensitivity 100% and specificity >87%) and men <55 years of age (sensitivity 100% for men <45 years and 80% for men 45 to 54 years old; specificity >88.2%). Moreover, in these patients, coronary CTA led to restratification from low to high risk (for positive findings on CTA) or from low to very low risk (for negative findings on CTA). In contrast, a negative result on CTA did not result in restratification to a low-risk category in women >65 years and men >55 years old. In conclusion, the present analysis provides initial evidence that men <55 years and women <65 years might benefit more from cardiac CTA than older patients. Thus, age and gender might serve as simple criteria to appropriately select patients who would derive the greatest diagnostic benefit from coronary CTA in the setting of acute chest pain.