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

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.

Methods of plaque quantification and characterization by cardiac computed tomography

The pathologic evolution of coronary artery atherosclerosis occurs slowly over decades, which may provide an opportunity for diagnostic imaging to identify patients before clinical events evolve. Cardiac computed tomography (CT) is an emerging noninvasive imaging tool, which can visualize the entire coronary tree with submillimeter resolution. We reviewed the current status of cardiac CT to qualitatively and quantitatively determine coronary plaque dimensions and composition, and its potential to improve our understanding of the natural history of coronary artery disease as well as prevention of cardiovascular events.

Coronary computerized tomography angiography for rapid discharge of low-risk patients with cocaine-associated chest pain

BACKGROUND

Most patients presenting to emergency departments (EDs) with cocaine-associated chest pain are admitted for at least 12 hours and receive a "rule out acute coronary syndrome" protocol, often with noninvasive testing prior to discharge. In patients without cocaine use, coronary computerized tomography angiography (CTA) has been shown to be useful for identifying a group of patients at low risk for cardiac events who can be safely discharged. It is unclear whether a coronary CTA strategy would be efficacious in cocaine-associated chest pain, as coronary vasospasm may account for some of the ischemia. We studied whether a negative coronary CTA in patients with cocaine-associated chest pain could identify a subset safe for discharge.

METHODS

We prospectively evaluated the safety of coronary CTA for low-risk patients who presented to the ED with cocaineassociated chest pain (self-reported or positive urine test). Consecutive patients received either immediate coronary CTA in the ED (without serial markers) or underwent coronary CTA after a brief observation period with serial cardiac marker measurements. Patients with negative coronary CTA (maximal stenosis less than 50%) were discharged. The main outcome was 30-day cardiovascular death or myocardial infarction.

RESULTS

A total of 59 patients with cocaine-associated chest pain were evaluated. Patients had a mean age of 45.6 +/- 6.6 yrs and were 86% black, 66% male. Seventy-nine percent had a normal or nonspecific ECG and 85% had a TIMI score <2. Twenty patients received coronary CTA immediately in the ED, 18 of whom were discharged following CTA (90%). Thirty-nine received coronary CTA after a brief observation period, with 37 discharged home following CTA (95%). Six patients had coronary stenosis >or=50%. During the 30-day follow-up period, no patients died of a cardiovascular event (0%; 95% CI, 0-6.1%) and no patient sustained a nonfatal myocardial infarction (0%; 95% CI, 0-6.1%).

CONCLUSIONS

Although cocaine-associated myocardial ischemia can result from coronary vasoconstriction, patients with cocaine associated chest pain, a non-ischemic ECG, and a TIMI risk score <2 may be safely discharged from the ED after a negative coronary CTA with a low risk of 30-day adverse events.

Myocardial ischemia in acute coronary syndrome: assessment using 64-MDCT

OBJECTIVE

We investigated the performance of 64-MDCT myocardial imaging in assessing myocardial ischemia in acute coronary syndrome (ACS).

MATERIALS AND METHODS

Cardiac CT was performed in 35 patients with ACS: 24 patients with acute myocardial infarction (AMI) and 11 patients with unstable angina pectoris (UAP). We reconstructed 2D myocardial images at diastolic and systolic phases using the same raw data as those used for coronary CT angiography. The CT number in the myocardium was used as an estimate of ischemia. The myocardium was shown using a color scale that depicts faint low-density areas more clearly than gray scale. We evaluated the variations in myocardial enhancement during the cardiac cycle in the territory of the culprit lesion. In addition, we classified patients on the basis of the transmurality of myocardial enhancement and examined whether this feature correlates with myocardial damage.

RESULTS

Myocardial imaging at systole showed myocardial hypoenhancement in territories of the culprit lesion in 91% of patients with ACS, 96% of patients with AMI, and 75% of patients with UAP. The hypoenhancement areas at systole tended to be more extensive than those at diastole. The transmural extent of hypoenhancement at systole correlated with myocardial damage, which was shown by myocardial biomarkers.

CONCLUSION

CT myocardial imaging can be used to assess myocardial ischemia in the appropriate region of ACS with high sensitivity.

Adoption and spread of new imaging technology: a case study

Technology is a major driver of health care costs. Hospitals are rapidly acquiring one new technology in particular: 64-slice computed tomography (CT), which can be used to image coronary arteries in search of blockages. We propose that it is more likely to be adopted by hospitals that treat cardiac patients, function in competitive markets, are reimbursed for the procedure, and have favorable operating margins. We find that early adoption is related to cardiac patient volume but also to operating margins. The paucity of evidence informing this technology's role in cardiac care suggests that its adoption by cardiac-oriented hospitals is premature. Further, adoption motivated by operating margins reinforces concerns about haphazard technology acquisition.

Risk assessment and predictive value of coronary artery disease testing

This review highlights and compares risk assessment, predictive accuracy, and economic outcomes for 3 commonly applied cardiac imaging procedures: stress myocardial perfusion SPECT or PET and coronary CT angiography (CCTA). This review highlights an expansive evidence base for stress myocardial perfusion imaging and reveals a decided advantage for higher-risk patients, notably those who have established coronary artery disease (CAD). It is likely that the use of CCTA will continue to expand, particularly for patients with more atypical symptoms and patients with a lower likelihood of CAD. Despite a high level of evidence, comparative research is not available across modalities that could definitively drive utilization of cardiac imaging modalities.

[Dual-source computed tomography in inpatients with atypical chest pain]

OBJECTIVE

To evaluate the potential usefulness of dual-source CT (DSCT) in the diagnostic work-up of inpatients with atypical chest pain of unknown etiology.

MATERIAL AND METHODS

Forty-one consecutive inpatients (25 male, 16 female; mean age 55.6+/-17.39 years) with atypical chest pain underwent DSCT to determine the cause of pain. Images were acquired with retrospective ECG gating after the administration of 120ml of iodinated contrast medium at 4ml/s using the bolus tracking technique. Two readers analyzed the images in consensus.

RESULTS

DSCT was diagnostic in all patients. We detected pulmonary embolisms in five patients and aortic disease in two (one aortic ulcer and one sacular aneurysm). Anomalies of the coronary arteries were depicted in 15 patients, two of whom presented luminal stenosis >50%. Extracardiovascular findings at DSCT included pneumonia in eleven patients, sarcoidosis in one, and non-small cell lung carcinoma in one. Pleural effusion was detected in four patients and pericardial effusion in another four. No pathological findings were observed in 22% of subjects. Evolution was favorable in all patients. No patients were readmitted for persistent pain or new onset of acute chest pain during the follow-up period.

CONCLUSION

DSCT can rule out most life-threatening clinical conditions that cause chest pain and is useful in determining the cause of chest pain in inpatients.

Diagnostic and prognostic value of absence of coronary artery calcification

OBJECTIVES

In this study, we systematically assessed the diagnostic and prognostic value of absence of coronary artery calcification (CAC) in asymptomatic and symptomatic individuals.

BACKGROUND

Presence of CAC is a well-established marker of coronary plaque burden and is associated with a higher risk of adverse cardiovascular outcomes. Absence of CAC has been suggested to be associated with a very low risk of significant coronary artery disease, as well as minimal risk of future events.

METHODS

We searched online databases (e.g., PubMed and MEDLINE) for original research articles published in English between January 1990 and March 2008 examining the diagnostic and prognostic utility of CAC.

RESULTS

A systematic review of published articles revealed 49 studies that fulfilled our criteria for inclusion. These included 13 studies assessing the relationship of CAC with adverse cardiovascular outcomes in 64,873 asymptomatic patients. In this cohort, 146 of 25,903 patients without CAC (0.56%) had a cardiovascular event during a mean follow-up period of 51 months. In the 7 studies assessing the prognostic value of CAC in a symptomatic population, 1.80% of patients without CAC had a cardiovascular event. Overall, 18 studies demonstrated that the presence of any CAC had a pooled sensitivity and negative predictive value of 98% and 93%, respectively, for detection of significant coronary artery disease on invasive coronary angiography. In 4,870 individuals undergoing myocardial perfusion and CAC testing, in the absence of CAC, only 6% demonstrated any sign of ischemia. Finally, 3 studies demonstrated that absence of CAC had a negative predictive value of 99% for ruling out acute coronary syndrome.

CONCLUSIONS

On the basis of our review of more than 85,000 patients, we conclude that the absence of CAC is associated with a very low risk of future cardiovascular events, with modest incremental value of other diagnostic tests in this very low-risk group.

One-year outcomes following coronary computerized tomographic angiography for evaluation of emergency department patients with potential acute coronary syndrome

OBJECTIVES

Coronary computerized tomographic angiography (CTA) has high correlation with cardiac catheterization and has been shown to be safe and cost-effective when used for rapid evaluation of low-risk chest pain patients from the emergency department (ED). The long-term outcome of patients discharged from the ED with negative coronary CTA has not been well studied.

METHODS

The authors prospectively evaluated consecutive low- to intermediate-risk patients who received coronary CTA in the ED for evaluation of a potential acute coronary syndrome (ACS). Patients with cocaine use, known cancer, and significant comorbidity reducing life expectancy and those found to have significant disease (stenosis > or = 50% or ejection fraction < 30%) were excluded. Demographics, medical and cardiac history, labs, and electrocardiogram (ECG) results were collected. Patients were followed by telephone contact and record review for 1 year. The main outcome was 1-year cardiovascular death or nonfatal acute myocardial infarction (AMI).

RESULTS

Of 588 patients who received coronary CTA in the ED, 481 met study criteria. They had a mean (+/-SD) age of 46.1 (+/-8.8) years, 63% were black or African American, and 60% were female. There were 53 patients (11%) rehospitalized and 51 patients (11%) who received further diagnostic testing (stress or catheterization) over the subsequent year. There was one death (0.2%; 95% confidence interval [CI] = 0.01% to 1.15%) with unclear etiology, no AMI (0%; 95% CI = 0 to 0.76%), and no revascularization procedures (0%; 95% CI = 0 to 0.76%) during this time period.

CONCLUSIONS

Low- to intermediate-risk patients with a Thrombosis In Myocardial Infarction (TIMI) score of 0 to 2 who present to the ED with potential ACS and have a negative coronary CTA have a very low likelihood of cardiovascular events over the ensuing year.

Low-risk patients with chest pain in the emergency department: negative 64-MDCT coronary angiography may reduce length of stay and hospital charges

OBJECTIVE

The current standard-of-care workup of low-risk patients with chest pain in an emergency department takes 12-36 hours and is expensive. We hypothesized that negative 64-MDCT coronary angiography early in the workup of such patients may enable a shorter length of stay and reduce charges.

MATERIALS AND METHODS

The standard-of-care evaluation consisted of serial cardiac enzyme tests, ECGs, and stress testing. After informed consent, we added cardiac CT early in the standard-of-care workup of 53 consecutive patients. Fifty patients had negative CT findings and were included in this series. The length of stay and charges were analyzed using actual patient data for all patients in the standard-of-care workup and for two earlier discharge scenarios based on negative cardiac CT results: First, CT plus serial enzyme tests and ECGs during an observation period followed by discharge if all were negative; and second, CT plus one set of enzyme tests and one ECG followed by discharge if all were negative. Comparisons were made using paired Student's t tests.

RESULTS

For standard of care and the two CT-based earlier discharge analyses, the mean lengths of stay were 25.4, 14.3, and 5.0 hours; mean charges were $7,597, $6,153, and $4,251. Length of stay and charges were both significantly less (p < 0.001) for the two CT-based analyses.

CONCLUSION

In low-risk patients with chest pain, discharge from the emergency department based on negative cardiac CT, enzyme tests, and ECG may significantly decrease both length of stay and hospital charges compared with the standard of care.

Whole-chest 64-MDCT of emergency department patients with nonspecific chest pain: Radiation dose and coronary artery image quality with prospective ECG triggering versus retrospective ECG gating

OBJECTIVE

The purpose of this study was to compare the patient radiation dose and coronary artery image quality of long-z-axis whole-chest 64-MDCT performed with retrospective ECG gating with those of CT performed with prospective ECG triggering in the evaluation of emergency department patients with nonspecific chest pain.

SUBJECTS AND METHODS

Consecutively registered emergency department patients with nonspecific low-to-moderate-risk chest pain underwent whole-chest CT with retrospective gating (n = 41) or prospective triggering (n = 31). Effective patient radiation doses were estimated and compared by use of unpaired Student's t tests. Two reviewers independently scored the quality of images of the coronary arteries, and the scores were compared by use of ordinal logistic regression.

RESULTS

Age, heart rate, body mass index, and z-axis coverage were not statistically different between the two groups. For retrospective gating, the mean effective radiation dose was 31.8 +/- 5.1 mSv; for prospective triggering, the mean effective radiation dose was 9.2 +/- 2.2 mSv (prospective triggering 71% lower, p < 0.001). Two of 512 segments imaged with retrospective gating were nonevaluable (0.4%), and two of 394 segments imaged with prospective triggering were nonevaluable (0.5%). Prospectively triggered images were 2.2 (95% CI, 1.1-4.5) times as likely as retrospectively gated images to receive a high image quality score for each segment after adjustment for segment differences (p < 0.05).

CONCLUSION

For long-z-axis whole-chest 64-MDCT of emergency department patients with nonspecific chest pain, use of prospective ECG triggering may result in substantially lower patient radiation doses and better coronary artery image quality than is achieved with retrospective ECG gating.

Quick identification of acute chest pain patients study (QICS)

Background

Patients with acute chest pain are often referred to the emergency ward and extensively investigated. Investigations are costly and could induce unnecessary complications, especially with invasive diagnostics. Nevertheless, chest pain patients have high mortalities. Fast identification of high-risk patients is crucial. Therefore several strategies have been developed including specific symptoms, signs, laboratory measurements, and imaging.

Methods/Design

The Quick Identification of acute Chest pain Study (QICS) will investigate whether a combined use of specific symptoms and signs, electrocardiography, routine and new laboratory measures, adjunctive imaging including electron beam (EBT) computed tomography (CT) and contrast multislice CT (MSCT) will have a high diagnostic yield for patients with acute chest pain. All patients will be investigated according a standardized protocol in the Emergency Department. Serum and plasma will be frozen for future analysis for a wide range of biomarkers at a later time point. The primary endpoint is the safe recognition of low-risk chest pain patients directly at presentation. Secondary endpoint is the identification of a wide range of sensitive predictive clinical markers, chemical biomarkers and radiological markers in acute chest pain patients. Chemical biomarkers will be compared to quantitative CT measurements of coronary atherosclerosis as a surrogate endpoint. Chemical biomarkers will also be compared in head to head comparison and for their additional value.

Discussion

This will be a very extensive investigation of a wide range of risk predictors in acute chest pain patients. New reliable fast and cheap diagnostic algorithm resulting from the test results might improve chest pain patients' prognosis, and reduce unnecessary costs and diagnostic complications.

Coronary computed tomography angiography for early triage of patients with acute chest pain: the ROMICAT (Rule Out Myocardial Infarction using Computer Assisted Tomography) trial

OBJECTIVES

This study was designed to determine the usefulness of coronary computed tomography angiography (CTA) in patients with acute chest pain.

BACKGROUND

Triage of chest pain patients in the emergency department remains challenging.

METHODS

We used an observational cohort study in chest pain patients with normal initial troponin and nonischemic electrocardiogram. A 64-slice coronary CTA was performed before admission to detect coronary plaque and stenosis (>50% luminal narrowing). Results were not disclosed. End points were acute coronary syndrome (ACS) during index hospitalization and major adverse cardiac events during 6-month follow-up.

RESULTS

Among 368 patients (mean age 53 +/- 12 years, 61% men), 31 had ACS (8%). By coronary CTA, 50% of these patients were free of coronary artery disease (CAD), 31% had nonobstructive disease, and 19% had inconclusive or positive computed tomography for significant stenosis. Sensitivity and negative predictive value for ACS were 100% (n = 183 of 368; 95% confidence interval [CI]: 98% to 100%) and 100% (95% CI: 89% to 100%), respectively, with the absence of CAD and 77% (95% CI: 59% to 90%) and 98% (n = 300 of 368, 95% CI: 95% to 99%), respectively, with significant stenosis by coronary CTA. Specificity of presence of plaque and stenosis for ACS were 54% (95% CI: 49% to 60%) and 87% (95% CI: 83% to 90%), respectively. Only 1 ACS occurred in the absence of calcified plaque. Both the extent of coronary plaque and presence of stenosis predicted ACS independently and incrementally to Thrombolysis In Myocardial Infarction risk score (area under curve: 0.88, 0.82, vs. 0.63, respectively; all p < 0.0001).

CONCLUSIONS

Fifty percent of patients with acute chest pain and low to intermediate likelihood of ACS were free of CAD by computed tomography and had no ACS. Given the large number of such patients, early coronary CTA may significantly improve patient management in the emergency department.

The disposition decision on emergency department patients with chest pain is affected by the results of multi-detector computed axial tomography scan of the coronary arteries

BACKGROUND

Few data exist on the frequency with which multidetector computed axial tomography (MDCT) scan of the coronary arteries changes the admission decisions of emergency physicians (EP) caring for patients with possible acute coronary syndrome (ACS). We measured if and how often these changes in decision-making would occur.

METHODS

The theoretical dispositions of 27 emergency department patients who presented with possible ACS were determined by four board-certified EPs after case presentations. Paired disposition decisions were made before and after knowledge of the MDCT scan results. Patients were selected from a sample of 103 from a prior study.

RESULTS

The study included 27 patients with a mean age of 55 +/- 9 years; 58% were male. The low-, intermediate-, and high-risk MDCT scan results were evenly distributed, as were the original providers' standard clinical risk assessments of ACS. Three patients had ACS and all were admitted both before and after review of MDCT scan results. Among 24 patients without ACS, a decision to admit was changed to discharge in 16 of 90 admission decisions (18%, 95% confidence interval [CI] 10-26%). Among 6 patients with projected discharges, 2 were inappropriately admitted after review of MDCT scan results. The odds ratio of discharge for patients without ACS increased by 3.95 (95% CI 1.96-7.95) after introduction of the MDCT scan results.

CONCLUSION

An MDCT scan of the coronary arteries will likely change emergency physicians' decisions on the disposition of patients presenting with possible ACS, many to appropriate discharges but also a minority to inappropriate admissions.

Triple rule-out CT in patients with suspicion of acute pulmonary embolism: findings and accuracy

RATIONALE AND OBJECTIVES

The aim of this study was to prospectively investigate the diagnostic value of triple rule-out computed tomography (CT) in patients suspected of having acute pulmonary embolism (PE).

MATERIALS AND METHODS

A total of 125 patients with suspicion of PE, of whom 14 patients had the additional clinical suspicion of acute aortic syndrome, underwent electrocardiogram-gated triple rule-out dual-source CT. The contrast media application protocol was adjusted to obtain a homogenous attenuation of the pulmonary arteries, thoracic aorta, and coronary arteries. The diagnostic performance of triple rule-out CT was assessed by using adjudicated discharge diagnoses as reference standards.

RESULTS

A total of 161 adjudicated cardiovascular discharge diagnoses were made in the 125 patients (including all true-positive and true-negative findings): acute PE was found in 26 (21%) and was excluded by CT in 99 (79%), coronary artery disease was found in 3 (3%) and was excluded by catheter angiography in 9 (6%), left ventricular systolic dysfunction was found in 2 (2%) and was excluded by echocardiography in 8 (6%), and acute aortic syndrome was found in 5 (4%) and was excluded by CT in 9 (7%) patients. Nonvascular chest disease was found in 34 (27%) and included pneumonia (n = 17), neoplasms (n = 5), fractures/osteolysis (n = 3), pericarditis (n = 2), and post-pneumonectomy syndrome (n = 1). Triple rule-out CT was normal in 53 (42%) patients. Overall sensitivity, specificity, and positive and negative predictive value of triple rule-out CT for cardiovascular disease were 100% (95% confidence interval [CI] 90-100%), 98% (95%CI 94-100%), 95% (95%CI 82-99%), and 100% (95%CI 97-100%, respectively).

CONCLUSIONS

Triple rule-out CT is feasible in patients with suspicion of PE, reveals a wide range of vascular and non-vascular chest disease, and offers an excellent overall diagnostic performance.

Usefulness of routine use of multidetector coronary computed tomography in the "fast track" evaluation of patients with acute chest pain

Recently published American Heart Association/American College of Cardiology guidelines suggest that multidetector computed tomography (MDCT) may be appropriate for investigating acute chest pain (ACP). Only a few small studies have evaluated the use of MDCT in ACP, where it was not part of routine investigation. We sought to evaluate the routine use of MDCT in a large cohort of patients presenting with ACP in a real-world setting. We studied 785 consecutive patients with ACP who underwent evaluation by MDCT or myocardial perfusion scintigraphy after an observation period of > or = 12 hours. Patients with findings suggestive of significant coronary artery disease (CAD) were referred to coronary angiography. Forty-two patients were hospitalized due to evidence of myocardial ischemia and 44 patients were discharged after the observation period. Of the remaining 699 patients, 340 underwent MDCT and 359 myocardial perfusion scintigraphy. In 22 patients (7%) multidetector computed tomogram showed significant CAD and in 32 (9%) patients myocardial perfusion scintigram showed significant ischemia. Significant CAD was confirmed by coronary angiography in 65% and 60%, respectively. Multidetector computed tomogram was nondiagnostic in 31 patients (9%). Extracardiac findings that might be related to ACP and/or necessitated further investigation were demonstrated by multidetector computed tomogram in 71 patients (21%). During 3-month follow-up, 1 patient (0.3%) with negative multidetector computed tomographic and 9 (3%) with negative myocardial perfusion scintigraphic findings developed an acute coronary syndrome or died. Rehospitalization, due to recurrent chest pain, occurred in 9 patients (3.3%) and 21 patients (7.2%), respectively. In conclusion, MDCT could be an appropriate alternative to traditional noninvasive techniques for investigating ACP.

Significance of cardiac computed tomography incidental findings in acute chest pain

BACKGROUND

Coronary computed tomography angiography might improve the management of patients presenting to the emergency department with acute chest pain; however, noncoronary incidental findings are frequently detected. The prevalence and clinical significance of these findings have not been well described.

METHODS

Consecutive patients presenting to the emergency department with acute chest pain and inconclusive initial evaluation between May 2005 and May 2007 underwent 64-slice coronary computed tomography angiography before hospital admission with noncoronary incidental findings immediately reported. An expert panel adjudicated which incidental findings changed in-hospital patient management, and projections for additional testing were based on standard medical practice.

RESULTS

Among 395 patients (37.0% were female, mean age 53 +/- 12 years), incidental findings were detected in 44.8% (n = 177): noncalcified pulmonary nodules (n = 94, 23.8%), simple liver cysts (n = 26, 6.6%), calcified pulmonary nodules (n = 16, 4.1%), and contrast-enhancing liver lesions (n = 9, 2.3%). In-hospital management was changed because of incidental finding reporting in 5 patients (1.3%), and a potential alternative diagnosis was offered in another 16 patients (4.1%). Subsequent diagnostic imaging tests were recommended in 81 patients (20.5%), including 74 chest computed tomography scans. After 6 months, biopsy was performed in 3 patients, revealing cancer in 2 (0.5%) who underwent successful tumor resection.

CONCLUSION

Clinically important findings are detected in up to 5% of patients with a lead symptom of acute chest pain and low to intermediate likelihood of acute coronary syndrome, but only few directly change patient management; 21% are recommended for further imaging tests, resulting in invasive procedures and detection of cancer in few patients.

Multislice coronary computed tomographic angiography in emergency department presentations of unsuspected acute myocardial infarction

BACKGROUND

Coronary computed tomographic angiography (CCTA) is not indicated in the setting of acute myocardial infarction in the emergency department (ED). Nonetheless, acute coronary syndromes may have atypical presentations, and CCTA may be inadvertently performed in this setting.

OBJECTIVES

This study was designed to determine the frequency and characteristics of CCTA imaging of unsuspected acute myocardial infarction in the ED.

METHODS

All CCTAs performed in the ED at Lenox Hill Hospital were reviewed for clinical indications and subsequent course; patients with documented acute myocardial infarction were identified.

RESULTS

Of the 500 CCTAs performed on ED patients in the Lenox Hill laboratory, 5 patients (1%) were imaged during the initial phase of an unsuspected acute myocardial infarction; in all cases the CCTAs were key to the diagnosis. The imaging characteristics were (1) total or subtotal occlusion and (2) transmural hypodensity in the infarct area.

CONCLUSION

Although acute myocardial infarction on CCTA in ED patients is an infrequent event, proper and prompt recognition is critical for appropriate patient care, particularly as applications to the ED increase.

Triple rule-out and dedicated coronary artery CTA: comparison of coronary artery image quality

RATIONALE AND OBJECTIVE

The aim of this study was to compare image quality on dedicated and triple rule-out coronary computed tomographic (CT) angiography (CTA) with respect to motion artifacts and the quality of coronary artery opacification.

MATERIALS AND METHODS

Twenty dedicated coronary CT angiographic studies and 20 emergency department triple rule-out CT angiographic studies (ie, to rule out pulmonary embolism, aortic dissection, and acute coronary syndrome) performed on 64-slice CT scanner were selected. Two radiologists, blinded to type of CTA, scored coronary artery image quality. Up to 14 coronary artery segments were scored for motion artifact on a scale ranging from 1 (no motion artifact) to 4 (severe motion artifact). The radiologists also scored the quality of opacification (1 = good opacification, 2 = limited opacification, 3 = vessel not seen). The average of all segments and dedicated larger and smaller coronary artery segments was compared.

RESULTS

The average motion-artifact scores per vessel segment for dedicated and triple rule-out studies were 1.64 and 1.72, respectively (P = .6). For larger segments, the average motion-artifact score was 1.41 for dedicated CTA compared to 1.55 for triple rule-out CTA (P = .2). The average coronary artery opacification for dedicated studies was 1.05 for all segments and 1.03 for larger segments, compared to triple rule-out studies, which had scores of 1.09 (P = .5) for all segments and 1.06 (P = .5) for larger segments. No statistically significant differences in favor of dedicated CTA were identified.

CONCLUSION

The image quality of triple rule-out CTA is comparable to that of dedicated coronary CTA, showing no statistically significant difference in motion artifacts or opacification, and therefore may be an alternative and useful diagnostic study in a select group of emergency department patients.

Radiation dose in a "triple rule-out" coronary CT angiography protocol of emergency department patients using 64-MDCT: the impact of ECG-based tube current modulation on age, sex, and body mass index

OBJECTIVE

"Triple rule-out" coronary CT angiography (CTA) using 64-MDCT technology is a new approach for evaluating emergency department patients presenting with symptoms suggestive of acute coronary syndrome (ACS). Our objective was to evaluate the reduction in effective radiation dose through the use of tube current modulation in patients who underwent a triple rule-out coronary CTA evaluation and to document how effective radiation dose was impacted by patient age, sex, and body mass index (BMI).

MATERIALS AND METHODS

A retrospective analysis of triple rule-out coronary CTA examinations performed on a 64-MDCT scanner was ordered on a prospective cohort of 267 consecutive low- to moderate-risk emergency department patients with suspected ACS from a single university hospital between October 2006 and March 2008. Tube current modulation was generally used in patients with heart rates below 65 beats per minute during the second half of the study period as a way to reduce radiation exposure. We calculated effective radiation exposure using actual patient coronary CTA scanning parameters by age, sex, and BMI.

RESULTS

Among the 172 patients evaluated without tube current modulation, effective dose averaged (+/- SD) 18.0 +/- 5.6 mSv (range, 9.9-31.3 mSv). Of the 95 patients who underwent CTA examination with tube current modulation, effective dose was significantly lower at 8.75 +/- 2.64 mSv (range, 5.4-16.6 mSv; p < 0.0001) and image quality was better (p < 0.0001) as compared with examinations without tube current modulation. There were no significant radiation differences by patient age, but tube current modulation decreased radiation exposure by at least half. Among the studies in which tube current modulation was not used, women received less radiation than men (17.0 vs 19.5 mSv, respectively; p < 0.001). For the studies with tube current modulation, there were no radiation differences by sex. Obese patients received significantly more radiation than overweight and normal-weight patients in the non-tube current modulation groups (20.9 mSv vs 15.0 and 14.9 mSv, respectively; p < 0.0001) and in the tube current modulation groups (10.3 mSv vs 7.6 and 7.1 mSv, p < 0.0001).

CONCLUSION

The overall effective radiation dose for triple rule-out coronary CTA was reduced by more than 50% with ECG-based tube current modulation without loss of image quality. Tube current modulation should be used for triple rule-out coronary CTA examinations whenever possible.

Predictors of image quality of coronary computed tomography in the acute care setting of patients with chest pain

OBJECTIVE

We aimed to determine predictors of image quality in consecutive patients who underwent coronary computed tomography (CT) for the evaluation of acute chest pain.

METHOD AND MATERIALS

We prospectively enrolled patients who presented with chest pain to the emergency department. All subjects underwent contrast-enhanced 64-slice coronary multi-detector CT. Two experienced readers determined overall image quality on a per-patient basis and the prevalence and characteristics of non-evaluable coronary segments on a per-segment basis.

RESULTS

Among 378 subjects (143 women, age: 52.9+/-11.8 years), 345 (91%) had acceptable overall image quality, while 33 (9%) had poor image quality or were unreadable. In adjusted analysis, patients with diabetes, hypertension and a higher heart rate during the scan were more likely to have exams graded as poor or unreadable (odds ratio [OR]: 2.94, p=0.02; OR: 2.62, p=0.03; OR: 1.43, p=0.02; respectively). Of 6253 coronary segments, 257 (4%) were non-evaluable, most due to severe calcification in combination with motion (35%). The presence of non-evaluable coronary segments was associated with age (OR: 1.08 annually, 95%-confidence interval [CI]: 1.05-1.12, p<0.001), baseline heart rate (OR: 1.35 per 10 beats/min, 95%-CI: 1.11-1.67, p=0.003), diabetes, hypertension, and history of coronary artery disease (OR: 4.43, 95%-CI: 1.93-10.17, p<0.001; OR: 2.27, 95-CI: 1.01-4.73, p=0.03; OR: 5.12, 95%-CI: 2.0-13.06, p<0.001; respectively).

CONCLUSION

Coronary CT permits acceptable image quality in more than 90% of patients with chest pain. Patients with multiple risk factors are more likely to have impaired image quality or non-evaluable coronary segments. These patients may require careful patient preparation and optimization of CT scanning protocols.

Presence and extent of coronary artery disease by cardiac computed tomography and risk for acute coronary syndrome in cocaine users among patients with chest pain

Cocaine users represent an emergency department (ED) population that has been shown to be at increased risk for acute coronary syndrome (ACS); however, there is controversy about whether this higher risk is mediated through advanced atherosclerosis. Thus, we aimed to determine whether history of cocaine use is associated with ACS and coronary artery disease. In this matched cohort study, we selected patients with a history of cocaine use and age- and gender-matched controls from a large cohort of consecutive patients who presented with acute chest pain to the ED. Coronary atherosclerotic plaque as detected by 64-slice coronary computed tomography was compared between the groups. Among 412 patients, 44 had a history of cocaine use (9%) and were matched to 132 controls (mean age 46 +/- 6 years, 86% men). History of cocaine use was associated with a sixfold higher risk for ACS (odds ratio 5.79, 95% confidence interval 1.24 to 27.02, p = 0.02), but was not associated with a higher prevalence of any plaque, calcified plaque, or noncalcified plaque (all p>0.58) or the presence of significant stenosis (p = 0.09). History of cocaine use was also not associated with the extent of any, calcified, or noncalcified plaque (all p>0.12). These associations persisted after adjustment for other cardiovascular risk factors. In conclusion, in patients presenting to the emergency department with acute chest pain, history of cocaine use is associated with an increase in risk for ACS; however, this was not attributable to a higher presence or extent of coronary atherosclerotic plaque.

Quantitative assessment of left atrial volume by electrocardiographic-gated contrast-enhanced multidetector computed tomography

BACKGROUND

Left atrial (LA) volume is a predictor of cardiovascular events. Information on LA volume is available on contrast-enhanced electrocardiogram (EGC)-gated multidetector computed tomography (MDCT) scans.

OBJECTIVE

To assess interobserver and intraobserver reproducibility of 3-dimensional threshold-based volume (3DTV) and 2-dimensional (2D) measurements for the assessment of LA volumes with contrast-enhanced cardiac 64-slice MDCT.

METHODS

Contrast-enhanced 64-slice MDCT (0.6-mm slice thickness, 120 kVp, 850 mAseff) was performed in 96 consecutive subjects (mean age 52 years; 48% women) as a subset of the Rule Out Myocardial Infarction using Computer Assisted Tomography trial. Two observers independently measured maximal (LAV(max)) and minimal (LAV(min)) LA volumes with (1) a modified Simpson's method (3DTV) based on delineation of LA areas in axial slices and (2) estimated LA volumes typically used in 2D echocardiography (area length and prolate ellipse). Interobserver and intraobserver reproducibility for each method as well as correlations between the methods were calculated.

RESULTS

Interobserver (n = 96) and intraobserver (n = 20) variability was significantly lower for 3DTV (8%) than for area length (13%; P < 0.001) or prolate ellipse (16%; P < 0.001). 2D-based measurements rendered significantly lower LA volumes than did 3DTV (area length: -17% and -22%; prolate ellipse: -43% and -46% for LAV(max) and LAV(min), respectively; P < 0.001 for all). By 3DTV, mean LA volume was 90.4 +/- 24.5 mL for LAV(max) and 52.5 +/- 17.6 mL for LAV(min).

CONCLUSION

ECG-gated contrast-enhanced cardiac MDCT offers volumetric assessment of LA volume with excellent reproducibility without additional contrast administration or radiation exposure. 3D measures of LA volume are more reproducible and render larger volumes than 2D-derived estimates, typically used in echocardiography.

[Update on interventional cardiology]

Percutaneous intervention, whether coronary or noncoronary, continues to be a highly active area of medicine. This article contains an overview of the most notable developments reported in recent months. Drug-eluting stents (DESs) have provided one of the major advances in interventional cardiology as they have very effectively reduced the restenosis rate. Both randomized clinical trials and large observational studies have confirmed their safety, and their use has been extended to include highly complex conditions. Although thrombosis is one complication that can affect both conventional stents and DESs, the rate of late stent thrombosis is slightly, though significantly, higher with DESs. Primary angioplasty is the treatment of choice for patients with acute myocardial infarction if carried out under appropriate conditions, within a reasonable time period in a specialized center by experienced personnel. Use of thrombectomy devices can improve procedural outcomes and it appears that DES implantation is safe and effective, though more data are still needed. In patients with non-ST-elevation acute coronary syndrome, early treatment using an invasive approach coupled to the administration of various combinations of antiplatelet and antithrombotic drugs continues to be fundamental. Although left main coronary artery lesions are generally treated surgically, advances in percutaneous techniques and the use of DESs mean that an increasing number of patients are being treated using percutaneous coronary interventions. A number of studies have shown good results in other lesions and in high-risk patients with, for example, bifurcation lesions, chronic occlusions or diabetes. Intracoronary ultrasound is the predominant intracoronary diagnostic technique and it can be used to assist in optimizing DES implantation. In addition, measurement of the fractional flow reserve is helpful in evaluating the severity of moderate lesions whereas the high-resolution images provided by optical coherence tomography are particularly informative. Multislice computed tomography enables the presence of coronary artery disease to be ruled out and the technique is also useful as a complementary tool for interventional cardiologists. Research into regenerative techniques is promising but remains experimental at present. With regard to noncoronary interventions, new data have become available that support the use of a percutaneous approach in patients with patent foramen ovale. In addition, clinical experience with percutaneous aortic valve replacement, via either the transfemoral or transapical route, is increasing.

Limitations of risk score models in patients with acute chest pain

OBJECTIVES

Cardiac multidetector computed tomography (CMCT) has potential to be used as a screening test for patients with acute chest pain, but several tools are already used to risk-stratify this population. Risk models exist that stratify need for intensive care (Goldman), short-term prognosis (Thrombolysis in Myocardial Infarction, TIMI), and 1-year events (Sanchis). We applied these cardiovascular risk models to candidates for CMCT and assessed sensitivity for prediction of in-hospital acute coronary syndrome (ACS). We hypothesized that none of the models would achieve a sensitivity of 90% or greater, thereby justifying use of CMCT in patients with acute chest pain.

METHODS

We analyzed TIMI, Goldman, and Sanchis in 148 consecutive patients with chest pain, nondiagnostic electrocardiogram, and negative initial cardiac biomarkers who previously met inclusion and exclusion criteria for the Rule-Out Myocardial Infarction Using Coronary Artery Tomography Study. ACS was adjudicated, and risk scores were categorized based on established criteria. Risk score agreement was assessed with weighted kappa statistics.

RESULTS

Overall, 17 (11%) of 148 patients had ACS. For all risk models, sensitivity was poor (range, 35%-53%), and 95% confidence intervals did not cross above 77%. Agreement to risk-classify patients was poor to moderate (weighted kappa range, 0.18-0.43). Patients categorized as "low risk" had nonzero rates of ACS using all 3 scoring models (range, 8%-9%).

CONCLUSIONS

Available risk scores had poor sensitivity to detect ACS in patients with acute chest pain. Because of the small number of patients in this data set, these findings require confirmation in larger studies.

Diagnostic Accuracy and Impact of Computed Tomographic Coronary Angiography on Utilization of Invasive Coronary Angiography

Background— Computed tomographic coronary angiography (CTA), given its high negative predictive value, is a potential gatekeeper for invasive coronary angiography (ICA). Before CTA can be further accepted into clinical practice, its impact on healthcare resources needs to be better understood. We sought to determine the clinical impact of CTA on ICA referrals, CTA accuracy, and normalcy rate.

Methods and Results— To determine the impact of CTA, consecutive patients (n=7017) undergoing ICA before and after implementing a dedicated cardiac CT program were reviewed and compared with 3 other centers (n=11 508). To determine CTA accuracy, we evaluated consecutive CTA patients who underwent ICA. For normalcy rate, we identified patients with a low pretest probability for obstructive coronary artery disease. With the implementation of a cardiac CT program, the frequency of normal ICA decreased from 31.5% (1114 of 3538 patients) to 26.8% (932 of 3479 patients) ( P <0.001). These findings were significantly different ( P =0.003) from the 3 centers, in which normal ICAs were unchanged (30.0% [1870 of 6224 patients] to 31.0% [1642 of 5284 patients]). CTA had excellent per-patient sensitivity (99% [CI, 95% to 100%]), positive predictive value (92% [CI, 86% to 96%]) and negative predictive value (95% [CI, 72% to 100%]). Because of referral bias, specificity (64% [CI, 44% to 81%]) was low; however, the normalcy rate of CTA was 94% (CI, 90% to 97%). After adjusting for referral bias, the adjusted sensitivity was 90% (CI, 89% to 91%), and the adjusted specificity was 95% (CI, 94% to 96%), with positive and negative predictive values of 92% (CI, 91% to 93%) and 93% (CI, 92% to 94%), respectively.

Conclusion— The clinical implementation of CTA appears to positively impact ICA by reducing the frequency of normal ICA. The operating characteristics of CTA support its potential role as a tool useful in ruling out obstructive coronary artery disease.

Coronary computed tomographic angiography for rapid discharge of low-risk patients with potential acute coronary syndromes

STUDY OBJECTIVE

Coronary computed tomographic (CT) angiography has excellent performance characteristics relative to coronary angiography and exercise or pharmacologic stress testing. We hypothesize that coronary CT angiography can identify a cohort of emergency department (ED) patients with a potential acute coronary syndrome who can be safely discharged with a less than 1% risk of 30-day cardiovascular death or nonfatal myocardial infarction.

METHODS

We conducted a prospective cohort study at an urban university hospital ED that enrolled consecutive patients with potential acute coronary syndromes and a low TIMI risk score who presented to the ED with symptoms suggestive of a potential acute coronary syndrome and received a coronary CT angiography. Our intervention was either immediate coronary CT angiography in the ED or after a 9- to 12-hour observation period that included cardiac marker determinations, depending on time of day. The main clinical outcome was 30-day cardiovascular death or nonfatal myocardial infarction.

RESULTS

Five hundred sixty-eight patients with potential acute coronary syndrome were evaluated: 285 of these received coronary CT angiography immediately in the ED and 283 received coronary CT angiography after a brief observation period. Four hundred seventy-six (84%) were discharged home after coronary CT angiography. During the 30-day follow-up period, no patients died of a cardiovascular event (0%; 95% confidence interval [CI] 0% to 0.8%) or sustained a nonfatal myocardial infarction (0%; 95% CI 0 to 0.8%).

CONCLUSION

ED patients with symptoms concerning for a potential acute coronary syndrome with a low TIMI risk score and a nonischemic initial ECG result can be safely discharged home after a negative coronary CT angiography test result.