Coronary Artery Calcium Scoring in the Emergency Department: Identifying Which Patients With Chest Pain Can Be Safely Discharged Home

Coronary Artery Disease: Role of Computed Tomography and Recent Advances

In this review, the authors summarize the role of coronary computed tomography angiography and coronary artery calcium scoring in different clinical presentations of chest pain and preventative care and discuss future directions and new technologies such as pericoronary fat inflammation and the growing footprint of artificial intelligence in cardiovascular medicine.

Coronary Calcium Predicts All-Cause Mortality in Suspected Acute Aortic Syndrome

PURPOSE

To determine long-term clinical outcomes in patients with suspected acute aortic syndrome (AAS) and evaluate the prognostic value of coronary calcium burden as assessed with CT aortography in this symptomatic population.

MATERIALS AND METHODS

A retrospective cohort of all patients who underwent emergency CT aortography from January 2007 through January 2012 for suspected AAS was assembled. A medical record survey tool was used to evaluate subsequent clinical events over 10 years of follow-up. Events included death, aortic dissection, myocardial infarction, cerebrovascular accident, and pulmonary embolism. Coronary calcium scores were computed from original images using a validated simple 12-point ordinal method and categorized into none, low (1-3), moderate (4-6), or high (7-12) groupings. Survival analysis with Kaplan-Meier curves and Cox proportional hazard modeling was performed.

RESULTS

The study cohort comprised 1658 patients (mean age, 60 years ± 16 [SD]; 944 women), with 595 (35.9%) developing a clinical event over a median follow-up of 6.9 years. Patients with high coronary calcium demonstrated the highest mortality rate (adjusted hazard ratio = 2.36; 95% CI: 1.65, 3.37). Patients with low coronary calcium demonstrated lower mortality, but rates were still almost twice as high compared with patients with no detectable calcium (adjusted hazard ratio = 1.89; 95% CI: 1.41, 2.53). Coronary calcium was a strong predictor of major adverse cardiovascular events (P < .001), which persisted after adjustment for common significant comorbidities.

CONCLUSION

Patients with suspected AAS had a high rate of subsequent clinical events, including death. CT aortography-based coronary calcium scores strongly and independently predicted all-cause mortality.Keywords: Acute Aortic Syndrome, Coronary Artery Calcium, CT Aortography, Major Adverse Cardiovascular Events, Mortality Supplemental material is available for this article. © RSNA, 2023See also commentary by Weir-McCall and Shambrook in this issue.

The Added Value of a High CT Coronary Artery Calcium Score in the Management of Patients Presenting with Acute Chest Pain vs. Stable Chest Pain

Background: Contrast computerized tomography (CT) scan is occasionally aborted due to a high coronary artery calcium score (CACS). For the same CACS in our clinical practice, we observed a higher occurrence of severe coronary artery disease (CAD) in patients with acute chest pain (ACP) compared to patients with stable chest pain (SCP). Since it is known that ACP differs in many ways from SCP, the aim of this study was to compare the predictive value of a high CACS for the diagnosis of severe CAD between ACP and SCP patients. Methods: This single center observational retrospective study included consecutive patients who underwent cardiac CT for chest pain and were found to have a CACS of >200 Agatston units. Patients were divided into two groups, ACP and SCP. Severe CAD was defined as ≥70% stenosis on coronary CT angiography or invasive coronary angiography. Baseline characteristics and final diagnosis of severe CAD were compared. Results: The cohort included 220 patients, 106 with ACP and 114 with SCP. ACP patients had higher severe CAD rates (60.4% vs. 36.8%; p < 0.001). On multivariate analysis including cardiac risk factors, CACS > 400 au (OR = 2.34 95% CI [1.32−4.15]; p = 0.004) and ACP (OR = 2.54 95% CI [1.45−4.45]; p = 0.001) were independent predictors of severe CAD. The addition of the clinical setting of ACP added significant incremental predictive value for severe stenosis. Conclusion: A high CACS is more associated with severe CAD in patients presenting with ACP than SCP. The findings suggest that the CACS could impact the management of patients during the scan.

Predictive Value of Coronary Artery Calcium in Patients Receiving Computed Tomography Pulmonary Angiography for Suspected Pulmonary Embolism in the Emergency Department

PURPOSE

Coronary artery calcium (CAC) is a frequent incidental finding on computed tomography pulmonary angiogram (CTPA) in the evaluation of pulmonary embolism (PE) in the emergency department (ED); however, its prognostic value is unclear. In this study, we interrogate the prognostic value of CAC identified on CTPA in predicting adverse outcomes in the evaluation of PE in the ED.

MATERIALS AND METHODS

In this retrospective cohort study, we identified 610 patients presenting to the ED in 2013 and evaluated with CTPA for suspected PE. Ordinal CAC scores were evaluated as absent (0), mild (1), moderate (2), or severe (3) in each of the 4 main coronary arteries. Composite CAC scores were subsequently compared against adverse clinical outcomes, defined as intensive care unit admission, hospital stay longer than 72 hours, or death during hospital course or at 6-month follow-up, using univariate and multivariate logistic regression analyses. Relevant exclusion criteria included a history of cardiovascular disease.

RESULTS

In all, 365 patients met the inclusion criteria (231 women, mean age 56±16 y) with 132 patients (36%) having some degree of CAC and 16 (4%) having severe CAC. Known malignancy was present in 151 (41%) patients and composite adverse clinical outcomes were observed in 98 patients (32%). Age, presence of acute PE, malignancy, and presence of CAC were significant predictors of adverse outcomes on both univariate and multivariate analyses. CAC was not an independent predictor of short-term adverse outcomes on multivariate analysis ( P =0.06) when all patients were considered. However, when patients with known malignancy were excluded, CAC was an independent predictor of short-term adverse outcomes (odds ratio=2.5, confidence interval=1.1-5.5, P =0.03) independent of age and presence of PE.

CONCLUSION

The presence of CAC on CT PA was predictive of adverse outcomes in patients without known cardiac disease presenting to the ED with suspected PE.

Cardiac CT angiography in current practice: An American society for preventive cardiology clinical practice statement✰

In this clinical practice statement, we represent a summary of the current evidence and clinical applications of cardiac computed tomography (CT) in evaluation of coronary artery disease (CAD), from an expert panel organized by the American Society for Preventive Cardiology (ASPC), and appraises the current use and indications of cardiac CT in clinical practice. Cardiac CT is emerging as a front line non-invasive diagnostic test for CAD, with evidence supporting the clinical utility of cardiac CT in diagnosis and prevention. CCTA offers several advantages beyond other testing modalities, due to its ability to identify and characterize coronary stenosis severity and pathophysiological changes in coronary atherosclerosis and stenosis, aiding in early diagnosis, prognosis and management of CAD. This document further explores the emerging applications of CCTA based on functional assessment using CT derived fractional flow reserve, peri‑coronary inflammation and artificial intelligence (AI) that can provide personalized risk assessment and guide targeted treatment. We sought to provide an expert consensus based on the latest evidence and best available clinical practice guidelines regarding the role of CCTA as an essential tool in cardiovascular prevention - applicable to risk assessment and early diagnosis and management, noting potential areas for future investigation.

Coronary Calcium to Rule Out Obstructive Coronary Artery Disease in Patients With Acute Chest Pain

OBJECTIVES

This study aimed to evaluate the ability of coronary artery calcium (CAC) as an initial diagnostic tool to rule out obstructive coronary artery disease (CAD) in a very large registry of patients presenting to the emergency department (ED) with acute chest pain (CP) who were at low to intermediate risk for acute coronary syndrome (ACS).

BACKGROUND

It is not yet well established whether CAC can be used to rule out obstructive CAD in the ED setting.

METHODS

We included patients from the Baptist Health South Florida Chest Pain Registry presenting to the ED with CP at low to intermediate risk for ACS (Thrombolysis In Myocardial Infarction risk score ≤2, normal/nondiagnostic electrocardiography, and troponin levels) who underwent CAC and coronary computed tomography angiography (CCTA) procedures for evaluation of ACS. To assess the diagnostic accuracy of CAC testing to diagnose obstructive CAD and identify the need for coronary revascularization during hospitalization, we estimated sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV).

RESULTS

Our study included 5,192 patients (mean age: 53.5 ± 10.8 years; 46% male; 62% Hispanic). Overall, 2,902 patients (56%) had CAC = 0, of which 135 (4.6%) had CAD (114 [3.9%] nonobstructive and 21 [0.7%] obstructive). Among those with CAC >0, 23% had obstructive CAD. Sensitivity, specificity, PPV, and NPV of CAC testing to diagnose obstructive CAD were 96.2%, 62.4%, 22.4%, and 99.3%, respectively. The NPV for identifying those who needed revascularization was 99.6%. Among patients with CAC = 0, 11 patients (0.4%) underwent revascularization, and the number needed to test with CCTA to detect 1 patient who required revascularization was 264.

CONCLUSIONS

In a large population presenting to ED with CP at low to intermediate risk, CAC = 0 was common. CAC = 0 ruled out obstructive CAD and revascularization in more than 99% of the patients, and <5% with CAC = 0 had any CAD. Integrating CAC testing very early in CP evaluation may be effective in appropriate triage of patients by identifying individuals who can safely defer additional testing and more invasive procedures.

Coronary artery calcium testing in low-intermediate risk symptomatic patients with suspected coronary artery disease: An effective gatekeeper to further testing?

Computed tomography for quantification of coronary artery calcium (CAC) is a simple non-invasive tool to assess atherosclerotic plaque burden. CAC is highly correlated with coronary atherosclerosis and is a robust predictor of cardiovascular outcomes. Recently, the 2018 ACC/AHA Cholesterol Guidelines endorsed the use of CAC scores in asymptomatic, intermediate risk individuals where the decision to initiate stain therapy is uncertain. However, whether quantification of CAC may play a role in the assessment of symptomatic individuals remains a matter of debate. In this review, we examine the evidence for the use of CAC in low-intermediate risk patients with chest pain. This appraisal places a particular focus on the growing body of literature supporting the negative predictive value of a CAC score of zero to rule out significant coronary artery disease in those without high-risk features. We also evaluate current guidelines, limitations, and future research directions for CAC scoring in this important subgroup of patients.

Postsystolic shortening on echocardiography as a gateway to cardiac computed tomography in patients with suspected stable angina pectoris

Postsystolic shortening (PSS) by speckle-tracking echocardiography (STE) is a marker of myocardial ischemia and may improve diagnostic strategy. We sought to evaluate if PSS is associated with the coronary artery calcium score (CACS) and stenosis by computed tomography angiography (CTA) in patients with suspected stable angina pectoris (SAP). We retrospectively studied 437 SAP patients (age 58 ± 11 years, 41% male) who underwent STE, evaluation of CACS and assessment of significant stenosis (≥ 50%) by CTA. The postsystolic index (PSI) was defined as follows: 100x([peak negative strain cardiac cycle - peak negative strain systole])/peak negative strain cardiac cycle. A wall had PSS if any segment within the wall had a PSI ≥ 20%. We defined categories for walls with PSS: 0, 1, 2 and ≥ 3, and CACS: 0, 1-100, 101-400 and > 400. Each additional wall with PSS was associated with a 43% relative increase in CACS (95%CI +9% to +87%, P = 0.010), while each 1% absolute increase in the PSI was associated with a 9% relative increase in CACS (95%CI +1% to +18%, P = 0.031). Walls with PSS (OR 1.81 per 1 wall increase, 95%CI 1.27-2.59, P = 0.001) and the PSI (OR 1.12 per 1% increase, 95%CI 1.04-1.21, P = 0.004) were associated with the occurrence of CACS > 400. Additionally, walls with PSS (OR 1.53 per 1 wall increase, 95%CI 1.21-1.93, P < 0.001) was a predictor of significant stenosis by CTA. PSS is associated with CACS and significant stenosis by CTA in patients with SAP and may aid in the selection of patients referred for cardiac computed tomography.

Current and future applications of CT coronary calcium assessment

INTRODUCTION

Computed tomographic (CT) coronary artery calcium scoring (CAC) has been validated as a well-established screening method for cardiovascular risk stratification and treatment management that is used in addition to traditional risk factors. The purpose of this review is to present an update on current and future applications of CAC. Areas covered: The topic of CAC is summarized from its introduction to current application with focus on the validation and clinical integration including cardiovascular risk prediction and outcome, cost-effectiveness, impact on downstream medical testing, and the technical advances in scanner and software technology that are shaping the future of CAC. Furthermore, this review aims to provide guidance for the appropriate clinical use of CAC. Expert commentary: CAC is a well-established screening test in preventive care that is underused in daily clinical practice. The widespread clinical implementation of CAC will be decided by future technical advances in CT image acquisition, cost-effectiveness, and reimbursement status.

Prognostic Value of Coronary Artery Calcium in the PROMISE Study (Prospective Multicenter Imaging Study for Evaluation of Chest Pain)

BACKGROUND

Coronary artery calcium (CAC) is an established predictor of future major adverse atherosclerotic cardiovascular events in asymptomatic individuals. However, limited data exist as to how CAC compares with functional testing (FT) in estimating prognosis in symptomatic patients.

METHODS

In the PROMISE trial (Prospective Multicenter Imaging Study for Evaluation of Chest Pain), patients with stable chest pain (or dyspnea) and intermediate pretest probability for obstructive coronary artery disease were randomized to FT (exercise electrocardiography, nuclear stress, or stress echocardiography) or anatomic testing. We evaluated those who underwent CAC testing as part of the anatomic evaluation (n=4209) and compared that with results of FT (n=4602). We stratified CAC and FT results as normal or mildly, moderately, or severely abnormal (for CAC: 0, 1-99 Agatston score [AS], 100-400 AS, and >400 AS, respectively; for FT: normal, mild=late positive treadmill, moderate=early positive treadmill or single-vessel ischemia, and severe=large ischemic region abnormality). The primary end point was all-cause death, myocardial infarction, or unstable angina hospitalization over a median follow-up of 26.1 months. Cox regression models were used to calculate hazard ratios (HRs) and C statistics to determine predictive and discriminatory values.

RESULTS

Overall, the distribution of normal or mildly, moderately, or severely abnormal test results was significantly different between FT and CAC (FT: normal, n=3588 [78.0%]; mild, n=432 [9.4%]; moderate, n=217 [4.7%]; severe, n=365 [7.9%]; CAC: normal, n=1457 [34.6%]; mild, n=1340 [31.8%]; moderate, n=772 [18.3%]; severe, n=640 [15.2%]; P<0.0001). Moderate and severe abnormalities in both arms robustly predicted events (moderate: CAC: HR, 3.14; 95% confidence interval, 1.81-5.44; and FT: HR, 2.65; 95% confidence interval, 1.46-4.83; severe: CAC: HR, 3.56; 95% confidence interval, 1.99-6.36; and FT: HR, 3.88; 95% confidence interval, 2.58-5.85). In the CAC arm, the majority of events (n=112 of 133, 84%) occurred in patients with any positive CAC test (score >0), whereas fewer than half of events occurred in patients with mildly, moderately, or severely abnormal FT (n=57 of 132, 43%; P<0.001). In contrast, any abnormality on FT was significantly more specific for predicting events (78.6% for FT versus 35.2% for CAC; P<0.001). Overall discriminatory ability in predicting the primary end point of mortality, nonfatal myocardial infarction, and unstable angina hospitalization was similar and fair for both CAC and FT (C statistic, 0.67 versus 0.64). Coronary computed tomographic angiography provided significantly better prognostic information compared with FT and CAC testing (C index, 0.72).

CONCLUSIONS

Among stable outpatients presenting with suspected coronary artery disease, most patients experiencing clinical events have measurable CAC at baseline, and fewer than half have any abnormalities on FT. However, an abnormal FT was more specific for cardiovascular events, leading to overall similarly modest discriminatory abilities of both tests.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01174550.

Impact of Coronary Calcification on Clinical Management in Patients With Acute Chest Pain

BACKGROUND

Coronary artery calcification (CAC) may impair diagnostic assessment of coronary computed tomography angiography (CTA). We determined whether CAC affects efficiency of coronary CTA in patients with suspected acute coronary syndrome (ACS).

METHODS AND RESULTS

This is a pooled analysis of ACRIN-PA (American College of Radiology Imaging Network-Pennsylvania) 4005 and the ROMICAT-II trial (Rule Out Myocardial Infarction/Ischemia Using Computer Assisted Tomography) comparing an initial coronary CTA strategy to standard of care in acute chest pain patients. In the CTA arms, we investigated appropriateness of downstream testing, cost, and diagnostic yield to identify patients with obstructive coronary artery disease on subsequent invasive coronary angiography across CAC score strata (Agatston score: 0, >0-10, >10-100, >100-400, >400). Out of 1234 patients (mean age 51±8.8 years), 80 (6.5%) had obstructive coronary artery disease (≥70% stenosis) and 68 (5.5%) had ACS. Prevalence of obstructive coronary artery disease (1%-64%), ACS (1%-44%), downstream testing (4%-72%), and total (2337-8484 US$) and diagnostic cost (2310-6678 US$) increased across CAC strata (P<0.001). As the increase in testing and cost were lower than the increase of ACS rate in patients with CAC>400, cost to diagnose one ACS was lowest in this group (19 283 US$ versus 464 399 US$) as compared with patients without CAC. The diagnostic yield of invasive coronary angiography was highest in patients with CAC>400 (87% versus 38%).

CONCLUSIONS

Downstream testing, total, and diagnostic cost increased with increasing CAC, but were found to be appropriate because obstructive coronary artery disease and ACS were more prevalent in patients with high CAC. In patients with acute chest pain undergoing coronary CTA, cost-efficient testing and excellent diagnostic yield can be achieved even with high CAC burden.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifiers: NCT01084239 and NCT00933400.

Diagnostic Value of the Updated Diamond and Forrester Score to Predict Coronary Artery Disease in Patients with Acute-Onset Chest Pain

OBJECTIVES

In the recently updated clinical guidelines from the European Society of Cardiology on the management of stable coronary artery disease (CAD), the updated Diamond Forrester score has been included as a pretest probability (PTP) score to select patients for further diagnostic testing. We investigated the validity of the new guidelines in a population of patients with acute-onset chest pain.

METHODS

We examined 527 consecutive patients with either an exercise-ECG stress test or single-photon emission computed tomography, and subsequently coronary computed tomography angiography (CCTA). We compared the diagnostic accuracy of PTP and stress testing assessed by the area under the receiver operating characteristic curve (AUC) to identify significant CAD, defined as at least 1 coronary artery branch with >70% diameter stenosis identified by CCTA.

RESULTS

The diagnostic accuracy of PTP was significantly higher than the stress test (AUC 0.80 vs. 0.69; p = 0.009), but the diagnostic accuracy of the combination of PTP and a stress test did not significantly increase when compared to PTP alone (AUC 0.86 vs. 0.80; p = 0.06).

CONCLUSIONS

PTP using the updated Diamond and Forrester Score is a very useful tool in risk-stratifying patients with acute-onset chest pain at a low-to-intermediate risk of having CAD. Adding a stress test to PTP does not appear to offer significant diagnostic benefit.

Low high-sensitivity troponin I and zero coronary artery calcium score identifies coronary CT angiography candidates in whom further testing could be avoided

RATIONALE AND OBJECTIVES

Pilot study to determine whether among subjects receiving coronary computed tomography angiography (CTA), the combination of high-sensitivity troponin I (hsTnI) and coronary artery calcium score (CACS) identifies a low-risk population in whom CTA might be avoided.

MATERIALS AND METHODS

A cross-sectional study of 314 symptomatic patients receiving CTA as part of their acute coronary syndrome evaluation was conducted. hsTnI was measured with Abbott Laboratories' hsTnI assay. CACSs were calculated via the Agatston method. Patients were followed for at least 30 days after discharge for the occurrence of major adverse cardiac events (MACEs; all-cause mortality, acute coronary syndrome, and revascularization).

RESULTS

Of 314 subjects studied, 213 (67.8%) had no coronary artery stenosis, and 67 (21.3%), 28 (8.9%), and 6 (1.9%) had maximal coronary artery stenosis of 1%-49%, 50%-69%, and 70% or greater, respectively. All MACEs occurred during index hospitalization and include one myocardial infarction and four revascularizations. Sixty-two percent (189/307) of subjects had zero CACS, and 24% (76/314) of subjects had undetected hsTnI. No subjects with undetectable hsTnI or zero CACS had an MACE. A strategy of avoiding further testing in subjects with undetectable initial hsTnI, performing CACS on subjects with detectable initial hsTnI but nonincreased hsTnI (less than 99th percentile), and obtaining CTA in subjects with Agatston greater than 0 will have a negative predictive value of 100.0% (95% confidence interval, 98.2%-100.0%). This strategy will avoid CTA in 63% (198/314) of subjects.

CONCLUSIONS

In this pilot study, the addition of CACS to hsTnI improves the identification of low-risk subjects in whom CTA might be avoided.

Use of coronary artery calcium scanning beyond coronary computed tomographic angiography in the emergency department evaluation for acute chest pain: the ROMICAT II trial

BACKGROUND

Whether a coronary artery calcium (CAC) scan provides added value to coronary computed tomographic angiography (CCTA) in emergency department patients with acute chest pain remains unsettled. We sought to determine the value of CAC scan in patients with acute chest pain undergoing CCTA.

METHODS AND RESULTS

In the multicenter Rule Out Myocardial Infarction using Computer-Assisted Tomography (ROMICAT) II trial, we enrolled low-intermediate risk emergency department patients with symptoms suggesting acute coronary syndrome (ACS). In this prespecified subanalysis of 473 patients (54±8 years, 53% men) who underwent both CAC scanning and CCTA, the ACS rate was 8%. Overall, 53% of patients had CAC=0 of whom 2 (0.8%) developed ACS, whereas 7% had CAC>400 with 49% whom developed ACS. C-statistic of CAC>0 was 0.76, whereas that using the optimal cut point of CAC≥22 was 0.81. Continuous CAC score had lower discriminatory capacity than CCTA (c-statistic, 0.86 versus 0.92; P=0.03). Compared with CCTA alone, there was no benefit combining CAC score with CCTA (c-statistic, 0.93; P=0.88) or with selective CCTA strategies after initial CAC>0 or optimal cut point CAC≥22 (P≥0.09). Mean radiation dose from CAC acquisition was 1.4±0.7 mSv. Higher CAC scores resulted in more nondiagnostic CCTA studies although the majority remained interpretable.

CONCLUSIONS

In emergency department patients with acute chest pain, CAC score does not provide incremental value beyond CCTA for ACS diagnosis. CAC=0 does not exclude ACS, nor a high CAC score preclude interpretation of CCTA in most patients. Thus, CAC results should not influence the decision to proceed with CCTA, and the decision to perform a CAC scan should be balanced with the additional radiation exposure required.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01084239.

Association Between Hematological Indices and Coronary Calcification in Symptomatic Patients without History of Coronary Artery Disease

Background:

Atherosclerotic coronary artery disease (CAD) has long been shown to involve chronic low-grade subclinical inflammation. However, whether there is association between hematological indices assessed by complete blood count (CBC) and coronary atherosclerotic burden has not been well studied.

Materials and Methods:

Consecutive 868 patients without known CAD who presented with acute chest pain to emergency department and underwent coronary artery calcium (CAC) scoring evaluation by multi-detector cardiac computed tomography were included in our study. Clinical characteristics and CBC indices were compared among different CAC groups.

Results:

The cohort comprised 60% male with a mean age of 61 (SD = 14) years. Median Framingham risk of CAD was 4% (range 1-16%). Median CAC score was 0 (IQR 0-43). Higher CAC groups had significantly higher Framingham risk of CAD than lower CAC groups (P < 0.001). Among different CAC categories, there was no statistically significant difference in hemoglobin level (p 0.45), mean corpuscular volume (p 0.43), mean corpuscular hemoglobin (p 0.28), mean corpuscular hemoglobin volume (p 0.36), red cell distribution width (0.42), total white blood cell counts (p 0.291), neutrophil counts (p 0.352), lymphocyte counts (p 0.92), neutrophil to lymphocyte ratio (p 0.68), monocyte count (p 0.48), and platelet counts (p 0.25).

Conclusion:

Our study did not detect significant association between hematological indices assessed with CBC and coronary calcification in symptomatic patients without known CAD.

Role of computed tomography for diagnosis and risk stratification of patients with suspected or known coronary artery disease

Cardiac computed tomographic angiography (CCTA) has emerged as a powerful imaging modality for the detection and prognostication of individuals with suspected coronary artery disease. Because calcification of coronary plaque occurs in proportion to the total atheroma volume, the initial diagnostic potential of CCTA focused on the identification and quantification of coronary calcium in low- to intermediate-risk individuals, a finding that tracks precisely with the risk of incident adverse clinical events. Beyond noncontrast detection of coronary calcium, CCTA using iodinated contrast yields incremental information about the degree and distribution of coronary plaques and stenosis, as well as vessel wall morphology and atherosclerotic plaque features. This additive information offers the promise of CCTA to provide a more comprehensive view of total atherosclerotic burden because it relates to myocardial ischemia and future adverse clinical events. Furthermore, emerging data suggest the prognostic and diagnostic importance of stenosis severity detection and atherosclerotic plaque features described by CCTA including positive remodeling, low-attenuation plaque, and spotty calcification, which have been associated with the vulnerability of plaque. We report a summary of the evidence supporting the role of CCTA in the detection of subclinical and clinical coronary artery disease in both asymptomatic and symptomatic patients and discuss the potential of CCTA to augment the identification of at-risk individuals. CCTA and coronary artery calcium scoring offer the ability to improve risk stratification, discrimination, and reclassification of the risk in patients with suspected coronary artery disease and to noninvasively determine the measures of stenosis severity and atherosclerotic plaque features.

Distribution of coronary calcifications in patients with suspected coronary heart disease

BACKGROUND

Coronary calcifications are a marker of coronary atherosclerosis. The role of coronary calcium scoring (CS) as part of the initial evaluation of patients with suspected coronary heart disease (CHD) is controversially discussed. The primary goal of this study was to characterize the coronary calcium distribution in this particular patient population. In a second step, we aimed to establish a possible clinical implication using CS for the diagnosis of CHD.

METHODS

Calcium scoring procedure was performed by either using a multidetector or a dual-source computed tomographic scanner. All patients underwent invasive coronary angiography (ICA) as the current criterion standard for CHD detection. A total of 4,137 (2,780 men, mean age 60.5 ± 12.4 years) consecutive patients were included.

RESULTS

Mean CS was 288 ± 446 (range 0-5,252). Overall coronary artery calcifications significantly increased with patients' age. In 2,048 patients (mean CS 101 ± 239, range 0-5252), significant CHD (≥50% stenosis) was excluded by ICA (1,939 patients without calcifications). In remaining 2,089 patients (51%, mean CS 607 ± 821, range 0-5,252), significant CHD was documented leading to intervention in 732 patients. A threshold of zero calcifications (existence of calcified tissue) had the best overall sensitivity and negative predictive value with 99%. Overall specificity with 34% and overall positive predictive value with 24% were rather low.

CONCLUSION

Coronary calcium scoring is able to exclude significant CHD in patients with suspected CHD with a high negative predictive value and, therefore, possibly reduce the number of invasive diagnostic examinations. Because of the low specificity and positive predictive value, CS cannot be used to indicate ICA.

Atherosclerosis burden in patients with acute chest pain: obesity paradox

Obesity paradox has been described in various populations of coronary artery disease, mainly asymptomatic subjects. However, relationship between obesity and coronary artery calcification detected by cardiac CT in symptomatic patients has rarely been demonstrated. This study seeks to investigate whether the paradoxical relationship between obesity and coronary artery calcification exists in patients with acute chest pain. A final cohort of 1030 chest pain patients presenting at our emergency department who underwent coronary evaluation by multidetector cardiac CT were examined. With absent-to-mild coronary calcification (CAC score < 100) as a referent, multivariable analysis showed that presence of obesity (OR 0.564; 95% CI 0.395, 0.806; P 0.002), body mass index (OR 0.945; 95% CI 0.920, 0.971; P < 0.001), body weight (OR 0.987; 95% CI 0.979, 0.995; P 0.001), and body surface area (OR 0.582; 95% CI 0.369, 0.920; P 0.020) were inversely associated with moderate-to-severe coronary calcification (CAC score ≥ 100). This study extends the concept of obesity paradox to symptomatic patients undergoing coronary artery calcium score assessment. However, biological explanation(s) of this paradox remains unanswered.

Multicenter, Randomized Trial of Quantitative Pretest Probability to Reduce Unnecessary Medical Radiation Exposure in Emergency Department Patients With Chest Pain and Dyspnea

Background—

Use of pretest probability can reduce unnecessary testing. We hypothesize that quantitative pretest probability, linked to evidence-based management strategies, can reduce unnecessary radiation exposure and cost in low-risk patients with symptoms suggestive of acute coronary syndrome and pulmonary embolism.

Methods and Results—

This was a prospective, 4-center, randomized controlled trial of decision support effectiveness. Subjects were adults with chest pain and dyspnea, nondiagnostic ECGs, and no obvious diagnosis. The clinician provided data needed to compute pretest probabilities from a Web-based system. Clinicians randomized to the intervention group received the pretest probability estimates for both acute coronary syndrome and pulmonary embolism and suggested clinical actions designed to lower radiation exposure and cost. The control group received nothing. Patients were followed for 90 days. The primary outcome and sample size of 550 was predicated on a significant reduction in the proportion of healthy patients exposed to >5 mSv chest radiation. A total of 550 patients were randomized, and 541 had complete data. The proportion with >5 mSv to the chest and no significant cardiopulmonary diagnosis within 90 days was reduced from 33% to 25% ( P =0.038). The intervention group had significantly lower median chest radiation exposure (0.06 versus 0.34 mSv; P =0.037, Mann–Whitney U test) and lower median costs ($934 versus $1275; P =0.018) for medical care. Adverse events occurred in 16% of controls and 11% in the intervention group ( P =0.06).

Conclusions—

Provision of pretest probability and prescriptive advice reduced radiation exposure and cost of care in low-risk ambulatory patients with symptoms of acute coronary syndrome and pulmonary embolism.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01059500.

Evaluation and outcomes of patients admitted to a tertiary medical assessment unit with acute chest pain of possible coronary origin

OBJECTIVES

The study aims to (i) profile clinical characteristics, risk estimates of acute coronary syndrome (ACS), use and yield of non-invasive cardiac testing, discharge diagnosis and 30-day outcomes among patients admitted with acute chest pain of possible coronary origin; and (ii) construct a risk stratification algorithm that informs management decisions.

METHODS

This is a retrospective cohort study of 130 consecutive patients admitted to a tertiary hospital medical assessment unit between 24 January and 22 March 2012. Estimates of ACS risk were based on Australian guidelines and Thrombolysis in Myocardial Infarction (TIMI) scores.

RESULTS

Patients were of mean age 61 years, 45% had known coronary artery disease (CAD), 58% presented with typical ischaemic pain, 82% had intermediate to high ACS risk and 61% underwent testing. Myocardial ischaemia was cardiologist-confirmed discharge diagnosis in 29% of patients, and was associated with known CAD, typical pain, multiple risk factors and high TIMI risk scores (P < 0.001 for all associations). Of 98 non-invasive investigations, 9% (95% CI, 5-17%) were positive for myocardial ischaemia. Major adverse event rate at 30 days was 0.8% (95% CI, <0.1-6%). An algorithm was constructed that integrates known CAD, ACS risk and TIMI scores in identifying low-risk patients capable of rapid discharge from EDs without further investigation, and classifying the remainder into risk groups that informs choice of investigations and need for telemetry.

CONCLUSIONS

In patients with indeterminate chest pain, clinical features and risk scores identify most with myocardial ischaemia. An algorithm is presented that might inform triaging, early discharge, choice of testing and need for telemetry.

Role of imaging for acute chest pain syndromes

Acute chest pain suggestive of ischemic cardiac origin, with a normal or nondiagnostic electrocardiogram and negative initial cardiac markers for myocardial necrosis represent a significant diagnostic dilemma for clinicians. Multiple imaging modalities play a pivotal role in early diagnosis and safe discharge of these patients. In this review, we compare the current imaging modalities available for these patients including their diagnostic accuracy, feasibility, and cost effectiveness. Acute rest myocardial perfusion imaging significantly improves the clinical outcome in these patients and reduces the overall cost when incorporated into the decision making pathway. The choice of imaging modality recommended should be based on local institutional expertise and the overall clinical presentation. The imaging modality with high diagnostic accuracy and negative predictive value will provide for precise risk stratification which is important to clinical decision making, including patients who require admission to the hospital and those who can be safely discharged.

Coronary calcium: new insights, recent data, and clinical role

Calcium artery calcium (CAC) scoring has become an integral part in the era of preventive cardiology, it has been extensively studied and been validated as a powerful tool for cardiovascular risk assessment in conjunction with other traditional well established scoring systems such as Framingham risk score. In addition, CAC testing has found its way into emergency department algorithms assessing low to intermediate risk patients presenting with chest pain, this strategy was recently adopted by the UK NICE guidelines, confidently ruling out cardiac origin of chest pain. Several studies have demonstrated that risk assessment using CAC was motivational to patients leading to better adherence to their preventive practices as well as to medications. Accordingly, this test has several recommendations for use by national and international guidelines.

Coronary Artery Calcium Testing in Symptomatic Patients: An Issue of Diagnostic Efficiency

The detection and quantification of coronary artery calcification (CAC) significantly improves cardiovascular risk prediction in asymptomatic patients. Many have advocated for expanded CAC testing in symptomatic patients based on data demonstrating that the absence of quantifiable CAC in patients with possible angina makes obstructive coronary artery disease (CAD) and subsequent adverse events highly unlikely. However, the widespread use of CAC testing in symptomatic patients may be limited by the high background prevalence of CAC and its low specificity for obstructive CAD, necessitating additional testing ('test layering') in a large percentage of eligible patients. Further, adequately powered prospective studies validating the comparative effectiveness of a 'CAC first' approach with regards to cost, safety, accuracy and clinical outcomes are lacking. Due to marked reductions in patient radiation exposure and higher comparative accuracy and prognostic value make coronary computed tomographic angiography the preferred CT-based test for appropriately selected symptomatic patients.

What is the role of calcium scoring in the age of coronary computed tomographic angiography?

Non-contrast-enhanced CT for coronary artery calcification (CAC) as a marker of coronary atherosclerosis has been studied extensively in the primary prevention setting. With rapidly evolving multidetector CT technology, contrast-enhanced coronary CT angiography (CCTA) has emerged as the non-invasive method of choice for detailed imaging of the coronary tree. In this review, we systematically evaluate the role of CAC testing in the age of CCTA in both asymptomatic and symptomatic patients, across varying levels of risk. Although the role of CAC testing is well established in asymptomatic subjects, its use in evaluating those with stable symptoms that represent possible obstructive coronary artery disease is controversial. Nevertheless, available data suggest that in low-to-intermediate risk symptomatic patients, CAC scanning may serve as an appropriate gatekeeper to further testing with either CCTA (if no or only mild CAC present) versus functional imaging or invasive coronary angiography (when moderate or severe CAC present). Given the strong short-term prognostic value of CAC = 0, studies are needed to further evaluate the role of CAC scanning in low-risk patients with acute chest pain presenting to the emergency room.

Role of nonenhanced multidetector CT coronary artery calcium testing in asymptomatic and symptomatic individuals

Arteriosclerotic cardiovascular disease is the leading cause of death in the United States, with coronary artery disease (CAD) accounting for half of all cardiovascular disease deaths. Current risk assessment approaches for coronary heart disease, such as the Framingham risk score, substantially misclassify intermediate- to long-term risk for the occurrence of CAD in asymptomatic individuals. A screening modality such as a simple non-contrast-enhanced, or noncontrast, computed tomographic (CT) detection of coronary artery calcium (CAC) improves the ability to accurately predict risk in vulnerable groups and adds information above and beyond global risk assessment as shown by the recent Multi-Ethnic Study of Atherosclerosis. In addition, absence of CAC is associated with a very low risk of future CAD and as a result can be used to identify a group among which further testing and pharmacotherapies can be avoided. The Expert Consensus Document by the American College of Cardiology Foundation and the American Heart Association now recommends screening individuals at intermediate risk but did not find enough evidence to recommend CAC testing and further stratification of those in the low- or high-risk categories for CAD. In addition, emerging guidelines have suggested that absence of CAC can act as a "gatekeeper" for further testing among low- and intermediate-risk patients presenting with chest pain. This review of the current literature outlines the role of CAC testing in both asymptomatic and symptomatic individuals.

Utility of coronary artery calcium scoring in the evaluation of patients with chest pain

Although coronary artery calcium (CAC) scoring has an established role in risk-stratifying asymptomatic patients at intermediate risk of coronary heart disease (CHD), its utility in the evaluation of patients with chest pain is uncertain. We conducted a literature review of articles investigating the utility of: (1) CAC scoring in elective patients with indeterminate chest pain symptoms, (2) CAC as a "gatekeeper" in the triage of patients presenting to the emergency department (ED) with chest pain, and (3) the cost-effectiveness of the use of CAC scoring in the ED. We also evaluated the predictive accuracy of the absence of CAC in a pooled analysis of applicable studies. Only studies evaluating patients classified as low or intermediate risk were included. Low to intermediate risk was established by Framingham risk scores, Thrombolysis in Myocardial Infarction scores, Diamond-Forrester classification, or by the absence of typical angina symptoms, ischemic electrocardiogram, positive cardiac biomarkers, or a prior history of CHD. In our pooled analysis, the presence of any CAC resulted in a high sensitivity (range 70%-100%) for predicting the presence of obstructive coronary disease among symptomatic patients subsequently referred for coronary angiography. More importantly, a CAC score of 0 in low- and intermediate-risk ED populations with chest pain had a high negative predictive value (99.4%) for CHD events over an average follow-up of 21 months. CAC scoring also seems cost-effective in this population. Although further research is needed, carefully selected ED patients with a normal electrocardiogram, normal cardiac biomarkers, and CAC = 0 may be considered for early discharge without further testing.

Cholesteryl esters associated with acyl-CoA:cholesterol acyltransferase predict coronary artery disease in patients with symptoms of acute coronary syndrome

OBJECTIVES

Identifying the likelihood of a patient having coronary artery disease (CAD) at the time of emergency department (ED) presentation with chest pain could reduce the need for stress testing or coronary imaging after myocardial infarction (MI) has been excluded. The authors aimed to determine if a novel cardiac biomarker consisting of plasma cholesteryl ester (CE) levels typically derived from the activity of the enzyme acyl-CoA:cholesterol acyltransferase (ACAT2) are predictive of CAD in a clinical model.

METHODS

A single-center prospective cohort design enrolled participants with symptoms of acute coronary syndrome (ACS) undergoing coronary computed tomography angiography (CCTA) or invasive angiography. Plasma samples were analyzed for CE composition with mass spectrometry. The primary endpoint was any CAD determined at angiography. Multivariable logistic regression analyses were used to estimate the relationship between the sum of the plasma concentrations from cholesteryl palmitoleate (16:1) and cholesteryl oleate (18:1) (defined as ACAT2-CE) and the presence of CAD. The added value of ACAT2-CE to the model was analyzed comparing the C-statistics and integrated discrimination improvement (IDI).

RESULTS

The study cohort was composed of 113 participants with a mean (± standard deviation [SD]) age of 49 (±11.7) years, 59% had CAD at angiography, and 23% had an MI within 30 days. The median (interquartile range [IQR]) plasma concentration of ACAT2-CE was 938 μmol/L (IQR = 758 to 1,099 μmol/L) in patients with CAD and 824 μmol/L (IQR = 683 to 998 μmol/L) in patients without CAD (p = 0.03). When considered with age, sex, and the number of conventional CAD risk factors, ACAT2-CE levels were associated with a 6.5% increased odds of having CAD per 10 μmol/L increase in concentration. The addition of ACAT2-CE significantly improved the C-statistic (0.89 vs. 0.95, p = 0.0035) and IDI (0.15, p < 0.001) compared to the reduced model. In the subgroup of low-risk observation unit patients, the CE model had superior discrimination compared to the Diamond-Forrester classification (IDI = 0.403, p < 0.001).

CONCLUSIONS

Plasma levels of ACAT2-CE have strong potential to predict a patient's likelihood of having CAD when considered in a clinical model but not when used alone. In turn, a clinical model containing ACAT2-CE could reduce the need for cardiac imaging after the exclusion of MI.

Coronary CT and the coronary calcium score, the future of ED risk stratification?

Accurate and efficient evaluation of acute chest pain remains clinically challenging because traditional diagnostic modalities have many limitations. Recent improvement in non-invasive imaging technologies could potentially improve both diagnostic efficiency and clinical outcomes of patients with acute chest pain while reducing unnecessary hospitalizations. However, there is still controversy regarding much of the evidence for these technologies. This article reviews the role of coronary artery calcium score and the coronary computed tomography in the assessment of individual coronary risk and their usefulness in the emergency department in facilitating appropriate disposition decisions. The evidence base and clinical applications for both techniques are also described, together with cost- effectiveness and radiation exposure considerations.

Does coronary artery calcium scoring add to the predictive value of coronary computed tomography angiography for adverse cardiovascular events in low-risk chest pain patients?

OBJECTIVES

Coronary angiography calcium score (CACS) is included for patients who receive coronary computed tomography angiography (CTA) as part of diagnostic testing for low-risk chest pain. Both tests add radiation exposure, and it is unclear whether the combination provides more information than either test alone. The objective was to asses if CACS = 0 determines freedom from coronary artery disease (CAD) and whether the addition of CACS to coronary CT angiography provides additional risk stratification information or helps predict 30-day cardiovascular outcomes.

METHODS

This was a secondary analysis of a prospective cohort study at an urban university hospital emergency department (ED), of patients with symptoms suggestive of potential acute coronary syndrome (ACS) and low Thrombolysis in Myocardial Infarction (TIMI) risk scores who received coronary CTA. Data collected included demographics and medical history. The main outcome was CAD, defined as the presence of a maximal stenosis >50% on coronary CTA, stratified by CACS results. The secondary outcome was cardiovascular events including death, myocardial infarction, or revascularization at 30 days. Data were analyzed with standard descriptive techniques and relative risks (RR) with 95% confidence intervals (CIs).

RESULTS

A total of 1,049 patients were enrolled (median age = 48.1 years; interquartile range [IQR] = 42.4 to 53.3 years); 55% were female, and 63% were black or African American. Of these, 17 of 795 (2.1%) with CACS of 0 had CAD, 16 of 169 patients (9.5%) with CACS of 0.1 to 99 had CAD, 53.3% (32 of 60) with CACS between 100 and 399 had CAD, and 10 of 23 (43.5%) with CACS ≥ 400 had CAD. There was a higher likelihood of significant CAD with increased CACS. Patients who had a calcium score of 0 but still had CAD were more likely to be young (50 years old or less; RR = 1.73, 95% CI = 1.01 to 2.96). For the secondary outcome, there were 15 cardiovascular events within 30 days: one patient with CACS = 0 and no CAD (1 of 733; 0.1%), one patient with CACS > 0 and no CAD (1 of 182; 0.5%), four patients with CACS = 0 and CAD (4 of 17; 23.5%), and nine patients with CACS > 0 and CAD (9 of 58; 15.5%), with a net reclassification index of -0.001 (p = 0.32).

CONCLUSIONS

In the study sample, elevated CACS was associated with a higher likelihood of underlying CAD on coronary CTA, but the addition of CACS to coronary CTA did not help predict 30-day cardiovascular events.

Immediate computed tomography coronary angiography versus delayed outpatient stress testing for detecting coronary artery disease in emergency department patients with chest pain

Noninvasive testing for coronary artery disease (CAD) is warranted for symptomatic patients with intermediate pretest likelihood of CAD. Accomplishing testing in an emergency department (ED) environment is challenging. We compared two strategies of CAD testing in ED patients: immediate computed tomography coronary angiography (CTCA) versus delayed outpatient stress testing. We conducted a historical control cohort study comparing symptomatic ED patients without an acute coronary syndrome who warranted noninvasive CAD testing. Two cohorts (50 patients each) were defined by CAD testing strategy, immediate CTCA versus delayed stress testing. Outcomes were duration of ED stay, detection of CAD, and 3-month rates of readmission, myocardial infarction, (MI) or death. Median duration of stay was 417.5 minutes (interquartile range [IQR] 359.0-581.0) in the CT cohort and 400.0 minutes (IQR 338.0-471.0) in the control cohort (P = 0.53). CAD was detected in 14 CT cohort patients versus 1 in control (P = 0.0004), due to low follow-up in the control cohort (18 of 50, 36%). Obstructive CAD was diagnosed in 6 CT cohort patients versus 1 in control (P = 0.11). During 3 months of follow-up, four patients in each cohort were reevaluated in the ED for chest pain; no patients suffered MI or death. A strategy of immediate CTCA is superior to a delayed stress testing strategy for detecting CAD in ED patients with chest pain and prompting appropriate referrals for further management. Delayed stress testing was primarily ineffective due to low follow-up. Immediate CTCA can be used safely without altering the ED duration of stay.