Prior restraint: a Bayesian perspective on the optimization of technology utilization for diagnosis of coronary artery disease

Efficacy of Coronary Computed Tomography Angiography Versus Nuclear Perfusion Stress in Preventing Downstream Imaging and Prolonged Inpatient Length of Stay in Low to Medium Risk Patients With Chest Pain

Background 

The first-line imaging for low to medium-risk patients presenting to the emergency department with stable chest pain is often a matter of debate. Chest pain is the second most common presentation to the emergency department. Non-invasive imaging has been useful in assisting in the diagnosis of coronary artery disease. 

Aim 

The aim of this study is to compare outcomes of Single Photon Emission Computed Tomography (SPECT) Nuclear Perfusion Stress and Coronary Computed Tomography Angiography (CCTA) performed in low to medium-risk patients and how they led to prolonged hospitalization and downstream testing.

Materials and methods

A total of 519 patients were selected for chart review using the following criteria: admitted for chest pain and older than 18 years of age. Those who presented with STEMI (ST-Elevation Myocardial Infarction) or non-(N)STEMI were excluded. Among these patients, four patients were excluded since their initial test was neither a CCTA nor SPECT Nuclear (NM) Perfusion Stress test. Another 30 patients were excluded based on HEART score (a clinical tool to stratify the risk of major adverse cardiac events) >7 and 111 patients with estimated glomerular filtration rate (eGFR) <60 were excluded. A total of 374 patients underwent analysis.

Results

Univariate data analysis of 374 patients demonstrated a higher percentage of patients with HEART scores 0-3 underwent CCTA (51.6% vs. 31.8% p=0.0250) when compared to patients with SPECT NM perfusion. Multivariable logistic regression revealed that the difference in length of stay between SPECT NM perfusion stress and CCTA was significant, patients with the CCTA test were less likely to have a length of stay ≥24 hours (odds ratio {OR}=0.41, p=0.0465) compared to patients with NM perfusion stress test.

Conclusion

This retrospective cohort study demonstrated that patients who underwent CCTA upon chest pain admission were more likely to have a decreased length of stay time to less than 24 hours. 

Diagnosis of obstructive coronary artery disease using computed tomography angiography in patients with stable chest pain depending on clinical probability and in clinically important subgroups: meta-analysis of individual patient data

OBJECTIVE

To determine whether coronary computed tomography angiography (CTA) should be performed in patients with any clinical probability of coronary artery disease (CAD), and whether the diagnostic performance differs between subgroups of patients.

DESIGN

Prospectively designed meta-analysis of individual patient data from prospective diagnostic accuracy studies.

DATA SOURCES

Medline, Embase, and Web of Science for published studies. Unpublished studies were identified via direct contact with participating investigators.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Prospective diagnostic accuracy studies that compared coronary CTA with coronary angiography as the reference standard, using at least a 50% diameter reduction as a cutoff value for obstructive CAD. All patients needed to have a clinical indication for coronary angiography due to suspected CAD, and both tests had to be performed in all patients. Results had to be provided using 2×2 or 3×2 cross tabulations for the comparison of CTA with coronary angiography. Primary outcomes were the positive and negative predictive values of CTA as a function of clinical pretest probability of obstructive CAD, analysed by a generalised linear mixed model; calculations were performed including and excluding non-diagnostic CTA results. The no-treat/treat threshold model was used to determine the range of appropriate pretest probabilities for CTA. The threshold model was based on obtained post-test probabilities of less than 15% in case of negative CTA and above 50% in case of positive CTA. Sex, angina pectoris type, age, and number of computed tomography detector rows were used as clinical variables to analyse the diagnostic performance in relevant subgroups.

RESULTS

Individual patient data from 5332 patients from 65 prospective diagnostic accuracy studies were retrieved. For a pretest probability range of 7-67%, the treat threshold of more than 50% and the no-treat threshold of less than 15% post-test probability were obtained using CTA. At a pretest probability of 7%, the positive predictive value of CTA was 50.9% (95% confidence interval 43.3% to 57.7%) and the negative predictive value of CTA was 97.8% (96.4% to 98.7%); corresponding values at a pretest probability of 67% were 82.7% (78.3% to 86.2%) and 85.0% (80.2% to 88.9%), respectively. The overall sensitivity of CTA was 95.2% (92.6% to 96.9%) and the specificity was 79.2% (74.9% to 82.9%). CTA using more than 64 detector rows was associated with a higher empirical sensitivity than CTA using up to 64 rows (93.4% v 86.5%, P=0.002) and specificity (84.4% v 72.6%, P<0.001). The area under the receiver-operating-characteristic curve for CTA was 0.897 (0.889 to 0.906), and the diagnostic performance of CTA was slightly lower in women than in with men (area under the curve 0.874 (0.858 to 0.890) v 0.907 (0.897 to 0.916), P<0.001). The diagnostic performance of CTA was slightly lower in patients older than 75 (0.864 (0.834 to 0.894), P=0.018 v all other age groups) and was not significantly influenced by angina pectoris type (typical angina 0.895 (0.873 to 0.917), atypical angina 0.898 (0.884 to 0.913), non-anginal chest pain 0.884 (0.870 to 0.899), other chest discomfort 0.915 (0.897 to 0.934)).

CONCLUSIONS

In a no-treat/treat threshold model, the diagnosis of obstructive CAD using coronary CTA in patients with stable chest pain was most accurate when the clinical pretest probability was between 7% and 67%. Performance of CTA was not influenced by the angina pectoris type and was slightly higher in men and lower in older patients.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42012002780.

Korean guidelines for the appropriate use of cardiac CT

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.

Obese sedentary patients with dyspnoea on exertion who are at low risk for coronary artery disease by clinical criteria have a very low prevalence of coronary artery disease

Dyspnoea, a much less specific symptom of ischaemia than chest discomfort, is common among obese patients. Patients with dyspnoea often undergo stress testing as part of their evaluation. We sought to examine the yield of stress testing in non-elderly, obese, sedentary patients with dyspnoea on exertion (DOE) as a chief complaint.We reviewed stress echocardiograms carried out on 203 patients in a stress testing laboratory at a major tertiary care centre. Of these, 81 (40%) fell into a group that was at low risk for coronary artery disease (CAD) by clinical criteria. Ischaemia was detected in two patients in the low-risk group (2.5%), and these results were likely false positives. In the higher risk group, 9.0% of functional tests showed ischaemia; after further testing, 2.5% of the higher risk patients were found to have obstructive coronary lesions. Clinical follow-up was performed for a mean of 815 days. New obstructive coronary disease was detected in 1.6% of all patients, and these patients were from the higher risk group. In obese sedentary patients with DOE but otherwise at low risk of coronary disease stress testing is of very low yield. DOE is generally not an anginal equivalent in this patient population.

Multi-marker strategies in heart failure: clinical and statistical approaches

Advances in genomics and proteomics promise to transform biomarker research, in which the major challenges will not be the discovery of new markers but rather the optimal selection and validation of a subgroup of clinically useful markers from the large pool of candidates. Critically, the value of new biomarkers panels will need to be assessed in the context of readily available clinical information in order to create more actionable knowledge rather than just greater complexity. Appropriate methodologies for the clinical and statistical evaluation of so called "multi-marker strategies" have not been systematically defined. Although specific criteria for the appropriate clinical and statistical evaluation of multi-marker strategies will vary based on the intended use (e.g., diagnosis vs. screening), the ultimate measure of success is the ability for a biomarker panel to both correct a meaningful portion of misclassification by standard methods (discrimination) and to improve quantification of absolute risk (calibration) in comparison to existing clinical information. Findings should be validated in an independent dataset of the representative patient population before a given multi-marker strategy can be considered for clinical use. Here, we define multi-marker strategies, summarize recent examples of biomarker combinations in heart failure, address key statistical and clinical issues, and discuss future directions for this rapidly evolving field.

Use of multiple biomarkers in heart failure

Biomarkers are becoming increasingly available for clinical use, particularly in the care of patients with heart failure. For health care providers, a major difficulty is how to interpret and apply these increasing amounts of diagnostic and prognostic information. Consequently, the scientific challenge is evolving from the discovery of biomarkers to the selection and validation of select panels of clinically useful markers that balance performance and practicality. Optimal combinations of biomarkers will vary based on the intended use (eg, diagnosis vs prognosis). The final goal must be to generate more actionable knowledge that improves patient management and outcomes, rather than merely creating greater complexity. Here we conceptually define multiple biomarker strategies, provide examples of emerging biomarker panels used in the care of patients with heart failure, and address key statistical and clinical issues for this rapidly evolving field.

Comparison of the atherosclerotic burden among asymptomatic patients vs matched volunteers

BACKGROUND

While asymptomatic patients should have a lower risk of cardiac events compared to symptomatic patients referred for cardiac stress testing, comparable event rates have been noted in some prior prognostic studies. To test if a high burden of undetected atherosclerosis among asymptomatic patients helps explain such findings, we compared atherosclerotic burden, as measured by coronary artery calcium (CAC) scanning, in propensity-matched groups of volunteers and asymptomatic patients.

METHODS

CAC scans were performed on a research basis in 136 asymptomatic patients referred for exercise myocardial perfusion SPECT and in 1,398 volunteers. We performed matching by propensity scores to compare volunteers with the same CAD risk factor profile as our asymptomatic patients.

RESULTS

Among our matched groups, asymptomatic patients had significantly greater mean CAC scores than volunteers (394 ± 805 vs 151 ± 349, P = .001), primarily due to a higher frequency of CAC scores >1,000 (15.4% vs 2.5%, P < .001). Inducible myocardial ischemia by SPECT was present in 7% of patients, but was selectively concentrated among those with CAC scores >1,000, occurring in 27.0% of such patients vs only 1.9% among patients with CAC scores <1,000 (P < .0001).

CONCLUSIONS

In contrast to asymptomatic volunteers, asymptomatic patients referred for cardiac stress testing possess more extensive atherosclerosis as measured by CAC. Among asymptomatic patients with high CAC scores, the frequency of concomitant inducible myocardial ischemia is high. These results help explain prior prognostic studies concerning asymptomatic patients and indicate the importance of making a clinical distinction between healthy subjects and asymptomatic patients with respect to atherosclerotic risk.

Women with high exercise tolerance and the role of myocardial perfusion imaging

BACKGROUND

Myocardial perfusion imaging (MPI) provides incremental diagnostic and prognostic information, even in patients with high exercise tolerance.

HYPOTHESIS

Myocardial perfusion imaging provides significant diagnostic value, specifically in women with high exercise tolerance.

METHODS

Our study population consisted of all women who underwent exercise MPI in our Department from January 1992 to June 1996 and reached at least Stage IV in the Bruce protocol. Patients were divided into those with known and those with possible coronary artery disease (CAD). All patients were followed for 3 years from the performance of MPI.

RESULTS

Of 4,803 women who underwent myocardial perfusion imaging, 3,183 had exercise stressing, and of those, 311 reached at least Stage IV in the Bruce protocol. Of these 311 MPI scans, only 23 (7.4%) were abnormal (reversible, fixed, or mixed) and the remaining 288 (92.6%) were normal. Of the 82 patients with known CAD, 13 (15.8%) had an abnormal MPI, while only 10 (4.4%) of the 229 patients with possible CAD. No myocardial infarction or cardiac death occurred within 3 years; one patient with normal MPI needed revascularization.

CONCLUSION

In women with high exercise tolerance, especially in those without already known CAD, the yield of MPI is very low. Women with high exercise tolerance have an excellent prognosis.

Recent advances in atherosclerosis-based proteomics: new biomarkers and a future perspective

Vascular proteomics is providing two main types of data: proteins that actively participate in vascular pathophysiological processes and novel protein candidates that can potentially serve as useful clinical biomarkers. Although both types of proteins can be identified by similar proteomic strategies and methods, it is important to clearly distinguish biomarkers from mediators of disease. A particular protein, or group of proteins, may participate in a pathogenic process but not serve as an effective biomarker. Alternatively, a useful biomarker may not mediate pathogenic pathways associated with disease (i.e., C-reactive protein). To date, there are no clear successful examples in which discovery proteomics has led to a novel useful clinical biomarker in cardiovascular diseases. Nevertheless, new sources of biomarkers are being explored (i.e., secretomes, circulating cells, exosomes and microparticles), an increasing number of novel proteins involved in atherogenesis are constantly described, and new technologies and analytical strategies (i.e., quantitative proteomics) are being developed to access low abundant proteins. Therefore, this presages a new era of discovery and a further step in the practical application to diagnosis, prognosis and early action by medical treatment of cardiovascular diseases.

Proteomic Biomarkers of Atherosclerosis

SUMMARY: Biomarkers provide a powerful approach to understanding the spectrum of cardiovascular diseases. They have application in screening, diagnostic, prognostication, prediction of recurrences and monitoring of therapy. The "omics" tool are becoming very useful in the development of new biomarkers in cardiovascular diseases. Among them, proteomics is especially fitted to look for new proteins in health and disease and is playing a significant role in the development of new diagnostic tools in cardiovascular diagnosis and prognosis. This review provides an overview of progress in applying proteomics to atherosclerosis. First, we describe novel proteins identified analysing atherosclerotic plaques directly. Careful analysis of proteins within the atherosclerotic vascular tissue can provide a repertoire of proteins involved in vascular remodelling and atherogenesis. Second, we discuss recent data concerning proteins secreted by atherosclerotic plaques. The definition of the atheroma plaque secretome resides in that proteins secreted by arteries can be very good candidates of novel biomarkers. Finally we describe proteins that have been differentially expressed (versus controls) by individual cells which constitute atheroma plaques (endothelial cells, vascular smooth muscle cells, macrophages and foam cells) as well as by circulating cells (monocytes, platelets) or novel biomarkers present in plasma.

Technology Insight: biomarker development in acute kidney injury--what can we anticipate?

Early diagnosis has been the 'Achilles heel' of acute kidney injury (AKI) that has prevented successful implementation of treatment strategies. To date, pharmacological intervention has been largely unsuccessful or equivocal, and morbidity and mortality associated with AKI have remained unacceptably high. Despite their well-known limitations, the most widely used biomarkers for the early diagnosis of AKI are serum creatinine, blood urea nitrogen and urine output. Development of new biomarkers is imperative. A variety of methods have been employed to discover new biomarkers of AKI, including transcriptomics, proteomics, gene arrays, lipidomics and imaging technologies. Clinical trials are underway to establish the validity of the biomarkers discovered using these techniques. This Review summarizes the importance of biomarkers of AKI, from their discovery to clinical practice, from the current perspective and that of what to expect in the future. Great strides forward are being made in breaking down important barriers to the successful prevention and treatment of this devastating disorder.

Clinical Outcomes After Both Coronary Calcium Scanning and Exercise Myocardial Perfusion Scintigraphy

OBJECTIVES

The purpose of this work was to assess the prognosis in patients undergoing both coronary artery calcium (CAC) scanning and exercise myocardial perfusion scintigraphy (MPS).

BACKGROUND

Whereas the prognostic effectiveness of MPS is well established, recent studies indicate that quantification of CAC also predicts cardiac outcomes. However, prognostic information is not yet available upon which to guide the management of patients who have had both tests.

METHODS

We assessed the frequency of cardiac death and myocardial infarction over a mean follow-up of 32 +/- 16 months in 1,153 patients undergoing both CAC scanning and MPS. Results were compared with those from a referent cohort of 9,308 patients who had earlier undergone MPS only.

RESULTS

The frequency of myocardial ischemia rose with increasing CAC scores (p < 0.001), but ischemia was present in only 64 patients. Among the 1,089 nonischemic patients, of which only 3 (0.3%) underwent early revascularization, the annualized cardiac event rate was <1% in all CAC subgroups, including those with CAC scores >1,000. Kaplan-Meier analysis revealed similarly low cardiac event rates among nonischemic patients with CAC scores >1,000 and nonischemic patients with Bayesian coronary artery disease likelihood > or =85%. Late myocardial revascularization rates were also similar in these 2 groups.

CONCLUSIONS

Among patients with nonischemic MPS studies, high CAC scores do not confer an increased risk for cardiac events. Thus, although patients with high CAC scores may be considered for intensive medical therapy to prevent future coronary artery disease events, a normal MPS study in such patients suggests no need for more aggressive interventions.

Relationship of socioeconomic markers to daily life ischemia and blood pressure reactivity in coronary artery disease patients

BACKGROUND

Socioeconomic status (SES) is an important predictor of clinical outcomes in patients with coronary artery disease (CAD).

PURPOSE

We hypothesized that a selected sample of low SES cardiac patients would display heightened cardiovascular stress responses in the laboratory and increased daily life ischemia compared to otherwise comparable higher SES patients.

METHODS

Eighty-two patients (M age=61.8+/-9.4 years; 71 men, 11 women) with a known history of CAD engaged in a stressful mental arithmetic task while blood pressure (BP) measures were collected. Myocardial ischemia was subsequently assessed via 48-hr ambulatory electrocardiographic monitoring in a subgroup of 51 patients. SES was defined by participants' residential block groups, which were linked to Census Bureau data about their neighborhood, including per capita income, percentage of the population below poverty, educational level, as well as self-report of number of years of education.

RESULTS

Contrary to expectation, high SES participants in the study displayed higher diastolic BP (p<.01) and systolic BP (p<.001) responses to mental stress in the laboratory.

CONCLUSIONS

Participants with daily life ischemia came from wealthier neighborhoods using indexes of poverty (p<.01), income (p<.02), and education (p<.04) compared to patients without ambulatory ischemia. This relationship was not accounted for by age, sex, race, body mass index, marital status, or measures of disease severity.

Is transesophageal echocardiography overused in the diagnosis of infective endocarditis?

Because of its greater sensitivity, transesophageal echocardiography (TEE) is often misused as a screening tool for the exclusion of infective endocarditis (IE) in patients with small clinical probability of the disease. This study examined the role of using TEE exclusively at a Canadian tertiary care center for the diagnosis of IE and determined which clinical variables are most often associated with positive or negative echocardiographic results supporting or refuting the diagnosis.

The role of likelihood ratio in clinical diagnosis: applicability in the setting of spontaneous bacterial peritonitis

Despite imperfect clinical information and uncertainty about clinical course and outcome, the clinician's main task is to make reasonable decisions about patient care. The clinical history and physical examination typically provide information that is useful for making a diagnosis; however, we still rely on laboratory and radiologic tests to confirm a diagnosis in most cases. Understanding the operative characteristic of a test is of key importance because it can change the probability that a patient has a disease before the result of a test is known. This operative characteristic, better known as the likelihood ratio (LR), is a global assessment of the information provided by a test. The LR allows calculating the odds that a patient has a disease after a test is performed. In this article, we explain the meaning of the LR, how it works, and the applicability of this tool in the setting of a challenging scenario in clinical practice, spontaneous bacterial peritonitis.

Clinical logistics in treadmill exercise stress testing

The predictability as to a positive or negative outcome of treadmill exercise stress testing in 341 consecutively studied patients referred for diagnostic purposes is presented. A clinical decision as to the result was derived by asking 2 simple questions and reviewing the pretest ECG. Additional clinical logistics included the type of physician ordering the study, smoking history, symptoms, and basic patient history. The predictable accuracy was 77.7% for the total patient group and 81.5% when the questionable cases (reflecting a neutral or ambivalent cardiologist's opinion) were eliminated.

Risk stratification in coronary artery disease: implications for stabilization and prevention

Noninvasive nuclear imaging techniques, including dual-isotope myocardial perfusion single-photon emission computed tomography (SPECT), have been employed in the development of strategies for diagnosis and risk stratification of patients with suspected or known coronary artery disease. These risk-stratification strategies are based on studies in which known outcome has been linked to diagnostic and prognostic information provided by myocardial perfusion SPECT. This article describes a validated dual-isotope exercise protocol for assessment of perfusion and function and reviews the evidence on which a cost-effective risk management strategy is based.