A blood-based gene expression test for obstructive coronary artery disease tested in symptomatic nondiabetic patients referred for myocardial perfusion imaging the COMPASS study

Peripheral blood RNA biomarkers for cardiovascular disease from bench to bedside: a position paper from the EU-CardioRNA COST action CA17129

Despite significant advances in the diagnosis and treatment of cardiovascular diseases, recent calls have emphasized the unmet need to improve precision-based approaches in cardiovascular disease. Although some studies provide preliminary evidence of the diagnostic and prognostic potential of circulating coding and non-coding RNAs, the complex RNA biology and lack of standardization have hampered the translation of these markers into clinical practice. In this position paper of the CardioRNA COST action CA17129, we provide recommendations to standardize the RNA development process in order to catalyse efforts to investigate novel RNAs for clinical use. We list the unmet clinical needs in cardiovascular disease, such as the identification of high-risk patients with ischaemic heart disease or heart failure who require more intensive therapies. The advantages and pitfalls of the different sample types, including RNAs from plasma, extracellular vesicles, and whole blood, are discussed in the sample matrix, together with their respective analytical methods. The effect of patient demographics and highly prevalent comorbidities, such as metabolic disorders, on the expression of the candidate RNA is presented and should be reported in biomarker studies. We discuss the statistical and regulatory aspects to translate a candidate RNA from a research use only assay to an in-vitro diagnostic test for clinical use. Optimal planning of this development track is required, with input from the researcher, statistician, industry, and regulatory partners.

Discrimination capability of pretest probability of stable coronary artery disease: a systematic review and meta-analysis suggesting how to improve validation procedures

OBJECTIVE

Externally validated pretest probability models for risk stratification of subjects with chest pain and suspected stable coronary artery disease (CAD), determined through invasive coronary angiography or coronary CT angiography, are analysed to characterise the best validation procedures in terms of discriminatory ability, predictive variables and method completeness.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Global Health (Ovid), Healthstar (Ovid) and MEDLINE (Ovid) searched on 22 April 2020.

ELIGIBILITY CRITERIA

We included studies validating pretest models for the first-line assessment of patients with chest pain and suspected stable CAD. Reasons for exclusion: acute coronary syndrome, unstable chest pain, a history of myocardial infarction or previous revascularisation; models referring to diagnostic procedures different from the usual practices of the first-line assessment; univariable models; lack of quantitative discrimination capability.

METHODS

Eligibility screening and review were performed independently by all the authors. Disagreements were resolved by consensus among all the authors. The quality assessment of studies conforms to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). A random effects meta-analysis of area under the receiver operating characteristic curve (AUC) values for each validated model was performed.

RESULTS

27 studies were included for a total of 15 models. Besides age, sex and symptom typicality, other risk factors are smoking, hypertension, diabetes mellitus and dyslipidaemia. Only one model considers genetic profile. AUC values range from 0.51 to 0.81. Significant heterogeneity (p<0.003) was found in all but two cases (p>0.12). Values of I² >90% for most analyses and not significant meta-regression results undermined relevant interpretations. A detailed discussion of individual results was then carried out.

CONCLUSIONS

We recommend a clearer statement of endpoints, their consistent measurement both in the derivation and validation phases, more comprehensive validation analyses and the enhancement of threshold validations to assess the effects of pretest models on clinical management.

PROSPERO REGISTRATION NUMBER

CRD42019139388.

External validation of integrated genetic-epigenetic biomarkers for predicting incident coronary heart disease

Aim: The Framingham Risk Score (FRS) and atherosclerotic cardiovascular disease (ASCVD) Pooled Cohort Equation (PCE) for predicting risk for incident coronary heart disease (CHD) work poorly. To improve risk stratification for CHD, we developed a novel integrated genetic-epigenetic tool. Materials & methods: Using machine learning techniques and datasets from the Framingham Heart Study (FHS) and Intermountain Healthcare (IM), we developed and validated an integrated genetic-epigenetic model for predicting 3-year incident CHD. Results: Our approach was more sensitive than FRS and PCE and had high generalizability across cohorts. It performed with sensitivity/specificity of 79/75% in the FHS test set and 75/72% in the IM set. The sensitivity/specificity was 15/93% in FHS and 31/89% in IM for FRS, and sensitivity/specificity was 41/74% in FHS and 69/55% in IM for PCE. Conclusion: The use of our tool in a clinical setting could better identify patients at high risk for a heart attack.

The GEnetic Syntax Score: a genetic risk assessment implementation tool grading the complexity of coronary artery disease-rationale and design of the GESS study

Background

Coronary artery disease (CAD) remains one of the leading causes of mortality worldwide and is associated with multiple inherited and environmental risk factors. This study is designed to identify, design, and develop a panel of genetic markers that combined with clinical and angiographic information, will facilitate the creation of a personalized risk prediction algorithm (GEnetic Syntax Score—GESS). GESS score could be a reliable tool for predicting cardiovascular risk for future adverse events and for guiding therapeutic strategies.

Methods

GESS (ClinicalTrials.gov Identifier: NCT03150680) is a prospective, non-interventional clinical study designed to enroll 1080 consecutive patients with no prior history of coronary revascularization procedure, who undergo scheduled or emergency coronary angiography in AHEPA, University General Hospital of Thessaloniki. Next generation sequencing (NGS) technology will be used to genotype specific single-nucleotide polymorphisms (SNPs) across the genome of study participants, which were identified as clinically relevant to CAD after extensive bioinformatic analysis of literature-based SNPs. Enrichment analyses of Gene Ontology-Molecular Function, Reactome Pathways and Disease Ontology terms were also performed to identify the top 15 statistically significant terms and pathways. Furthermore, the SYNTAX score will be calculated for the assessment of CAD severity of all patients based on their angiographic findings. All patients will be followed-up for one-year, in order to record any major adverse cardiovascular events.

Discussion

A group of 228 SNPs was identified through bioinformatic and pharmacogenomic analysis to be involved in CAD through a wide range of pathways and was correlated with various laboratory and clinical parameters, along with the patients' response to clopidogrel and statin therapy. The annotation of these SNPs revealed 127 genes being affected by the presence of one or more SNPs. The first patient was enrolled in the study in February 2019 and enrollment is expected to be completed until June 2021. Hence, GESS is the first trial to date aspiring to develop a novel risk prediction algorithm, the GEnetic Syntax Score, able to identify patients at high risk for complex CAD based on their molecular signature profile and ultimately promote pharmacogenomics and precision medicine in routine clinical settings.

Trial registration GESS trial registration: ClinicalTrials.gov Number: NCT03150680. Registered 12 May 2017- Prospectively registered, https://clinicaltrials.gov/ct2/show/NCT03150680.

Nourin-Dependent miR-137 and miR-106b: Novel Biomarkers for Early Diagnosis of Myocardial Ischemia in Coronary Artery Disease Patients

Background: Although cardiovascular imaging techniques are widely used to diagnose myocardial ischemia in patients with suspected stable coronary artery disease (CAD), they have limitations related to lack of specificity, sensitivity and “late” diagnosis. Additionally, the absence of a simple laboratory test that can detect myocardial ischemia in CAD patients, has led to many patients being first diagnosed at the time of the development of myocardial infarction. Nourin is an early blood-based biomarker rapidly released within five minutes by “reversible” ischemic myocardium before progressing to necrosis. Recently, we demonstrated that the Nourin-dependent miR-137 (marker of cell damage) and miR-106b-5p (marker of inflammation) can diagnose myocardial ischemia in patients with unstable angina (UA) and also stratify severity of ischemia, with higher expression in acute ST-segment elevation myocardial infarction (STEMI) patients compared to UA patients. Minimal baseline-gene expression levels of Nourin miRNAs were detected in healthy subjects. Objectives: To determine: (1) whether Nourin miRNAs are elevated in chest pain patients with myocardial ischemia suspected of CAD, who also underwent dobutamine stress echocardiography (DSE) or ECG/Treadmill stress test, and (2) whether the elevated levels of serum Nourin miRNAs correlate with results of ECHO/ECG stress test in diagnosing CAD patients. Methods: Serum gene expression levels of miR-137, miR-106b-5p and their corresponding molecular pathway network were measured blindly in 70 enrolled subjects using quantitative real time PCR (qPCR). Blood samples were collected from: (1) patients with chest pain suspected of myocardial ischemia (n = 38) both immediately “pre-stress test” and “post-stress test” 30 min. after test termination; (2) patients with acute STEMI (n = 16) functioned as our positive control; and (3) healthy volunteers (n = 16) who, also, exercised on ECG/Treadmill stress test for Nourin baseline-gene expression levels. Results: (1) strong correlation was observed between Nourin miRNAs serum expression levels and results obtained from ECHO/ECG stress test in diagnosing myocardial ischemia in CAD patients; (2) positive “post-stress test” patients with CAD diagnosis showed upregulation of miR-137 by 572-fold and miR-106b-5p by 122-fold, when compared to negative “post-stress test” patients (p < 0.001); (3) similarly, positive “pre-stress test” CAD patients showed upregulation of miR-137 by 1198-fold and miR-106b-5p by 114-fold, when compared to negative “pre-stress test” patients (p < 0.001); and (4) healthy subjects had minimal baseline-gene expressions of Nourin miRNAs. Conclusions: Nourin-dependent miR-137 and miR-106b-5p are promising novel blood-based biomarkers for early diagnosis of myocardial ischemia in chest pain patients suspected of CAD in outpatient clinics. Early identification of CAD patients, while patients are in the stable state before progressing to infarction, is key to providing crucial diagnostic steps and therapy to limit adverse cardiac events, improve patients’ health outcome and save lives.

PR3 levels are impaired in plasma and PBMCs from Arabs with cardiovascular diseases

Cardiovascular disease (CVD) risks persist in patients despite treatment. CVD susceptibility also varies with sex and ethnicity and is not entirely explained by conventional CVD risk factors. The aim of the present study was to identify novel CVD candidate markers in circulating Peripheral blood mononuclear cells (PBMCs) and plasma from Arab obese subjects with and without CVD using proteomic approaches. Human adults with confirmed CVD (n = 208) and matched non-CVD controls (n = 152) living in Kuwait were examined in the present cross-sectional study. Anthropometric and classical biochemical parameters were determined. We employed a shotgun proteomic profiling approach on PBMCs isolated from a subset of the groups (n = 4, each), and differentially expressed proteins selected between the two groups were validated at the mRNA level using RT-PCR (n = 6, each). Plasma levels of selected proteins from the proteomics profiling: Proteinase-3 (PR3), Annexin-A3 (ANX3), Defensin (DEFA1), and Matrix Metalloproteinase-9 (MMP9), were measured in the entire cohort using human enzyme-linked immunosorbent assay kits and were subsequently correlated with various clinical parameters. Out of the 1407 we identified and quantified from the proteomics profiling, 47 proteins were dysregulated with at least twofold change between the two subject groups. Among the differentially expressed proteins, 11 were confirmed at the mRNA levels. CVD influenced the levels of the shortlisted proteins (MMP9, PR3, ANX3, and DEFA1) in the PBMCs and plasma differentially. Despite the decreased levels of both protein and mRNA in PBMCs, PR3 circulating levels increased significantly in patients with CVD and were influenced by neither diabetes nor statin treatment. No significant changes were; however, observed in the DEFA1, MMP9, and ANX3 levels in plasma. Multivariate logistic regression analysis revealed that only PR3 was independently associated with CVD. Our results suggest that the dysregulation of PR3 levels in plasma and PBMCs reflects underlying residual CVD risks even in the treated population. More prospective and larger studies are required to establish the role of PR3 in CVD progression.

Integrative Omics Approach to Identifying Genes Associated With Atrial Fibrillation

Rationale: GWAS (Genome-Wide Association Studies) have identified hundreds of genetic loci associated with atrial fibrillation (AF). However, these loci explain only a small proportion of AF heritability. Objective: To develop an approach to identify additional AF-related genes by integrating multiple omics data. Methods and Results: Three types of omics data were integrated: (1) summary statistics from the AFGen 2017 GWAS; (2) a whole blood EWAS (Epigenome-Wide Association Study) of AF; and (3) a whole blood TWAS (Transcriptome-Wide Association Study) of AF. The variant-level GWAS results were collapsed into gene-level associations using fast set-based association analysis. The CpG-level EWAS results were also collapsed into gene-level associations by an adapted SNP-set Kernel Association Test approach. Both GWAS and EWAS gene-based associations were then meta-analyzed with TWAS using a fixed-effects model weighted by the sample size of each data set. A tissue-specific network was subsequently constructed using the NetWAS (Network-Wide Association Study). The identified genes were then compared with the AFGen 2018 GWAS that contained more than triple the number of AF cases compared with AFGen 2017 GWAS. We observed that the multiomics approach identified many more relevant AF-related genes than using AFGen 2018 GWAS alone (1931 versus 206 genes). Many of these genes are involved in the development and regulation of heart- and muscle-related biological processes. Moreover, the gene set identified by multiomics approach explained much more AF variance than those identified by GWAS alone (10.4% versus 3.5%). Conclusions: We developed a strategy to integrate multiple omics data to identify AF-related genes. Our integrative approach may be useful to improve the power of traditional GWAS, which might be particularly useful for rare traits and diseases with limited sample size.

Identification of a blood-based 12-gene signature that predicts the severity of coronary artery stenosis: An integrative approach based on gene network construction, Support Vector Machine algorithm, and multi-cohort validation

BACKGROUND AND AIMS

We aimed to identify a blood-based gene expression score (GES) to predict the severity of coronary artery stenosis in patients with known or suspected coronary artery disease (CAD) by integrative use of gene network construction, Support Vector Machine (SVM) algorithm, and multi-cohort validation.

METHODS

In the discovery phase, a public blood-based microarray dataset of 110 patients with known CAD was analyzed by weighted gene coexpression network analysis and protein-protein interaction network analysis to identify candidate hub genes. In the training set with 151 CAD patients, bioinformatically identified hub genes were experimentally verified by real-time polymerase chain reaction, and statistically filtered with the SVM algorithm to develop a GES. Internal and external validation of GES was performed in patients with suspected CAD from two validation cohorts (n = 209 and 206).

RESULTS

The discovery phase screened 15 network-centric hub genes significantly correlated with the Duke CAD Severity Index. In the training cohort, 12 of 15 hub genes were filtered to construct a blood-based GES12, which showed good discrimination for higher modified Gensini scores (AUC: 0.798 and 0.812), higher Sullivan Extent scores (AUC: 0.776 and 0.778), and the presence of obstructive CAD (AUC: 0.834 and 0.792) in two validation cohorts. A nomogram comprising GES12, smoking status, hypertension status, low density lipoprotein cholesterol level, and body mass index further improved performance, with respect to discrimination, risk classification, and clinical utility, for prediction of coronary stenosis severity.

CONCLUSIONS

GES12 is useful in predicting the severity of coronary artery stenosis in patients with known or suspected CAD.

Interdisciplinary Models for Research and Clinical Endeavors in Genomic Medicine: A Scientific Statement From the American Heart Association

The completion of the Human Genome Project has unleashed a wealth of human genomics information, but it remains unclear how best to implement this information for the benefit of patients. The standard approach of biomedical research, with researchers pursuing advances in knowledge in the laboratory and, separately, clinicians translating research findings into the clinic as much as decades later, will need to give way to new interdisciplinary models for research in genomic medicine. These models should include scientists and clinicians actively working as teams to study patients and populations recruited in clinical settings and communities to make genomics discoveries-through the combined efforts of data scientists, clinical researchers, epidemiologists, and basic scientists-and to rapidly apply these discoveries in the clinic for the prediction, prevention, diagnosis, prognosis, and treatment of cardiovascular diseases and stroke. The highly publicized US Precision Medicine Initiative, also known as All of Us, is a large-scale program funded by the US National Institutes of Health that will energize these efforts, but several ongoing studies such as the UK Biobank Initiative; the Million Veteran Program; the Electronic Medical Records and Genomics Network; the Kaiser Permanente Research Program on Genes, Environment and Health; and the DiscovEHR collaboration are already providing exemplary models of this kind of interdisciplinary work. In this statement, we outline the opportunities and challenges in broadly implementing new interdisciplinary models in academic medical centers and community settings and bringing the promise of genomics to fruition.

The Clinical Utility of a Precision Medicine Blood Test Incorporating Age, Sex, and Gene Expression for Evaluating Women with Stable Symptoms Suggestive of Obstructive Coronary Artery Disease: Analysis from the PRESET Registry

Background: Evaluating women with symptoms suggestive of coronary artery disease (CAD) remains challenging. A blood-based precision medicine test yielding an age/sex/gene expression score (ASGES) has shown clinical validity in the diagnosis of obstructive CAD. We assessed the effect of the ASGES on the management of women with suspected obstructive CAD in a community-based registry.

Materials and Methods: The prospective PRESET (A Registry to Evaluate Patterns of Care Associated with the Use of Corus^® CAD in Real World Clinical Care Settings) Registry (NCT01677156) enrolled 566 patients presenting with symptoms suggestive of stable obstructive CAD from 21 United States primary care practices from 2012 to 2014. Demographics, clinical characteristics, and referrals to cardiology or further functional and/or anatomical cardiac studies after ASGES testing were collected for this subgroup analysis of women from the PRESET Registry. Patients were followed for 1-year post-ASGES testing.

Results: This study cohort included 288 women with a median age 57 years. The median body mass index was 29.2, with hyperlipidemia and hypertension present in 48% and 43% of patients, respectively. Median ASGES was 8.5 (range 1–40), with 218 (76%) patients having low (≤15) ASGES. Clinicians referred 9% (20/218) low ASGES versus 44% (31/70) elevated ASGES women for further cardiac evaluation (odds ratio 0.14, p < 0.0001, adjusted for patient demographics and clinical covariates). Across the score range, higher ASGES were associated with a higher likelihood of posttest cardiac referral. At 1-year follow-up, low ASGES women experienced fewer major adverse cardiac events than elevated ASGES women (1.3% vs. 4.2% respectively, p = 0.16).

Conclusions: Incorporation of ASGES into the diagnostic workup demonstrated clinical utility by helping clinicians identify women less likely to benefit from further cardiac evaluation.

Transcriptomic studies in tolerance: Lessons learned and the path forward

Immunosuppression after solid organ transplantation is a delicate balance of the immune response and is a complex phenomenon with many factors involved. Despite advances in the care of patients receiving organ transplants the adverse effects associated with immunosuppressive agents and the risks of long-term immunosuppression present a series of challenges and the need to weigh the risks and benefits of either over or under-immunosuppression. Ideally, if all transplant recipients could develop donor-specific immunological tolerance, it could drastically improve long-term graft survival without the need for immunosuppressive agents. In the absence of this ideal situation, the next best approach would be to develop tools to determine the adequacy of immunosuppression in each patient, in a manner that would individualize or personalize therapy. Despite current genomics-based studies of tolerance biomarkers in transplantation there are currently, no clinically validated tools to safely increase or decrease the level of IS that is beneficial to the patient. However, the successful identification of biomarkers and/or mechanisms of tolerance that have implications on long-term graft survival and outcomes depend on proper integration of study design, experimental protocols, and data-driven hypotheses. The objective of this article is to first, discuss the progress made on genomic biomarkers of immunological tolerance and the future avenues for the development of such biomarkers specifically in kidney transplantation. Secondly, we provide a set of guiding principles and identify the pitfalls, advantages, and drawbacks of studies that generate genomic data aimed at understanding transplant tolerance that is applicable to all solid transplants.

High-Sensitivity Cardiac Troponin I and the Diagnosis of Coronary Artery Disease in Patients With Suspected Angina Pectoris

BACKGROUND

We determined whether high-sensitivity cardiac troponin I can improve the estimation of the pretest probability for obstructive coronary artery disease (CAD) in patients with suspected stable angina.

METHODS AND RESULTS

In a prespecified substudy of the SCOT-HEART trial (Scottish Computed Tomography of the Heart), plasma cardiac troponin was measured using a high-sensitivity single-molecule counting assay in 943 adults with suspected stable angina who had undergone coronary computed tomographic angiography. Rates of obstructive CAD were compared with the pretest probability determined by the CAD Consortium risk model with and without cardiac troponin concentrations. External validation was undertaken in an independent study population from Denmark comprising 487 patients with suspected stable angina. Higher cardiac troponin concentrations were associated with obstructive CAD with a 5-fold increase across quintiles (9%-48%; P<0.001) independent of known cardiovascular risk factors (odds ratio, 1.35; 95% confidence interval, 1.25-1.46 per doubling of troponin). Cardiac troponin concentrations improved the discrimination and calibration of the CAD Consortium model for identifying obstructive CAD (C statistic, 0.788-0.800; P=0.004; χ2=16.8 [P=0.032] to 14.3 [P=0.074]). The updated model also improved classification of the American College of Cardiology/American Heart Association pretest probability risk categories (net reclassification improvement, 0.062; 95% confidence interval, 0.035-0.089). The revised model achieved similar improvements in discrimination and calibration when applied in the external validation cohort.

CONCLUSIONS

High-sensitivity cardiac troponin I concentration is an independent predictor of obstructive CAD in patients with suspected stable angina. Use of this test may improve the selection of patients for further investigation and treatment.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01149590.

Age, Sex, and Gene Expression Score identifies a symptomatic, nondiabetic male patient as being at high risk of obstructive coronary artery disease

In October 2015, a 74-year-old Caucasian male patient (past medical history of hyperlipidemia, paroxysmal atrial fibrillation, hypertension, and hypothyroidism) presented to the cardiologist for follow-up outpatient evaluation of exertional chest pain. The patient had recently been seen at the Emergency Department for the same complaint. At that time, the patient’s cardiac markers, EKG, and pharmacological nuclear stress testing were all reported as normal. At presentation to the cardiologist, the patient’s physical examination findings were unremarkable. Over the course of the following year, repeat electrocardiograms and myocardial perfusion imaging studies demonstrated no evidence of ischemia. Despite the persistence of symptoms, the patient was reluctant to undergo invasive testing. The cardiologist ordered a simple blood test: the Age, Sex, and Gene Expression Score, which provides the current likelihood of obstructive coronary artery disease in nondiabetic patients. Based on the high Age, Sex, and Gene Expression Score result, the patient underwent invasive coronary angiography and a 98% stenotic lesion in the proximal left anterior descending artery was discovered. A drug-eluting coronary stent was placed and resulted in the complete resolution of the patient’s symptoms.

The Expressed Genome in Cardiovascular Diseases and Stroke: Refinement, Diagnosis, and Prediction: A Scientific Statement From the American Heart Association

There have been major advances in our knowledge of the contribution of DNA sequence variations to cardiovascular disease and stroke. However, the inner workings of the body reflect the complex interplay of factors beyond the DNA sequence, including epigenetic modifications, RNA transcripts, proteins, and metabolites, which together can be considered the "expressed genome." The emergence of high-throughput technologies, including epigenomics, transcriptomics, proteomics, and metabolomics, is now making it possible to address the contributions of the expressed genome to cardiovascular disorders. This statement describes how the expressed genome can currently and, in the future, potentially be used to diagnose diseases and to predict who will develop diseases such as coronary artery disease, stroke, heart failure, and arrhythmias.

Utility of a Precision Medicine Test in Elderly Adults with Symptoms Suggestive of Coronary Artery Disease

BACKGROUND

Diagnosing obstructive coronary artery disease (CAD) is challenging in elderly adults, and current diagnostic approaches for CAD expose these individuals to risks from contrast dye and invasive procedures.

DESIGN

A Registry to Evaluate Patterns of Care Associated with the Use of Corus CAD in Real World Clinical Care Settings (PRESET; NCT01677156), pragmatic clinical trial.

SETTING

Community, 21 primary care practices.

PARTICIPANTS

Of 566 stable, nonacute outpatients presenting with symptoms suggestive of obstructive CAD, the 176 who were aged 65 and older (median age 70, 61% female) were the current study participants.

INTERVENTION

Blood-based precision medicine test, incorporating age, sex, and gene expression score (ASGES) to improve clinical decision-making and quality of care.

MEASUREMENTS

Information on demographic characteristics, clinical factors, ASGES results (range 1-40; low (≤15), high (>15)), referral patterns to cardiology and advanced cardiac testing, and major adverse cardiac events (MACEs) was collected in a subgroup analysis of elderly adults in the PRESET Registry. Follow-up was for 1 year after ASGES testing.

RESULTS

Median ASGES was 25, and 40 (23%) participants had a low score. Clinicians referred 12.5% of participants with a low ASGES and 49.3% with a high ASGES to cardiology or advanced cardiac testing (odds ratio for referral = 0.12, P < .001, adjusted for participants demographics and clinical covariates). Higher scores were associated with greater likelihood of posttest cardiac referral. At 1-year follow-up, the incidence of a MACE or revascularization was 10% (13/136) in the high ASGES group and 0% (0/40) in the low ASGES group (P = .04).

CONCLUSION

The ASGES test showed potential clinical utility in the evaluation of elderly outpatients with symptoms suggestive of obstructive CAD. Test use may reduce unnecessary referrals and the risk of procedure-related complications in individuals with low ASGES, who are unlikely to benefit from further testing, while also identifying individuals who may benefit from further cardiac evaluation and management.

Rheumatoid arthritis complicates noninvasive whole blood gene expression testing for coronary artery disease

BACKGROUND

Our objective was to evaluate an age- and sex-specific gene expression score (ASGES) previously validated to detect obstructive coronary artery disease (CAD) in patients with rheumatoid arthritis (RA).

METHODS

We evaluated 20 pairs of nondiabetic coronary patients with and without RA, selected by matching on age, sex, race, body mass index, tobacco use, and number of diseased coronary vessels. Peripheral blood gene expression levels of 23 CAD-associated genes were measured, and a previously validated CAD risk score including age, sex, and gene expression levels (Corus CAD) was computed. Linear regression was used to determine effects of both CAD and RA on the ASGES.

RESULTS

Among patients with RA, the ASGES was not associated with CAD. The ASGES was elevated in patients with RA (P<.04) when compared with matched controls. The presence of RA was associated with significantly altered expression for 6 of the 23 genes (P<.05 for all, not adjusted for multiple comparisons): S100 calcium binding protein A12, interleukin-18 receptor accessory protein, caspase 5, S100 calcium binding protein A8, aquaporin 9, and cluster of differentiation 79b.

CONCLUSIONS

Across a range of coronary artery disease severity, RA was associated with altered expression of CAD-associated genes. Notably, 2 of these genes, S100 calcium binding protein A8 and A12, are associated with neutrophil activation and are under investigation as therapeutic targets for both RA and CAD. These findings highlight common pathogenic mechanisms for RA and CAD and validate the prior exclusion of RA patients from ASGES-based evaluation of CAD likelihood.

Clinical Utility of a Precision Medicine Test Evaluating Outpatients with Suspected Obstructive Coronary Artery Disease

BACKGROUND

Identifying patients with obstructive coronary artery disease can be challenging for primary care physicians. Advances in precision medicine may help augment clinical tools and redefine the paradigm for evaluating coronary artery disease in the outpatient setting. A blood-based age/sex/gene expression score (ASGES) incorporating key features of precision medicine has shown clinical validity with a 96% negative predictive value and 89% sensitivity in estimating a symptomatic patient's current likelihood of obstructive coronary artery disease. To better characterize the clinical utility of the ASGES and measure its impact on clinician decision-making, a community-based registry was established.

METHODS

The prospective PRESET Registry (NCT01677156) enrolled stable, nonacute adult patients presenting with typical or atypical symptoms suggestive of obstructive coronary artery disease from 21 US primary care practices from August 2012 to August 2014. Demographics, clinical characteristics, and ASGES results (predefined as low [ASGES ≤15] or elevated [ASGES >15]) were collected, as were referrals to Cardiology or further functional/anatomic cardiac testing after ASGES testing. Patients were followed for 1 year post ASGES testing.

RESULTS

Among the 566-patient cohort (median age 56 years), clinicians referred 26/252 (10%) of patients with low scores vs 137/314 (44%) of patients with elevated scores to Cardiology or advanced cardiac testing for further evaluation (unadjusted odds ratio 0.15, P <.0001; adjusted odds ratio after accounting for clinical covariates = 0.18, P <.0001). Data on 84 patients referred for advanced cardiac testing showed abnormal findings in 0 of 13 (0%) low ASGES and 10 of 71 (14%) elevated ASGES patients. Major adverse cardiovascular events and revascularization were noted in 3/252 (1.2%) patients with low ASGES and 14/314 (4.5%) patients with elevated ASGES score (P <.03).

CONCLUSIONS

In this community-based cardiovascular registry, the ASGES demonstrated clinical utility in the evaluation of patients with suspected obstructive coronary artery disease. Low-score patients were less likely to undergo cardiac referral, were unlikely to have positive findings on further cardiac work-up, and had a low rate of adverse cardiovascular events in 1-year follow-up. Our work provides evidence supporting the value of using precision medicine in the delivery of cardiovascular care.

An age- and sex-specific gene expression score is associated with revascularization and coronary artery disease: Insights from the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) trial

BACKGROUND

Identifying predictors of coronary artery disease (CAD)-related procedures and events remains a priority.

METHODS

We measured an age- and sex-specific gene expression score (ASGES) previously validated to detect obstructive CAD (oCAD) in symptomatic nondiabetic patients in the PROMISE trial. The outcomes were oCAD (≥70% stenosis in ≥1 vessel or ≥50% left main stenosis on CT angiography [CTA]) and a composite endpoint of death, myocardial infarction, revascularization, or unstable angina.

RESULTS

The ASGES was determined in 2370 nondiabetic participants (47.5% male, median age 59.5 years, median follow-up 25 months), including 1137 with CTA data. An ASGES >15 was associated with oCAD (odds ratio 2.5 [95% CI 1.6-3.8], P<.001) and the composite endpoint (hazard ratio [HR] 2.6 [95% CI 1.8-3.9], P<.001) in unadjusted analyses. After adjustment for Framingham risk, an ASGES >15 remained associated with the composite endpoint (P=.02); the only component that was associated was revascularization (adjusted HR 2.69 [95% CI 1.52-4.79], P<.001). Compared to noninvasive testing, the ASGES improved prediction for the composite (increase in c-statistic=0.036; continuous net reclassification index=43.2%). Patients with an ASGES ≤15 had a composite endpoint rate no different from those with negative noninvasive test results (3.2% vs. 2.6%, P=.29).

CONCLUSIONS

A blood-based genomic test for detecting oCAD significantly predicts near-term revascularization procedures, but not non-revascularization events. Larger studies will be needed to clarify the risk with non-revascularization events.

Ratios of leptin to insulin and adiponectin to endothelin are sex-dependently associated with extent of coronary atherosclerosis

OBJECTIVE

Noninvasive diagnostics of early stages of coronary artery disease and discrimination between various extents of vascular lesions in patients is an important clinical problem especially considering wide spread use of cholesterol lowering drugs that affect lipid and lipoprotein profiling. The main goal of our study was to evaluate applicability of new combinations of noninvasive biomarkers such as leptin to insulin and adiponectin to endothelin ratios, for detection of early stages of coronary atherosclerosis versus later stages of the disease.

PATIENTS AND METHODS

A number of previously validated serum biomarkers were tested in a group of 500 patients with coronary artery disease and examined for their association with severity of coronary lesion according to Gensini score determined by coronary angiography.

RESULTS

Lowest extent of coronary lesions was associated with significant increase in apoA-I levels and with significantly increased ratios of adiponectin to endothelin and leptin to insulin. In male but not in female patients, adiponectin to endothelin ratio below 7.0 was associated with Gensini score representing early to high coronary lesions (p = 0.02). In female but not in male patients, leptin to insulin ratio below 3.5 was associated with Gensini score representing early to high coronary lesions (p = 0.013).

CONCLUSION

Leptin to insulin and adiponectin to endothelin ratios are novel derived biomarkers useful for noninvasive diagnostics of initial stages of coronary lesions in patients with coronary artery disease.

Genetics paired with CT angiography in the setting of atherosclerosis

Coronary artery disease (CAD) continues to be the leading cause of morbidity and mortality globally. Although the etiological mechanisms for CAD have not been fully elucidated, however, most would agree that atherosclerotic plaques progressively narrow the coronary arteries are the earliest manifestations and the principal cause of CAD. The emergence of revolutionary imaging technologies such as cardiac CT angiography, noninvasive computed fractional flow reserve and intravascular ultrasound provided the possibility of detecting and monitoring phenotypes associated with subclinical atherosclerosis. Meanwhile, with the widespread use of high-throughput genotyping pipeline such as next-generation sequencing, combined with big data-driven solutions in bioinformatics, translating the emerging genetic technologies into clinical practice and, therefore, provide valuable insight into the CAD study. In this review, we briefly describe the latest noninvasive cardiac imaging techniques for atherosclerosis-related phenotypes' detection, mainly focusing on the coronary artery calcification, plaque burden and stenosis. Furthermore, we highlight the state-of-the-art genotyping techniques and its application in the field of CAD translational study. Finally, we discuss the clinical relevance of genetics paired with noninvasive imaging in the setting of coronary artery atherosclerosis.

Epidemiology of cardiovascular disease: recent novel outlooks on risk factors and clinical approaches

INTRODUCTION

Cardiovascular (CVD) risk assessment with traditional risk factors (age, sex, blood pressure, lipids, smoking and diabetes) has remained relatively invariant over the past decades despite some inaccuracies associated with this approach. However, the search for novel, robust and cost-effective risk markers of CVD risk is ongoing.

AREAS COVERED

A large share of the major developments in CVD risk prediction during the past five years has been made in large-scale biomarker discovery and the so called 'omics' - the rapidly growing fields of genomics, transcriptomics, epigenetics and metabolomics. This review focuses on how these new technologies are helping drive primary CVD risk estimation forward in recent years, and speculates on how they could be utilized more effectively for discovering novel risk factors in the future. Expert commentary: The search for new CVD risk factors is currently undergoing a significant revolution as the simple relationship between single risk factors and disease will have to be replaced by models that strive to integrate the whole field of omics into medicine.

Novel biomarkers for cardiovascular risk assessment: current status and future directions

Cardiovascular disease (CVD) is the leading cause of mortality in the modern world. Traditional risk algorithms may miss up to 20% of CVD events. Therefore, there is a need for new cardiac biomarkers. Many fields of research are dedicated to improving cardiac risk prediction, including genomics, transcriptomics and proteomics. To date, even the most promising biomarkers have only demonstrated modest associations and predictive ability. Few have undergone randomized control trials. A number of biomarkers are targets to new therapies aimed to reduce cardiovascular risk. Currently, some of the most promising risk prediction has been demonstrated with panels of multiple biomarkers. This article reviews the current state and future of proteomic biomarkers and aggregate biomarker panels.

Gene Expression Signatures and the Spectrum of Coronary Artery Disease

Over the past 10-15 years, developments in gene expression profiling have opened new arenas for the discovery of important factors in the pathogenesis of numerous disease processes, including coronary artery disease. Messenger RNA and microRNA are differentially expressed in patients with coronary plaques, acute plaque rupture, and response to well-established treatments for acute coronary syndromes. In this review, we will explore recent developments in messenger RNA and microRNA technology at each stage of a patient's progression through the natural history of cardiovascular disease, including evaluation of risk factors, prediction and detection of coronary artery disease and acute coronary syndromes, and finally, response to treatments for coronary artery disease and its sequelae including congestive heart failure.

Impact of exercise stress testing on diagnostic gene expression in patients with obstructive and nonobstructive coronary artery disease

A blood-based gene expression test can diagnose obstructive coronary artery disease (CAD). The test is sensitive to inflammatory and immune processes associated with atherosclerosis. Acute exercise engages short-term inflammatory pathways, and exercise stress testing may affect results of gene expression testing during the same diagnostic workup. The objective of this study was to evaluate the effect of exercise on diagnostic gene expression testing. Ten patients with obstructive CAD (≥50% stenosis) and 10 with no/minimal CAD (≤20% stenosis) were identified by angiography. Blood samples for gene expression were obtained at baseline, peak exercise, 30 to 60 minutes after testing, and 24 to 36 hours after testing. Core-lab gene expression analysis yielded raw gene expression scores (GES) for each time point. Linear models were used to estimate changes in GES, adjusting for CAD status and other covariates. GES increased during peak exercise across both genders, with no significant differences as a function of CAD status. The overall adjusted mean GES increase at peak exercise was 0.29 (95% confidence interval 0.22 to 0.36; p <0.001). GES after exercise were not significantly different from baseline. The change in gene expression levels during peak exercise may reflect a transient inflammatory response to acute exercise that may be independent of patient gender or CAD status. In conclusion, CAD GES increase at peak exercise testing and rapidly return to baseline. Such may reflect a transient inflammatory response to acute exercise independent of gender or extent of CAD.

Outcomes of anatomical versus functional testing for coronary artery disease

BACKGROUND

Many patients have symptoms suggestive of coronary artery disease (CAD) and are often evaluated with the use of diagnostic testing, although there are limited data from randomized trials to guide care.

METHODS

We randomly assigned 10,003 symptomatic patients to a strategy of initial anatomical testing with the use of coronary computed tomographic angiography (CTA) or to functional testing (exercise electrocardiography, nuclear stress testing, or stress echocardiography). The composite primary end point was death, myocardial infarction, hospitalization for unstable angina, or major procedural complication. Secondary end points included invasive cardiac catheterization that did not show obstructive CAD and radiation exposure.

RESULTS

The mean age of the patients was 60.8±8.3 years, 52.7% were women, and 87.7% had chest pain or dyspnea on exertion. The mean pretest likelihood of obstructive CAD was 53.3±21.4%. Over a median follow-up period of 25 months, a primary end-point event occurred in 164 of 4996 patients in the CTA group (3.3%) and in 151 of 5007 (3.0%) in the functional-testing group (adjusted hazard ratio, 1.04; 95% confidence interval, 0.83 to 1.29; P=0.75). CTA was associated with fewer catheterizations showing no obstructive CAD than was functional testing (3.4% vs. 4.3%, P=0.02), although more patients in the CTA group underwent catheterization within 90 days after randomization (12.2% vs. 8.1%). The median cumulative radiation exposure per patient was lower in the CTA group than in the functional-testing group (10.0 mSv vs. 11.3 mSv), but 32.6% of the patients in the functional-testing group had no exposure, so the overall exposure was higher in the CTA group (mean, 12.0 mSv vs. 10.1 mSv; P<0.001).

CONCLUSIONS

In symptomatic patients with suspected CAD who required noninvasive testing, a strategy of initial CTA, as compared with functional testing, did not improve clinical outcomes over a median follow-up of 2 years. (Funded by the National Heart, Lung, and Blood Institute; PROMISE ClinicalTrials.gov number, NCT01174550.).

The diagnosis of CAD in women: addressing the unmet need - a report from the national expert roundtable meeting

A multistakeholder panel comprising experts in the fields of clinical cardiology, medical technology innovation, women's health research and policy analysis, personalized medicine, payers (including self-insured employers), patient advocacy, and health economics was convened at the Heart House in Washington, DC. The following points emerged as key concepts: (1) Diagnostic challenges in the evaluation of women with symptoms suggestive of obstructive coronary artery disease (CAD) result from: (a) presentation with atypical symptoms and lower pretest probability of disease compared to men, (b) fatty tissue and breast tissue attenuation on cardiac imaging leading to false positive findings, and (c) the presence of microvascular CAD. (2) Diagnostic challenges lead to both over-testing of low-risk women and under-testing of high-risk women. (3) Efforts should be directed toward increasing clinician, clinical professional society, and consumer awareness and understanding of sex-specific differences between men and women in the pathophysiology of CAD. (4) Multiple health care stakeholders should be made aware of new advances in genomic approaches to address the challenges of diagnosing obstructive CAD; specifically, the Corus CAD gene expression test, which was shown to have high sensitivity and negative predictive value in a recent clinical trial. As such, it has promise as a tool to help clinicians to rule out obstructive CAD as a cause of a patient's symptoms. (Population Health Management 2015;18:86-92).

Personalized antiplatelet and anticoagulation therapy: applications and significance of pharmacogenomics

In recent years, substantial effort has been made to better understand the influence of genetic factors on the efficacy and safety of numerous medications. These investigations suggest that the use of pharmacogenetic data to inform physician decision-making has great potential to enhance patient care by reducing on-treatment clinical events, adverse drug reactions, and health care-related costs. In fact, integration of such information into the clinical setting may be particularly applicable for antiplatelet and anticoagulation therapeutics, given the increasing body of evidence implicating genetic variation in variable drug response. In this review, we summarize currently available pharmacogenetic information for the most commonly used antiplatelet (ie, clopidogrel and aspirin) and anticoagulation (ie, warfarin) medications. Furthermore, we highlight the currently known role of genetic variability in response to next-generation antiplatelet (prasugrel and ticagrelor) and anticoagulant (dabigatran) agents. While compelling evidence suggests that genetic variants are important determinants of antiplatelet and anticoagulation therapy response, significant barriers to clinical implementation of pharmacogenetic testing exist and are described herein. In addition, we briefly discuss development of new diagnostic targets and therapeutic strategies as well as implications for enhanced patient care. In conclusion, pharmacogenetic testing can provide important information to assist clinicians with prescribing the most personalized and effective antiplatelet and anticoagulation therapy. However, several factors may limit its usefulness and should be considered.

BiomarCaRE: rationale and design of the European BiomarCaRE project including 300,000 participants from 13 European countries

Biomarkers are considered as tools to enhance cardiovascular risk estimation. However, the value of biomarkers on risk estimation beyond European risk scores, their comparative impact among different European regions and their role towards personalised medicine remains uncertain. Biomarker for Cardiovascular Risk Assessment in Europe (BiomarCaRE) is an European collaborative research project with the primary objective to assess the value of established and emerging biomarkers for cardiovascular risk prediction. BiomarCaRE integrates clinical and epidemiological biomarker research and commercial enterprises throughout Europe to combine innovation in biomarker discovery for cardiovascular disease prediction with consecutive validation of biomarker effectiveness in large, well-defined primary and secondary prevention cohorts including over 300,000 participants from 13 European countries. Results from this study will contribute to improved cardiovascular risk prediction across different European populations. The present publication describes the rationale and design of the BiomarCaRE project.

Precision phenotyping, panomics, and system-level bioinformatics to delineate complex biologies of atherosclerosis: rationale and design of the "Genetic Loci and the Burden of Atherosclerotic Lesions" study

BACKGROUND

Complex biological networks of atherosclerosis are largely unknown.

OBJECTIVE

The main objective of the Genetic Loci and the Burden of Atherosclerotic Lesions study is to assemble comprehensive biological networks of atherosclerosis using advanced cardiovascular imaging for phenotyping, a panomic approach to identify underlying genomic, proteomic, metabolomic, and lipidomic underpinnings, analyzed by systems biology-driven bioinformatics.

METHODS

By design, this is a hypothesis-free unbiased discovery study collecting a large number of biologically related factors to examine biological associations between genomic, proteomic, metabolomic, lipidomic, and phenotypic factors of atherosclerosis. The Genetic Loci and the Burden of Atherosclerotic Lesions study (NCT01738828) is a prospective, multicenter, international observational study of atherosclerotic coronary artery disease. Approximately 7500 patients are enrolled and undergo non-contrast-enhanced coronary calcium scanning by CT for the detection and quantification of coronary artery calcium, as well as coronary artery CT angiography for the detection and quantification of plaque, stenosis, and overall coronary artery disease burden. In addition, patients undergo whole genome sequencing, DNA methylation, whole blood-based transcriptome sequencing, unbiased proteomics based on mass spectrometry, as well as metabolomics and lipidomics on a mass spectrometry platform. The study is analyzed in 3 subsequent phases, and each phase consists of a discovery cohort and an independent validation cohort. For the primary analysis, the primary phenotype will be the presence of any atherosclerotic plaque, as detected by cardiac CT. Additional phenotypic analyses will include per patient maximal luminal stenosis defined as 50% and 70% diameter stenosis. Single-omic and multi-omic associations will be examined for each phenotype; putative biomarkers will be assessed for association, calibration, discrimination, and reclassification.

Biological and analytical stability of a peripheral blood gene expression score for obstructive coronary artery disease in the PREDICT and COMPASS studies

A gene expression score (GES) for obstructive coronary artery disease (CAD) has been validated in two multicenter studies. Receiver-operating characteristics (ROC) analysis of the GES on an expanded Personalized Risk Evaluation and Diagnosis in the Coronary Tree (PREDICT) cohort (NCT no. 00500617) with CAD defined by quantitative coronary angiography (QCA) or clinical reads yielded similar performance (area under the curve (AUC) = 0.70, N = 1,502) to the original validation cohort (AUC = 0.70, N = 526). Analysis of 138 non-Caucasian and 1,364 Caucasian patients showed very similar performance (AUCs = 0.72 vs. 0.70). To assess analytic stability, stored samples of the original validation cohort (N = 526) was re-tested after 5 years, and the mean score changed from 20.3 to 19.8 after 5 years (N = 501, 95 %). To assess patient scores over time, GES was determined on samples from 173 Coronary Obstruction Detection by Molecular Personalized Gene Expression (COMPASS) study (NCT no. 01117506) patients at approximately 1 year post-enrollment. Mean scores increased slightly from 15.9 to 17.3, corresponding to a 2.5 % increase in obstructive CAD likelihood. Changes in cardiovascular medications did not show a significant change in GES.

Biomarkers of coronary artery disease: the promise of the transcriptome

The last years have witnessed tremendous technical advances in the field of transcriptomics that enable the simultaneous assessment of nearly all transcripts expressed in a tissue at a given time. These advances harbor the potential to gain a better understanding of the complex biological systems and for the identification and development of novel biomarkers. This article will review the current knowledge of transcriptomics biomarkers in the cardiovascular field and will provide an overview about the promises and challenges of the transcriptomics approach for biomarker identification.

PROspective Multicenter Imaging Study for Evaluation of chest pain: rationale and design of the PROMISE trial

BACKGROUND

Suspected coronary artery disease (CAD) is one of the most common, potentially life-threatening diagnostic problems clinicians encounter. However, no large outcome-based randomized trials have been performed to guide the selection of diagnostic strategies for these patients.

METHODS

The PROMISE study is a prospective, randomized trial comparing the effectiveness of 2 initial diagnostic strategies in patients with symptoms suspicious for CAD. Patients are randomized to either (1) functional testing (exercise electrocardiogram, stress nuclear imaging, or stress echocardiogram) or (2) anatomical testing with ≥64-slice multidetector coronary computed tomographic angiography. Tests are interpreted locally in real time by subspecialty certified physicians, and all subsequent care decisions are made by the clinical care team. Sites are provided results of central core laboratory quality and completeness assessment. All subjects are followed up for ≥1 year. The primary end point is the time to occurrence of the composite of death, myocardial infarction, major procedural complications (stroke, major bleeding, anaphylaxis, and renal failure), or hospitalization for unstable angina.

RESULTS

More than 10,000 symptomatic subjects were randomized in 3.2 years at 193 US and Canadian cardiology, radiology, primary care, urgent care, and anesthesiology sites.

CONCLUSION

Multispecialty community practice enrollment into a large pragmatic trial of diagnostic testing strategies is both feasible and efficient. The PROMISE trial will compare the clinical effectiveness of an initial strategy of functional testing against an initial strategy of anatomical testing in symptomatic patients with suspected CAD. Quality of life, resource use, cost-effectiveness, and radiation exposure will be assessed.

Evaluation of a solid matrix for collection and ambient storage of RNA from whole blood

Background

Whole blood gene expression-based molecular diagnostic tests are becoming increasingly available. Conventional tube-based methods for obtaining RNA from whole blood can be limited by phlebotomy, volume requirements, and RNA stability during transport and storage. A dried blood spot matrix for collecting high-quality RNA, called RNA Stabilizing Matrix (RSM), was evaluated against PAXgene® blood collection tubes.

Methods

Whole blood was collected from 25 individuals and subjected to 3 sample storage conditions: 18 hours at either room temperature (baseline arm) or 37°C, and 6 days at room temperature. RNA was extracted and assessed for integrity by Agilent Bioanalyzer, and gene expression was compared by RT-qPCR across 23 mRNAs comprising a clinical test for obstructive coronary artery disease.

Results

RSM produced RNA of relatively high integrity across the various tested conditions (mean RIN ± 95% CI: baseline arm, 6.92 ± 0.24; 37°C arm, 5.98 ± 0.48; 6-day arm, 6.72 ± 0.23). PAXgene samples showed comparable RNA integrity in both baseline and 37°C arms (8.42 ± 0.17; 7.92 ± 0.1 respectively) however significant degradation was observed in the 6-day arm (3.19 ± 1.32). Gene expression scores on RSM were highly correlated between the baseline and 37°C and 6-day study arms (median r = 0.96, 0.95 respectively), as was the correlation to PAXgene tubes (median r = 0.95, p < 0.001).

Conclusion

RNA obtained from RSM shows little degradation and comparable RT-qPCR performance to PAXgene RNA for the 23 genes analyzed. Further development of this technology may provide a convenient method for collecting, shipping, and storing RNA for gene expression assays.

Cost effectiveness of a gene expression score and myocardial perfusion imaging for diagnosis of coronary artery disease

BACKGROUND

Over 3 million patients annually present with symptoms suggestive of obstructive coronary artery disease (oCAD) in the United States (US), but a cardiac etiology is found in as few as 10% of cases. Usual care may include advanced cardiac testing with myocardial perfusion imaging (MPI), with attendant radiation risks and increased costs of care. We estimated the cost effectiveness of CAD diagnostic strategies including "no test," a gene expression score (GES) test, MPI, and sequential strategies combining GES and MPI.

METHODS

We developed a Markov-based decision analysis model to simulate outcomes and costs in patients presenting to clinicians with symptoms suggestive of oCAD in the US. We estimated quality-adjusted life years (QALYs), total costs, and incremental cost-effectiveness ratios (ICERs) for each strategy.

RESULTS

In our base case, the 2-threshold GES strategy is the most cost-effective strategy at a threshold of $100,000 per QALY gained, with an ICER of approximately $72,000 per QALY gained relative to no testing. Myocardial perfusion imaging alone and the 1-threshold strategy are weakly dominated. In sensitivity analysis, ICERs fall as the probability of oCAD increases from the base case value of 15%. The ranking of ICERs among strategies is sensitive to test costs, including the time cost for testing. The analysis reveals ways to improve on prespecified GES thresholds.

CONCLUSIONS

Diagnostic testing for oCAD with a novel GES strategy in a 2-threshold model is cost effective by conventional standards. This diagnostic approach is more efficient than usual care of MPI alone or a 1-threshold GES strategy in most scenarios.

Economic utility of a blood-based genomic test for the assessment of patients with symptoms suggestive of obstructive coronary artery disease

Approximately 3 million patients with symptoms suggestive of obstructive coronary artery disease (CAD) present to primary care offices in the United States annually, resulting in approximately $6.7 billion in cardiac workup costs. Despite wide application of existing diagnostic technologies, yield of obstructive CAD at invasive coronary angiography (ICA) is low. This study used a decision analysis model to assess the economic utility of a novel gene expression score (GES) for the diagnosis of obstructive CAD. Within a representative commercial health plan's adult membership, current practice for obstructive CAD diagnosis (usual care) was compared to a strategy that incorporates the GES test (GES-directed care). The model projected the number of diagnostic tests and procedures performed, the number of patients receiving medical therapy, type I and type II errors for each strategy of obstructive CAD diagnosis, and the associated costs over a 1-year time horizon. Results demonstrate that GES-directed care to exclude the diagnosis of obstructive CAD prior to myocardial perfusion imaging may yield savings to health plans relative to usual care by reducing utilization of noninvasive and invasive cardiac imaging procedures and increasing diagnostic yield at ICA. At a 50% capture rate of eligible patients in GES-directed care, it is projected that a commercial health plan will realize savings of $0.77 per member per month; savings increase proportionally to the GES capture rate. These findings illustrate the potential value of this new blood-based, molecular diagnostic test for health plans and patients in an age of greater emphasis on personalized medicine.

A peripheral blood gene expression score is associated with atherosclerotic Plaque Burden and Stenosis by cardiovascular CT-angiography: results from the PREDICT and COMPASS studies

OBJECTIVE

We previously validated a gene expression score (GES) based on age, sex and peripheral blood cell expression levels of 23 genes measured by quantitative real-time PCR (qRT-PCR) for diagnosis of obstructive coronary artery disease (CAD) (≥ 50% luminal diameter stenosis). In this study we sought to determine the association between the GES and coronary arterial Plaque Burden and Stenosis by CT-angiography.

METHODS

A total of 610 patients (mean age: 57 ± 11; 50% male) from the PREDICT and COMPASS studies from 59 centers were analyzed. Coronary artery calcium (CAC) scoring, CT angiography (CTA)-based plaque and stenosis and GES measurements were performed. CAC was expressed as Agatston score and CTA evaluated for stenosis severity: 0. None; 1. Minimal, 2. Mild, 3. Moderate, 4. Severe and 5. Occluded. Correlation analysis, one-way analysis of variance (ANOVA) and receiver operating characteristics (ROC) analyses were performed.

RESULTS

GES was significantly associated with plaque burden by CAC (r = 0.50; p < 0.001) and CTA (segment involvement score index: r = 0.37, p < 0.001); a low score (≤ 15) had sensitivity of 0.71 and a high score (≥ 28) a specificity of 0.97 for the prediction of zero vs. non-zero CAC. Increasing GES was associated with a greater degree of categorical stenosis by ANOVA (p < 0.001); GES significantly correlated with maximum luminal stenosis (r = 0.41; p < 0.01) and segment stenosis score index (r = 0.38; p < 0.01). A low score had sensitivity of 0.90 and a high score a specificity of 0.87 for ≥ 70% stenosis.

CONCLUSIONS

A previously validated GES is significantly associated with Plaque Burden and Stenosis by CT.

CLINICAL TRIAL REGISTRATION

(PREDICT [NCT00500617] and COMPASS [NCT01117506]), www.clinicaltrials.gov.