Comparative Effectiveness of Exercise Electrocardiography With or Without Myocardial Perfusion Single Photon Emission Computed Tomography in Women With Suspected Coronary Artery Disease

Diagnosing and characterizing coronary artery disease in women: developments in noninvasive and invasive imaging techniques

Cardiovascular disease is the leading cause of death in men and women in the USA; yet, coronary artery disease (CAD) continues to be underrecognized and underdiagnosed in women. Noninvasive and invasive imaging techniques are constantly being developed in order to more accurately assess CAD. At the same time, the impact of gender on the interpretation and accuracy of these studies is still being elucidated. Furthermore, new imaging techniques have improved our understanding of CAD pathophysiology and progression and have begun to reveal gender differences in the development of CAD. This article will review current imaging techniques and their application to diagnosing and understanding CAD in women.

Influence of sex on risk stratification with stress myocardial perfusion Rb-82 positron emission tomography: Results from the PET (Positron Emission Tomography) Prognosis Multicenter Registry

OBJECTIVES

The aim of the current analysis was to compare sex differences in the prognostic accuracy of stress myocardial perfusion rubidum-82 (Rb-82) positron emission tomography (PET).

BACKGROUND

The diagnostic evaluation of women presenting with suspected cardiac symptoms is challenging with reported reduced accuracy, attenuation artifact, and more recent concerns regarding radiation safety. Stress myocardial perfusion Rb-82 PET is a diagnostic alternative with improved image quality and radiation dosimetry. Currently, the prognostic accuracy of stress Rb-82 PET in women has not been established.

METHODS

A total of 6,037 women and men were enrolled in the PET Prognosis Multicenter Registry. Patients were followed for the occurrence of coronary artery disease (CAD) mortality, with a median follow-up of 2.2 years. Cox proportional hazards modeling was used to estimate CAD mortality. The net re-classification improvement index (NRI) was calculated.

RESULTS

The 5-year CAD mortality was 3.7% for women and 6.0% for men (p < 0.0001). Unadjusted CAD mortality ranged from 0.9% to 12.9% for women (p < 0.0001) and from 1.5% to 17.4% for men (p < 0.0001) for 0% to ≥15% abnormal myocardium at stress. In multivariable models, the percentage of abnormal stress myocardium was independently predictive of CAD mortality in women and men. An interaction term of sex by the percentage of abnormal stress myocardium was nonsignificant (p = 0.39). The categorical NRI when Rb-82 PET data was added to a clinical risk model was 0.12 for women and 0.17 for men. Only 2 cardiac deaths were reported in women <55 years of age; accordingly the percentage of abnormal myocardium at stress was of borderline significance (p = 0.063), but it was highly significant for women ≥55 years of age (p < 0.0001), with an increased NRI of 0.21 (95% confidence interval: 0.09 to 0.34), including 17% of CAD deaths and 3.9% of CAD survivors that were correctly re-classified in this older female subset.

CONCLUSIONS

Stress Rb-82 PET provides significant and clinically meaningful effective risk stratification of women and men, supporting this modality as an alternative to comparative imaging modalities. Rb-82 PET findings were particularly helpful at identifying high-risk, older women.

Exercise stress tests for detecting myocardial ischemia in asymptomatic patients with diabetes mellitus

The predominant cause of death in diabetes mellitus (DM) is coronary artery disease (CAD). Little is known about prevalence of silent ischemia in developing nations. We compared prevalence of silent ischemia in DM to a control group by exercise myocardial perfusion imaging (MPI) and electrocardiogram (ECG) in developing nations. The prospective multinational Ischemia Assessment with Exercise imaging in Asymptomatic Diabetes study recruited participants at 12 sites in Asia, Africa, and Latin America. DM participants were age- and gender-matched 2:1 to non-DM individuals with ≥1 CAD risk factor. Subjects underwent exercise tests that were interpreted in core labs in blinded fashion. The study included 392 DM and 205 control participants. Among participants with diagnostic ECGs, a similar proportion of DM and controls had ischemic ECG (15% vs 12%, p = 0.5). A significantly higher proportion of DM group had MPI abnormalities compared with controls (26% vs 14%, p <0.001). In participants with ischemia on MPI, only 17% had ischemic ECG, whereas in those without ischemia on MPI, 10% had ischemic ECG. In a multivariable model, DM was independently associated with abnormal MPI (odds ratio 2.1, 95% confidence interval 1.3-3.5, p = 0.004). Women were less likely to have ischemia by MPI than men (10% vs 30%, p <0.001) and concordance between ECG and MPI was much worse in women. In conclusion, in this large prospective study, asymptomatic DM participants had (1) more ischemia by exercise MPI than ECG, (2) more ischemia by MPI but not ECG than control group, and (3) ischemia by MPI was less in women than men.

Prognosis in patients with suspected or known ischemic heart disease and normal myocardial perfusion: long-term outcome and temporal risk variations

BACKGROUND

The prognostic value of a normal myocardial perfusion scintigraphy (MPS) may be well described, but long-term follow-up data are sparse, and temporal variations in risk are insufficiently elucidated.

METHODS AND RESULTS

During long-term follow-up (mean 6.2 years) of 1,327 consecutive Danish patients with normal MPS, the rate of all-cause death (ACD) was 1.9%/year (differing by gender) and of cardiac death (CD)/myocardial infarction (MI) 0.8%/year (differing by coronary artery disease, CAD). Female gender (HR: 0.60), age (HR: 1.07 per-year increment), and known CAD without prior revascularization (HR: 2.17) were statistically significant factors for ACD, whereas diabetes and previous MI per se were not. Known CAD with previous revascularization carried a low risk of ACD when adjusted for gender and age (HR: 0.56). For CD/MI, risk increased with age and threefold with known CAD, previous MI, and previous percutaneous coronary intervention. Judged from smoothed hazard functions, mortality risk increased further with time for men, elderly, and diabetics and markedly further with known CAD without prior revascularization.

CONCLUSIONS

Following a normal MPS, rates of death and hard cardiac events were low. Risk varied with age, gender, and disease history. Novel aspects of temporal risk variation suggested a general warranty period of 5 years, but less in risk groups.

The clinical utility of gene expression testing on the diagnostic evaluation of patients presenting to the cardiologist with symptoms of suspected obstructive coronary artery disease: results from the IMPACT (Investigation of a Molecular Personalized Coronary Gene Expression Test on Cardiology Practice Pattern) trial

Accurate, noninvasive evaluation for obstructive coronary artery disease (CAD) remains challenging and inefficient. In this study, 171 patients presenting with stable chest pain and related symptoms without a history of CAD were referred to 6 cardiologists for evaluation. In the prospective cohort of 88 patients, the cardiologist's diagnostic strategy was evaluated before and after gene expression score (GES) testing. The GES is a validated, quantitative blood-based diagnostic test measuring peripheral blood cell expression levels of 23 genes to determine the likelihood of obstructive CAD (at least 1 vessel with ≥ 50% angiographic coronary artery stenosis). The objective of the study was to measure the effect of the GES on diagnostic testing using a pre/post study design. There were 83 prospective patients evaluable for study analysis, which included 57 (69%) women, mean age 53 ± 11 years, and mean GES 12.5 ± 9. Presenting symptoms were classified as typical angina, atypical angina, and noncardiac chest pain in 33%, 60%, and 7% of patients (n = 27, 50, and 6), respectively. After GES, changes in diagnostic testing occurred in 58% of patients (n = 48, P < 0.001). Of note, 91% (29/32) of patients with decreased testing had low GES (≤ 15), whereas 100% (16/16) of patients with increased testing had elevated GES (P < 0.001). A historical cohort of 83 patients, matched to the prospective cohort by clinical factors, had higher diagnostic test use compared with the post-GES prospective cohort (P < 0.001). In summary, the GES showed clinical utility in the evaluation of patients with suspected obstructive CAD presenting to the cardiologist's office.

A multicenter, prospective study to evaluate the use of contrast stress echocardiography in early menopausal women at risk for coronary artery disease: trial design and baseline findings

AIMS

This multisite prospective trial, Stress Echocardiography in Menopausal Women At Risk for Coronary Artery Disease (SMART), aimed to evaluate the prognostic value of contrast stress echocardiography (CSE), coronary artery calcification (CAC), and cardiac biomarkers for prediction of cardiovascular events after 2 and 5 years in early menopausal women experiencing chest pain symptoms or risk factors. This report describes the study design, population, and initial test results at study entry.

METHODS

From January 2004 through September 2007, 366 early menopausal women (age 54±5 years, Framingham risk score 6.51%±4.4 %, range 1%-27%) referred for stress echocardiography were prospectively enrolled. Image quality was enhanced with an ultrasound contrast agent. Tests for cardiac biomarkers [high-sensitivity C-reactive protein (hsCRP), atrial natriuretic protein (ANP), brain natriuretic protein (BNP), endothelin (ET-1)] and cardiac computed tomography (CT) for CAC were performed.

RESULTS

CSE (76% exercise, 24% dobutamine) was abnormal in 42 women (11.5%), and stress electrocardiogram (ECG) was positive in 22 women (6%). Rest BNP correlated weakly with stress wall motion score index (WMSI) (r=0.189, p<0.001). Neither hsCRP, ANP, endothelin, nor CAC correlated with stress WMSI. Predictors of abnormal CSE were body mass index (BMI), diabetes mellitus, family history of premature coronary artery disease (CAD), and positive stress ECG. Twenty-four women underwent clinically indicated coronary angiography (CA); 5 had obstructive (≥50%), 15 had nonobstructive (10%-49%), and 4 had no epicardial CAD.

CONCLUSIONS

The SMART trial is designed to assess the prognostic value of CSE in early menopausal women. Independent predictors of positive CSE were BMI, diabetes mellitus, family history of premature CAD, and positive stress ECG. CAC scores and biomarkers (with the exception of rest BNP) were not correlated with CSE results. We await the follow-up data.

A multicenter evaluation of the appropriate use of single-photon emission tomography myocardial perfusion imaging in Greece

BACKGROUND

This study evaluates the appropriate use of myocardial perfusion imaging (MPI) and determines patterns and variables associated with inappropriate testing.

METHODS

Over a 10-month period data were collected prospectively from consecutive patients referred for MPI in four academic departments and an appropriate use grade was assigned (appropriate, uncertain, inappropriate, and unclassifiable scans) according to established criteria.

RESULTS

Among 3,032 referrals appropriate MPI had 72.8% of patients and 19.2% of studies were inappropriate, the remaining being uncertain (7.2%) or unclassifiable (0.8%). In multivariate analysis the asymptomatic status (odds ratio 10.7, P < .001), good functional capacity (odds ratio 1.9, P < .001), an interpretable resting electrocardiogram (odds ratio 1.8, P = .004), an age <65 years (odds ratio 1.5, P = .001) and the absence of diabetes (odds ratio 1.7, P < .001) or dyslipidemia (odds ratio 1.3, P = .014) were independent predictors of inappropriate scintigraphy. The most common indication for inappropriate testing was the assessment of asymptomatic patients <2 years after percutaneous coronary intervention (PCI) (38.9%).

CONCLUSIONS

The appropriate use of MPI is relatively high, but a considerable proportion of inappropriate scans is noted which is associated with markers of lower risk. The most common source of inappropriate testing is the assessment of asymptomatic patients <2 years after PCI.

Cardiovascular disease in women

Gender-specific data focused on cardiovascular disease (CVD) are becoming increasingly available. This is of great importance, given that CVD has become the number 1 killer of women, and unlike for men, mortality rates do not seem to be declining. Many factors are cited as the causes of sex-based differences, including delays in recognizing symptoms, underutilization of diagnostic tests and treatments, as well as anatomic, physiological, and genetic factors. Evidence of fundamental biological differences in vascular function and the underlying pathologic processes is only beginning to elucidated, motivated by growing evidence of differences in clinical presentations and outcomes between men and women. The good news is that we are starting to see improvements in outcomes for women, such as after coronary revascularization; decrease in complication rates with the advent of new techniques, such as radial access for cardiac catheterizations; as well as increased participation of women in clinical trials. The underlying mechanisms of ischemic heart disease remain to be elucidated, and will help guide therapy and ultimately may explain the higher prevalence of : subendocardial myocardial infarctions, spontaneous arterial dissections, plaque erosion, increased vasospastic disorders, such as coronary microvascular disease, and pulmonary hypertension in women compared with men. We have made great progress in understanding gender-related differences in CVDs, but much remains to be done to optimize the prevention of CVD for both men and women.

Cost-effectiveness and future implications for cardiovascular imaging

This review highlights the current economic climate for health care and the evidentiary standards that are increasingly applied to appropriate use of cardiovascular imaging. Additionally, the evidence on cost efficiency and effectiveness is explored in this review. Ongoing multicentre registries and clinical trials will further enrich this evidence base with regard to value-based imaging strategies that provide enhanced effectiveness and efficiency resulting in improved patient outcomes.

Improving the positive predictive value of exercise testing in women for coronary artery disease

The exercise treadmill test (ETT) in women has been limited by a low positive predictive value (PPV) for coronary artery disease (CAD). However, the reliability of previous studies was unsatisfactory because of the inclusion of younger women with a low prevalence of CAD. To further evaluate the diagnostic properties of the ETT in women, we evaluated a group of women with chest pain who had a positive ETT result and subsequent coronary angiography. Of the 111 women, 56 had significant CAD on angiogram, yielding a PPV of 51% for the group. However, inclusion in the analysis of several pretest attributes and specific exercise test responses improved the PPV of the ETT. Age had a major effect, with the youngest group (35 to 50 years old) having a PPV of 36% compared to 68% in the oldest group (>65 years old). Several specific exercise responses (ST-segment depression >2 mm and delayed ST-segment recovery >3.0 minutes) further separated true from false positives across all age groups, increasing the PPV to approximately 80%. Onset of ischemia at a relatively low cardiac workload of <80% maximum predicted heart rate was not a significant predictor. In conclusion, the standard ETT should remain the test of choice in ambulatory women with chest pain and no significant abnormalities on baseline electrocardiogram especially in those >65 years of age.

Coronary computed tomographic angiography as a gatekeeper to invasive diagnostic and surgical procedures: results from the multicenter CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: an International Multicenter) registry

OBJECTIVES

This study sought to examine patterns of follow-up invasive coronary angiography (ICA) and revascularization (REV) after coronary computed tomography angiography (CCTA).

BACKGROUND

CCTA is a noninvasive test that permits direct visualization of the extent and severity of coronary artery disease (CAD). Post-CCTA patterns of follow-up ICA and REV are incompletely defined.

METHODS

We examined 15,207 intermediate likelihood patients from 8 sites in 6 countries; these patients were without known CAD, underwent CCTA, and were followed up for 2.3 ± 1.2 years for all-cause mortality. Coronary artery stenosis was judged as obstructive when ≥50% stenosis was present. A multivariable logistic regression was used to estimate ICA use. A Cox proportional hazards model was used to estimate all-cause mortality.

RESULTS

During follow-up, ICA rates for patients with no CAD to mild CAD according to CCTA were low (2.5% and 8.3%), with similarly low rates of REV (0.3% and 2.5%). Most ICA procedures (79%) occurred ≤3 months of CCTA. Obstructive CAD was associated with higher rates of ICA and REV for 1-vessel (44.3% and 28.0%), 2-vessel (53.3% and 43.6%), and 3-vessel (69.4% and 66.8%) CAD, respectively. For patients with <50% stenosis, early ICA rates were elevated; over the entirety of follow-up, predictors of ICA were mild left main, mild proximal CAD, respectively, or higher coronary calcium scores. In patients with <50% stenosis, the relative hazard for death was 2.2 (p = 0.011) for ICA versus no ICA. Conversely, for patients with CAD, the relative hazard for death was 0.61 for ICA versus no ICA (p = 0.047).

CONCLUSIONS

These findings support the concept that CCTA may be used effectively as a gatekeeper to ICA.

Patterns and predictors of stress testing modality after percutaneous coronary stenting: data from the NCDR(®)

OBJECTIVES

We evaluated temporal trends and geographic variation in choice of stress testing modality after percutaneous coronary intervention (PCI), as well as associations between modality and procedure use after testing.

BACKGROUND

Stress testing is frequently performed post-PCI, but the choices among available modalities (electrocardiography only, nuclear, or echocardiography; pharmacological or exercise stress) and consequences of such choices are not well characterized.

METHODS

CathPCI Registry(®) data were linked with identifiable Medicare claims to capture stress testing use between 60 and 365 days post-PCI and procedures within 90 days after testing. Testing rates and modality used were modeled on the basis of patient, procedure, and PCI facility factors, calendar quarter, and Census Divisions using Poisson and logistic regression. Post-test procedure use was assessed using Gray's test.

RESULTS

Among 284,971 patients, the overall stress testing rate after PCI was 53.1 per 100 person-years. Testing rates declined from 59.3 in quarter 1 (2006) to 47.1 in quarter 4 (2008), but the relative use of modalities changed little. Among exercise testing recipients, adjusted proportions receiving electrocardiography-only testing varied from 6.8% to 22.8% across Census Divisions; and among exercise testing recipients having an imaging test, the proportion receiving echocardiography (versus nuclear) varied from 9.4% to 34.1%. Post-test procedure use varied among modalities; exercise electrocardiography-only testing was associated with more subsequent stress testing (13.7% vs. 2.9%; p < 0.001), but less catheterization (7.4% vs. 14.1%; p < 0.001) than imaging-based tests.

CONCLUSIONS

Modest reductions in stress testing after PCI occurring between 2006 and 2008 cannot be ascribed to trends in use of any single modality. Additional research should assess whether this trend represents better patient selection for testing or administrative policies (e.g., restricted access for patients with legitimate testing needs). Geographic variation in utilization of stress modalities and differences in downstream procedure use among modalities suggest a need to identify optimal use of the different test modalities in individual patients.

An update on exercise stress testing

Exercise stress testing is the most commonly used noninvasive method to evaluate for coronary artery disease in men and women. Although emphasis has been placed on the diagnostic value of ST-segment depression, the exercise stress test provides other valuable diagnostic and prognostic data, beyond ST-segment depression. The value of these variables, which include exercise capacity, chronotropic response, heart rate recovery, blood pressure response, and the Duke Treadmill Score, are reviewed in this article. In addition, the gender differences seen with these exercise testing variables are reviewed. In this modern era of exercise stress testing, making use of all the information from a stress test and creating a comprehensive stress testing report are recommended in the evaluation of patients with suspected coronary artery disease who undergo exercise stress testing.

Imaging Tests, Provocative Tests, Including Exercise Testing in Women with Suspected Coronary Artery Disease

Evolving knowledge regarding sex differences in coronary heart disease has demonstrated that the prevalence, symptomatology, and pathophysiology of coronary atherosclerosis vary between genders. Women experience higher mortality rates and more adverse outcomes after acute myocardial infarction than men, despite a lower prevalence of obstructive coronary artery disease. Based on recent insights into the complex pathophysiology of coronary heart disease which includes a spectrum of obstructive coronary artery disease and dysfunction of the coronary microvasculature and endothelium, the term ischemic heart disease is a more accurate term for discussion of coronary atherosclerosis specific to women. In women, with clinical features and risk factors for ischemic heart disease, the detection and evaluation of ischemic heart disease is challenging due to the diverse pathogenic mechanisms of ischemic heart diseases in women. In this article, we discuss noninvasive imaging tests, provocative tests, including exercise testing in women with suspected ischemic heart disease.

Noninvasive diagnostic techniques for coronary disease in women

Significant advances in medical treatment, medical technology, and the focus on sex-specific research have contributed to a reduction in cardiovascular mortality in women. Despite these advances, coronary artery disease (CAD) is the leading cause of cardiovascular death of women in the Western world. In the past 2 decades, the focused research on women at risk for CAD has helped to clarify our understanding of some of the sex-specific factors that are important in the detection of CAD. In women, the detection and evaluation of physiologically significant CAD can be challenging. Many of the traditional tests that are designed to detect focal areas of coronary artery stenosis are less sensitive and specific in female patients, who have a greater burden of symptoms, higher atherosclerotic burden, and lower prevalence of obstructive coronary disease. In this article, we review the available evidence on the role of contemporary noninvasive diagnostic techniques in the evaluation of women with symptoms of CAD. The authors have no funding, financial relationships, or conflicts of interest to disclose.

Nuclear perfusion imaging for functional evaluation of patients with known or suspected coronary artery disease: the future is now

Nuclear imaging, with both single-photon emission computed tomography and PET, has a well-established role in the assessment of patients with known or suspected coronary artery disease. There is a large body of evidence regarding the diagnostic accuracy and prognostic value of these modalities, however, they continue to evolve rapidly with advances in camera and tracer technology, as well as changes in imaging protocols to increase lab efficiency, improve image quality and to decrease radiation exposure to patients. Nuclear imaging also provides insights into atherogenesis at a molecular level and can be combined with other imaging modalities, providing both functional and structural data and complimentary information on the presence of coronary disease and its functional implications.

Circulation: Cardiovascular Imaging Editors’ Picks

The following articles are being highlighted as part of Circulation: Cardiovascular Imaging ’s Topic Review. This series summarize the most important articles, as selected by the editors, that have been published in the Circulation portfolio. The studies included in this article represent the most significant research in clinical translation of novel imaging technologies.

An Approach to Asymptomatic and Atypically or Typically Symptomatic Women with Cardiac Disease

The evaluation of women who are asymptomatic or presenting for evaluation of stable cardiac disease symptoms has been the focus of much research in the past decade. The rationale for this research has been that fatality rates for coronary heart disease remain higher for women than men. Detection of high-risk populations is a core component of targeted therapeutic risk reduction and is a valuable way to identify women who may benefit from early intervention that could result in improved clinical outcomes. This article discusses the evidence on assessment of women with and without suspected cardiac symptoms.