Sex and test verification bias. Impact on the diagnostic value of exercise echocardiography

Multimodality Imaging in the Detection of Ischemic Heart Disease in Women

Women with coronary artery disease tend to have a worse short and long-term prognosis relative to men and the incidence of atherosclerotic cardiovascular disease is increasing. Women are less likely to present with classic anginal symptoms when compared with men and more likely to be misdiagnosed. Several non-invasive imaging modalities are available for diagnosing ischemic heart disease in women and many of these modalities can also assist with prognostication and help to guide management. Selection of the optimal imaging modality to evaluate women with possible ischemic heart disease is a scenario which clinicians often encounter. Earlier modalities such as exercise treadmill testing demonstrate significant performance variation in men and women, while newer modalities such as coronary CT angiography, myocardial perfusion imaging and cardiac magnetic resonance imaging are highly specific and sensitive for the detection of ischemia and coronary artery disease with greater parity between sexes. Individual factors, availability, diagnostic performance, and female-specific considerations such as pregnancy status may influence the decision to select one modality over another. Emerging techniques such as strain rate imaging, CT-myocardial perfusion imaging and cardiac magnetic resonance imaging present additional options for diagnosing ischemia and coronary microvascular dysfunction.

Adjusting for verification bias in diagnostic accuracy measures when comparing multiple screening tests - an application to the IP1-PROSTAGRAM study

Introduction

Novel screening tests used to detect a target condition are compared against either a reference standard or other existing screening methods. However, as it is not always possible to apply the reference standard on the whole population under study, verification bias is introduced. Statistical methods exist to adjust estimates to account for this bias. We extend common methods to adjust for verification bias when multiple tests are compared to a reference standard using data from a prospective double blind screening study for prostate cancer.

Methods

Begg and Greenes method and multiple imputation are extended to include the results of multiple screening tests which determine condition verification status. These two methods are compared to the complete case analysis using the IP1-PROSTAGRAM study data. IP1-PROSTAGRAM used a paired-cohort double-blind design to evaluate the use of imaging as alternative tests to screen for prostate cancer, compared to a blood test called prostate specific antigen (PSA). Participants with positive imaging (index) and/or PSA (control) underwent a prostate biopsy (reference standard).

Results

When comparing complete case results to Begg and Greenes and methods of multiple imputation there is a statistically significant increase in the specificity estimates for all screening tests. Sensitivity estimates remained similar across the methods, with completely overlapping 95% confidence intervals. Negative predictive value (NPV) estimates were higher when adjusting for verification bias, compared to complete case analysis, even though the 95% confidence intervals overlap. Positive predictive value (PPV) estimates were similar across all methods.

Conclusion

Statistical methods are required to adjust for verification bias in accuracy estimates of screening tests. Expanding Begg and Greenes method to include multiple screening tests can be computationally intensive, hence multiple imputation is recommended, especially as it can be modified for low prevalence of the target condition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01481-w.

Safety and feasibility of dopamine-atropine stress echocardiography

BACKGROUND

Dobutamine-atropine stress echocardiography (DSE) has lower sensitivity in patients with advanced liver disease (ALD) due to vasodilation.

HYPOTHESIS

Dopamine-atropine stress echocardiography (DopSE) may be an alternative to DSE in ALD patients by improving the blood pressure response to stress.

METHODS

The safety and tolerability of DSE and DopSE were compared in 10 volunteers. The safety, adverse effects, and efficacy of DopSE were then assessed in 105 patients, 98 of whom had ALD. Dopamine was infused in stepwise fashion from 5 µg/kg/min to a peak dose of 40 µg/kg/min. Atropine was given before and in early stages of dopamine infusion up to cumulative dose of 1.5 mg. The hemodynamic responses of 98 ALD patients were compared with 102 patients with ALD who underwent standard DSE.

RESULTS

In normal volunteers, systolic BP increased more with DopSE compared to DSE (61 ± 19 mm Hg vs 39 ± 15 mm Hg, P = .008). In 105 patients who underwent DopSE, none had adverse effects that required early stress termination. In the groups with ALD, the systolic BP increase (38 ± 28 mm Hg vs 12 ± 27 mm Hg, P < .001) and peak rate pressure product (RPP) (22 861 ± 5289 vs 17 211 ± 3848, P = <.001) were both higher in those undergoing DopSE versus DSE. The sensitivity and specificity of DopSE were 45% and 88%, respectively for coronary disease (≥70% stenosis) in 37 patients who had angiography.

CONCLUSIONS

Dopamine-atropine stress echocardiography appears to be a safe stress modality and provides greater increases in RPP in patients with ALD compared to DSE.

Diagnostic Performance of Dobutamine Stress Echocardiography in End-Stage Liver Disease

OBJECTIVES

This study determined the test performance of dobutamine stress echocardiography (DSE) in end-stage liver disease (ESLD).

BACKGROUND

The reported sensitivity of DSE in ESLD has been variable.

METHODS

Data from 633 ESLD patients who had coronary angiography within 6 months after DSE was analyzed.

RESULTS

The prevalence of coronary arterial disease (CAD) (≥70% stenosis by quantitative angiography) was 12% (74 of 633 patients). DSE sensitivity was 24% (17 of 72 patients), and specificity was 90% (503 of 559 patients). The positive and negative predictive values were 23% (17 of 73 patients) and 90% (503 of 558 patients), respectively. Stratifying the cohort into low-, intermediate-, and high-risk CAD groups yielded sensitivities of 0%, 21%, and 32%, respectively. Independent predictors of an accurate ischemic DSE result included left ventricular internal dimension at end-diastole (LVIDd) >4.8 cm and assigning ischemia based on tardokinesis or lack of low-to-peak dose hyperkinesis (p < 0.05 for all). DSE sensitivity was 38% in LVIDd >4.8 cm versus 13% with LVIDd ≤4.8 cm (p = 0.013). The sensitivity was 67% when tardokinesis or lack of hyperkinesis was considered abnormal versus 15% (p < 0.001) for readings that did not consider tardokinesis or lack of hyperkinesis abnormal. There was a higher frequency of cardiac events in patients with significant CAD who had abnormal (45%) versus normal (18%) DSE (p = 0.01).

CONCLUSIONS

The sensitivity of DSE in ESLD was low. DSE sensitivity was higher for those with larger cavity dimension and when tardokinesis or lack of hyperkinesis was considered abnormal. An abnormal DSE in those with significant CAD was associated with worse outcome.

Practical guidance for the implementation of stress echocardiography

Exercise stress testing has been widely undertaken for the diagnosis of heart diseases. The accurate assessment of clinical conditions can be conducted by comparing the findings obtained from the results of stress echocardiography with the changes in the blood/heart rate and electrocardiograms. Numerous overseas studies have reported the utility of stress echocardiography in diagnosing myocardial ischemia; in Japan, the use of this modality for this purpose was included in the national health insurance reimbursable list in 2012. Nevertheless, stress echocardiography is far from being a widespread practice in Japan. This might be due to insufficient equipment (e.g., ergometers, space for test implementation) at each medical institution, shortage of technicians and sonographers who are well experienced and who are responsible for obtaining images during stress testing. The other possible reasons include the limited evidence available in Japan and the lack of a standardized testing protocol. Further dissemination of the practice of exercise stress echocardiography in this country is deemed necessary to establish satisfactory evidence for the use of stress echocardiography in the Japanese population. To this end, efforts are underway to develop a standardized protocol and report format to be adopted throughout Japan. We here present a guideline created by the Guideline Development Committee of the Japanese Society of Echocardiography that describes safe and effective stress echocardiography protocols and report formats. The readers are encouraged to perform exercise stress echocardiography using the proposed template for consensus document and report attached to this guideline.

Positive Predictive Value of Noninvasive Stress Testing Is Poor in the Real World

Abnormal noninvasive stress test (NIST) findings do not always correlate with angiographically significant (luminal obstruction ≥50%) coronary artery disease. Positive predictive value (PPV) of NIST in the real clinical practice is not well known. The goal of this retrospective study was to determine the PPV of NIST and assess the factors affecting PPV in a US community hospital. This study included all consecutive patients (n = 355) who underwent invasive coronary angiography after a positive NIST within ~1-year duration at our institution. Three hundred twenty-four patients were included in the analysis after exclusion of 31 patients. Sixty percent of patients were female and mean age was 63.2 (SD 12.4). Myocardial perfusion imaging, echocardiogram (treadmill or dobutamine), and treadmill electrocardiogram were the tests of choice in 95% (n = 307), 4% (n = 14), and 1% (n = 3) of patients, respectively. Overall PPV of NIST was 36.4% (118/324). When patients were stratified by age (<50 years, 50-65 years, ≥65 years), older age groups had significantly higher PPV (<0.001). When patients were grouped by body mass index (<25, 25-30, ≥30), those in lower body mass index groups had higher PPV (P = 0.01). Stress echocardiogram had significantly higher PPV compared with myocardial perfusion imaging stress test (71% vs. 35%; P < 0.005). Stress test site (in-hospital vs. outpatient office) or specialty of interpreting physician did not significantly impact PPV. Multivariable logistic regression analysis revealed that older age, male sex, and total number of cardiac risk factors were significant determinants of higher PPV. Our single-center study revealed that overall PPV of NIST is poor (36.4%), more notably in young, female, or obese patients.

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.

[Myocardial ischaemia detection in women]

Screening of myocardial ischemia refers to the use of one or more diagnostic tests for coronary heart disease with a dual objective of appropriateness and promptness. In women, as compared to men, the accuracy of the different tests is worse. Thus, to overcome this sex-related penalty, we must define a diagnosis strategy based on risk stratification, enabling the identification of patients requiring invasive investigations. This review discusses various non-invasive diagnostic tests focusing on a female-specific approach and defines the use of numerous diagnostic tests with respect to both risk stratification and symptoms.

The role of stress echocardiography in the evaluation of coronary artery disease and myocardial ischemia in women

Considering the unfavorable prognosis of women with ischemic heart disease, an aggressive but safe approach to evaluate women presenting with chest pain is warranted so that coronary artery disease (CAD) can be identified and treated early. Stress echocardiography (SE) has matured into an invaluable technique for the noninvasive detection of obstructive epicardial CAD. Its versatility, accuracy, safety, noninvasiveness, and lack of radiation exposure make SE an attractive technique to apply to the assessment of women with known or suspected heart disease. This article focuses on the current evidence supporting the role of SE in the assessment of CAD and myocardial ischemia in women.

[Recommendations of the ESC guidelines regarding cardiovascular imaging]

Cardiac imaging plays a key role in the diagnosis and risk stratification in the ESC guidelines for the management of patients with stable coronary artery disease. Demonstration of myocardial ischaemia guides the decision which further diagnostic and therapeutic strategy should be followed in these patients. One should, however, not forget that there are no randomised studies supporting this type of management. In patients with a low pretest probability coronary CT angiography is the optimal tool to exclude coronary artery stenoses rapidly and effectively. In the near future, however, better data is needed showing how much cardiac imaging is really necessary and how cost-effective it is in patients with stable coronary artery disease.

The Challenges of Prevention, Diagnosis and Treatment of Ischemic Heart Disease in Women

Increasing evidence suggests that there are significant differences in the presentation, diagnosis and treatment of ischemic heart disease in women compared to men. Women often present with atypical symptoms, and this, in association with a consistent underestimation of their risk for ischemic heart disease, leads to underdiagnosis and undertreatment in women. Cardiovascular risk factors unique to women have only recently been recognized, and moreover, traditional risk factors have recently been shown to have greater impacts on women. Consequently, women suffer more disability and poorer clinical outcomes, with higher cardiovascular morbidity and mortality. These discrepancies may in part be secondary to the higher prevalence of nonobstructive coronary artery disease in women with persistent chest pain symptoms as compared to men when evaluated invasively. Focused diagnostic and therapeutic strategies unique to women are thus needed, but unfortunately, such sex-specific guidelines do not yet exist, largely due to lack of awareness, both on the part of providers and patients, as well as a paucity of evidence-based research specific to women. Although underutilized in women, diagnostic modalities, including functional and anatomic cardiac tests as well as physiologic assessments of endothelial and microvascular function, are useful for establishing the diagnosis and prognosis of suspected ischemic heart disease in women. This review discusses the current challenges of prevention, diagnosis and treatment of ischemic heart disease in women.

Noninvasive Stress Testing for Coronary Artery Disease

Stress testing remains the cornerstone for noninvasive assessment of patients with possible or known coronary artery disease (CAD). The most important application of stress testing is risk stratification. Most patients who present for evaluation of stable CAD are categorized as low risk by stress testing. These low-risk patients have favorable clinical outcomes and generally do not require coronary angiography. Standard exercise treadmill testing is the initial procedure of choice in patients with a normal or near-normal resting electrocardiogram who are capable of adequate exercise. Stress imaging is recommended for patients with prior revascularization, uninterpretable electrocardiograms, or inability to adequately exercise.

Cardiac CT vs. Stress Testing in Patients with Suspected Coronary Artery Disease: Review and Expert Recommendations

Diagnosis and management of coronary artery disease represent a major challenge to our health care systems affecting millions of patients each year. Until recently, the diagnosis of coronary artery disease could be conclusively determined only by invasive coronary angiography. To avoid risks from cardiac catheterization, many healthcare systems relied on stress testing as gatekeeper for coronary angiography. Advancements in cardiac computed tomography angiography technology now allows to noninvasively visualize coronary artery disease, challenging the role of stress testing as the default noninvasive imaging tool for evaluating patients with chest pain. In this review, we summarize current data on the clinical utility of cardiac computed tomography and stress testing in stable patients with suspected coronary artery disease.

Serum ubiquitin C-terminal hydrolase L1 as a biomarker for traumatic brain injury: a systematic review and meta-analysis

OBJECTIVE

Serum ubiquitin C-terminal hydrolase L1 (UCH-L1) has been proposed as a biomarker of traumatic brain injury (TBI). However, previous studies on levels of UCH-L1 in serum remain inconsistent. This systematic review and meta-analysis were conducted on observational studies that reported the association between serum UCH-L1 levels and TBI.

METHODS

Studies were identified by searching PubMed and ISI Web of Science up to February 2015. For the continuous outcomes, we calculated the weighted mean difference and 95% confidence interval. The statistical analysis was performed by RevMan 5.1 and Stata 12 software. Only case-control studies were included if they had data on serum UCH-L1 levels in TBI patients and healthy controls. Funnel plot and Egger's regression test were applied to assess the potential publication bias.

RESULTS

Of the 145 selected studies, 11 observational studies (including 9 case-control and 2 case-crossover studies) met the selection criteria, containing a total of 1138 TBI cases and 1373 controls. Finally, 5 case-control studies (including 673 TBI and 1004 controls) were eligible for the present meta-analysis. The results of our study showed that there was a significant increase in serum UCH-L1 levels in patients with TBI compared to controls (weighted mean difference, 0.96; 95% confidence interval, 0.31-1.61; P = .004).

CONCLUSION

In conclusion, TBI cases had higher serum UCH-L1 concentrations than matched controls. This reinforces the conceptualization of UCH-L1 as a potential biomarker of TBI.

Noninvasive stress testing for coronary artery disease

Stress testing remains the cornerstone for noninvasive assessment of patients with possible or known coronary artery disease (CAD). The most important application of stress testing is risk stratification. Most patients who present for evaluation of stable CAD are categorized as low risk by stress testing. These low-risk patients have favorable clinical outcomes and generally do not require coronary angiography. Standard exercise treadmill testing is the initial procedure of choice in patients with a normal or near-normal resting electrocardiogram who are capable of adequate exercise. Stress imaging is recommended for patients with prior revascularization, uninterpretable electrocardiograms, or inability to adequately exercise.

New insights from major prospective cohort studies with cardiac CT

Each year, 11 million patients present in the USA with new symptoms suggestive of obstructive coronary artery disease (CAD). Most undergo stress testing but <10% demonstrate myocardial ischemia. Moreover, up to 60% will have CAD which adversely affects outcomes. Cardiac computed tomography (CCT) is being used increasingly as an alternative to stress testing to rule out obstructive CAD in symptomatic patients, and large cohort studies in asymptomatic patients have identified burden of coronary atherosclerosis as a predictor of major adverse cardiovascular events (MACE). This review article will critically evaluate major clinical studies on the use of CCT in both symptomatic and asymptomatic patients and discuss the lessons for the clinical use of CCT.

Clinical implications of referral bias in the diagnostic performance of exercise testing for coronary artery disease

BACKGROUND

Exercise testing with echocardiography or myocardial perfusion imaging is widely used to risk-stratify patients with suspected coronary artery disease. However, reports of diagnostic performance rarely adjust for referral bias, and this practice may adversely influence patient care. Therefore, we evaluated the potential impact of referral bias on diagnostic effectiveness and clinical decision-making.

METHODS AND RESULTS

Searching PubMed and EMBASE (1990-2012), 2 investigators independently evaluated eligibility and abstracted data on study characteristics and referral patterns. Diagnostic performance reported in 4 previously published meta-analyses of exercise echocardiography and myocardial perfusion imaging was adjusted using pooled referral rates and Bayesian methods. Twenty-one studies reported referral patterns in 49 006 patients (mean age 60.7 years, 39.6% women, and 0.8% prior history of myocardial infarction). Catheterization referral rates after normal and abnormal exercise tests were 4.0% (95% CI, 2.9% to 5.0%) and 42.5% (36.2% to 48.9%), respectively, with odds ratio for referral after an abnormal test of 14.6 (10.7 to 19.9). After adjustment for referral, exercise echocardiography sensitivity fell from 84% (80% to 89%) to 34% (27% to 41%), and specificity rose from 77% (69% to 86%) to 99% (99% to 100%). Similarly, exercise myocardial perfusion imaging sensitivity fell from 85% (81% to 88%) to 38% (31% to 44%), and specificity rose from 69% (61% to 78%) to 99% (99% to 100%). Summary receiver operating curve analysis demonstrated only modest changes in overall discriminatory power but adjusting for referral increased positive-predictive value and reduced negative-predictive value.

CONCLUSIONS

Exercise echocardiography and myocardial perfusion imaging are considerably less sensitive and more specific for coronary artery disease after adjustment for referral. Given these findings, future work should assess the comparative ability of these and other tests to rule-in versus rule-out coronary artery disease.

A systematic review classifies sources of bias and variation in diagnostic test accuracy studies

OBJECTIVE

To classify the sources of bias and variation and to provide an updated summary of the evidence of the effects of each source of bias and variation.

STUDY DESIGN AND SETTING

We conducted a systematic review of studies of any design with the main objective of addressing bias or variation in the results of diagnostic accuracy studies. We searched MEDLINE, EMBASE, BIOSIS, the Cochrane Methodology Register, and Database of Abstracts of Reviews of Effects (DARE) from 2001 to October 2011. Citation searches based on three key papers were conducted, and studies from our previous review (search to 2001) were eligible. One reviewer extracted data on the study design, objective, sources of bias and/or variation, and results. A second reviewer checked the extraction.

RESULTS

We summarized the number of studies providing evidence of an effect arising from each source of bias and variation on the estimates of sensitivity, specificity, and overall accuracy.

CONCLUSIONS

We found consistent evidence for the effects of case-control design, observer variability, availability of clinical information, reference standard, partial and differential verification bias, demographic features, and disease prevalence and severity. Effects were generally stronger for sensitivity than for specificity. Evidence for other sources of bias and variation was limited.

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.

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.

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.

Gender-based prognostic value of pharmacological cardiac magnetic resonance stress testing: head-to-head comparison of adenosine perfusion and dobutamine wall motion imaging

This study evaluated the gender related long-term prognostic value of adenosine perfusion and dobutamine wall motion imaging as assessed during a combined single-session stress cardiac magnetic resonance (CMR) examination. In 717 patients a combined CMR stress examination was performed. Inducible perfusion deficits and wall motion abnormalities were identified visually. Clinical parameters were assessed at the time of the CMR examination. All patients were contacted to determine the occurrence of hard cardiac events (cardiac death, myocardial infarction) during a median follow-up period of 5.3 years. A complete combined CMR examination and follow-up data were available in 679 patients (471 men). A total of 77 hard cardiac events (63 in men) occurred during follow-up. Multivariate analysis revealed the presence of inducible perfusion deficits or wall motion abnormalities as independent predictors of hard cardiac events for both gender with an incremental value over conventional cardiovascular risk factors. In case of a negative stress test result, event-free survival was 100% in women for 4 years and >99% in men for 2 years after the CMR examination. CMR perfusion and wall motion testing are equally suited for cardiac risk stratification in men and women. Stress CMR negative women exhibited very low event rates up to 4 years following the examination, while in men annual event rates increased after the second year. Consequently, the generally proposed 2-year warranty period of non-invasive stress testing may be prolonged to a 4 year level in CMR stress testing negative women.

Exercise-induced left ventricular systolic dysfunction in women heterozygous for dystrophinopathy

BACKGROUND

Mutations in the X-linked gene encoding dystrophin cause skeletal and cardiac muscle diseases in men. Female "carriers" also can develop overt disease. The purpose of this study was to ascertain the prevalence of cardiac contractile abnormalities in dystrophinopathy carriers.

METHODS

Twenty-four dystrophinopathy heterozygotes and 24 normal women each underwent standard exercise stress echocardiography.

RESULTS

Heterozygotes demonstrated mildly lower left ventricular ejection fractions (LVEFs) at rest compared with controls (0.56 + or - 0.10 vs 0.62 + or - 0.07, P = .02). After exercise, the mean LVEF fell to 0.53 + or - 0.14 in heterozygotes but rose to 0.73 + or - 0.07 in controls (P < .001). Twenty-one of 24 dystrophinopathy heterozygotes demonstrated > or = 1 of the following: abnormal resting LVEF, abnormal LVEF response to exercise, or exercise-induced wall motion abnormality.

CONCLUSIONS

Women heterozygous for dystrophinopathy demonstrate significant left ventricular systolic dysfunction, which is unmasked by exercise. This finding has mechanistic implications for both inherited and acquired cardiac disease states.

Myocardial perfusion scintigraphy in asymptomatic diabetic patients: a critical review

The increasing prevalence of diabetes mellitus and the associated high cardiovascular risk has made the non-invasive identification of silent coronary heart disease in diabetic individuals an important issue. This strategy could identify higher risk asymptomatic patients with diabetes mellitus in whom coronary revascularization may improve the outcome beyond that achieved by currently recommended medical management. Stress myocardial perfusion imaging has been shown to be effective in detecting coronary heart disease and predicting adverse cardiac events in asymptomatic diabetic patients. However, the clinical utility of myocardial perfusion scintigraphy is debated intensively due to the paucity of prospective and outcome based evidence. The controversy stems from several observational studies, epidemiologic data and cost-effectiveness analyses. Thus, although several authors and professional organizations advocate the use of stress imaging for screening higher risk asymptomatic diabetic patients, others are cautious in recommending any kind of stress testing in that population. This review is based on a broad survey of the literature and discusses the potential role of stress myocardial perfusion scintigraphy in screening asymptomatic diabetic subjects for coronary heart disease in the current era and in relation with other non-invasive screening tools.

Characteristics and outcomes of patients with abnormal stress echocardiograms and angiographically mild coronary artery disease (<50% stenoses) or normal coronary arteries

BACKGROUND

Abnormal cardiac stress imaging findings are not always associated with angiographically significant coronary artery disease. The outcomes of patients with such false-positive findings have not been extensively examined. The aim of this retrospective study was to describe the characteristics and outcomes of patients with abnormal stress echocardiographic findings who had false-positive results compared with those who had true-positive results.

METHODS

Of 1,477 consecutive patients (mean age, 66 +/- 12 years; 61% men) with abnormal stress echocardiographic findings who underwent coronary arteriography within 30 days, death from any cause was ascertained.

RESULTS

At coronary arteriography, 997 patients (67.5%) had true-positive results, defined by the presence of angiographically significant coronary artery disease (> or = 50% stenoses), and 480 (32.5%) had false-positive results, defined by <50% stenoses or normal coronary arteries. Of the subgroup of patients with markedly abnormal stress echocardiographic findings (n = 605), 28% had <50% stenoses or normal coronary arteries. During an average follow-up period of 2.4 +/- 1.0 years, there were 140 deaths. The adjusted likelihood of subsequent death for patients with <50% stenoses compared to patients with > or = 50% stenoses after abnormal stress echocardiography was 1.05 (95% confidence interval, 0.86-1.31; P = .62).

CONCLUSIONS

A sizable proportion of patients with abnormal stress echocardiographic results who are referred for coronary angiography have false-positive findings. The outcomes of patients with false-positive results were similar to those of patients with true-positive results. This finding suggests that patients with false-positive results on stress echocardiography should still receive intensive risk factor management and careful clinical follow-up.

Factors affecting sensitivity and specificity of diagnostic testing: dobutamine stress echocardiography

BACKGROUND

Clinical characteristics of patients, angiographic referral bias, and several technical factors may all affect the reported diagnostic accuracy of tests. The aim of this study was to assess their influence on the diagnostic accuracy of dobutamine stress echocardiography (DSE).

METHODS

The medical literature from 1991 to 2006 was searched for diagnostic studies using DSE and meta-analysis was applied to the 62 studies thus retrieved, including 6881 patients. These studies were analyzed for patient characteristics, angiographic referral bias, and several technical factors.

RESULTS

The sensitivity of DSE was significantly related to the inclusion of patients with prior myocardial infarctions (0.834 vs 0.740, P < .01) and defining the results of DSE as already positive in case of resting wall motion abnormalities rather than obligatory myocardial ischemia (0.786 vs 0.864, P < .01). Specificity tended to be lower when patients with resting wall motion abnormalities were included in a study (0.812 vs 0.877, P < .10). The presence of referral bias adversely affected the specificity of DSE (0.771 vs 0.842, P < .01).

CONCLUSION

This analysis suggests that the reported sensitivity of DSE is likely higher and the specificity lower than expected in routine clinical practice because of the inappropriate inclusion of patients with prior myocardial infarctions, the definition of positive results on DSE, and the negative influence of referral bias. However, in the patient subset that will be sent to coronary angiography, the opposite results can be expected.

A randomized cross-over study for evaluation of the effect of image optimization with contrast on the diagnostic accuracy of dobutamine echocardiography in coronary artery disease The OPTIMIZE Trial

OBJECTIVES

The purpose of this study was to evaluate whether the addition of a contrast agent to dobutamine stress echocardiography (DSE) improves its diagnostic accuracy for coronary artery disease (CAD) and to determine the effect of image quality on the diagnostic impact of contrast agent use in this setting.

BACKGROUND

Contrast agents can improve endocardial border definition. To date, however, there are no randomized trials that have evaluated the impact of contrast agent use on the accuracy of DSE.

METHODS

Patients referred for stress testing with dobutamine echocardiography underwent 2 DSE studies: 1 with and 1 without a contrast agent, at least 4 h apart in a randomized order and within a 24-h period.

RESULTS

A total of 101 patients underwent both DSE studies. Similar hemodynamics were achieved during the 2 stress testing sessions. The use of a contrast agent improved the percentage of segments adequately visualized at baseline (from 72 +/- 24% to 95 +/- 8%) and more so at peak stress (67 +/- 28% to 96 +/- 7%); both p < 0.001. Interpretation of wall motion with high confidence also increased with contrast agent use from 36% to 74% (p < 0.001). Segment visualization with the use of a contrast agent improved in all views, but was more pronounced in the apical views. In unenhanced DSE, 36% of studies were normal, 51% had ischemia, and 8% were uninterpretable-all of which became interpretable with the use of a contrast agent. When compared with angiography (n = 92; 55 patients with CAD), accurate detection of ischemia was higher with contrast-enhanced studies versus nonenhanced studies (p = 0.02). As endocardial visualization and confidence of interpretation decreased in unenhanced studies, a greater impact of the use of a contrast agent on DSE accuracy was observed (p < 0.01).

CONCLUSIONS

During dobutamine stress echocardiography, contrast agent administration improves endocardial visualization at rest and more so during stress, leading to a higher confidence of interpretation and greater accuracy in evaluating CAD. The lesser the endocardial border visualization, the higher the impact of contrast echocardiography on accuracy.

Statistical methods to correct for verification bias in diagnostic studies are inadequate when there are few false negatives: a simulation study

BACKGROUND

A common feature of diagnostic research is that results for a diagnostic gold standard are available primarily for patients who are positive for the test under investigation. Data from such studies are subject to what has been termed "verification bias". We evaluated statistical methods for verification bias correction when there are few false negatives.

METHODS

A simulation study was conducted of a screening study subject to verification bias. We compared estimates of the area-under-the-curve (AUC) corrected for verification bias varying both the rate and mechanism of verification.

RESULTS

In a single simulated data set, varying false negatives from 0 to 4 led to verification bias corrected AUCs ranging from 0.550 to 0.852. Excess variation associated with low numbers of false negatives was confirmed in simulation studies and by analyses of published studies that incorporated verification bias correction. The 2.5th - 97.5th centile range constituted as much as 60% of the possible range of AUCs for some simulations.

CONCLUSION

Screening programs are designed such that there are few false negatives. Standard statistical methods for verification bias correction are inadequate in this circumstance.

How to improve noninvasive coronary artery disease diagnostics in premenopausal women? The influence of menstrual cycle on ST depression, left ventricle contractility, and chest pain observed during exercise echocardiography in women with angina and normal coronary angiogram

BACKGROUND

The aim was to assess the influence of menstrual cycle on results of exercise echocardiography and electrocardiography.

METHODS

Premenopausal women (n=28) with regular monthly menses, presented typical angina, positive electrocardiogram (ECG) exercise stress test, and normal coronary angiogram were recruited. Exercise supine bicycle echocardiography with simultaneous recording of 12-lead ECG was performed once a week for 4 consecutive weeks. Occurrence of angina, time to angina, time to significant ST deviation, and segmental myocardial contractility were analyzed. Blood samples were drawn to estimate follicle-stimulating hormone, luteinizing hormone, beta-estradiol, progesterone concentration and confirm the position in menstrual cycle. In correlation analysis, linear and logistic regression were used as appropriate. Qualitative variables were categorized into quartiles in logistic regression analysis.

RESULTS

Exercise ST depression was more frequently observed in both luteal phases (early luteal 78%, late luteal 86%) compared to the late follicular phase (50%, P<.05). Time to ST depression was significantly longer in late follicular phase compared to other phases. The rate of segmental exercise left ventricular hypokinesis was low and not significantly related to menstrual cycle. Using linear regression, significant positive correlation was found between estradiol-progesterone ratio and time to ST depression. Using multiple logistic regression, we confirmed that progesterone level is independent factor influencing the presence of ST depression.

CONCLUSION

In women with typical angina and normal coronary angiogram, the position in menstrual cycle influences the ST depression but not myocardial contractility during exercise echocardiography.

Defining optimal research study design for cardiovascular imaging using computed tomography angiography as a model

Patients, physicians, and payers are facing a significant increase in cardiovascular (CV) imaging use, resulting in skyrocketing societal costs, without clear improvement in patient outcomes. The need for studies evaluating the effects of CV imaging that assess appropriate end points is critical to address continued concerns over the lack of well-designed clinical studies. Thus, the investigators propose a framework, using computed tomographic angiography as a model, that should be considered in the optimal design of future imaging research and would potentially provide payers with data to make appropriate reimbursement decisions. The inclusion of risk stratification, randomization, multiple-site participation, and multigeography site enrollment are key elements in the construction of such studies. Meaningful end points with regard to operating characteristics, downstream testing, CV event rates, outcomes, and costs are essential to appropriately evaluate any new imaging technology. Only once better level evidence is formed to support CV imaging can the central issues of quality and appropriateness of CV imaging truly be evaluated. If the CV community does not embrace this type of scientific evaluation of CV imaging modalities and fails to adequately identify the value in these techniques, it may ultimately lose the ability to use them to provide optimal care to its patients.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Feasibility and diagnostic power of transthoracic coronary Doppler for coronary flow velocity reserve in patients referred for myocardial perfusion imaging

Background

Myocardial perfusion imaging (MPI), using single photon emission computed tomography (SPECT) is a validated method for detecting coronary artery disease. Transthoracic Doppler echocardiography (TTDE) of flow at rest and during adenosine provocation has previously been evaluated in selected patient groups. We therefore wanted to compare the diagnostic ability of TTDE in the left anterior descending coronary artery (LAD) to that of MPI in an unselected population of patients with chest pain referred for MPI. Our hypothesis was that TTDE with high accuracy would identify healthy individuals and exclude them from the need for further studies, enabling invasive investigations to be reserved for patients with a high probability of disease.

Methods

Sixty-nine patients, 44 men and 25 women, age 61 ± 10 years (range 35–82), with a clinical suspicion of stress induced myocardial ischemia, were investigated. TTDE was performed at rest and during adenosine stress for myocardial scintigraphy.

Results

We found that coronary flow velocity reserve (CFVR) determined from diastolic measurements separated normal from abnormal MPI findings with statistical significance. TTDE identified coronary artery disease, defined from MPI, as reversible ischemia and/or permanent defect, with a sensitivity of 60% and a specificity of 79%. The positive predictive value was 43% and the negative predictive value was 88%. There was an overlap between groups which could be due to abnormal endothelial function in patients with normal myocardial perfusion having either hypertension or diabetes.

Conclusion

TTDE is an attractive non-invasive method to evaluate chest pain without the use of isotopes, but the diagnostic power is strongly dependent on the population investigated. Even in our heterogeneous clinical cardiac population, we found that CFVR>2 in the LAD excluded significant coronary artery disease detected by MPI.

A methodological framework to distinguish spectrum effects from spectrum biases and to assess diagnostic and screening test accuracy for patient populations: application to the Papanicolaou cervical cancer smear test

BACKGROUND

A spectrum effect was defined as differences in the sensitivity or specificity of a diagnostic test according to the patient's characteristics or disease features. A spectrum effect can lead to a spectrum bias when subgroup variations in sensitivity or specificity also affect the likelihood ratios and thus post-test probabilities. We propose and illustrate a methodological framework to distinguish spectrum effects from spectrum biases.

METHODS

Data were collected for 1781 women having had a cervical smear test and colposcopy followed by biopsy if abnormalities were detected (the reference standard). Logistic models were constructed to evaluate both the sensitivity and specificity, and the likelihood ratios, of the test and to identify factors independently affecting the test's characteristics.

RESULTS

For both tests, human papillomavirus test, study setting and age affected sensitivity or specificity of the smear test (spectrum effect), but only human papillomavirus test and study setting modified the likelihood ratios (spectrum bias) for clinical reading, whereas only human papillomavirus test and age modified the likelihood ratios (spectrum bias) for "optimized" interpretation.

CONCLUSION

Fitting sensitivity, specificity and likelihood ratios simultaneously allows the identification of covariates that independently affect diagnostic or screening test results and distinguishes spectrum effect from spectrum bias. We recommend this approach for the development of new tests, and for reporting test accuracy for different patient populations.

Stress echocardiography from 1979 to present

Stress echocardiography was initially developed in 1979 and has seen substantial success in the evaluation of patients with known or suspected coronary artery disease. It has proven applicable to clinical questions of diagnosis, prognosis and follow-up. It has been heavily dependent on technologic advancements, initially digital capturing for side-by-side visualization and, more recently, developments in detailed methods of evaluating myocardial mechanics and contrast echocardiography for perfusion.

Enhanced diagnosis of coronary artery disease in women by dobutamine thallium-201 ST-segment/heart rate slope and thallium-201 myocardial SPECT

BACKGROUND/PURPOSE

The diagnosis of coronary artery disease (CAD) in women presents a great challenge because of poor exercise capacity and inadequate heart rate response during stress test. The clinical significance of stress-related ST-segment/heart rate slope (ST/HR slope) value for evaluating CAD in women remains controversial. Therefore, we conducted the present study to assess the diagnostic performance of dobutamine ST/HR slope in women, compared with myocardial perfusion study using thallium-201 single-photon emission computed tomography (Tl-201 SPECT).

METHODS

A total of 51 female patients with suspected CAD underwent simultaneous 12-lead electrocardiographic recording during 3-minute stages of dobutamine infusion as well as Tl-201 SPECT, and coronary angiography was performed within 2 weeks post Tl-201 SPECT. The sensitivity, specificity, positive predictive value and negative predictive value of dobutamine ST/HR slope and Tl-201 SPECT were assessed, and the results of coronary angiography were used as a gold standard.

RESULTS

The sensitivity, specificity and accuracy of dobutamine ST/HR slope in detecting CAD were 43%, 83% and 61%, and those of Tl-201 SPECT were 71%, 87% and 78%, respectively. However, using both positive results of Tl-201 SPECT and ST/HR slope for detecting CAD, the diagnostic specificity increased from 87% to 96%. Using both negative results of Tl-201 SPECT and ST/HR slope to exclude CAD, the negative predictive value increased from 71% to 85%. The accuracy of dobutamine ST/HR slope in detecting CAD was not affected by the use of beta-blockers.

CONCLUSION

Dobutamine ST/HR slope is less sensitive and less accurate than Tl-201 SPECT for detecting CAD in women. However, it adds diagnostic benefit to Tl-201 SPECT with only a little extra calculation.

From trees to wood and back: perspective on clinical data analysis in thoracic surgery

General thoracic surgery has been slow to embrace advanced statistical techniques to assess outcome and direct future therapy to individual patients (the "trees") based on aggregating data and discovering informative patterns in them (the "wood"). This is due in part to the nature and complexity of the practice. However, methods exist that deal with problems of small numbers, variable case volume, and heterogeneity of patients, diseases, and therapies. For effective analysis of these multiple variables, modern strategies must be used and pitfalls avoided. For generating new knowledge about appropriateness of therapy, the focus of analyses must include long-term outcome. Quality improvement efforts may be assisted by in-depth analysis of short-term outcome from a select number of centers to inform future universal efforts. Ultimately, these results need to feed back to improved management of the individual patient.