Noninvasive diagnosis of coronary artery stenosis in women with limited exercise capacity: comparison of dobutamine stress echocardiography and 99mTc sestamibi single-photon emission CT

[The Clinical use of Stress Echocardiography in Ischemic Heart Disease Cardiovascular Ultrasound (2017)15:7. Translation authors: Arystan A.Zh., Fettser D.V.]

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows detecting myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependence on operator expertise, the lack of outcome data (a widespread problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

The clinical use of stress echocardiography in ischemic heart disease

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows to detect myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician.

The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependance on operator expertise, the lack of outcome data (a widesperad problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

Gender differences in the diagnostic accuracy of SPECT myocardial perfusion imaging: a bivariate meta-analysis

BACKGROUND

It remains controversial whether the diagnostic accuracy of single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) is different in men as compared to women. We performed a meta-analysis to investigate gender differences of SPECT MPI for the diagnosis of CAD (≥50% stenosis).

METHOD

Two investigators independently performed a systematic review of the MEDLINE and EMBASE databases from inception through January 2012 for English-language studies determining the diagnostic accuracy of SPECT MPI. We included prospective studies that compared SPECT MPI with conventional coronary angiography which provided sufficient data to calculate gender-specific true and false positives and negatives. Data from studies evaluating <20 patients of one gender were excluded. Bivariate meta-analysis was used to create summary receiver operating curves.

RESULTS

Twenty-six studies met inclusion criteria, representing 1,148 women and 1,142 men. Bivariate meta-analysis yielded a mean sensitivity and specificity of 84.2% (95% confidence interval [CI] 78.7%-88.6%) and 78.7% (CI 70.0%-85.3%) for SPECT MPI in women and 89.1% (CI 84.0%-92.7%) and 71.2% (CI 60.8%-79.8%) for SPECT MPI in men. There was no significant difference in the sensitivity (P = .15) or specificity (P = .23) between male and female subjects.

CONCLUSION

In a bivariate meta-analysis of the available literature, the diagnostic accuracy of SPECT MPI is similar for both men and women.

Diagnostic efficacy of a low-dose 32-projection SPECT 99mTc-sestamibi myocardial perfusion imaging protocol in routine practice

BACKGROUND

99mTc-labeled tracers can provide better imaging quality than does TI for myocardial perfusion imaging (MPI). Nevertheless, a large study showed no significant difference in diagnostic efficacy, implying that image quality, though not optimal, may be still adequate for reliable interpretation. We thus proposed a suboptimal low-dose 32-projection single-photon emission computed tomography (SPECT) 99mTc-sestamibi (99mTc-methoxyisobutylisonitrile) MPI protocol and evaluated its diagnostic efficacy.

METHODS

A total of 1007 patients undergoing the proposed rest-stress MPI protocol were included in the study for analysis. Among them, 218 had coronary angiography, which was used as the 'gold standard' for evaluating sensitivity and specificity. The normalcy rate was obtained from 47 patients with a low cardiovascular risk. The injected dosage for 99mTc-methoxyisobutylisonitrile resting and dipyridamole stress imaging is 185 and 555 MBq, respectively, with an interval of about 2 h between the two injections. Most of the patients completed the whole MPI within 3 h.

RESULTS

Using this protocol, the sensitivity and specificity of the 218 patients with subsequent coronary angiography for determining coronary artery disease were 95 and 63%, respectively. The normalcy rate was 87%. Both the rest and stress images were adequate for confident interpretation.

CONCLUSION

The proposed low-dose 32-projection SPECT protocol has a diagnostic efficacy comparable with that reported in the literature, most of which used a higher dose and 64-projection SPECT, with additional benefits of lower radiation exposure, lower cost, and shorter study time.

Impact of gender on risk stratification by stress echocardiography

OBJECTIVE

To compare the prognostic value of stress echocardiography results in men and women with known and suspected coronary artery disease.

METHODS

We analyzed the data of 8737 patients (5529 men and 3208 women) who underwent stress echocardiography (exercise in 523 patients, dipyridamole in 6227 patients, dobutamine in 1987) for evaluating known (n=3857) or suspected (n=4880) coronary artery disease. Patients were followed up for the occurrence of overall mortality or nonfatal myocardial infarction.

RESULTS

During a median follow-up of 25 months, 1218 cardiac events (693 deaths and 525 infarctions) occurred. Moreover, 2263 patients (1731 men [31%] and 532 women [17%]; P<.0001) underwent coronary revascularization and were censored. Stress echocardiography results added prognostic information to that of clinical findings and resting wall motion score index in men and women with both known and suspected coronary artery disease. In patients with known coronary artery disease, women had a higher (P=.01) event rate than men in the presence of ischemia. The annual event rate was worse for nondiabetic women (P=.007) but not diabetic women; age had a neutral prognostic effect in the 2 sexes. In patients with suspected coronary artery disease, men without ischemia had a higher (P<.0001) event rate than women. The annual event rate was worse in men aged less than 65 years (P<.0001) or more than 65 years (P=.04), and those with (P=.03) or without (P<.0001) diabetes.

CONCLUSION

Prognosis is at least comparable in men and women with ischemia and in those with coronary artery disease and no ischemia at stress echocardiography. In these clinical settings, availability for major procedures should be similar for both genders.

In search of the false-negative exercise treadmill testing evidence-based use of exercise echocardiography

BACKGROUND

Controversy exists regarding the role of exercise treadmill testing (ETT) versus exercise stress echocardiography (ESE) as the appropriate initial noninvasive test to risk-stratify patients with chest pain. The majority of studies to date that evaluated these methodologies included patients with poor functional status and baseline electrocardiogram (ECG) abnormalities, potentially limiting the sensitivity of ETT.

HYPOTHESIS

We examined the hypothesis that given stringent standards of exercise duration and ECG interpretability, the ETT would have a high diagnostic sensitivity for the presence of significant coronary artery disease (CAD).

METHODS

Results of concurrent ETT and ESE in 3,098 patients were examined, and the subset of patients with a negative ETT and positive ESE (-ETT/ + ESE) were reviewed for the presence of CAD as a function of exercise duration (< or > or = 6 min) and baseline ECG normality.

RESULTS

In those patients with a - ETT/ + ESE who exercised > or = 6 min, 54 had a normal baseline ECG, 22 underwent angiography and 6 had CAD (all of whom had either small, grafted or collateralized vessels). Patients with a - ETT/ + ESE who were incapable of exercising 6 min were more frequently older and female. Mortality was significantly greater in the < 6 min exercise duration group (31.4 versus 3.1%).

CONCLUSIONS

These findings support the use of the ETT without imaging as the initial test in patients with chest pain who have a normal baseline ECG and are able to exercise 6 min. Using these criteria, false negative findings are generally seen in patients without critical large vessel epicardial disease. The ESE should be reserved as the initial test for patients with an abnormal baseline ECG or reduced functional capacity.

Dobutamine stress echocardiography for the detection of coronary artery disease in women

Dobutamine stress echocardiography (DSE) has good diagnostic accuracy for the diagnosis of coronary artery disease (CAD). However, in most published diagnostic studies, patients are predominantly men. In women, diagnostic accuracy may be lower because of a lower prevalence and extent of CAD, a higher incidence of dobutamine stress-induced hypotension (resulting in less stress or even nondiagnostic test results), smaller left ventricular chamber size, and the beneficial effects of estrogens on the induction of myocardial ischemia. To determine the diagnostic accuracy of DSE in women, 14 diagnostic studies published through 2006 were identified through a Medline search. For a total of 901 patients, the weighted mean sensitivity and specificity were 72% and 88%, respectively. In 7 studies directly comparing results in women and men, conflicting results were reported. However, pooled data showed nearly identical values for sensitivity and specificity in women and men. Additionally, in 6 studies directly comparing DSE results in women with those of stress nuclear scintigraphy, DSE was as sensitive and more specific to detect CAD (90% vs 70%, p <0.0001). The excellent specificity of DSE in women was also confirmed by excellent normalcy rates, ranging from 92% to 100% in women, with a <5% pretest probability of CAD. In conclusion, despite some theoretical limitations, DSE has reasonable sensitivity and excellent specificity for the detection of CAD in women. Considering the diagnostic problems of exercise electrocardiography and nuclear scintigraphy in women, stress echocardiography may be the stress modality of choice in women because of its superior diagnostic specificity.

Mechanisms of regional wall motion abnormalities in contrast-enhanced Dobutamine Stress Echocardiography

BACKGROUND

In the diagnosis of coronary artery disease (CAD) with Dobutamine Stress Echocardiography (DSE), regional wall motion abnormalities (RWMA) are assumed to indicate a perfusion deficit.

METHODS AND RESULTS

For a more particular examination of RWMAs, we compared simultaneous echo-contrast (Optisone)-enhanced DSE (0-40 microg/kg Dobutamine, 16-segment- model) and MiBi-SPECT in a prospective double-blinded study design in 69 non-selected consecutive patients (44 male, 25 female, age 64+/-12 years). Additionally, all patients were examined by coronary-angiography. The prevalence of significant CAD (stenosis >50% lumen diameter) was 52%. DSE had a sensitivity of 78% and a specificity of 66% for the detection of significant CAD with a positive and negative predictive value of 72 and 73%, respectively. Among 28 patients with significant CAD and positive DSE study (true positive), 78% displayed a corresponding perfusion deficit in MiBi-SPECT. Among 11 patients with a positive DSE study but no current significant coronary stenosis (false positive), 82% showed stress-induced RWMAs in the inferior/posterior region, 73% displayed left ventricular hypertrophy, 54% resting-ECG abnormalities and 45% resting-RWMA (3 previous MI, 2 previous CABG surgery). Among 8 patients with negative DSE study but significant coronary stenosis (false negative), 75% had a stenosis of the LCX, 63% displayed resting- WMA, 63% displayed left bundle branch block or ST-segment depression, 50% displayed only peripheral coronary stenosis, and DSE visualization was suboptimal in 38%.

CONCLUSION

This prospective study in non-selected patients shows that the majority of RWMAs in DSE are matched to a perfusion deficit detectable by nuclear imaging. Nevertheless, pre-existing cardiac abnormalities may also lead to stress-induced RWMA not associated with a perfusion deficit or mask a perfusion deficit upon DSE. Particularly in patients with LV hypertrophy, resting-RWMA, bundle branch block or ST segment depression, the predictive value of DSE may, therefore, be limited.

Noninvasive diagnosis of coronary artery disease in women

Cardiovascular disease is the leading cause of mortality and significant morbidly among women in the United States. The frequent absence of antecedent symptoms, the potential for an initial fatal cardiac event and the limitations of currently available noninvasive diagnostic tests pose challenges to healthcare practitioners as they try to optimally risk stratify patients. Therefore, the purpose of this article is to discuss the accuracy of noninvasive tests for CAD diagnosis in women.

A meta-analytic comparison of echocardiographic stressors

BACKGROUND

The relative performance of alternative stressors for stress echocardiography for the diagnosis of coronary artery disease (CAD) is not well established.

METHODS

All studies published between 1981 to December 2001 who met inclusion criteria were included in this analysis. We performed a summary receiver operator characteristic (SROC) analysis and calculated weighted mean of the likelihood ratio and sensitivity/specificity. A covariate analysis using meta-regression methods was also performed.

RESULTS

Forty-four studies presented data on Exercise, 11 on Adenosine, 80 on Dobutamine, 40 on Dipyridamole, 16 on transatrial pacing transesophageal echocardiography (Tap-TEE), and 7 on transatrial pacing transthorasic echocardiography (Tap-TTE). SROC analysis showed that the following order of most discriminatory to least: Tap-TEE, Exercise, Dipyridamole, Dobutamine and Adenosine. Weighted means sensitivity/specificity were Exercise: 82.6/84.4%, Adenosine: 68.4/80.9%, Dobutamine: 79.6/85.1%, Dipyridamole: 71.0/92.2%, Tap-TTE: 90.7/86.1%, and Tap-TEE: 86.2/91.3%. Covariate analysis showed that the discriminatory power of Exercise decreased with increasing mean age.

CONCLUSIONS

Tap-TEE is a very accurate test for both ruling in and ruling out CAD although its invasiveness may limit its clinical acceptability. Exercise is a well-balanced satisfactory test for both ruling in and ruling out but performance might be lower for the elderly. Dobutamine offers a reasonable compromise for Exercise. Dipyridamole might be good for ruling in but not for ruling out CAD. The incapability in ruling-out CAD was a major problem in clinical application of the stress. Adenosine was the least useful stressor in diagnosing CAD.

The use of stress echocardiography for prognostication in coronary artery disease: an overview

PURPOSE OF REVIEW

Stress echocardiography has a high accuracy for the detection of coronary artery disease. Additionally, it provides clinically useful prognostic information, such as resting left ventricular function, myocardial viability, stress-induced ischemia, vascular extent of wall motion abnormalities, and changes in end-systolic volume and ejection fraction with stress.

RECENT DEVELOPMENTS

The timing, extent, and severity of the stress-induced wall motion abnormalities are important determinants of long-term prognosis. Previous studies have shown the efficacy of stress echocardiography in predicting long-term cardiac events in mixed patient groups and the value of this test in selected patient subsets.

SUMMARY

This review attempts to define the role of stress echocardiography for prognostication in coronary artery disease, pointing out the ability of this technique to identify low-risk and high-risk subsets among patients with known or suspected coronary artery disease and thus guide patient management decisions.

The diagnostic value of QRS changes for prediction of coronary artery disease during exercise testing in women: false-positive rates

OBJECTIVES

The false positive rate of electrocardiographic exercise testing (ET) for coronary artery disease (CAD) in women ranges from 38 to 67%, using the ST-T changes (ST-T) criteria. The aim of this study was to compare the diagnostic accuracy of QRS duration change criteria with ST-T change criteria during ET.

METHODS

We studied 234 women (mean age 58+/-17 years, range 27-83 years), of whom 160 were pre-menopausal (PrMW; mean age 41+/-9, range 27-56) and 74 were post-menopausal (PoMW; mean age 65+/-7, range 57-83). All participants underwent ET to rule out CAD, followed by thallium stress testing (TL). QRS duration, measured with a computerized optical scanner and ST-T changes at peak ET were compared with TL. An ischemic QRS response was defined as an exercise-induced prolongation of QRS duration >3 ms.

RESULTS

The sensitivities of QRS duration changes for the entire study group, the PrMW group and the PoMW group in comparison with TL, were 93, 88 and 92%, respectively, while the corresponding rates of specificity were 91, 85 and 91%, respectively. The sensitivities of ET ST-T changes for the entire study group, for the PrMW group and for the PoMW group were 48, 46 and 54%, respectively, while the corresponding rates of specificity were 62, 75 and 79%, respectively. The false-positive rate was 20% for ischemic ST-T and 4% for ischemic QRS duration for the entire study population.

CONCLUSIONS

Computer-measured QRS duration changes during ET are more sensitive and specific than ST-T changes for the detection of ischemia in women.

Myocardial perfusion scintigraphy: the evidence

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies.

Use of pharmaceuticals in noninvasive cardiovascular diagnosis

A number of pharmaceuticals are employed as diagnostic agents for cardiovascular diseases. Four groups of agents are reviewed here: 1) vasoactive substances employed as adjuncts to physical maneuvers in diagnosis of structural heart disease; 2) vasodilators used to produce heterogeneity of coronary flow; 3) sympathomimetic agents simulating the effects of exercise on the heart for the purpose of detection of coronary artery stenosis; and 4) ultrasonic contrast agents used to enhance myocardial imaging for the assessment of segmental wall motion. In the first group are amyl nitrate, a vasodilator, and methoxamine and phenylephrine, both vasopressors. The vasodilators of the second group are dipyridamole and adenosine. When combined with scintigraphic perfusion imaging or with echocardiographic assessment of segmental wall motion, these agents can detect single- or multiple-vessel coronary artery disease with sensitivity and specificity comparable to submaximal exercise. They are especially useful for preoperative risk assessment before noncardiac surgery. The sympathomimetic agents of the third group, dobutamine and arbutamine, increase myocardial contractility and heart rate, and dilate the peripheral vasculature. As with the vasodilators, when combined with nuclear or echocardiographic techniques they are equivalent to exercise in detection of coronary disease. They are especially useful in patients with bronchospastic disease and for assessment of myocardial viability. Agents from groups 2 and 3 have acceptable side-effect and safety profiles. The last group reviewed includes echocardiographic contrast agents that, in this investigative setting, are employed to enhance detection of segmental wall motion when used with agents from groups 2 and 3.

MR flow mapping in coronary artery bypass grafts: a validation study with Doppler flow measurements

PURPOSE

To validate fast magnetic resonance (MR) flow mapping with intravascular Doppler flow measurements in vitro and in patients with nonstenotic and stenotic coronary artery bypass grafts.

MATERIALS AND METHODS

MR and Doppler flow measurements were performed in a small-diameter flow phantom with physiologic flow conditions and at baseline and during adenosine stress in 27 grafts in 23 patients, who were scheduled for cardiac catheterization. At invasive analysis, the grafts were divided into those with stenosis of less than 50% (nonstenotic) and those with stenosis greater than or equal to 50% (stenotic). In vitro velocity values and velocity values in nonstenotic and stenotic grafts were compared with linear regression analysis, and the in vitro interstudy variability was determined.

RESULTS

Excellent correlations in average peak velocity (r = 0.99, P <.001) and diastolic peak velocity (r = 0.99, P <.001) were demonstrated in vitro between MR and Doppler flow measurements, with less than 5% interstudy variability. MR and Doppler flow measurements revealed good correlations in peak velocity and velocity reserve both in nonstenotic (n = 20) (average peak velocity: r = 0.81, P <.001; diastolic peak velocity: r = 0.83, P <.001; velocity reserve: r = 0.56, P =.010) and stenotic (n = 7) (average peak velocity: r = 0.83, P <.001; diastolic peak velocity: r = 0.78, P =.001; velocity reserve: r = 0.70, P =.078) grafts.

CONCLUSION

Fast MR flow mapping provides noninvasive measures of peak velocity and velocity reserve, which closely correlate with Doppler values both in vitro and in nonstenotic and stenotic grafts.

Pharmacologic stress testing for coronary disease diagnosis: A meta-analysis

BACKGROUND

Although noninvasive pharmacologic stress tests are widely used, their relative performance is not clear. We compared the performance of pharmacologic stress tests combined with echocardiography or nuclear imaging for the diagnosis of coronary disease.

METHODS

We performed a regression meta-analysis of published data. We included studies published between January 1975 and June 1999 in which subjects underwent echocardiographic or single-photon emission computed tomography (SPECT) stress testing with adenosine, dipyridamole, or dobutamine for diagnosis of coronary artery disease. All subjects also underwent coronary angiography. Two independent reviewers abstracted population characteristics, technical factors, methodologic factors, and results and calculated test sensitivity and specificity.

RESULTS

Eighty-two studies met the inclusion criteria. The sensitivity of dipyridamole SPECT imaging, 89% (95% CI, 84%-93%), was higher than that of dipyridamole echocardiography, but the specificity of dipyridamole SPECT imaging, 65% (95% CI, 54%-74%), was lower than that of dipyridamole echocardiography. Dipyridamole and adenosine tests had similar sensitivities and specificities. The sensitivity of dobutamine echocardiography, 80% (95% CI, 77%-83%) was similar to that of dobutamine SPECT imaging, but dobutamine echocardiography had a higher specificity, 84% (95% CI, 80%-86%) than dobutamine SPECT imaging did.

CONCLUSIONS

The findings of our study can be used to guide the selection of the optimal pharmacologic stress test for each patient. Maximum sensitivity can be attained by use of a vasodilator combined with SPECT imaging. Maximum specificity can be attained by use of a vasodilator with echocardiography. The highest combination of sensitivity and specificity can be attained with dobutamine echocardiography.