Influence of left ventricular hypertrophy on detection of coronary artery disease using exercise echocardiography

Silent coronary artery disease in asymptomatic patients with severe aortic stenosis and normal exercise testing

OBJECTIVE

There are no data about the prevalence of silent coronary artery disease in asymptomatic severe aortic stenosis patients with normal exercise testing. Importantly, unmasking significant coronary artery disease in patients with aortic stenosis could influence the choice/timing of treatment in these patients.

METHOD

Exercise testing was performed on semi-supine ergobicycle. Cardiopulmonary analysis during exercise testing, echocardiography, and laboratory analysis at rest was done. Standard clinical/electrocardiography criteria were assessed for symptoms/signs of ischemia during/after exercise testing. In patients with normal exercise testing coronary angiography was performed using standard femoral/radial percutaneous approach. Coronary stenosis was considered significant if >70% of vessel diameter or 50%-70% with fractional flow reserve ≤0.8.

RESULTS

Total of 96 patients with normal exercise testing were included (67.6 years, 50.6% males). No patient had any complication or adverse event. The Pmean was 52.7 mmHg, mean indexed aortic valve area was 0.36 cm/m and left ventricular ejection fraction, 69.5%. 19/96 patients (19.8%) had significant coronary artery disease on coronary angiography. Multivariate logistic regression analysis revealed brain natriuretic peptide and blood glucose as independent predictors of silent coronary artery disease. Brain natriuretic peptide value of 118 pg/ml had sensitivity/specificity of 63%/73% for predicting coronary artery disease (area under the curve 0.727, P = 0.006).

CONCLUSION

Our results are the first to show that in patients with severe aortic stenosis, normal left ventricular ejection fraction,, and normal exercise testing, significant coronary artery disease is present in as many as 1/5 patients. In such patients, further prospective studies are warranted to address the diagnostic value of brain natriuretic peptide in detecting silent coronary artery disease.

Pathophysiology, Diagnosis, and Treatment of Patients with Concomitant Severe Aortic Stenosis and Coronary Artery Disease: A Closer Look to the Unresolved Perplexity

Degenerative aortic stenosis (AS) and coronary artery disease (CAD) are the most prevalent cardiovascular diseases in developed countries, and they coexist in up to 50% of patients. The pathophysiological rationale behind concomitant AS and CAD is discussed in detail in this review, together with prognostic implications. Detecting CAD in patients with AS may be challenging, as AS may mask the existence and symptoms of CAD. The safety and reliability of invasive and non-invasive physiological assessment for epicardial coronary disease are also a matter of debate. Finally, the selection and timing of optimal treatment of CAD in patients with severe AS are still unclear. Given the aging of the population, the increase in the prevalence of AS, and the ongoing paradigm shift in its treatment, controversies in the diagnosis and treatment of CAD in the setting of AS are deemed to grow in importance. In this paper, we present contemporary issues in the diagnosis and management of CAD in patients with severe AS who are transcatheter aortic valve implantation (TAVI) candidates and provide perspective on the treatment approach.

French Society of Cardiology guidelines on exercise tests (part 2): Indications for exercise tests in cardiac diseases

The exercise test is performed routinely in cardiology; its main indication is the diagnosis of myocardial ischemia, evaluated along with the subject's pretest probability and cardiovascular risk level. Other criteria, such as analysis of repolarization, must be taken into consideration during the interpretation of an exercise test, to improve its predictive value. An exercise test is also indicated for many other cardiac diseases (e.g. rhythm and conduction disorders, severe asymptomatic aortic stenosis, hypertrophic cardiomyopathy, peripheral artery disease, hypertension). Moreover, an exercise test may be indicated for specific populations (women, the elderly, patients with diabetes mellitus, patients in a preoperative context, asymptomatic patients and patients with congenital heart defects). Some cardiac diseases (such as chronic heart failure or arterial pulmonary hypertension) require a cardiopulmonary exercise test. Finally, an exercise test or a cardiopulmonary exercise test is indicated to prescribe a cardiac rehabilitation programme, adapted to the patient.

ST segment/heart rate hysteresis improves the diagnostic accuracy of ECG stress test for coronary artery disease in patients with left ventricular hypertrophy

BACKGROUND

The exercise electrocardiographic stress test (ExET) is the most widely used non-invasive diagnostic method to detect coronary artery disease. However, the sole ST depression criteria (ST-max) have poor specificity for coronary artery disease in patients with left ventricular hypertrophy. We hypothesised that ST-segment depression/heart rate hysteresis, depicting the relative behaviour of ST segment depression during the exercise and recovery phase of the test might increase the diagnostic accuracy of ExET for coronary artery disease detection in such patients.

METHODS

In three cardiology centres, we studied 113 consecutive patients (mean age 66 ± 2 years; 88% men) with hypertension-related left ventricular hypertrophy at echocardiography, referred to coronary angiography after an ExET. The following ExET criteria were analysed: ST-max, chronotropic index, heart rate recovery, Duke treadmill score, ST-segment depression/heart rate hysteresis.

RESULTS

We detected significant coronary artery disease at coronary angiography in 61 patients (53%). At receiver-operating characteristic analysis, ST-segment depression/heart rate hysteresis had the highest area under the curve value (0.75, P < 0.001 when compared with the 'neutral' receiver-operating characteristic curve value of 0.5). Area under the curve values were 0.68 (P < 0.01) for the chronotropic index, 0.58 (P = NS) for heart rate recovery, 0.57 (P = NS) for ST-max and 0.52 (P = NS) for the Duke treadmill score.

CONCLUSIONS

Among currently available ExET diagnostic variables, ST-segment depression/heart rate hysteresis offers a substantially better diagnostic accuracy for coronary artery disease than conventional criteria in patients with hypertension-related left ventricular hypertrophy.

Impact of electrocardiographic interpretability on outcome in patients referred for stress testing

BACKGROUND

There is limited insight into the association of electrocardiographic interpretability with outcome in patients referred for stress testing.

METHODS

Exercise echocardiography was performed in 8226 patients with known or suspected coronary artery disease. Electrocardiograms were considered uninterpretable in the presence of left bundle-branch block (LBBB), left ventricular hypertrophy (LVH) with strain, repolarization abnormalities because of digitalis therapy, ventricular paced rhythm, preexcitation or ST depression ≥ 0.1 mV because of other causes. End points were all-cause mortality, cardiac death and hard cardiac events (i.e. cardiac death or nonfatal myocardial infarction).

RESULTS

A total of 2450 patients had uninterpretable electrocardiograms. During a follow-up period of 4.1 ± 3.5 years, there were 1011 deaths (of which 478 were cardiac deaths) and 1069 patients experienced a hard cardiac event. The 5-year rates of death, cardiac death and hard cardiac events were, respectively, 18.7%, 10.9% and 18.8% in patients with uninterpretable ECGs, compared with 9.5%, 4.1% and 10.9% in those with interpretable ECGs (P < 0.001). After covariate adjustment, lack of ECG interpretability remained an independent predictor of all-cause mortality (hazard ratio [HR] 1.25, 95% confidence interval [CI] 1.08-1.44, P = 0.002), cardiac death (HR 1.63, 95% CI 1.32-2.01, P < 0.001) and hard cardiac events (HR 1.28, 95% CI 1.11-1.47, P < 0.001). When the specific ECG abnormalities were included as covariates, LBBB, LVH and digitalis therapy remained predictors of cardiac death; LBBB and LVH were predictors of hard cardiac events, and LVH remained predictive of all-cause mortality.

CONCLUSION

Uninterpretable ECGs portend a worse prognosis in patients referred for stress testing.

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.

Usefulness of a novel ultrasound transducer for continuous monitoring treadmill exercise echocardiography to assess coronary artery disease

BACKGROUND

The feasibility of a novel ultrasound probe, which can be attached to the left ventricular (LV) apex chest wall and allows free rotation around its long axis direction for the continuous monitoring of LV wall motion, was tested.

METHODS AND RESULTS

There were 36 subjects who had coronary artery disease (CAD). By attaching a novel ultrasound probe to the chest wall, the LV apical views were recorded during treadmill exercise stress echocardiography (Echo). The continuous monitoring of LV wall motion was satisfactorily feasible in 30 of 36 patients. The visualization rate of the overall LV segments was higher at rest (90%) compared to that during peak exercise (77%). The segments were better visualized in apical portions (90-100%) than in mid (77-96%) or basal portions (68-87%). The sensitivity, specificity, and accuracy for detecting CAD were 61, 100 and 77%, respectively. The wall motion score index 3 and 6 min after exercise decreased significantly compared to those at peak exercise. The number of segments with dyssynergy was highest at the peak exercise. Ischemic ST-T depression on electrocardiography was observed only at peak stress periods.

CONCLUSIONS

Continuous monitoring treadmill exercise Echo using a novel ultrasound probe seems feasible for the non-invasive and physiological assessment of CAD.

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.

Stress Echocardiography

Stress echocardiography is commonly employed for the clinical management of known or suspected coronary artery disease. This review discusses the accuracy of the technique, which is equivalent to that of competing imaging techniques, as well as its overall role in patient management. The utilization of stress echocardiographic modalities in clinical presentations, such as chest pain, congestive heart failure, and valvular heart disease, and preoperative risk assessment, as well as determining myocardial viability, are discussed.

Diagnostic value of the recovery time-course of st slope on exercise ECG in discriminating false-from true-positive ST-segment depressions

BACKGROUND

Using the exercise ECG for diagnosing coronary artery disease (CAD) is hampered by the occurrence of false-positive (FP) ST-segment depression. Because it is known that the recovery ST-T time-course in CAD differs from that in FP subjects, the ST slope may help discriminate FP from true-positive (TP) results.

METHODS AND RESULTS

Treadmill digitized ECG from patients with significant ST-segment depressions and normal resting ECG were analyzed in 134 patients with CAD on angiography (>50% narrowing) and reversible perfusion defects (TP group), and 64 subjects with normal perfusion (FP group) on exercise single photon emission computed tomography. The ST slope between the J-point and J(80) was measured every minute up to 6-min postexercise. The ST slope was significantly higher in FP than in TP at peak exercise, and at postexercise 1-, 2- and 3-min (p<0.01, all). Thereafter, it gradually increased in TP, while monotonically decreasing in FP. Its decrease from 3- to 6-min could correctly diagnose 88% of FP subjects, whereas it was found in only 19% of TP patients (total accuracy 83%).

CONCLUSIONS

The ST slope change from early to late recovery is a simple yet reliable marker for discriminating FP from TP ST-segment responses in subjects with a normal resting ECG.

Comparison of the predictive value of exercise-induced ST depression versus exercise technetium-99m sestamibi single-photon emission computed tomographic imaging for detection of coronary artery disease in patients with left ventricular hypertrophy

Scant knowledge exists regarding the significance of either additional ST depression in the presence of baseline depression or new stress-induced ST depression in patients with left ventricular (LV) hypertrophy. Accordingly, the purpose of this investigation is to determine whether the appearance and/or severity of ST abnormalities during exercise stress testing can accurately predict the prevalence of ischemic burden as measured by quantitative technetium-99m-sestamibi single-photon emission computed tomographic imaging in patients with LV hypertrophy. The results show that the presence of exercise ST-segment depression, as well as its magnitude, are not accurate predictors for identifying patients with coronary artery disease in the presence of electrocardiographic criteria for LV hypertrophy.

Prediction of outcomes in hypertensive patients with suspected coronary disease

Stress echocardiography has been shown to improve the diagnosis of coronary artery disease in the presence of hypertension, but its value in prognostic evaluation is unclear. We sought to determine whether stress echocardiography could be used to predict mortality in 2363 patients with hypertension, who were followed for up to 10 years (mean 4.0+/-1.8) for death and revascularization. Stress echocardiograms were normal in 1483 patients (63%), 16% had resting left ventricular (LV) dysfunction alone, and 21% had ischemia. Abnormalities were confined to one territory in 489 patients (21%) and to multiple territories in 365 patients (15%). Cardiac death was less frequent among the patients able to exercise than among those undergoing dobutamine echocardiography (4% versus 7%, P< 0.001). The risk of death in patients with a negative stress echocardiogram was <1% per year. Ischemia identified by stress echocardiography was an independent predictor of mortality in those able to exercise (hazard ratio 2.21, 95% confidence intervals 1.10 to 4.43, P=0.0001) as well as those undergoing dobutamine echo (hazard ratio 2.39, 95% confidence intervals 1.53 to 3.75, P=0.0001); other predictors were age, heart failure, resting LV dysfunction, and the Duke treadmill score. In stepwise models replicating the sequence of clinical evaluation, the results of stress echocardiography added prognostic power to models based on clinical and stress-testing variables. Thus, the results of stress echocardiography are an independent predictor of cardiac death in hypertensive patients with known or suspected coronary artery disease, incremental to clinical risks and exercise results.

Advantages of exercise echocardiography in comparison to dobutamine echocardiography in the diagnosis of coronary artery disease in hypertensive subjects

OBJECTIVE

The aim of the study was to compare the efficacy and safety of two stress echocardiography methods, exercise and dobutamine, in the diagnosis of coronary artery disease in hypertensive patients with angina.

PATIENTS AND METHODS

A total of 197 treated hypertensive patients, age 53 +/- 9 years (65 women) with no history of myocardial infarction referred for coronary angiography were prospectively investigated with exercise electrocardiography (ECG), exercise and dobutamine echocardiography.

RESULTS

Sensitivity of the exercise ECG, exercise echocardiography and dobutamine echocardiography did not differ (77%, 82% and 75%). Negative predictive value of exercise ECG was significantly lower than exercise echocardiography (64% vs 79%, P < 0.01). Specificity and positive predictive value of exercise ECG were markedly lower than exercise and dobutamine echocardiography (57%, 96%, 98% and 72%, 97%, 98%, P < 0.0001 for both stress echocardiography vs ECG). Specificity and sensitivity of diagnostic methods were not influenced by the presence of echocardiographic left ventricular hypertrophy. Dobutamine infusion in comparison to exercise was more often associated with substantial arterial blood pressure rise or fall (7% vs 2%, P < 0.05) and with simple ventricular ectopy (15,7% vs 6,1%, P < 0.05).

CONCLUSIONS

In hypertensive patients with the symptoms of angina, both stress echo methods are significantly more specific than the exercise ECG test. Maximal exercise is associated with less frequent side effects than infusion of dobutamine, so exercise echocardiography may be preferred in the diagnosis of angina in hypertensive patients.

Diagnosis of myocardial ischemia in hypertensive patients

Arterial hypertension can provoke a reduction in coronary flow reserve through several mechanisms that are not mutually exclusive (i.e. epicardial coronary artery disease (CAD), left ventricular hypertrophy and structural and/or functional microvascular disease). These different targets of arterial hypertension should be explored with different diagnostic markers. In fact, stress-induced wall motion abnormalities are highly specific for angiographically assessed epicardial CAD, whereas ST segment depression and/or myocardial perfusion abnormalities are frequently found with angiographically normal coronary arteries associated with left ventricular hypertrophy and/or microvascular disease. Exercise-electrocardiography stress test can be used to screen patients with negative maximal test due to its excellent negative predictive value, which is high and comparable in normotensives and hypertensives. When exercise-electrocardiography stress test is positive (or uninterpretable or ambiguous), an imaging stress-echo test is warranted for a reliable identification of significant, prognostically malignant epicardial CAD in view of an ischemia-guided revascularization.

Anatomy of a meta-analysis: a critical review of "exercise echocardiography or exercise SPECT imaging? A meta-analysis of diagnostic test performance"

BACKGROUND

Accurate diagnosis of coronary heart disease has the potential to contribute substantially to cost-effective delivery of health services. Recent work by Fleischmann et al (JAMA 1998;280:913-20) represents an effort to summarize the accuracy of exercise echocardiography and exercise single photon emission computed tomography (SPECT).

METHODS AND RESULTS

A critique of the previous work was constructed, obtaining the 44 articles used. These articles were reviewed and summarized with established techniques for meta-analysis. The studies summarized by Fleischmann et al were found to be significantly heterogeneous (echocardiography and SPECT, both P<.001). In the SPECT cohort, combination of different radioisotopes and reading techniques, and inclusion of reports using experimental techniques, were sources of heterogeneity. In the echocardiography cohort, experimental techniques and an individual series were identified. When the sample was stratified for sources of heterogeneity, it was found that there was no significant difference in diagnostic accuracy between the echocardiography and SPECT techniques used in current clinical practice. Meta-regression with summary receiver operating characteristic curve techniques, after adjustment of the model for multicolinearity and outliers, revealed that there were no significant differences between SPECT as used in current clinical practice and echocardiography.

CONCLUSION

The report by Fleischmann et al contains serious flaws that limit its validity and generalizability.

Diagnostic and prognostic use of stress echocardiography in stable patients

Stress echocardiography is an effective diagnostic and prognostic technique in stable patients with known or suspected coronary artery disease (CAD), myocardial infarction, or chronic left ventricular dysfunction and those undergoing noncardiac surgery. Stress echocardiography is sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events regardless of the clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Stress echocardiography provides incremental prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable to that from radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for one-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.

Exercise echocardiography versus exercise electrocardiography in the diagnosis of coronary artery disease in hypertension

In hypertension, coronary artery disease (CAD) can be overestimated by stress electrocardiography (ECG) and scintigraphy due to frequent false-positive results. Exercise tests are also limited by an excessive blood pressure increase, and pharmacologic pressure normalization decreases the accuracy of the test. The aim of this study was to assess the accuracy of exercise echocardiography as an alternative test for CAD detection in hypertension, both before and after adequate blood pressure control. We studied 59 hypertensive and 59 normotensive patients undergoing coronary angiography for chest pain. Upright bicycle exercise ECG and echocardiographic tests were performed in each group in the absence of therapy; in hypertensives, the tests were repeated a day apart after blood pressure normalization with sublingual nifedipine. Significant CAD (lumen narrowing >50%) was detected in 22 hypertensive and 41 normotensive patients. In the two groups, sensitivity, specificity, and diagnostic accuracy of exercise echocardiography performed before treatment were not statistically different (95%, 94%, 94% in hypertensives and 82%, 77%, 83% in normotensives, respectively), but were significantly higher than for the exercise ECG test (68%, 70%, and 69%, respectively). After blood pressure lowering, exercise echocardiography sensitivity slightly decreased (91%), whereas specificity (100%) and diagnostic accuracy (96%) did not vary; on the contrary, exercise ECG sensitivity decreased to 45%. Therefore, according to our data, exercise echocardiography can be an accurate test and more reliable than exercise ECG to detect CAD in normotensives as well as in hypertensives. Normalization of blood pressure with nifedipine does not affect its accuracy, but markedly reduces the sensitivity of exercise ECG.

Dobutamine-atropine stress echocardiography for the detection of coronary artery disease in patients with left ventricular hypertrophy. Importance of chamber size and systolic wall stress

BACKGROUND

Left ventricular hypertrophy is a heterogeneous disorder with distinct morphologies. Changes in wall thickness, left ventricular chamber diameter, and mass alter systolic wall stress of the left ventricle and may influence ischemic threshold. Thus, the goal of this study was to investigate the effect of the different patterns of left ventricular hypertrophy on the accuracy of dobutamine-atropine stress echocardiography.

METHODS AND RESULTS

Three-hundred eighty-six patients underwent multistage dobutamine-atropine stress echocardiography and diagnostic angiography. Echocardiograms were measured for mean and relative wall thicknesses, chamber size, left ventricular mass, and end-systolic wall stress. The patterns of ventricular hypertrophy were concentric hypertrophy (increased wall thickness and mass), eccentric hypertrophy (normal wall thickness and increased mass), and concentric remodeling (increased wall thickness and normal mass). The overall sensitivity, specificity, and accuracy of dobutamine-atropine stress echocardiography for the detection of coronary artery disease were 85%, 87%, and 86%, respectively. Increased left ventricular mass index alone did not affect accuracy. Sensitivity was markedly reduced (36%) only in those with concentric remodeling. The univariate predictors of false-negative studies were single-vessel left circumflex disease, increased wall thickness, small chamber size, hyperdynamic ejection fraction, and left ventricular concentric remodeling. Multivariate predictors were concentric remodeling (P<0.0001; odds ratio, 13.5), left ventricular ejection fraction >2 SD above normal (P<0.0001), and single-vessel left circumflex disease (P<0.0007; odds ratio, 7.6). Sensitivity was excellent in patients with small ventricles and normal wall thickness and in those with normal or large chambers regardless of wall thickness.

CONCLUSIONS

Dobutamine-atropine stress echocardiography is an accurate test in most patients with left ventricular hypertrophy, but it is insensitive in the small subset with concentric remodeling.

Prevention of coronary heart disease. Part II. Secondary prevention, detection of subclinical disease, and emerging risk factors

The prevention of CHD should be a major priority among primary care physicians and subspecialists who have any dealing with the cardiovascular system. There is ample evidence from epidemiologic studies for the impact of specific risk factors on CHD events. There is also ample evidence from observational studies and clinical trials that interventions of lifestyle and pharmacologic therapy can decrease morbidity and mortality from CHD before or after the first event. It behooves the physician who wishes to practice good medicine to understand the pathophysiologic roles of the risk factors and the evidence from epidemiologic studies and clinical trials for their association with cardiovascular disease. It is important to determine the efficacy of interventions, both lifestyle and pharmacologic, in modifying CHD risk. To be effective in doing so, the practicing physician has to have the motivation to determine target goals for risk factor modification in each patient, to understand the patient's own motivations in modifying risk factors, and to define clearly with the patient the expectations of such interventions. Although there are guidelines for risk factor modification in modification of cholesterol and in hypertension, the periodic renewal of these guidelines reflects the changing concepts of risk and its modification. A cardiovascular risk factor intervention categorization is presented in Table 12. The physician must be convinced that such intervention is beneficial to the patient, cost-effective, and thus fulfills the expectations of medical practice. The practice of medicine in the evaluation and treatment of coronary heart disease has always been challenging and stimulating. The prevention of CAD disease should ultimately provide the greatest accomplishment.

Screening for coronary artery disease

Unidentified coronary artery disease remains a significant cause of premature death and morbidity during the prime of life. The availability of effective interventions for the management of ischemia has provoked new interest in screening for this condition in asymptomatic patients, in the hope of reducing the burden of this condition. Although widespread use of stress testing is ineffective, the use of imaging techniques may offer better accuracy for detection of ischemia. Other tests that identify evidence of atheroma in the peripheral or coronary circulation may be useful to identify patients at risk.

Diagnostic and Prognostic Use of Stress Echocardiography and Radionuclide Scintigraphy

Stress echocardiography and radionuclide scintigraphy are effective diagnostic and prognostic techniques in patients with known or suspected coronary artery disease (CAD), myocardial infarction (MI), chronic left ventricular dysfunction (LVD), and those undergoing noncardiac surgery. Both are sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events irrespective of clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Both provide incremental diagnostic and prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable with radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for single-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.

Advances in Exercise Echocardiography Can This Technique Still Thrive in the Era of Pharmacologic Stress Testing?

In the current literature, pharmacologic stress techniques are the focus of interest and excitement regarding new technologies and new indications such as the diagnosis of viable myocardium. In contrast, exercise echocardiography has evolved less and is less amenable to the introduction of new technologies. This article reviews the indications for exercise echocardiography (especially in contrast to pharmacologic stress), its accuracy relative to other testing, and application to clinical decision making. Exercise echocardiography remains to be well accepted as a diagnostic and risk-assessment technique, and in some clinical situations it provides valuable data that are not available during pharmacologic stress testing.

Choosing the appropriate stress modality. A clinical cardiologist's perspective

The principle application of stress testing is the detection of myocardial ischemia in patients suspected of having coronary artery disease. Stress testing is also used to assess physical exercise capacity in normal controls and patients with various types of heart disease, such as cardiomyopathy and valvular disease. The various choices of stress modalities are discussed in this article.

Exercise echocardiography. Principles, methods, and clinical use

Stress echocardiography is composed of a family of examinations in which various forms of cardiovascular stress are combined with echocardiographic imaging to assist in the diagnosis of coronary artery disease. Exercise cardiography has evolved over the past 20 years into a routinely available clinical tool employed in both university and community hospital settings. This article discusses advantages and disadvantages of using exercise echocardiography.

Use of dobutamine echocardiography for cardiac risk stratification of patients with chronic renal failure

OBJECTIVES

This study sought to define the value of dobutamine echocardiography (DbE) for cardiac risk stratification in patients with chronic renal failure (CRF).

DESIGN

Outcome study correlating results of DbE with late cardiac events in patients with CRF.

SETTING

Academic medical centre.

SUBJECTS

All patients with CRF (serum creatinine > 2.5 mg dL-1) undergoing DbE were studied; we analysed 193 consecutive patients (aged 63 +/- 13 years, 73 men).

INTERVENTIONS

A standard dobutamine-atropine stress was administered until attainment of peak dose, or the development of severe ischaemia or side-effects. The electrocardiogram (ECG) and echocardiogram were obtained before, during and after stress. Ischaemia was identified by new or worsening wall-motion abnormalities with stress.

OUTCOME MEASURES

Patients were followed up after 38 +/- 14 months for cardiac death, myocardial infarction or coronary disease progression requiring revascularization.

RESULTS

DbE demonstrated ischaemia in 36 patients (19%), scar in 36 (19%) and a normal study in 121 patients. The heart-rate response to dobutamine was submaximal (< 85% age-predicted heart rate) in the absence of wall-motion abnormalities in 69 patients (36%), 54 of whom completed the protocol. Follow-up data were complete in 191 patients (99%); cardiac events occurred in 33 patients (17%), including 17 with cardiac death, 7 with infarction, and 9 requiring late revascularization. Spontaneous events occurred in 7 patients with ischaemia, 3 with scar (8%), 11 with a nondiagnostic study (16%) and 3 patients with a normal study (6%). Over the entire follow-up, the event-free survival in patients with ischaemia (66%) was markedly lower than those without ischaemia (84%, P = 0.006). However, the event rate in patients with nonischaemic responses increased from 8% to 16% between 24 and 40 months, and whilst ischaemia was an independent predictor of outcome at 24 months, it was not at 40 months.

CONCLUSIONS

In patients with CRF, the identification of ischaemia at DbE is associated with a significant risk of adverse cardiac events. Patients with nonischaemic scans have a low frequency of events over short-term follow-up, but this increases at later follow-up. These later events may reflect progressive coronary disease, attributable to the atherogenic milieu of these patients, and imply that repeated testing may be required to maintain cardiac risk stratification in patients with CRF.

Value of dobutamine stress echocardiography for the detection of multivessel coronary artery disease

Dobutamine stress echocardiography has been shown to accurately detect coronary artery disease (CAD), but it is not clear whether it has the ability to detect multivessel CAD relative to clinical and exercise electrocardiography. Therefore, the aim of this study was to evaluate the ability of dobutamine stress echocardiography to identify multivessel CAD and ascertain its incremental value when combined with clinical and exercise test variables. One hundred twenty-one consecutive patients referred for coronary arteriography on the basis of symptoms and exercise electrocardiography underwent dobutamine stress echocardiography. Significant multivessel CAD was defined as the presence of > or =70% diameter stenosis in > or =2 major epicardial arteries. Stepwise logistic regression analysis was performed using the clinical exercise test and echocardiographic variables. The strongest independent variables predicting the presence of multivessel CAD were systolic wall thickening index at peak stress (p < 0.0001), presence of wall thickening abnormalities in multiple vascular territories (p = 0.001), and a history of acute myocardial infarction (p = 0.04). Furthermore, dobutamine echocardiography significantly enhanced the prediction of multivessel disease when combined with clinical and exercise test variables (p = 0.001). Dobutamine stress echocardiography adds independent and incremental information to clinical and exercise test variables for identifying multivessel CAD.

Outcome after normal exercise echocardiography and predictors of subsequent cardiac events: follow-up of 1,325 patients

OBJECTIVES

This study sought to examine the outcome of a large group of patients after normal exercise echocardiography and to identify potential predictors of subsequent cardiac events.

BACKGROUND

Earlier studies suggested that prognosis after normal exercise echocardiography is favorable, with a low subsequent cardiac event rate. These studies involved a small number of patients and did not have sufficient statistical power to stratify risk.

METHODS

The outcomes of 1,325 patients who had normal exercise echocardiograms were examined. End points were overall and cardiac event-free survival. Cardiac events were defined as cardiac death, nonfatal myocardial infarction and coronary revascularization. Patient characteristics were analyzed in relation to time to first cardiac event in a univariate and multivariate manner to determine which, if any, were associated with an increased hazard of subsequent cardiac events.

RESULTS

Overall survival of the study group was significantly better than that of an age- and gender-matched group obtained from life tables (p < 0.0001). The cardiac event-free survival rates at 1, 2 and 3 years were 99.2%, 97.8% and 97.4%, respectively. The cardiac event rate per person-year of follow-up was 0.9%. Subgroups with an intermediate or high pretest probability of having coronary artery disease also had low cardiac event rates. Multivariate predictors of subsequent cardiac events were angina during treadmill exercise testing (risk ratio [RR] 4.1, 95% confidence interval [CI] 1.5 to 11.0), low work load (defined as < 7 metabolic equivalents [METs] for men and < 5 METs for women; RR 3.2, 95% CI 1.4 to 7.6), echocardiographic left ventricular hypertrophy (RR 2.6, 95% CI 1.1 to 6.3) and advancing age (RR 1.04/year, 95% CI 1.0 to 1.1).

CONCLUSIONS

The outcome after normal exercise echocardiography is excellent. Subgroups with an intermediate or high pretest probability of having coronary artery disease also have a favorable prognosis after a normal exercise echocardiogram. Characteristics predictive of subsequent cardiac events (i.e., patient age, work load, angina during exercise testing and echocardiographic left ventricular hypertrophy) should be considered in the clinical interpretation of a normal exercise echocardiogram.

Relation of exercise-induced myocardial ischemia to cardiac and carotid structure

There is a strong relation of carotid atherosclerosis to coronary artery disease and left ventricular hypertrophy. In addition, abnormalities of carotid structure are strongly associated with abnormal left ventricular geometry and structure. However, little is known regarding the relation of exercise-induced ST depression to carotid atherosclerosis, carotid, or left ventricular structure in the absence of apparent coronary disease. The relationship of exercise ECG myocardial ischemia to the presence of carotid atherosclerosis and to carotid and left ventricular structure was assessed in 204 asymptomatic subjects free of clinical evidence of cardiovascular disease. Myocardial ischemia on the exercise ECG, defined by a chronotropically adjusted ST/HR slope of >3.47 microV/bpm, was associated with a nearly threefold greater likelihood of discrete carotid atherosclerosis (50% [6 of 12] versus 17% [29 of 192], P=.007) and with older age, male sex, higher systolic and diastolic blood pressures, greater left ventricular mass and mass index, and greater common carotid artery intimal-medial thickness and cross-sectional area index. Stepwise logistic regression analyses, including standard risk factors, revealed that only carotid artery cross-sectional area index (P=.0007) and systolic blood pressure (P=.005) independently predicted an abnormal chronotropically adjusted ST/heart rate slope. Moreover, among 132 subjects with > or = 10 microV of ST-segment depression, only left ventricular mass index and carotid artery cross-sectional area index were significant predictors of the chronotropically adjusted ST/heart rate slope response. Subendocardial ischemia on the exercise ECG is strongly associated with the presence of carotid atherosclerosis and is related to systolic blood pressure, carotid artery cross-sectional area index, and left ventricular mass index, independent of age, sex, and other cardiac risk factors. These findings provide additional insights into the relation between coronary and carotid atherosclerosis and suggest that an association among ischemia and left ventricular and carotid structural abnormalities may contribute to the pathogenesis of coronary events.

Use of exercise echocardiography for prognostic evaluation of patients with known or suspected coronary artery disease

OBJECTIVES

This study prospectively compared the incremental prognostic benefit of exercise echocardiography with that of exercise testing in a large cohort.

BACKGROUND

Exercise echocardiography is widely accepted as a diagnostic tool, but the prognostic information provided by this test, incremental to clinical and stress testing evaluation, is ill-defined.

METHODS

Clinical, exercise and echocardiographic variables were studied in a consecutive group of 500 patients undergoing exercise echocardiography. After exclusion of patients who underwent revascularization within 3 months of the stress test (n = 16, 3%) and those lost to follow-up (n = 21, 4%), the remaining 463 patients (mean [+/-SD] age 57 +/- 12 years, 302 men) were followed-up for 44 +/- 11 months. Outcome was related to the exercise and echocardiographic findings, and the incremental prognostic benefit of exercise echocardiography was compared with that of standard exercise testing.

RESULTS

Cardiac events occurred in 81 patients (17%), including 33 (7%) with spontaneous events (cardiac death, myocardial infarction and unstable angina) and 48 with late revascularizations due to progressive symptoms. In a multivariate Cox proportional hazards model, the likelihood of any cardiac event was increased in the presence of ischemia (relative risk [RR] 5.06, 95% confidence interval [CI] 3.09 to 8.29, p < 0.001) and lessened by more maximal stress, measured as percent age-predicted maximal heart rate (RR per 5% increment 0.84, 95% CI 0.77 to 0.92, p < 0.001). Spontaneous events were more strongly predicted by ischemia (RR 8.20, 95% CI 3.41 to 19.71, p < 0.001) and percent age-predicted maximal heart rate (RR per 5% increment 0.78, 95% CI 0.67 to 0.91, p < 0.001). An interactive logistic regression model showed that the addition of echocardiographic to exercise and clinical data offered incremental predictive value.

CONCLUSIONS

The presence of ischemia on the exercise echocardiogram can predict whether patients will experience an event. This relation is independent of, and incremental to, clinical and exercise data.

Detection of coronary artery disease in the presence of left ventricular atrophy

To evaluate the accuracy of exercise echocardiography for the recognition of coronary artery disease in the presence of left ventricular hypertrophy 70 patients were studied. Significant coronary artery disease was present in 25 patients and left ventricular hypertrophy had 29 patients. All patients underwent an exercise ECG and echocardiographic test during which cine-loop digitized echocardiography was obtained. Wall motion was analyzed and a regional wall motion score index was calculated. The overall sensitivities of exercise ECG and echocardiography for detecting coronary artery disease were 60% and 64%, respectively, and the specificities were 49% and 78%, respectively. In patients with left ventricular hypertrophy the specificity of exercise echocardiography was higher (71%) compared to exercise ECG (21%) while in patients without hypertrophy the sensitivity was higher (70% vs. 40%, respectively). Of the 19 patients with a non-diagnostic stress ECG, echocardiography correctly identified 100% of those with coronary artery disease but only 53% of those without disease. It is concluded that exercise digital echocardiography represents a good diagnostic alternative to the exercise ECG for identifying coronary artery disease in the presence of left ventricular hypertrophy and should be useful in patients with a non-diagnostic exercise ECG.