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

Evaluation of suspected ischemic heart disease in symptomatic women

There is a wealth of evidence about the role of a variety of diagnostic testing modalities to define coronary artery disease (CAD) risk in women presenting for evaluation of suspected myocardial ischemia. The exercise electrocardiogram (ECG) is the core index procedure, which can define risk in women capable of performing maximal exercise. Stress imaging, using echocardiography or myocardial perfusion single-photon emission computed tomography/positron emission tomography, is useful for symptomatic women with an abnormal resting ECG or for those who are functionally disabled. For women with low-risk stress imaging findings, there is a very low risk of CAD events, usually < 1%. There is a gradient relationship between the extent and severity of inducible abnormalities and CAD event risk. Women at high risk are those defined as having moderate to severely abnormal wall motion or abnormal perfusion imaging findings. In addition to stress imaging, the evidence of the relationship between CAD extent and severity and prognosis has been clearly defined with coronary computed tomographic angiography. In women, prognosis for those with mild but nonobstructive CAD is higher when compared with those without any CAD. The current evidence base clearly supports that women presenting with chest pain can benefit from one of the commonly applied diagnostic testing modalities.

Improving prediction of outcomes in African Americans with normal stress echocardiograms using a risk scoring system

Cardiovascular mortality is high in African Americans, and those with normal results on stress echocardiography remain at increased risk. The aim of this study was to develop a risk scoring system to improve the prediction of cardiovascular events in African Americans with normal results on stress echocardiography. Clinical data and rest echocardiographic measurements were obtained in 548 consecutive African Americans with normal results on rest and stress echocardiography and ejection fractions ≥50%. Patients were followed for myocardial infarction and death for 3 years. Predictors of cardiovascular events were determined with Cox regression, and hazard ratios were used to determine the number of points in the risk score attributed to each independent predictor. During follow-up of 3 years, 47 patients (8.6%) had events. Five variables-age (≥45 years in men, ≥55 years in women), history of coronary disease, history of smoking, left ventricular hypertrophy, and exercise intolerance (<7 METs in men, <5 METs in women, or need for dobutamine stress)-were independent predictors of events. A risk score was derived for each patient (ranging from 0 to 8 risk points). The area under the curve for the risk score was 0.82 with the optimum cut-off risk score of 6. Among patients with risk scores ≥6, 30% had events, compared with 3% with risk score <6 (p <0.001). In conclusion, African Americans with normal results on stress echocardiography remain at significant risk for cardiovascular events. A risk score can be derived from clinical and echocardiographic variables, which can accurately distinguish high- and low-risk patients.

Meta-analysis of optimal risk stratification in patients >65 years of age

This meta-analysis evaluated the optimal noninvasive strategy for cardiac risk assessment of patients >65 years of age with known or suspected coronary artery disease using the available literature. Patients >65 years of age constitute a growing proportion of the population and have higher cardiovascular morbidity and mortality, but an optimal strategy to predict the risk of cardiac events in this group is unknown. A systematic search of MEDLINE was performed for cohort studies of ≥100 patients >65 years old with ≥12 months of follow-up that reported cardiac death and/or nonfatal myocardial infarction after any of stress myocardial perfusion imaging (MPI), stress echocardiography, or exercise tolerance testing (ETT) for known or suspected coronary artery disease. Pooled annualized event rates were calculated for each technique. Summary odds ratios (ORs) between normal and abnormal test results were calculated using a random-effects model. Seventeen studies (MPI 7, stress echocardiography 7, ETT 3) in 13,304 patients (mean age 75.5 years) were included. Abnormal compared to normal stress MPI (OR 11.8, 95% confidence interval [CI] 7.5 to 18.7) and stress echocardiography (OR 3.2, 95% CI 2.6 to 3.9) accurately stratified risk in patients. However, patients with abnormal and normal ETT results had similar cardiac event rates (OR 3.1, 95% CI 0.8 to 11.5). In conclusion, stress imaging with MPI or stress echocardiography effectively stratified risk in patients, whereas ETT alone did not.

Non-invasive imaging in coronary artery disease including anatomical and functional evaluation of ischaemia and viability assessment

Coronary artery disease has an important impact on the morbidity and mortality statistics and health economics worldwide. Diagnosis of coronary artery disease is important in risk stratification and guides further management. Invasive coronary angiography is the traditional method of imaging the coronary arteries and remains the gold standard. It detects luminal stenosis but provides little information about the vessel wall or plaques. Besides, not all anatomical lesions are functionally significant. This has lent itself to a wide variety of imaging techniques to identify and assess a flow-limiting stenosis. The approach to diagnosis of coronary artery disease is broadly based on anatomical and functional imaging. Coronary CT and MRI of coronary arteries provide an anatomical assessment of coronary stenosis. Coronary calcium score and coronary CT assess subclinical atherosclerosis by assessing the atherosclerotic plaque burden. The haemodynamic significance of a coronary artery stenosis can be assessed by stress radioisotope studies, stress echocardiography and stress MRI. The more recent literature also focuses on plaque assessment and identification of plaques that are likely to give rise to an acute coronary syndrome. There is an explosion of literature on the merits and limitations of the different imaging modalities. This review article will provide an overview of all the imaging modalities in the diagnosis of coronary artery disease.

Stress echocardiography vs nuclear stress imaging in clinical cardiology

Stress echocardiography and nuclear stress imaging are important non-invasive tools in clinical cardiology. This review discusses the uses, strengths and limitations of these imaging modalities and looks at whether stress echocardiography can actually replace nuclear stress imaging.

The role of dobutamine stress cardiovascular magnetic resonance in the clinical management of patients with suspected and known coronary artery disease

BACKGROUND

Recent studies have demonstrated the consistently high diagnostic and prognostic value of dobutamine stress cardiovascular magnetic resonance (DCMR). The value of DCMR for clinical decision making still needs to be defined. Hence, the purpose of this study was to assess the utility of DCMR regarding clinical management of patients with suspected and known coronary artery disease (CAD) in a routine setting.

METHODS AND RESULTS

We prospectively performed a standard DCMR examination in 1532 consecutive patients with suspected and known CAD. Patients were stratified according to the results of DCMR: DCMR-positive patients were recommended to undergo invasive coronary angiography and DCMR-negative patients received optimal medical treatment. Of 609 (40%) DCMR-positive patients coronary angiography was performed in 478 (78%) within 90 days. In 409 of these patients significant coronary stenoses ≥ 50% were present (positive predictive value 86%). Of 923 (60%) DCMR-negative patients 833 (90%) received optimal medical therapy. During a mean follow-up period of 2.1 ± 0.8 years (median: 2.1 years, interquartile range 1.5 to 2.7 years) 8 DCMR-negative patients (0.96%) sustained a cardiac event.In 131 DCMR-positive patients who did not undergo invasive angiography, 20 patients (15%) suffered cardiac events. In 90 DCMR-negative patients (10%) invasive angiography was performed within 2 years (range 0.01 to 2.0 years) with 56 patients having coronary stenoses ≥ 50%.

CONCLUSION

In a routine setting DCMR proved a useful arbiter for clinical decision making and exhibited high utility for stratification and clinical management of patients with suspected and known CAD.

Synergistic effect of coronary artery disease risk factors on long-term survival in patients with normal exercise SPECT studies

BACKGROUND

Normal exercise single-photon emission computed tomography (SPECT) studies are associated with a low event rate (<1.0%/year) during short-term follow-up. The influence of cardiac risk factors on long-term outcomes in such patients has not been well studied.

MATERIAL AND METHODS

2,597 patients (55 ± 12 years, male 41%) without a history of heart disease and a normal exercise SPECT between the years 1995 and 2006 were followed for a mean 6.8 ± 3.1 years for all-cause mortality assessed for using the Social Security Death Index. Baseline clinical risk factors and other clinical information were recorded for each patient and compared to outcomes.

RESULTS

The mortality rate was 0.9%/year for our overall study population but varied according to individual baseline risk factors. Three coronary artery disease (CAD) risk factors were significant predictors of all-cause mortality: hypertension, diabetes, and smoking. When all three were absent, long-term all-cause mortality rate averaged 0.2%/year and when all three were present, all-cause mortality averaged 1.8%/year, constituting a 5.7-fold adjusted increase in risk (95% CI 2.7-12.8, P < .0001).

CONCLUSIONS

During follow-up, annualized mortality rate varies markedly according to the number of CAD risk factors in patients without known heart disease and a normal exercise SPECT stress. Despite overall excellent long-term prognosis of a normal exercise SPECT, the burden of traditional CAD risk factors exert a strong synergistic influence on long-term survival and warrant aggressive treatment in this patient population.

Stress echocardiography in the district hospital setting: a cost-saving analysis

AIMS

Accurate and cost-effective techniques are required for investigating patients experiencing chest pain, given the significant workload this patient cohort represents. We determined the cost impact of stress echocardiography compared with myocardial perfusion scintigraphy and coronary angiography in the investigation of patients with chest pain deemed unsuitable for exercise treadmill testing.

METHODS AND RESULTS

A total of 200 patients with chest pain-with a low-intermediate probability of coronary artery disease-consecutively referred for stress echocardiography were recruited. Referring clinicians were asked which management strategy they would have chosen were the stress echocardiography service unavailable. The cost saving of stress echocardiography, an accuracy analysis, and adverse outcomes at 6 and 24 months follow-up were determined. The total cost attributable to the stress echocardiography service was Pound Sterling 58 368. If unavailable, 78 (39%) patients would have been referred for angiography and 122 (61%) for perfusion scintigraphy at a cost of Pound Sterling 56 316 and Pound Sterling 42 090, respectively, with a total cost of Pound Sterling 98 406. This represents a cost saving of Pound Sterling 40 038.

CONCLUSION

Stress echocardiography is a cost saving method for the investigation of chest pain in patients with low-intermediate risk of flow limiting coronary artery disease in the district hospital setting.

Pre-exercise cardiology screening guidelines for asymptomatic patients with diabetes

Coronary heart disease is a major cause of morbidity and mortality in persons with diabetes mellitus. Exercise is an important cornerstone in the treatment and management of diabetes but is also associated with a heightened risk of sudden cardiac death in those with occult coronary heart disease. Before beginning a physical activity program that involves anything greater than moderate intensity exercise, consideration should be given to screening asymptomatic persons with diabetes for silent myocardial ischemia.

Safety of contrast in stress echocardiography in stable patients and in patients with suspected acute coronary syndrome but negative 12-hour troponin

Limited studies are available demonstrating the safety of contrast agents in patients undergoing stress echocardiography and none in patients with suspected acute coronary syndrome (ACS). Therefore, we sought to assess the safety profile of contrast agents in patients with stable chest pain and in those with suspected ACS (nondiagnostic electrocardiogram and negative initial 12-hour cardiac troponin test results). During a 4-year period, 3,704 patients underwent stress echocardiography (exercise or dobutamine), of whom, 929 (25%) had suspected ACS. Contrast agents (SonoVue 46%, Luminity 54%) were used in 1,150 patients (31%). No patients died with or without contrast administration. No nonfatal acute myocardial infarction occurred in patients administered contrast agents compared with 3 cases of acute myocardial infarction in the noncontrast group (p = 0.24). Two cases of sustained ventricular tachycardia developed, one in each group (p = 0.98). Compared with those who did not receive contrast, patients in both the stable chest pain and the suspected ACS groups had a greater burden of cardiovascular risk factors. The left ventricular function at rest was significantly worse in the patients who received contrast than in those who did not in the suspected ACS group. Also, a greater ischemic burden was present in those receiving contrast than in those not receiving it in both the stable chest pain and the suspected ACS groups. In conclusion, despite the presence of greater risk features compared with patients undergoing unenhanced stress echocardiography, the administration of ultrasound contrast agents (SonoVue and Luminity) in those with stable chest pain and those with suspected ACS was not associated with excess adverse events.

Are some false-positive stress echocardiograms a forme fruste variety of apical ballooning syndrome?

The mechanisms for abnormal stress echocardiograms (SEs) in patients with normal coronary arteries have not been clearly elucidated. We hypothesized that in some patients, this phenomenon may represent a forme fruste of apical ballooning syndrome (ABS). The aim of the study was to evaluate the characteristics of patients with strongly false-positive SEs and determine whether there were similarities to ABS. Thirty-one patients from the Mayo Clinic stress echocardiography database who had normal function at rest, extensive regional wall motion abnormalities in association with an abnormal response of left ventricular end-systolic cavity size at peak stress, and angiographically normal coronary arteries were evaluated. Eighty-four percent were women with a mean age of 61 +/- 12 years, 6% had a positive stress electrocardiogram, and only 26% had a hypertensive response to stress. In 81%, left ventricular ejection fraction decreased with stress and 97% developed new regional wall motion abnormalities in > or =4 segments. Peak wall motion score index was 1.65 +/- 0.39. Midventricular (100%) and apical (87%) segments were most often involved with relative sparing of the basal segments (77%; p = 0.01). There were no deaths during follow-up (2.3 +/- 0.7 years). In conclusion, the major findings of this study were that strongly false-positive SEs occurred predominantly in postmenopausal women, and frequently involved the apical and mid-left ventricular segments, features that were similar to ABS. Data were consistent with the hypothesis that some false-positive SEs may represent a forme fruste of ABS.

American Society of Echocardiography Consensus Statement on the Clinical Applications of Ultrasonic Contrast Agents in Echocardiography

ACCREDITATION STATEMENT: The American Society of Echocardiography (ASE) is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The ASE designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit.trade mark Physicians should only claim credit commensurate with the extent of their participation in the activity. The American Registry of Diagnostic Medical Sonographers and Cardiovascular Credentialing International recognize the ASE's certificates and have agreed to honor the credit hours toward their registry requirements for sonographers. The ASE is committed to resolving all conflict-of-interest issues, and its mandate is to retain only those speakers with financial interests that can be reconciled with the goals and educational integrity of the educational program. Disclosure of faculty and commercial support sponsor relationships, if any, have been indicated.

TARGET AUDIENCE

This activity is designed for all cardiovascular physicians, cardiac sonographers, and nurses with a primary interest and knowledge base in the field of echocardiography; in addition, residents, researchers, clinicians, sonographers, and other medical professionals having a specific interest in contrast echocardiography may be included.

OBJECTIVES

Upon completing this activity, participants will be able to: 1. Demonstrate an increased knowledge of the applications for contrast echocardiography and their impact on cardiac diagnosis. 2. Differentiate the available ultrasound contrast agents and ultrasound equipment imaging features to optimize their use. 3. Recognize the indications, benefits, and safety of ultrasound contrast agents, acknowledging the recent labeling changes by the US Food and Drug Administration (FDA) regarding contrast agent use and safety information. 4. Identify specific patient populations that represent potential candidates for the use of contrast agents, to enable cost-effective clinical diagnosis. 5. Incorporate effective teamwork strategies for the implementation of contrast agents in the echocardiography laboratory and establish guidelines for contrast use. 6. Use contrast enhancement for endocardial border delineation and left ventricular opacification in rest and stress echocardiography and unique patient care environments in which echocardiographic image acquisition is frequently challenging, including intensive care units (ICUs) and emergency departments. 7. Effectively use contrast echocardiography for the diagnosis of intracardiac and extracardiac abnormalities, including the identification of complications of acute myocardial infarction. 8. Assess the common pitfalls in contrast imaging and use stepwise, guideline-based contrast equipment setup and contrast agent administration techniques to optimize image acquisition.

Non-invasive cardiac imaging techniques and vascular tools for the assessment of cardiovascular disease in type 2 diabetes mellitus

Cardiovascular disease is the major cause of mortality in type 2 diabetes mellitus. The criteria for the selection of those asymptomatic patients with type 2 diabetes who should undergo cardiac screening and the therapeutic consequences of screening remain controversial. Non-invasive techniques as markers of atherosclerosis and myocardial ischaemia may aid risk stratification and the implementation of tailored therapy for the patient with type 2 diabetes. In the present article we review the literature on the implementation of non-invasive vascular tools and cardiac imaging techniques in this patient group. The value of these techniques as endpoints in clinical trials and as risk estimators in asymptomatic diabetic patients is discussed. Carotid intima-media thickness, arterial stiffness and flow-mediated dilation are abnormal long before the onset of type 2 diabetes. These vascular tools are therefore most likely to be useful for the identification of 'at risk' patients during the early stages of atherosclerotic disease. The additional value of these tools in risk stratification and tailored therapy in type 2 diabetes remains to be proven. Cardiac imaging techniques are more justified in individuals with a strong clinical suspicion of advanced coronary heart disease (CHD). Asymptomatic myocardial ischaemia can be detected by stress echocardiography and myocardial perfusion imaging. The more recently developed non-invasive multi-slice computed tomography angiography is recommended for exclusion of CHD, and can therefore be used to screen asymptomatic patients with type 2 diabetes, but has the associated disadvantages of high radiation exposure and costs. Therefore, we propose an algorithm for the screening of asymptomatic diabetic patients, the first step of which consists of coronary artery calcium score assessment and exercise ECG.

Can we identify those at risk for a nondiagnostic treadmill test in a chest pain observation unit?

BACKGROUND

Exercise treadmill testing (ETT) is a testing modality that has shown to be a useful chest pain observation unit (CPU). One limitation of this tool is the high rate of nondiagnostic tests. We aim to create a predictive model to discriminate a patient's risk for a nondiagnostic test.

METHODS

This is a retrospective analysis of consecutive subjects admitted to our CPU and undergoing an ETT from January 2001 to December 2006. To account for any variation in physician practice, the training set was those patients admitted January 2004 to December 2006 and the testing set comprised those evaluated January 2001 to December 2003. Recursive partitioning with 10-fold cross validation was used to identify significant variables associated with the outcome measure of a nondiagnostic treadmill test. The beta coefficient from the regression model was used to create a risk score. This risk score was then used stratify patients.

RESULTS

A total of 1708 subjects underwent ETT during the study period. The training set comprised 408 subjects with 62 having a nondiagnostic test. Logistic regression identified age, prior history of coronary artery disease, smoking, and diabetes variables used to create a scoring system. The testing set identified 387 (29.7) subjects meeting our criteria as low risk (9.0%) nondiagnostic test and identified 298 (22.9%) at high risk for a nondiagnostic test (32.8%).

CONCLUSION

Using a simple scoring system to stratify patients undergoing ETT into 3 risk groups, we were able to identify a low-risk group <10% and a high-risk group >30% for having a nondiagnostic ETT.

Usefulness of high functional capacity in patients with exercise-induced ST-depression to predict a negative result on exercise echocardiography and low prognostic risk

Although exercise electrocardiography (ExECG) is commonly used to detect coronary artery disease, the diagnostic accuracy and reliability of positive (ischemic) results of ExECG in low- and intermediate-risk populations are limited. Accordingly, many patients with positive results of ExECG undergo secondary evaluation using noninvasive stress imaging such as exercise echocardiography. Functional capacity is a strong predictor of prognosis and, indirectly, of high-risk coronary artery disease. It was hypothesized that high functional capacity in patients with positive results of ExECG would predict (1) negative results on subsequent exercise echocardiography and (2) a low risk for late mortality. Results were analyzed in 104 consecutive patients (79 men, 25 women; mean age 49 years, range 27 to 76) referred for exercise echocardiography after positive results of ExECG with a treadmill workload of > or =10 METs. Late all-cause mortality was also determined in these patients. Exercise echocardiographic results were negative in 93% of patients (97 of 104; 92% of men [73 of 79] and 100% of women [25 of 25]) and positive in 7% (7 of 104). During a mean follow-up period of 7.2 +/- 1.9 years, there was 1 death. In conclusion, high functional capacity in patients with positive results of ExECG is associated with negative exercise echocardiographic results in most patients and very low late mortality. Patients with ischemic ST-segment response on ExECG who achieve workloads of > or =10 METs infrequently require additional noninvasive or invasive evaluation.

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.

Usefulness of stress echocardiography for risk stratification and prognosis of patients with left ventricular hypertrophy

The purpose of this study was to evaluate the role of stress echocardiography in the risk stratification and prognosis of patients with left ventricular (LV) hypertrophy. One thousand two patients (mean age 62 +/- 13 years, 35% men) with LV hypertrophy (defined by LV mass index >115 g/m(2) for men and >95 g/m(2) for women) were evaluated. LV mass was calculated using the linear dimension method, as recommended by the American Society of Echocardiography. The calculation of relative wall thickness was performed using the formula (2 x posterior wall thickness)/LV internal diameter. Concentric and eccentric LV hypertrophy were defined as relative wall thicknesses > or =0.42 and <0.42 cm, respectively. Follow-up (2.6 +/- 1.1 years) for confirmed myocardial infarction and cardiac death (n = 71) was obtained. Four hundred seventy-three patients (47%) had concentric hypertrophy, and 529 patients (53%) had eccentric hypertrophy. In patients with either concentric or eccentric LV hypertrophy, stress echocardiography was able to effectively risk-stratify normal versus abnormal subgroups (event rate 1.1% vs 4.9% per year, p <0.0001), whereas stress electrocardiography was unable to do so. In the cohort with normal stress echocardiographic results, patients with concentric LV hypertrophy had an event rate 5 times higher than those with eccentric LV hypertrophy (event rate 1.7% vs 0.3% per year, p = 0.007). In conclusion, stress echocardiography effectively risk-stratifies patients with LV hypertrophy compared with stress electrocardiography. Normal stress echocardiographic results in patients with concentric LV hypertrophy indicate a worse prognosis than in patients with eccentric LV hypertrophy, probably reflecting decreased sensitivity in this cohort. However, abnormal stress echocardiographic results portend a worse prognosis in patients with either concentric or eccentric LV hypertrophy.

Prognostic value of myocardial contrast echocardiography in patients presenting to hospital with acute chest pain and negative troponin

We hypothesized that myocardial contrast echocardiography (MCE) could be used to stratify risk in patients with suspected acute coronary syndrome but a nondiagnostic electrocardiogram and negative troponin. Pretest Thrombolysis In Myocardial Infarction (TIMI) scores were determined. Exercise electrocardiographic data in those patients undergoing treadmill stress echocardiography as part of risk evaluation were analyzed independently of echocardiographic data. On a separate day, low-power MCE at rest and during vasodilator stress was performed. All patients were followed for cardiac events (cardiac death, myocardial infarction, and revascularization). Of 148 patients, 27 demonstrated abnormal myocardial contrast echocardiographic results and had higher cardiac event rates compared with those with normal myocardial contrast echocardiographic findings (59% vs 7%, p <0.0001) at follow-up (8 +/- 5 months). Hard cardiac event rates (death and nonfatal myocardial infarction) were low (3%) in patients with normal myocardial contrast echocardiographic findings. Cardiac events in patients with abnormal myocardial contrast echocardiographic findings (59%) were significantly higher than those predicted by a high-risk TIMI score (33%, p = 0.0023) and compared with those predicted by high-risk exercise electrocardiography (80% vs 57%, p = 0.0003). In conclusion, stress MCE was superior to TIMI risk score and exercise electrocardiography in the assessment of risk in patients with suspected acute coronary syndrome, nondiagnostic electrocardiogram, and negative troponin.

Role of non-invasive imaging in the management of coronary artery disease: an assessment of likely change over the next 10 years. A report from the British Cardiovascular Society Working Group

Coronary angiography has been the gold standard for determining the severity, extent and prognosis of coronary atheromatous disease for the past 15-20 years. However, established non-invasive testing (such as myocardial perfusion scintigraphy and stress echocardiography) and newer imaging modalities (multi-detector x ray computed tomography and cardiovascular magnetic resonance) now need to be considered increasingly as a challenge to coronary angiography in contemporary practice. An important consideration is the degree to which appropriate use of such techniques impacts on the need for coronary angiography over the next 10-15 years. This review aims to determine the role of the various investigation techniques in the management of coronary artery disease and their resource implications, and should help determine future service provision, accepting that we are in a period of significant technological change.

The Prognostic Value of Normal Exercise Myocardial Perfusion Imaging and Exercise Echocardiography

OBJECTIVES

The purpose of this work was to determine the prognostic value of normal exercise myocardial perfusion imaging (MPI) tests and exercise echocardiography tests, and to determine the prognostic value of these imaging modalities in women and men.

BACKGROUND

Exercise MPI and exercise echocardiography provide prognostic information that is useful in the risk stratification of patients with suspected coronary artery disease (CAD).

METHODS

We searched the PubMed, Cochrane, and DARE databases between January 1990 and May 2005, and reviewed bibliographies of articles obtained. We included prospective cohort studies of subjects who underwent exercise MPI or exercise echocardiography for known or suspected CAD, and provided data on primary outcomes of myocardial infarction (MI) and cardiac death with at least 3 months of follow-up. Secondary outcomes (unstable angina, revascularization procedures) were abstracted if provided. Studies performed exclusively in patients with CAD were excluded.

RESULTS

The negative predictive value (NPV) for MI and cardiac death was 98.8% (95% confidence interval [CI] 98.5 to 99.0) over 36 months of follow-up for MPI, and 98.4% (95% CI 97.9 to 98.9) over 33 months for echocardiography. The corresponding annualized event rates were 0.45% per year for MPI and 0.54% per year for echocardiography. In subgroup analyses, annualized event rates were <1% for each MPI isotope, and were similar for women and men. For secondary events, MPI and echocardiography had annualized event rates of 1.25% and 0.95%, respectively.

CONCLUSIONS

Both exercise MPI and exercise echocardiography have high NPVs for primary and secondary cardiac events. The prognostic utility of both modalities is similar for both men and women.

Relationship between coronary artery calcification detected by electron-beam computed tomography and abnormal stress echocardiography: association and prognostic implications

OBJECTIVES

The purpose of this study was to compare the results and prognostic value of electron-beam computed tomography (EBCT) and exercise echocardiography.

BACKGROUND

Although patients with elevated coronary artery calcium scores (CACS) might be referred for exercise echocardiography, the association of EBCT CACS with wall motion score index (WMSI) is not known.

METHODS

Patients without known coronary artery disease who underwent both clinically indicated EBCT and exercise echocardiography within a 3-month period were identified. Exercise WMSI was based on a 16-segment model (normal = 1; abnormal >1). The EBCT CACS was derived with the Agatston scoring system. Follow-up was obtained for the combined end point of death and myocardial infarction.

RESULTS

The study population included 556 patients (age 54 +/- 10 years; 65% male). Correlation between EBCT CACS and exercise WMSI was limited (r = 0.17, p < 0.0001) but statistically significant. The proportion of patients with abnormal exercise WMSI increased with increasing CACS severity (chi-square = 19.1, p < 0.001). However, even in those with CACS >400, 66% had normal exercise WMSI. Age, CACS, and chest pain were independently associated with abnormal exercise WMSI. Events occurred in 12 (2%) patients. Wall motion score index (risk ratio [RR] 3.7, p = 0.023) and age (RR 1.9, p = 0.019) were associated with events.

CONCLUSIONS

Electron-beam computed tomography CACS was predictive of abnormal exercise WMSI, but the majority of patients with elevated CACS had normal WMSI. Wall motion score index and age were the best predictors of events. Prospective studies are indicated to establish the relative roles of these tests in risk stratification.

Prognosis of patients with good exercise capacity and mildly abnormal exercise echocardiography results: identification of an at-risk subgroup

BACKGROUND

Patients with good exercise capacity and mildly abnormal exercise echocardiography results have a favorable overall prognosis.

OBJECTIVE

We sought to define subgroups that might be at higher risk.

METHODS

We examined outcomes of 868 patients (women, > or = 5 metabolic equivalents; men, > or = 7 metabolic equivalents) with mild rest- or exercise-induced wall-motion abnormalities and evaluated potential predictors of time to cardiac death or nonfatal myocardial infarction (MI).

RESULTS

Mean age was 64 +/- 10 years; 477 patients (55%) were men. Mean follow-up was 3.1 +/- 1.5 years; cardiac event rate was 1.2% per person-year. A history of MI was the only significant predictor (risk ratio, 3.9; 95% confidence interval, 1.9-7.8; P = .0001), with 1-, 3-, and 5-year event-free survival of 98.5% +/- 1.1%, 92.6% +/- 2.6%, and 83.3% +/- 5.1%, respectively (event rate, 3.4%).

CONCLUSIONS

Patients with a history of MI have a higher annual cardiac event rate and may benefit from reevaluation, whereas no history of MI connotes a favorable prognosis.

Predictive Value of Normal Left Atrial Volume in Stress Echocardiography

OBJECTIVES

Our objective was to evaluate whether normal left atrial volume index (LAVI) is a predictor of a normal stress echocardiogram and thus a predictor of low ischemic risk.

BACKGROUND

Left atrial enlargement is closely related to the chronicity and intensity of the burden of increased ventricular filling pressure. Typically ischemic heart disease (IHD) has a long period of subclinical dysfunction. Increased filling pressure, reflected by enlarged LAVI, is hypothesized to mirror the burden of subclinical and overt IHD. We hypothesized that a normal LAVI might also be useful in predicting low IHD risk.

METHODS

One hundred eighty randomly selected patients (mean age, 63 +/- 15 years; 53% men) underwent outpatient exercise or dobutamine stress echocardiography for known or suspected coronary artery disease. Left atrial volume index was measured retrospectively with the biplane area-length method. The stress echocardiogram was interpreted as abnormal if wall motion abnormalities (WMAs) were noted at rest and/or with stress.

RESULTS

Left atrial volume index was categorized as < or =28 ml/m2 (normal), 28.1 to 32 ml/m2, 32.1 to 36 ml/m2, and >36 ml/m2. Abnormal stress echocardiography was identified in 57 patients (31.7%). The percentage of abnormal stress echocardiograms in each LAVI category was 5.7%, 21.9%, 38.7%, and 54.7%, respectively. The negative predictive value for LAVI < or =28 ml/m2 was 94.3%.

CONCLUSIONS

Normal resting LAVI (< or =28 ml/m2) was strongly predictive of a normal stress echocardiogram. Left atrial volume index might be a simple means of identifying patients with low ischemic risk and should be further evaluated as a complement to the assessment of ischemic risk.

Stress Function Index, a Novel Index for Risk Stratification and Prognosis Using Stress Echocardiography

OBJECTIVES

The purpose of the study was to define an appropriate parameter for risk stratification and prognosis of patients undergoing stress echocardiography.

BACKGROUND

Among stress echocardiography variables, peak wall-motion score index (WMSI) and ejection fraction (EF) have been shown to be independent and significant predictors of cardiovascular morbidity and mortality. Data on the impact and importance of each parameter in risk stratification and prognosis are limited.

METHODS

We evaluated 1560 patients (59 +/- 13 years; 51% men) undergoing stress echocardiography (36% treadmill, 64% dobutamine). Peak WMSI was derived from the cumulative sum of 16 left ventricular segments divided by sum of visualized segments at peak stress. The ratio of peak WMSI to EF was calculated for the entire cohort. Based on this ratio and using the receiver operating characteristic curve, patients were divided into 3 groups: low- (< 1.9), intermediate- (1.9-3.1), and high- (> 3.1) risk subgroups. Follow-up (2.8 +/- 1.1 years) for confirmed myocardial infarction (n = 26) and cardiac death (n = 38) were obtained.

RESULTS

Stress echocardiography effectively risk stratified patients into low- (0.7%/y), intermediate- (2.0%/y), and high- (4.4%/y) risk subgroups (P < .0001) based on the ratio of peak WMSI to EF. Cox proportional hazard model showed that risk stratification based on the ratio of peak WMSI to EF (global chi2 = 106.05; P < .0001) provided incremental value beyond that provided by risk stratification by peak WMSI (global chi2 = 79.23; P < .0001) or risk stratification by EF alone (global chi2 = 87.12; P < .0001).

CONCLUSIONS

The ratio of peak WMSI to EF (stress function index) provides best incremental prognostic value and effectively risk stratifies patients into low-, intermediate-, and high-risk subgroups and is better than risk stratification by either peak WMSI or EF alone. The results of stress echocardiography should routinely combine peak WMSI and EF for effective risk stratification.

Clinical and prognostic implications of angina pectoris developing during dobutamine stress echocardiography in the absence of inducible wall motion abnormalities

This study assessed the incidence, clinical correlates, and prognostic significance of angina during dobutamine stress echocardiography (DSE) in patients who did not have inducible wall motion abnormalities. We studied 2,117 patients (61 +/- 13 years of age; 1,149 men) who underwent large-dose DSE and had no new or worsening wall motion abnormalities during DSE. Follow-up events were hard cardiac events (cardiac death or nonfatal myocardial infarction) and myocardial revascularization. Angina was induced in 217 patients (10%) during stress. DSE was normal in 1,198 patients (57%), whereas 919 patients (43%) had fixed wall motion abnormalities. During a mean follow-up of 5.5 +/- 3.7 years, 143 patients (7%) died of cardiac causes and 78 (4%) had nonfatal myocardial infarction. Patients who developed angina during DSE were more likely to have a history of exertional angina (64% vs 16%, p <0.001) and had a higher wall motion score index at rest (1.29 +/- 0.5 vs 1.17 +/- 0.4, p = 0.01) compared with patients who did not have angina. Annual hard cardiac event rates were 2.2% in patients who had dobutamine-induced angina (DIA) and 2.1% in patients who did not (p = NS). Myocardial revascularization was performed more frequently in patients who had DIA than in those who did not (39% vs 14%, p <0.0001). In Cox's regression model, independent predictors of hard events were age (RR 1.03, 95% confidence interval [CI] 1.02 to 1.04), male gender (RR 1.6, 95% CI 1.1 to 2.2), smoking (RR 1.5, 95% CI 1.1 to 2.9), and wall motion score index at rest (RR 2.6, 95% CI 1.8 to 3.8). In conclusion, in patients who do not have ischemia by echocardiographic criteria during DSE, inducible angina pectoris is associated with a high incidence of revascularization during follow-up. However, the hard cardiac event rate does not differ in patients who develop DIA from those who do not.

Comparison of prognostic value of stress echocardiography versus stress electrocardiography in patients with suspected coronary artery disease

Stress electrocardiographic (ECG) ST-segment depression is a prognostic marker of adverse cardiac outcomes in coronary artery disease. However, use of concurrent stress echocardiography (ECHO) has lead to concordant and discordant findings on stress electrocardiogram during stress studies. The prognostic value of stress ECHO in the setting of these stress ECG findings has not been previously evaluated. Outcomes of 1,268 patients (60 +/- 12 years old, 48% women) who had normal electrocardiograms and underwent stress ECHO were analyzed. ST-segment depression > or =1.5 mm in 2 contiguous leads on stress electrocardiogram and a wall motion score index of >1 on peak stress echocardiogram were considered abnormal. Events of nonfatal myocardial infarction (n = 18) and cardiac death (n = 32) were analyzed during follow-up (2.8 +/- 0.9 years). In 91 patients (7%) who had abnormal findings on stress electrocardiogram, 38 (41%) had an abnormal finding on stress echocardiogram and 4 had cardiac events (0.6% per year), and all who had a normal finding on stress echocardiogram had no events (n = 53, 59%, p = 0.01). Among 46 events (92%) with a normal finding on stress electrocardiogram, 30 (60%) showed a discordantly abnormal finding on stress echocardiogram (3.2% per year, p <0.01). Overall, the cohort that had normal findings on stress echocardiogram showed a lower event rate (72%, 16 events, 1.1% per year) compared with the cohort that had abnormal findings on stress echocardiogram (28%, 34 events, 3.6% per year, p <0.001), independent of stress ECG response. Peak wall motion score index (hazard ratio 2.55, p <0.001) and left ventricular ejection fraction (hazard ratio 0.99, p <0.001) were independent and incremental (global chi-square, p <0.001) prognostic markers by stress ECHO. In conclusion, a normal finding on stress echocardiogram confers a benign prognosis independent of the type of stress ECG response during stress studies. In addition, peak wall motion score index and ejection fraction by ECHO are stronger prognostic markers over stress electrocardiography in patients who are evaluated for coronary artery disease.

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 role of non-invasive imaging in the risk stratification of asymptomatic diabetic subjects

AIMS

Coronary artery disease (CAD) is the leading cause of death in patients with diabetes. Patients often present with advanced and asymptomatic disease. Proposed strategies that may favourably affect CAD risk and outcomes in this patient population include identifying diabetic patients with subclinical disease at high risk of future cardiac events. The purpose of this article was to review the role of both atherosclerosis imaging tests (coronary calcium imaging and high-resolution ultrasound assessment of carotid intima-media thickness) and functional imaging techniques [stress echocardiography and radionuclide myocardial perfusion imaging (MPI)] in the diagnostic and prognostic evaluation of asymptomatic diabetic subjects.

METHODS AND RESULTS

We identified studies using MEDLINE searches (1966 to April 2005) and by reviewing reference lists. A comprehensive list of search terms was applied. All stress echocardiography and MPI studies evaluating the prevalence and/or prognostic value of myocardial ischaemia (n = 19) and coronary calcium imaging studies (n = 2) evaluating the prognostic value of subclinical atherosclerosis in diabetic patients were included.

CONCLUSION

Asymptomatic myocardial ischaemia can be detected in a significant proportion of diabetic subjects by non-invasive imaging tests such as MPI and stress echocardiography. The results of ongoing and future studies may be helpful in guiding the selection of asymptomatic diabetic subjects to undergo non-invasive imaging, establishing the cost-effectiveness of various testing strategies and their impact on prognosis.

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.

Stress echocardiography for the diagnosis and risk stratification of patients with suspected or known coronary artery disease: a critical appraisal. Supported by the British Society of Echocardiography

Stress echocardiography today has matured into a robust and reliable technique not only for the diagnosis of suspected coronary artery disease (CAD) but also for the accurate risk stratification of patients with suspected and established CAD. This is mainly because of rapid advances in image acquisition, digital display, and the development of harmonic and contrast imaging. Stress echocardiography today is also utilised in patients with heart failure both for assessing the cause of heart failure and determining the extent of hibernating myocardium. With advances in myocardial perfusion imaging, stress echocardiography now allows simultaneous assessment of myocardial function and perfusion. Tissue Doppler imaging allows quantitation of wall motion. Ready availability and reliability makes stress echocardiography a cost effective technique for the assessment of CAD.

Risk reduction of cardiac events by screening of unknown asymptomatic coronary artery disease in subjects with type 2 diabetes mellitus at high cardiovascular risk: an open-label randomized pilot study

BACKGROUND

Evaluated the efficacy of reducing the risk of cardiac events by a preclinical diagnosis of CAD in subjects with type 2 diabetes mellitus with 2 or more cardiovascular risk factors.

METHODS

One hundred forty-one subjects with type 2 diabetes mellitus without known cardiac disease and asymptomatic, aged >45 to <76 years, were randomized into the screening arm for CAD (71 patients) or to the control arm (70 patients). The screening consisted in performing an exercise electrocardiogram test and dipyridamole stress echocardiography; if 1 test was abnormal, coronary angiography is done. Screening was positive in 15 subjects (21.4%). At coronary angiography, which was performed in 14 of 15 patients, stenoses > or =50% of vessel diameter were present in 9 patients, of these 4 underwent coronary artery bypass grafting and 4 underwent percutaneous transluminal coronary angioplasty. Stenoses <50% of vessel diameter were present in 5 patients.

RESULTS

Mean follow-up was 53.5 months (range, 42-54 months). During this period, 1 major (myocardial infarction) and 3 minor events (angina) occurred in the screening arm. Eleven major and 4 minor events occurred in the control arm. In the screened arm, the proportion of all events was significantly less (P = .018) (RR .226, 95% CI 0.707-0.719, P = .012); the proportion of major to minor events was significantly less (P = .006) (RR .07, 95% CI 0.0087-0.565, P = .013).

CONCLUSIONS

The preclinical diagnosis of CAD is effective in reducing the risk of cardiac events, especially major events, in subjects with type 2 diabetes mellitus at high cardiovascular risk.

Stress echocardiography versus myocardial SPECT for risk stratification of patients with coronary artery disease

PURPOSE OF REVIEW

Diagnostic testing using noninvasive imaging has become an integral part of risk stratification in patients with coronary artery disease. It is important to understand the integral strengths and weaknesses between the different modalities of stress testing and to apply accurately the type of test the clinical scenario demands.

RECENT FINDINGS

There have been tremendous advances made in the field of cardiac imaging. Both myocardial perfusion imaging and stress echocardiographic techniques continue to evolve and play an important role in the assessment of patients with coronary artery disease.

SUMMARY

In this review the authors discuss the relative merits of both stress echocardiography and myocardial single photon emission computed tomographic imaging for diagnosis and risk stratification of patients with coronary artery disease.

Prognostic value of exercise echocardiography in patients with classic angina pectoris

The role of stress echocardiography in the prognostic evaluation of patients with angina pectoris is not well defined. This study included 437 patients (241 men and 196 women) with angina pectoris and a pretest probability of coronary artery disease (CAD) of > or = 0.7 who were referred for exercise echocardiography. No patient had a history of acute myocardial infarction or coronary revascularization. Mean age was 65 +/- 10 years. During a median follow-up of 2.7 years, hard cardiac events (cardiac death or nonfatal myocardial infarction) occurred in 19 patients and 53 patients underwent coronary revascularization. Event-free survival rates in patients with normal versus abnormal stress echocardiograms were 98% versus 83% at 1 year, 96% versus 75% at 3 years, and 87% versus 69% at 5 years, respectively. In a multivariate analysis of clinical, exercise stress, and echocardiographic parameters, independent predictors of hard cardiac events were Q waves on the electrocardiogram (chi-square 8.7, p = 0.003) and the presence of wall motion abnormalities during exercise in multivessel distribution (chi-square 5.3, p = 0.02). In an incremental model of clinical, exercise, and echocardiographic variables for the prediction of all cardiac events, the addition of echocardiographic data increased the chi-square of the model from 62 to 78 (p = 0.0003). Exercise echocardiography provides useful information in the risk stratification of patients with suspected CAD and a high pretest probability of CAD. Patients with normal exercise echocardiograms have a low event rate and therefore can be exempted from invasive procedures during the 3 years after a normal exercise echocardiogram.

A clinical and echocardiographic score for assigning risk of major events after dobutamine echocardiograms

OBJECTIVES

We sought to develop and validate a risk score combining both clinical and dobutamine echocardiographic (DbE) features in 4890 patients who underwent DbE at three expert laboratories and were followed for death or myocardial infarction for up to five years.

BACKGROUND

In contrast to exercise scores, no score exists to combine clinical, stress, and echocardiographic findings with DbE.

METHODS

Dobutamine echocardiography was performed for evaluation of known or suspected coronary artery disease in 3156 patients at two sites in the U.S. After exclusion of patients with incomplete follow-up, 1456 DbEs were randomly selected to develop a multivariate model for prediction of events. After simplification of each model for clinical use, the models were internally validated in the remaining DbE patients in the same series and externally validated in 1733 patients in an independent series.

RESULTS

The following score was derived from regression models in the modeling group (160 events): DbE risk = (age.0.02) + (heart failure + rate-pressure product <15000).0.4 + (ischemia + scar).0.6. The presence of each variable was scored as 1 and its absence scored as 0, except for age (continuous variable). Using cutoff values of 1.2 and 2.6, patients were classified into groups with five-year event-free survivals >95%, 75% to 95%, and <75%. Application of the score in the internal validation group (265 events) gave equivalent results, as did its application in the external validation group (494 events, C index = 0.72).

CONCLUSIONS

A risk score based on clinical and echocardiographic data may be used to quantify the risk of events in patients undergoing DbE.