Long-term prognostic value of exercise echocardiography compared with exercise 201Tl, ECG, and clinical variables in patients evaluated for coronary artery disease

Abnormal Exercise Electrocardiography With Normal Stress Echocardiography Is Associated With Subclinical Coronary Atherosclerosis

BACKGROUND

Patients with abnormal (positive) exercise electrocardiography, but normal stress echocardiography (+ECG/-Echo), have an increased risk of adverse cardiovascular events compared with patients with a normal (negative) ECG and a normal stress Echo (-ECG/-Echo). However, it is unclear if +ECG/-Echo discordance is associated with a greater burden of subclinical coronary atherosclerosis.

METHODS

Project Baseline Health Study participants who underwent a stress Echo and coronary artery calcium (CAC) scan were stratified by stress Echo result: -ECG/-Echo or +ECG/-Echo. Multivariable regression investigated the association between stress Echo results and CAC burden. Event-free survival from a composite of adverse cardiovascular events was compared between groups.

RESULTS

Among 1630 asymptomatic participants in this observational cohort study, 1503 (92.2%) had a -ECG/-Echo, 105 (6.4%) had a +ECG/-Echo, and 22 (1.3%) had a +Echo. The +ECG/-Echo group had a significantly greater burden of coronary atherosclerosis than the -ECG/-Echo group (mean CAC score, 198±470 versus 53±186; P<0.001; CAClog, 2.2±2.7 versus 1.2±2.0; P<0.001). The -ECG/-Echo group was more likely to have CAC=0 compared with the +ECG/-Echo group (65.9% versus 53.3%; P=0.01), whereas the +ECG/-Echo group more commonly had CAC ≥100 (28.6% versus 11.4%; P<0.001). After adjustment, CAClog scores were 52% higher in the +ECG/-Echo group than in the -ECG/-Echo group (P=0.002). Compared with the -ECG/-Echo group, the +ECG/-Echo group was 4.5× more likely to have a CAC score ≥400 (adjusted odds ratio, 4.54 [95% CI, 1.95-10.05]; P<0.001). After a median follow-up of 4.3 years, a trend toward increased adverse cardiovascular events was observed among participants with +ECG/-Echo.

CONCLUSIONS

Individuals with a +ECG/-Echo have a higher burden of subclinical coronary atherosclerosis than those with a -ECG/-Echo, which may explain, at least in part, the increased risk for adverse cardiac events in this population. Further study is needed to determine the optimal strategy for mitigating cardiovascular risk in these patients.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03154346.

Combined low-dose dobutamine and exercise stress echocardiography: a new hybrid protocol to detect inducible ischaemia

Aims

Myocardial response to stress echocardiography may be elicited physiologically, through exercise, or pharmacologically, often with dobutamine. Both have advantages but also limitations due to reduced exercise capacity or side-effects to stressor agent/lack of closeness to true pathophysiology of ischaemic cascade. We have combined low-dose dobutamine and exercise, creating a 'hybrid' protocol to utilize the advantages of both techniques and limit the drawbacks. The aim of the study was to evaluate its safety and feasibility.

Methods and results

In the hybrid protocol, low-dose dobutamine infusion (up to 10 µg/kg/min) is enhanced by supine bicycle exercise at 3-min increments of workload of 25 W to achieve target heart rate (THR). We analysed safety and outcome data for all the patients who underwent this protocol from 2017 to 2022. Out of 835, 727 (87.1%) patients referred for evaluation of ischaemia underwent the hybrid protocol. The median age was 61 years old and 61% (442/727) were men. The median exercise time was 11 (9-13.5) min with a median maximum workload of 100 W (75-125). Out of 727, 670 (92.2%) achieved THR. Atropine was not used. Out of 727, 192 (26.4%) of studies were positive for ischaemia. Out of 122, 102 (83.6%) with positive stress who underwent invasive angiography had significant coronary disease. The incidence of complications was low: 1/727-severe arrhythmia, 5/727 (0.7%) developed a vasovagal episode, and 14/727 (1.9%) had a hypertensive response to exercise.

Conclusion

Our findings suggest that this protocol is safe, feasible, and has a high success rate in achieving THR.

Strain Rate Changes during Stress Echocardiography Are the Most Accurate Predictors of Significant Coronary Artery Disease in Patients with Previously Treated Acute Coronary Syndrome

BACKGROUND AND AIMS

Dobutamine stress echocardiography (DSE) is a well-established non-invasive investigation for the detection of ischemic myocardial dysfunction. The aim of this study was to evaluate the accuracy of myocardial deformation parameters measured by speckle tracking echocardiography (STE) in predicting culprit coronary artery lesions in patients with prior revascularization and acute coronary syndrome (ACS).

METHODS

We prospectively studied 33 patients with ischemic heart disease, a history of at least one episode of ACS and prior revascularization. All patients underwent a complete stress Doppler echocardiographic examination, including the myocardial deformation parameters of peak systolic strain (PSS), peak systolic strain rate (SR) and wall motion score index (WMSI). The regional PSS and SR were analyzed for different culprit lesions.

RESULTS

The mean age of patients was 59 ± 11 years and 72.7% were males. At peak dobutamine stress, the change in regional PSS and SR in territories supplied by the LAD showed smaller increases compared to those in patients without culprit LAD lesions (p < 0.05 for all). Likewise, the regional parameters of myocardial deformation were reduced in patients with culprit LCx lesions compared to those with non-culprit LCx lesions and in patients with culprit RCA legions compared to those with non-culprit RCA lesions (p < 0.05 for all). In the multivariate analysis, the △ regional PSS (1.134 (CI = 1.059-3.315, p = 0.02)) and the △ regional SR (1.566 (CI = 1.191-9.013, p = 0.001)) for LAD territories predicted the presence of LAD lesions. Similarly, in a multivariable analysis, the △ regional PSS and the △SR predicted LCx culprit lesions and RCA culprit lesions (p < 0.05 for all). In an ROC analysis, the PSS and SR had higher accuracies compared to the regional WMSI in predicting culprit lesions. A △ regional SR of -0.24 for the LAD territories was 88% sensitive and 76% specific (AUC = 0.75; p < 0.001), a △ regional PSS of -1.20 was 78% sensitive and 71% specific (AUC = 0.76, p < 0.001) and a △ WMSI of -0.35 was 67% sensitive and 68% specific (AUC = 0.68, p = 0.02) in predicting LAD culprit lesions. Similarly, the △ SR for LCx and RCA territories had higher accuracies in predicting LCx and RCA culprit lesions.

CONCLUSIONS

The myocardial deformation parameters, particularly the change in regional strain rate, are the most powerful predictors of culprit lesions. These findings strengthen the role of myocardial deformation in increasing the accuracy of DSE analyses in patients with prior cardiac events and revascularization.

Exercise stress echocardiography: Where are we now?

Exercise stress echocardiography (ESE) is a widely used diagnostic test in cardiology departments. ESE is mainly used to study patients with coronary artery disease; however, it has increasingly been used in other clinical scenarios including valve pathology, congenital heart disease, hypertrophic and dilated cardiomyopathies, athlete evaluations, diastolic function evaluation, and pulmonary circulation study. In our laboratories, we use an established methodology in which cardiac function is evaluated while exercising on a treadmill. After completing the exercise regimen, patients remain in a standing position or lie down on the left lateral decubitus, depending on the clinical questions to be answered for further evaluation. This method increases the quality and quantity of information obtained. Here, we present the various methods of exercise stress echocardiography and our experience in many clinical arenas in detail. We also present alternatives to ESE that may be used and their advantages and disadvantages. We review recent advances in ESE and future directions for this established method in the study of cardiac patients and underline the advantage of using a diagnostic tool that is radiation-free.

Does chest shape influence exercise stress echocardiographic results in patients with suspected coronary artery disease?

Despite the good specificity of exercise stress echocardiography (ESE) for the detection of coronary artery disease (CAD), false positive (FP) results may occur. We have previously reported that chest abnormalities may affect parameters of cardiac contractility. The influence of chest shape on ESE results has never been previously investigated. We retrospectively analyzed 160 consecutive patients (64.4 ± 13.0-year old, 91 women) who had undergone coronary angiography at our Institution because of positive ESE, between June 2014 and May 2020. Modified Haller index (MHI; chest transverse diameter over the distance between sternum and spine) was assessed in all patients. Obstructive CAD was diagnosed by ≥ 70% stenosis in any epicardial coronary artery. Outcome was false-positivity at ESE. 80.6% of patients were diagnosed with obstructive CAD, while 19.4% had no CAD (FP). We separately analyzed patients with normal chest shape (MHI ≤ 2.5) and those with concave-shaped chest wall (MHI > 2.5). These latter were mostly women with small cardiac chambers, mitral valve prolapse (MVP) and exercise-induced ST-segment changes. Likelihood of false-positivity was significantly higher in subjects with MHI > 2.5 than those with MHI ≤ 2.5 (30.7% vs 9.4%, p = 0.001). By multivariate logistic regression analysis, MHI > 2.5 (OR 4.04, 95%CI 1.45-11.2, p = 0.007), MVP (OR 3.47, 95%CI 1.32-9-12, p = 0.01) and dyssynergy in the left circumflex territory (OR = 3.35, 95%CI 1.26-8.93, p = 0.01) were independently associated with false-positivity. Concave-shaped chest wall (MHI > 2.5) may be associated with false-positive stress echocardiographic result. Mechanisms underpinning this finding need to be further explored.

Prognostic Value of Modified Haller Index in Patients with Suspected Coronary Artery Disease Referred for Exercise Stress Echocardiography

Background:

The influence of chest conformation on outcome of patients with suspected coronary artery disease (CAD) is actually unknown.

Materials and Methods:

This retrospective study included all consecutive patients who underwent exercise stress echocardiography (ESE) for suspected CAD at our institution between February 2011 and September 2019. Modified Haller index (MHI; chest transverse diameter over the distance between sternum and spine) was assessed in all patients. Obstructive CAD was diagnosed by ≥70% stenosis in any epicardial coronary artery. During the follow-up time, we evaluated the occurrence of any of the following: (1) cardiovascular (CV) hospitalizations and (2) cardiac death or sudden death.

Results:

A total of 1091 consecutive patients (62.4 ± 12.6 years, 57.2% of men) were included in the study. Patients with normal chest shape (MHI ≤2.5) and those with concave-shaped chest wall (MHI >2.5) were separately analyzed. A positive ESE was diagnosed in 171 patients of which 80.7% had an obstructive CAD (true positive), while 19.3 not (false positive [FP]). Majority of FP ESE (70.9%) derived from concave-shaped chest wall group. During follow-up time (2.5 ± 1.9 years), 9 patients died and 281 were hospitalized because of heart failure (163), acute coronary syndromes (39), and arrhythmias (79). At the multivariate Cox regression analysis, age (heart rate [HR]: 1.02, 95% confidence interval [CI]: 1.01–1.03), MHI >2.5 (HR: 0.39, 95% CI: 0.26–0.56), diabetes mellitus (HR: 4.89, 95% CI: 3.78–6.32), horizontal ST depression ≥1 mm (HR: 2.86, 95% CI: 1.98–4.15), peak exercise average E/e' ratio (HR: 1.08, 95% CI: 1.06–1.10), and peak exercise wall motion score index (HR: 1.79, 95% CI: 1.36–2.35) were independently correlated with outcome.

Conclusions:

Patients with concave-shaped chest wall (MHI >2.5) have a significantly lower probability of CV events than those with normal chest shape (MHI ≤2.5) over a medium-term follow-up. A noninvasive chest shape assessment could identify subjects at lower risk of CV events.

Implications of Abnormal Exercise Electrocardiography With Normal Stress Echocardiography

IMPORTANCE

Patients with abnormal (positive) exercise electrocardiography, but normal stress echocardiography (+ECG/-Echo) are commonly encountered in clinical practice; however, the prognostic significance of this discordant result is unclear.

OBJECTIVE

To determine whether patients with +ECG/-Echo have a higher rate of adverse clinical events and a poorer prognosis than patients with negative exercise ECG and normal stress Echo imaging (-ECG/-Echo).

DESIGN, SETTING, AND PARTICIPANTS

Between January 1, 2000, and February 28, 2014, a total of 47 944 consecutive patients without known coronary artery disease who underwent exercise stress Echo at Duke University Medical Center were evaluated for inclusion in this observational cohort study. Data analysis was conducted from January 1, 2000, to December 31, 2016.

INTERVENTIONS/EXPOSURES

Patients were categorized as having -ECG/-Echo, +ECG/-Echo, or +Echo (-ECG/+Echo and +ECG/+Echo).

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite end point of death, myocardial infarction, hospitalization for unstable angina, and coronary revascularization. Secondary outcomes included individual adverse events and downstream testing.

RESULTS

After excluding submaximal tests and nondiagnostic ECG or stress imaging results, 15 077 patients (mean [SD] age, 52 [13] years; 6228 [41.3%] men) were classified by stress test results. Of these, 12 893 patients (85.5%) had -ECG/-Echo, 1286 patients (8.5%) had +ECG/-Echo, and 898 patients (6.0%) had +Echo. Through a median follow-up of 7.3 (interquartile range, 4.4-10.0) years, the composite end point occurred in 794 patients with -ECG/-Echo (8.5%), 142 patients with +ECG/-Echo (14.6%), and 297 patients with +Echo (37.4%). Death occurred in 425 patients with -ECG/-Echo (4.8%), 50 patients with +ECG/-Echo (5.9%), and 70 patients with +Echo (11.2%). Myocardial infarction occurred in 195 patients with -ECG/-Echo (2.2%), 31 patients with +ECG/-Echo (3.6%), and 59 patients with +Echo (8.7%). The addition of stress ECG findings to clinical and exercise data yielded incremental prognostic value. Patients with -ECG/-Echo imaging results had the least downstream testing (2.3%), followed by +ECG/-Echo (12.8%), and +Echo (33.6%) (P < .001).

CONCLUSIONS AND RELEVANCE

The presence of +ECG results with normal stress Echo imaging may identify a population of patients who are at slightly increased risk for adverse cardiac events, which was not previously recognized. Further study is needed to determine whether these patients will benefit from intensification of medical management.

Clinical outcomes of discordant exercise electrocardiographic and echocardiographic findings compared with concordant findings in patients with chest pain and no history of coronary artery disease: An observational study

The aim of this study was to evaluate comparative clinical outcomes of discordant electrocardiographic (ECG) and echocardiographic (Echo) findings compared with concordant findings during treadmill exercise echocardiography in patients with chest pain and no history of coronary artery disease (CAD).A total of 1725 consecutive patients who underwent treadmill echocardiography with chest pain and no history of CAD were screened. The patients were classified into 4 groups: ECG-/Echo- (negative ECG and Echo), ECG+/Echo- (positive ECG and negative Echo), ECG-/Echo+, and ECG+/Echo+. Concomitant CAD was determined using coronary angiography or coronary computed tomography. Major adverse cardiac events (MACEs) were defined as a composite of coronary revascularization, acute myocardial infarction, and death.MACEs were similar between ECG-/Echo- and ECG+/Echo- groups. Compared with ECG+/Echo- group, ECG-/Echo+ group had more MACEs (adjusted hazard ratio [HR] adjusted by clinical risk factors [95% confidence interval {CI}], 3.57 [1.75-7.29], P < .001). Compared with ECG+/Echo+ group, ECG-/Echo+ group had lower prevalence of concomitant CAD and fewer MACEs (HR, 0.49 [0.29-0.81], P = .006).Positive exercise Echo alone during treadmill exercise echocardiography had worse clinical outcomes than positive ECG alone, and the latter had similar outcomes to both negative ECG and Echo. Positive exercise Echo alone also had better clinical outcomes than both positive ECG and Echo. Therefore, exercise Echo findings might be superior for predicting clinical outcomes compared with exercise ECG findings. Additional consideration of ECG findings on positive exercise Echo will also facilitate better prediction of clinical outcomes.

Cardiac stress imaging for the prediction of very long-term outcomes: Dobutamine stress echocardiography or dobutamine 99mTc-sestamibi SPECT?

BACKGROUND

Both dobutamine stress echocardiography (DSE) and myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) are frequently used for cardiac risk stratification. The long-term relative prognostic value of these modalities has not been studied. Therefore, this study evaluated the long-term prognostic value of DSE compared to MPI in patients unable to perform exercise testing.

METHODS

This prospective, single center study included 301 patients (mean age 59 ± 12 years, 56% men) unable to perform exercise tests who underwent DSE and dobutamine stress 99mTc-sestamibi MPI. End points during follow-up were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction (MI). Univariable and multivariable Cox proportional hazards regression models were used to identify independent predictors of outcome. The probability of survival was calculated using the Kaplan-Meier method.

RESULTS

A total of 182 patients (60%) had an abnormal DSE and 198 (66%) patients had an abnormal MPI. The agreement between DSE and MPI was 82% (κ = 0.62). During a median follow-up of 14 years (range 5-18), 172 deaths (57%) occurred, of which 72 (24%) were due to cardiac causes. Nonfatal MI occurred in 46 patients (15%). The multivariable analysis demonstrated that an abnormal DSE was a significant predictor of cardiac mortality (HR 2.35, 95% CI [1.17-4.73]) and hard cardiac events (HR 2.11, 95% CI [1.25-3.57]). Also, an abnormal MPI result was a significant predictor of cardiac mortality (HR 3.03, 95% CI [1.33-6.95]) and hard cardiac events (HR 2.06, 95% CI [1.12-3.79]).

CONCLUSIONS

DSE and MPI are comparable in predicting long-term cardiac mortality and hard cardiac events in patients unable to perform exercise testing.

Noninvasive Stress Testing for Coronary Artery Disease

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

Noninvasive stress testing for coronary artery disease

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

Comparative definitions for moderate-severe ischemia in stress nuclear, echocardiography, and magnetic resonance imaging

The lack of standardized reporting of the magnitude of ischemia on noninvasive imaging contributes to variability in translating the severity of ischemia across stress imaging modalities. We identified the risk of coronary artery disease (CAD) death or myocardial infarction (MI) associated with ≥10% ischemic myocardium on stress nuclear imaging as the risk threshold for stress echocardiography and cardiac magnetic resonance. A narrative review revealed that ≥10% ischemic myocardium on stress nuclear imaging was associated with a median rate of CAD death or MI of 4.9%/year (interquartile range: 3.75% to 5.3%). For stress echocardiography, ≥3 newly dysfunctional segments portend a median rate of CAD death or MI of 4.5%/year (interquartile range: 3.8% to 5.9%). Although imprecisely delineated, moderate-severe ischemia on cardiac magnetic resonance may be indicated by ≥4 of 32 stress perfusion defects or ≥3 dobutamine-induced dysfunctional segments. Risk-based thresholds can define equivalent amounts of ischemia across the stress imaging modalities, which will help to translate a common understanding of patient risk on which to guide subsequent management decisions.

Prognostic value of normal stress echocardiography in obese patients

BACKGROUND

Chest pain is a common problem in obese patients. Because of the body habitus, the results of noninvasive evaluation for CAD may be limited in this group.

METHODS

We reviewed the records of 1446 consecutive patients who had undergone clinically indicated stress echocardiography (SE). We compared major adverse cardiac events (MACE; myocardial infarction, cardiac intervention, cardiac death, subsequent hospitalization for cardiac events, and emergency department visits) at 1 year in normal weight, overweight, and obese subjects with normal SE.

RESULTS

Excluding patients with an abnormal and indeterminate SE and those who were lost to follow-up, a retrospective analysis of 704 patients was performed. There were 366 obese patients (BMI ≥ 30), 196 overweight patients (BMI 25-29.9), and 142 patients with normal BMI (18.5-24.9). There was no MACE in the groups at 1-year follow-up after a normal SE.

CONCLUSIONS

In obese patients including those with multiple risk factors and symptoms concerning for cardiac ischemia, stress echocardiography is an effective and reliable noninvasive tool for identifying those with a low 1-year risk of cardiac events.

Clinical applications of exercise stress echocardiography in the treadmill with upright evaluation during and after exercise

Exercise stress echocardiography is the most frequently used stress test in our laboratory. Exercise echocardiography is used mainly in the study of patients with coronary artery disease. However, the technique is increasingly being used to study other diseases. In our centre, we use an original methodology, published by us in 2000, in which we evaluate heart function during exercise in the treadmill. After the exercise, patients are maintained in orthostatic position when appropriate or lying down in left lateral decubitus for further evaluation. Since this method seems to increase the quality and the quantity of information obtained in so many clinical arenas, we now present a detailed review of this methodology and its applications.

Myocardial Blood Flow and Flow Reserve in Proximal and Mid-to-Distal Lesions of Left Anterior Descending Artery Measured By N-13 Ammonia PET/CT

PURPOSE

The purpose of this study is to compare the myocardial blood flow (MBF) and flow reserve (MFR) between proximal and mid-to-distal lesions of the left anterior descending artery (pLAD and mdLAD, respectively) using N-13 ammonia positron emission tomography/computed tomography (PET/CT).

METHODS

Subjects were 11 patients (six men and five women, mean age 64.5 years) with known coronary artery disease (CAD) involving LAD studied by N-13 ammonia PET/CT. They were divided into two groups by the location of stenotic lesions, i.e. pLAD versus mdLAD. Global and regional MBF and MFR were measured and compared. Characteristics of perfusion defects including the number of involved segments, basal area involvement, location, size, and shape were also compared between the two groups.

RESULTS

The regional MFR in mid-anterior segment was significantly lower in pLAD group (1.80 ± 0.35 vs 2.76 ± 1.13 for pLAD and mdLAD groups, respectively, p = 0.034), while global MFR was not different (2.10 ± 1.10 vs 2.34 ± 0.84). Both stress and rest MBF in LAD territories were not different in both groups. The size of the perfusion defects were significantly larger in pLAD group (44.0 ± 11.5 % vs 21.1 ± 15.8 %, p = 0.041). Other characteristics such as location, basal area involvement, and shape were not significantly different between two groups.

CONCLUSIONS

The proximal lesion makes lower MFR in the mid-anterior segment and larger perfusion defect in the LAD territory but comparable MBF compared with mdLAD lesion.

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.

Diagnostic accuracy of exercise stress testing for coronary artery disease: a systematic review and meta-analysis of prospective studies

BACKGROUND

Exercise stress testing offers a non-invasive, less expensive way of risk stratification prior to coronary angiography, and a negative stress test may actually avoid angiography. However, previous meta-analyses have not included all exercise test modalities, or patients without known Coronary artery disease (CAD).

METHODS AND RESULTS

We systematically reviewed the literature to determine the diagnostic accuracy of exercise stress testing for CAD on angiography. MEDLINE (January 1966 to November 2009), MEDION (1966 to July 2009), CENTRAL (1966 to July 2009) and EMBASE (1980-2009) databases were searched for English language articles on diagnostic accuracy of exercise stress testing. We included prospective studies comparing exercise stress testing with a reference standard of coronary angiography in patients without known CAD. From 6,055 records, we included 34 studies with 3,352 participants. Overall, we found published studies regarding five different exercise testing modalities: treadmill ECG, treadmill echo, bicycle ECG, bicycle echo and myocardial perfusion imaging. The prevalence of CAD ranged from 12% to 83%. Positive and negative likelihood ratios of stress testing increased in low prevalence settings. Treadmill echo testing (LR+ = 7.94) performed better than treadmill ECG testing (LR+ = 3.57) for ruling in CAD and ruling out CAD (echo LR- = 0.19 vs. ECG LR- = 0.38). Bicycle echo testing (LR+ = 11.34) performed better than treadmill echo testing (LR+ = 7.94), which outperformed both treadmill ECG and bicycle ECG. A positive exercise test is more helpful in younger patients (LR+ = 4.74) than in older patients (LR+ = 2.8).

CONCLUSIONS

The diagnostic accuracy of exercise testing varies, depending upon the age, gender and clinical characteristics of the patient, prevalence of CAD and modality of test used. Exercise testing, whether by echocardiography or ECG, is more useful at excluding CAD than confirming it. Clinicians have concentrated on individualising the treatment of CAD, but there is great scope for individualising the diagnosis of CAD using exercise testing.

Assessing risk in acute chest pain: The value of stress myocardial perfusion imaging in patients admitted through the emergency department

BACKGROUND

To prospectively assess the clinical value of stress-gated myocardial single photon emission computed tomography (SPECT) for triaging patients admitted through the emergency department (ED) with acute chest pain (ACP).

METHODS

Prospective, observational cohort study in 1,576 consecutive patients who were evaluated for ACP over a 29-month period. Stress SPECT was performed within 24 hours of admission from the ED. Analysis included quantification of total and ischemic left ventricular perfusion defect size (PDS). Cardiac events were defined as an acute coronary syndrome during the index hospitalization or in follow-up over 7.3 ± 2.8 months.

RESULTS

Eighty-five cardiac events occurred in 77 patients (4.9%). SPECT was abnormal in 135 patients (8.6%) of whom 83 (61.5%) had a reversible defect. Event rates were significantly higher in patients with an abnormal (40%) versus a normal (1.6%) SPECT (P < .0001); and in those with a (1) large (>15%) versus small (≤15%) PDS (50.0% vs 33.7%, P = .05) and (2) large (>10%) versus small (≤10%) ischemic PDS (87.5% vs 42.4%, P < .0001, respectively). SPECT best predicted cardiac events by multivariate analysis. The addition of SPECT to clinical variables significantly improved overall risk prediction (global χ(2) 103.6 vs 207.1, P < .001).

CONCLUSIONS

Stress SPECT can accurately assess risk in a heterogeneous group of patients with ACP of unclear cardiac etiology, and beyond that provided by a clinical risk assessment alone. Our results support the use of stress SPECT for identifying very low-risk ACP patients with normal study results who can be safely discharged home.

Development and validation of a case ascertainment tool for ankylosing spondylitis

OBJECTIVE

Ankylosing spondylitis (AS) diagnosis is often delayed. The availability of effective biologic agents for treating AS has increased the importance of early diagnosis. We tested questions derived from a comprehensive literature review and an advisory board in a case-control study designed to identify patients with AS from among patients with chronic back pain (CBP).

METHODS

Question items were cognitively tested among patients with AS, and then in case-control studies for validation and creation of a scoring algorithm and question item reduction. AS cases were recruited from a known database, and CBP subjects (controls) were recruited from clinics, employers, and from the SpineUniverse Web site. We used individual question items in a multivariate framework to discriminate between people with and without AS.

RESULTS

Forty-three questions yielded 24 items for analyses; 12 of these were entered into a multivariate regression model. Individual items yielded odds ratios ranging from 0.07 to 30.31. Question items with a significant positive relationship to AS included male sex, neck or hip pain/stiffness, longer pain duration, decreased pain/stiffness with daily physical activity, pain relief within 48 hours of nonsteroidal antiinflammatory drugs, and diagnosis of iritis. The tool demonstrated a sensitivity of 67.4 and a specificity of 94.6. The tool was developed from clinically and radiologically diagnosed AS cases and therefore is designed to distinguish AS cases among CBP subjects. In addition, approximately 54% of the AS cases in the study were treated with biologic agents, which may impact questionnaire responses.

CONCLUSION

This tool can identify undiagnosed patients with AS and, potentially, those at an earlier stage in their disease course.

The coronary artery calcium score and stress myocardial perfusion imaging provide independent and complementary prediction of cardiac risk

OBJECTIVES

This study sought to examine the relationship between coronary artery calcium score (CACS) and single-photon emission computed tomography (SPECT) results for predicting the short- and long-term risk of cardiac events.

BACKGROUND

The CACS and SPECT results both provide important prognostic information. It is unclear whether integrating these tests will better predict patient outcome.

METHODS

We followed-up 1,126 generally asymptomatic subjects without previous cardiovascular disease who had a CACS and stress SPECT scan performed within a close time period (median 56 days). The median follow-up was 6.9 years. End points analyzed were total cardiac events and all-cause death/myocardial infarction (MI).

RESULTS

An abnormal SPECT result increased with increasing CACS from <1% (CACS < or =10) to 29% (CACS >400) (p < 0.001). Total cardiac events and death/MI also increased with increasing CACS and abnormal SPECT results (p < 0.001). In subjects with a normal SPECT result, CACS added incremental prognostic information, with a 3.55-fold relative increase for any cardiac event (2.75-fold for death/MI) when the CACS was severe (>400) versus minimal (< or =10). Separation of the survival curves occurred at 3 years after initial testing for all cardiac events and at 5 years for death/MI.

CONCLUSIONS

The CACS and SPECT findings are independent and complementary predictors of short- and long-term cardiac events. Despite a normal SPECT result, a severe CACS identifies subjects at high long-term cardiac risk. After a normal SPECT result, our findings support performing a CACS in patients who are at intermediate or high clinical risk for coronary artery disease to better define those who will have a high long-term risk for adverse cardiac events.

Exercise echocardiography in rheumatoid arthritis: a case-control study

BACKGROUND

Rheumatoid arthritis (RA) is associated with increased cardiovascular risk.

METHODS

To assess the role of exercise echocardiography (EE) in the evaluation of patients with RA, follow-up (mean, 6.7+/-3.7 years) was retrospectively obtained in 159 patients with RA who underwent EE. Patients were matched for age, gender, and cardiovascular risk factors with 454 controls who underwent EE.

RESULTS

Patients with RA were more likely to have positive results for ischemia on EE (odds ratio, 2.32; 95% confidence interval, 1.48-3.64; P=.0003). Rest and exercise wall motion score indexes were higher in the RA group (1.14+/-0.33 and 1.22+/-0.39, respectively, vs 1.06+/-0.18 and 1.10+/-0.24 in controls; P < .005 for each). Logistic regression adjusted for age revealed an increased odds ratio for myocardial ischemia of 1.06 (95% confidence interval, 1.02-1.11; P=.005) per year of RA. Five-year all-cause mortality in subjects with RA with myocardial ischemia on EE was 14.9%, compared with 4.3% in RA subjects without ischemia (P=.028).

CONCLUSION

RA was associated with a 2-fold increased risk for myocardial ischemia on EE; risk increased with the duration of RA. Mortality was increased in patients with RA with ischemia on EE.

Prognostic value of exercise echocardiography in diabetic patients

BACKGROUND

Coronary artery disease (CAD) is the leading cause of death in diabetic patients. Although exercise echocardiography (EE) is established as a useful method for diagnosis and stratification of risk for CAD in the general population, there are few studies on its value as a prognostic tool in diabetic patients. The purpose of this investigation was to evaluate the value of EE in predicting cardiac events in diabetics.

METHODS

193 diabetic patients, 97 males, 59.8 +/- 9.3 yrs (mean +/- SD) were submitted to EE between 2001 and 2006 and followed from 7 to 65 months with median of 29 months by phone calls and personal interviews with patients and their primary physician, and reviewing medical records and death certificates. The end points were cardiac events, defined as non-fatal myocardial infarction, late myocardial revascularization and cardiac death. Sudden death without another explanation was considered cardiac death. Survival free of end points was estimated by the Kaplan-Meier method.

RESULTS

Twenty-six cardiac events were registered in 24 individuals during the follow-up. The rates of cardiac events were 20.6 and 7% in patients with positive and negative EE, respectively (p < 0.001). Predictors of cardiac events included sedentary lifestyle, with RR of 2.57 95%CI [1.09 to 6.02] (P = 0.03) and positive EE, with RR 3.63, 95%CI [1.44 to 9.16] (P = 0.01). Patients with positive EE presented higher rates of cardiac events at 12 months (6.8% vs. 2.2%), p = 0.004.

CONCLUSION

EE is a useful method to predict cardiac events in diabetic patients with suspected or known CAD.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Predicting clinically unrecognized coronary artery disease: use of two- dimensional echocardiography

BACKGROUND

2-D Echo is often performed in patients without history of coronary artery disease (CAD). We sought to determine echo features predictive of CAD.

METHODS

2-D Echo of 328 patients without known CAD performed within one year prior to stress myocardial SPECT and angiography were reviewed. Echo features examined were left ventricular and atrial enlargement, LV hypertrophy, wall motion abnormality (WMA), LV ejection fraction (EF) < 50%, mitral annular calcification (MAC) and aortic sclerosis/stenosis (AS). High risk myocardial perfusion abnormality (MPA) was defined as >15% LV perfusion defect or multivessel distribution. Severe coronary artery stenosis (CAS) was defined as left main, 3 VD or 2VD involving proximal LAD.

RESULTS

The mean age was 62 +/- 13 years, 59% men, 29% diabetic (DM) and 148 (45%) had > 2 risk factors. Pharmacologic stress was performed in 109 patients (33%). MPA was present in 200 pts (60%) of which, 137 were high risk. CAS was present in 166 pts (51%), 75 were severe. Of 87 patients with WMA, 83% had MPA and 78% had CAS. Multivariate analysis identified age >65, male, inability to exercise, DM, WMA, MAC and AS as independent predictors of MPA and CAS. Independent predictors of high risk MPA and severe CAS were age, DM, inability to exercise and WMA. 2-D echo findings offered incremental value over clinical information in predicting CAD by angiography. (Chi square: 360 vs. 320 p = 0.02).

CONCLUSION

2-D Echo was valuable in predicting presence of physiological and anatomical CAD in addition to clinical information.

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.

Quantification of transmural gradient of blood flow in myocardial ischemia with real-time myocardial contrast echocardiography and dipyridamole stress test

Transmural redistribution of myocardial blood flow (MBF) is the earliest sign of myocardial ischemia. We aimed to evaluate the ability of real-time myocardial contrast echocardiography (MCE) combined with dipyridamole stress to quantify the transmural gradient of MBF during graded coronary stenosis. Real-time MCE was performed in 14 open-chest dogs at seven experimental stages: baseline; hyperemia induced by 6-min infusion of dipyridamole; 50%, 75% and 90% reduction of hyperemic flow after constriction in each stage for 10 min; reperfusion for 10 min; and subtotal occlusion of the left anterior descending coronary artery (LAD) for 90 min. We obtained MCE perfusion parameters from subendocardial (A-endo, beta-endo and A x beta-endo) and subepicardial (A-epi, beta-epi and A x beta-epi) layers of the ventricular septum and calculated their transmural gradients (A-EER, beta-EER and A x beta-EER) and systolic wall thickening (SWT). The sensitivity and specificity of each parameter for predicting 75% reduction of hyperemic flow, which was defined as mild myocardial ischemia, were derived by receiver operating characteristic (ROC) curve analysis. No transmural gradients were found at baseline; during maximal hyperemia and 50% reduction of hyperemic flow. beta-endo, A x beta-endo, beta-EER and A x beta-EER decreased significantly when the hyperemic flow was reduced by 75% or more. In contrast, SWT remained unchanged until the hyperemic flow was reduced by 90%. Among all parameters measured, beta-EER and A x beta-EER had the highest and SWT the lowest sensitivity and specificity in predicting mild myocardial ischemia. In conclusion, real-time MCE combined with dipyridamole stress allows for quantification of the transmural gradient of MBF. beta-EER and A x beta-EER are more sensitive than SWT and other MCE parameters in detecting mild myocardial ischemia.

Prognostic significance of exercise stress echocardiography in 3329 outpatients (5-year longitudinal study)

BACKGROUND

Appraisal of the risk to which outpatients with chest pain are exposed is a major clinical problem. Up to now, there have been no reports on the prognostic significance of exercise stress echocardiography in this patient cohort.

PATIENTS AND METHODS

In order to investigate the prognostic significance of exercise stress echocardiography (SE) in outpatients only, 3329 patients were monitored during a long-term follow-up regarding the occurrence of hard events (cardiac death, myocardial infarction, revascularization). The patients came to the cardiology practice complaining of chest pain.

RESULTS

The sensitivity/specificity of SE for hard events was 81.1/92.8 in the first year, that of exercise ECG, 27.4/87.0. During the observation period (5.1+/-1.1 years (median 5.2, 3-7 years)), a total of 446 (13.4%) hard events occurred. In patients with positive SE findings, 262 (61.9%) hard events occurred, in patients with negative SE findings, hard events were rarer (184, 6.3%, p<0.001). In the multivariate analysis, the positive SE finding was the most unambiguous, significant independent predictor of hard events (HR 6.6, CI 5.21-8.25, p<0.001).

CONCLUSIONS

In outpatients with chest pains, exercise stress echocardiography is of major prognostic significance (independent of other parameters) and its prognostic reliability is clearly superior to that of the exercise ECG. SE should always be performed in cases with symptoms requiring clarification.

Risk Stratification Using Stress Echocardiography: Incremental Prognostic Value over Historic, Clinical, and Stress Electrocardiographic Variables Across a Wide Spectrum of Bayesian Pretest Probabilities for Coronary Artery Disease

OBJECTIVES

We sought to evaluate the risk stratification ability and incremental prognostic value of stress echocardiography over historic, clinical, and stress electrocardiographic (ECG) variables, over a wide spectrum of bayesian pretest probabilities of coronary artery disease (CAD).

BACKGROUND

Stress echocardiography is an established technique for the diagnosis of CAD. However, data on incremental prognostic value of stress echocardiography over historic, clinical, and stress ECG variables in patients with known or suggested CAD is limited.

METHODS

We evaluated 3259 patients (60 +/- 13 years, 48% men) undergoing stress echocardiography. Patients were grouped into low (<15%), intermediate (15-85%), and high (>85%) pretest CAD likelihood subgroups using standard software. The historical, clinical, stress ECG, and stress echocardiographic variables were recorded for the entire cohort. Follow-up (2.7 +/- 1.1 years) for confirmed myocardial infarction (n = 66) and cardiac death (n = 105) was obtained.

RESULTS

For the entire cohort, an ischemic stress echocardiography study confers a 5.0 times higher cardiac event rate than the normal stress echocardiography group (4.0% vs 0.8%/y, P < .0001). Furthermore, Cox proportional hazard regression model showed incremental prognostic value of stress echocardiography variables over historic, clinical, and stress ECG variables across all pretest probability subgroups (global chi2 increased from 5.1 to 8.5 to 20.1 in the low pretest group, P = .44 and P = .01; from 20.9 to 28.2 to 116 in the intermediate pretest group, P = .47 and P < .0001; and from 17.5 to 36.6 to 61.4 in the high pretest group, P < .0001 for both groups).

CONCLUSIONS

A normal stress echocardiography portends a benign prognosis (<1% event rate/y) in all pretest probability subgroups and even in patients with high pretest probability and yields incremental prognostic value over historic, clinical, and stress ECG variables across all pretest probability subgroups. The best incremental value is, however, in the intermediate pretest probability subgroup.

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.

Treating the right patient at the right time: Access to echocardiography in Canada

The Canadian Cardiovascular Society is the national professional society for cardiovascular specialists and researchers in Canada. In the spring of 2004, the Canadian Cardiovascular Society Council formed the Access to Care Working Group ('Working Group') to use the best science and information available to establish reasonable triage categories and safe wait times for access to common cardiovascular procedures. The Working Group decided to publish a series of commentaries to initiate a structured national discussion on this important issue, and the present commentary proposes recommended wait times for access to echocardiography. 'Emergent' echocardiograms should be performed within 24 h, 'urgent' within seven days and 'scheduled' (elective) within 30 days. A framework for a solution-oriented approach to improve access is presented.

Role of Biplane and Biplane Echocardiographically Guided 3-Dimensional Echocardiography During Dobutamine Stress Echocardiography

Image acquisition time and wall-motion score of conventional 2-dimensional (2D) dobutamine stress echocardiography (DSE) were compared with those of biplane and 3-dimensional (3D) DSE in 50 patients (age 67 +/- 13 years) with regular rhythms during clinically indicated DSE. Commercially available systems were used for the study. We used a conventional transducer for 2D and a matrix-array transducer (x4 or x3-1) for two biplane (60- and 120-degree) images and one 3D full-volume image. Image quality was scored as 1 = good; 2 = adequate; and 3 = inadequate. Segmental wall-motion scores for each method were analyzed in blinded fashion. Acquisition times of biplane (9.3 +/- 2.8 seconds) and biplane-guided 3D (additional 2.6 +/- 1.0 seconds) echocardiography were significantly shorter than those of conventional 2D DSE (60.0 +/- 26.7 seconds) (P < .001). Image quality was adequate or good in 94% for biplane and 96% for 3D echocardiography. Agreement of segmental wall-motion score was present in 87.6% of segments for 2D versus biplane and 85.9% for 2D versus 3D at baseline and in 88.0% for 2D versus biplane and 87.4% for 2D versus 3D at peak stress. Acquisition of biplane or biplane-guided 3D volumetric data during DSE with use of a new matrix-array transducer was feasible and shortened image acquisition time without affecting the diagnostic yield compared with conventional 2D imaging.

Detection of coronary artery disease using real-time myocardial contrast echocardiography: a comparison with dual-isotope resting thallium-201/stress technectium-99m sestamibi single-photon emission computed tomography

Real-time myocardial contrast echocardiography (MCE) has the potential to evaluate myocardial perfusion and wall motion (WM) simultaneously. The purposes of this study were to correlate the diagnostic value of MCE with radionuclide single-photon emission computed tomography (SPECT), and to assess the sensitivity and specificity of real-time MCE in detecting coronary artery disease (CAD). Seventy patients with clinically suspected CAD underwent MCE and SPECT at baseline and after dipyridamole infusion. Segmental perfusion with MCE using low mechanical index after 0.3-0.4-ml bolus injections of perfluorocarbon exposed sonicated dextrose albumin solution was performed. All patients had a dual-isotope (rest thallium-201, stress sestamibi) study performed both at baseline and after dipyridamole infusion, and 40 patients had subsequent quantitative coronary angiography. Abnormalities were noted in 27 patients (38.6%) by MCE, in 29 patients (41.4%) by WM analysis, and in 30 patients (42.9%) by SPECT imaging. When MCE and WM analysis were combined, the agreement with SPECT imaging improved from 75.7% (Kappa = 0.50) to 82.0% (Kappa = 0.62). In 40 patients (120 territories) who underwent coronary angiography, good perfusion concordance was achieved for the left anterior descending and left circumflex arteries, and was fair for the right coronary arteries. Compared with quantitative angiography, there was no difference in sensitivity, specificity, and accuracy in detecting significant CAD among the three modalities. The combination of MCE and WM had a better sensitivity (84%), specificity (93.3%), and accuracy (87.5%) than the MCE and WM analysis alone. However, the difference did not reach statistical significance. Real-time MCE has a good agreement with SPECT imaging for detecting CAD. The combination of MCE and WM appears to have higher sensitivity, specificity, and accuracy in detecting CAD than either technique alone.

Automated quantification of the spatial extent of perfusion defects and viability on myocardial contrast echocardiography

The spatial extent of hypoperfusion or viability is important in the treatment of patients with coronary artery disease. We hypothesized that computerized pixel intensity threshold analysis (PITA) could be used for the automated analysis of perfusion defect size during myocardial contrast echocardiography (MCE). For calibration studies, MCE was performed in 6 dogs undergoing ischemia and reperfusion. Infarct size was determined by PITA, which automatically calculates the percentage of pixels within the myocardium that fail to exceed a predetermined threshold of maximum contrast enhancement. A threshold of 10% of maximum yielded infarct sizes that most closely correlated with those determined by histologic staining. For clinical validation, MCE was performed in 30 patients with acute myocardial infarction before primary percutaneous coronary intervention (PCI) for measurement of risk area; and within 5 days and at 4 weeks after PCI to determine infarct size. The defect size by PITA with a 10% threshold value closely correlated with those measured by expert reader planimetry on background-subtracted color-coded image sets (r = 0.95, P < .001). We conclude that automated analysis of perfusion defect size on MCE is possible by PITA. This technique may be useful for rapid and objective analysis of the extent of ischemia and viability, and for clinical experimentation where accurate and sequential analysis of perfusion defect size is imperative.