Incremental prognostic power of clinical history, exercise electrocardiography and myocardial perfusion scintigraphy in suspected coronary artery disease

Self-reported exercise activity influences the relationship between coronary computed tomography angiographic finding and mortality

AIM

Recent studies suggest that the application of exercise activity questionnaires, including the use of a single-item exercise question, can be additive to the prognostic efficacy of imaging findings. This study aims to evaluate the prognostic efficacy of exercise activity in patients undergoing coronary computed tomography angiography (CCTA).

METHODS AND RESULTS

We assessed 9772 patients who underwent CCTA at a single center between 2007 and 2020. Patients were divided into 4 groups of physical activity as no exercise (n ​= ​1643, 17%), mild exercise (n ​= ​3156, 32%), moderate exercise (n ​= ​3542, 36%), and high exercise (n ​= ​1431,15%), based on a single-item self-reported questionnaire. Coronary stenosis was categorized as no (0%), non-obstructive (1-49%), borderline (50-69%), and obstructive (≥70%). During a median follow-up of 4.64 (IQR 1.53-7.89) years, 490 (7.6%) died. There was a stepwise inverse relationship between exercise activity and mortality (p ​< ​0.001). Compared with the high activity group, the no activity group had a 3-fold higher mortality risk (HR: 3.3, 95%CI (1.94-5.63), p ​< ​0.001) after adjustment for age, clinical risk factors, symptoms, and statin use. For any level of CCTA stenosis, mortality rates were inversely associated with the degree of patients' exercise activity. The risk of all-cause mortality was similar among the patients with obstructive stenosis with high exercise versus those with no coronary stenosis but no exercise activity (p ​= ​0.912).

CONCLUSION

Physical activity as assessed by a single-item self-reported questionnaire is a strong stepwise inverse predictor of mortality risk among patients undergoing CCTA.

Long-Term Risk Assessment After the Performance of Stress Myocardial Perfusion Imaging

Stress-rest myocardial perfusion imaging (MPI) is a potent method for assessing the presence and magnitude of inducible myocardial ischemia. Stress MPI currently faces increased scrutiny for its therapeutic effectiveness because of the emergence of other competing means for assessing clinical risk. New data have examined the usefulness stress-rest-MPI as a predictor for long-term clinical outcomes, in contrast to its traditional role for assessing short-term cardiovascular risk. These data indicates that temporal risk is highly influenced by both the magnitude of ischemia and various baseline clinical factors. An optimized assessment of stress MPI, which includes long-term risk prediction, might improve the potential future clinical effectiveness of this imaging modality.

Recommendations for the evaluation and management of observation services: a consensus white paper: the Society of Cardiovascular Patient Care

Observation Services (OS) was founded by emergency physicians in an attempt to manage "boarding" issues faced by emergency departments throughout the United States. As a result, OS have proven to be an effective strategy in reducing costs and decreasing lengths of stay while improving patient outcomes. When OS are appropriately leveraged for maximum efficiency, patients presenting to emergency departments with common disease processes can be effectively treated in a timely manner. A well-structured observation program will help hospitals reduce the number of inappropriate, costly inpatient admissions while avoiding the potential of inappropriate discharges. Observation medicine is a complicated multidimensional issue that has generated much confusion. This service is designed to provide the best possible patient care in a value-based purchasing environment where quality, cost, and patient satisfaction must continually be addressed. Observation medicine is a service not a status. Therefore, patients are admitted to the service as outpatients no matter whether they are placed in a virtual or dedicated observation unit. The key to a successful observation program is to determine how to maximize efficiencies. This white paper provides the reader with the foundational guidance for observational services. It defines how to set up an observational service program, which diagnoses are most appropriate for admission, and what the future holds. The goal is to help care providers from any hospital deliver the most appropriate level of treatment, to the most appropriate patient, in the most appropriate location while controlling costs.

Comparison of the prognostic value of normal regadenoson with normal adenosine myocardial perfusion imaging with propensity score matching

OBJECTIVES

The aim of this study was to test the hypothesis that patients with normal regadenoson myocardial perfusion imaging (MPI) have a low rate of cardiac events, similar to patients with normal adenosine MPI.

BACKGROUND

Regadenoson, a new selective adenosine A(2A) receptor agonist, is now a widely used stress agent for MPI. The low rate of cardiac events in patients with normal adenosine MPI is well-documented, but the prognostic implications of a normal regadenoson MPI have not been examined and compared with those with adenosine.

METHODS

Data on primary composite endpoint (cardiac death, myocardial infarction, and coronary revascularization) were collected for 2,000 patients (1,000 regadenoson, and 1,000 adenosine stress) with normal myocardial perfusion and left ventricular ejection fraction referred for vasodilator MPI. In addition, propensity scores were used to assemble a balanced cohort of 505 pairs of patients who were balanced on 36 baseline characteristics.

RESULTS

The primary endpoint occurred in 21 (2.1%; 1.1%/year) patients in the regadenoson group and 33 (3.3%; 1.7%/year) patients in the adenosine group (hazard ratio [HR] for regadenoson vs. adenosine: 0.62; 95% confidence interval [CI]: 0.36 to 1.08; p = 0.090). In the propensity-matched pairs, the primary endpoint occurred in 7 (1.4%; 0.7%/year) patients in the regadenoson group and 13 (2.6%; 1.3%/year) patients in the adenosine group (matched HR: 0.58; 95% CI: 0.23 to 1.48; p = 0.257). Cardiac deaths were infrequent in the entire sample and in the propensity-matched groups; the cardiac death rate was 0.9%/year and 1.15%/year in the regadenoson and adenosine groups (HR: 0.77; 95% CI: 0.42 to 1.43; p = 0.404) in the pre-match sample and 0.5%/year and 0.7%/year in the matched groups, respectively (HR: 0.83; 95% CI: 0.25 to 2.73; p = 0.763).

CONCLUSIONS

Major cardiac events are infrequent in patients with normal regadenoson MPI. These findings provide assurance that normal MPI using a simpler stress protocol with regadenoson provides prognostic data similar to normal adenosine MPI.

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.

Prognostic value of a nine-minute treadmill test in patients undergoing myocardial perfusion scintigraphy

Exercise capacity is an important predictor of risk in known or suspected coronary disease. A negative treadmill test to 9 minutes of the Bruce protocol is often used in the screening process for vocational licensing; myocardial perfusion scintigraphy is an alternative for those unable to exercise, with apparent incremental prognostic power above exercise testing alone. We compared exercise test and myocardial perfusion scintigraphic (MPS) findings and risk of hard cardiac events (median 4 years) in patients completing ≥ 9-minute treadmill exercise. Patients undergoing myocardial perfusion scintigraphy who completed a 9-minute Bruce protocol exercise were identified over a 2-year period. Follow-up was performed by telephone, with case-note review when necessary; this was 97% complete. Five hundred sixteen patients were identified (73% men, median age 53 year). One hundred eighty-one (35%) had known coronary disease. One hundred forty-nine (29%) had a "high-risk" exercise test result (limiting chest pain or ST-segment depression), and 69 (13%) had high-risk MPS findings (>10% myocardium ischemic or ejection fraction <40%). Of 367 patients with a reassuring exercise test result, 38 (10.4%) had high-risk MPS findings. Of 149 with a high-risk exercise test, 118 (79%) had reassuring MPS findings. At median follow-up of 49 months, there were 8 cardiac events (1.6%). Only 2 patients with high-risk exercise test results (1.4%) and 1 with high-risk MPS findings (1.5%) had an event. In conclusion, for patients able to manage a 9-minute Bruce protocol, presence/absence of symptoms or electrocardiographic changes is a poor predictor of MPS findings. Irrespective of test findings, however, subsequent cardiac risk is extremely low. Ability to complete a 9-minute Bruce protocol treadmill exercise may itself provide adequate prognostic reassurance for most purposes.

Emergency department and office-based evaluation of patients with chest pain

The management of patients with chest pain is a common and challenging clinical problem. Although most of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent management of a serious problem such as acute coronary syndrome (ACS) and those with more benign entities who do not require admission. Although clinical judgment continues to be paramount in meeting this challenge, new diagnostic modalities have been developed to assist in risk stratification. These include markers of cardiac injury, risk scores, early stress testing, and noninvasive imaging of the heart. The basic clinical tools of history, physical examination, and electrocardiography are currently widely acknowledged to allow early identification of low-risk patients who have less than 5% probability of ACS. These patients are usually initially managed in the emergency department and transitioned to further outpatient evaluation or chest pain units. Multiple imaging strategies have been investigated to accelerate diagnosis and to provide further risk stratification of patients with no initial evidence of ACS. These include rest myocardial perfusion imaging, rest echocardiography, computed tomographic coronary angiography, and cardiac magnetic resonance imaging. All have very high negative predictive values for excluding ACS and have been successful in reducing unnecessary admissions for patients at low to intermediate risk of ACS. As patients with acute chest pain transition from the evaluation in the emergency department to other outpatient settings, it is important that all clinicians involved in the care of these patients understand the tools used for assessment and risk stratification.

Chronic coronary artery disease: diagnosis and management

Coronary artery disease (CAD) is the single most common cause of death in the developed world, responsible for about 1 in every 5 deaths. The morbidity, mortality, and socioeconomic importance of this disease make timely accurate diagnosis and cost-effective management of CAD of the utmost importance. This comprehensive review of the literature highlights key elements in the diagnosis, risk stratification, and management strategies of patients with chronic CAD. Relevant articles were identified by searching the PubMed database for the following terms: chronic coronary artery disease or stable angina. Novel imaging modalities, pharmacological treatment, and invasive (percutaneous and surgical) interventions have revolutionized the current treatment of patients with chronic CAD. Medical treatment remains the cornerstone of management, but revascularization continues to play an important role. In the current economic climate and with health care reform very much on the horizon, the issue of appropriate use of revascularization is important, and the indications for revascularization, in addition to the relative benefits and risks of a percutaneous vs a surgical approach, are discussed.

The Prognostic Value of Vasodilator Myocardial Perfusion Imaging in Octogenarians

The ability of single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) to stratify risk in octogenarians is poorly defined. The authors identified 439 octogenarians who underwent vasodilator SPECT MPI between 1994 and 2000. Over a mean 2.5 years of follow-up, moderate and large stress defects were associated with increased crude mortality (normal: 24.5%, small defect: 21.9%, moderate or large stress defect: 41.4%, p for trend < 0.001). The degree of defect reversibility was also strongly associated with increased mortality (normal: 24.5%, no reversibility: 22.0%, small reversible defect: 36.5%, moderate or large reversible defect: 50.0%, p for trend < 0.001). In multivariable analysis, stress defects were the strongest predictor of mortality (hazard ratio, 2.39; 95% confidence interval, 1.56-3.65). The mortality of octogenarians with moderate or large perfusion defects is nearly double that of patients with normal or mildly abnormal MPI. Appropriately selected octogenarians with abnormal vasodilator SPECT imaging may benefit from more aggressive management of their cardiac disease.

From here to eternity: a unified kinetic model for the pathophysiology of atherosclerotic events

Two operative pathophysiological models underlie the clinical management of ischemic heart disease: a physical model founded on the magnitude of vascular stenosis and a biochemical model founded on the inflammatory processes within the atherosclerotic plaque. Despite their complementary natures, these 2 models are implicitly competitive--the stenotic model supporting the primacy of aggressive interventional procedures and the inflammatory model supporting the primacy of conservative medical management. We unified these alternative perspectives through a kinetic model that characterizes the pathophysiology of cardiovascular events as a network of exponential transitions between the inflammatory and stenotic states. According to this model, the prevalence of the normative (nonstenotic and noninflammatory) state falls exponentially, while the prevalences of the inflammatory and stenotic states rise to a peak and then fall off exponentially. According to this model, event rate increases as a complex function of both myocardial ischemia and vascular inflammation. Although the model has yet to be prospectively validated, it provides a theoretical foundation for predicting the degree to which atherosclerotic events are due to inflammation versus stenosis and the degree to which they can thereby be prevented by treatment strategies directed at plaque stabilization or relief of ischemia.

Correlation between myocardial perfusion abnormalities detected with intermittent imaging using intravenous perfluorocarbon microbubbles and radioisotope imaging during high-dose dipyridamole stress echo

BACKGROUND

The clinical accuracy of myocardial contrast echocardiography (MCE) using intermittent harmonic imaging and intravenous perfluorocarbon containing microbubbles during dipyridamole stress has not been evaluated in a multicenter setting.

HYPOTHESIS

The accuracy of dipyridamole stress contrast echo in the detection of coronary artery disease (CAD) using myocardial perfusion images is high in comparison with technetium-99 (99Tc) sestamibi single-photon emission computed tomography (MIBI SPECT) and increases the accuracy of wall motion data.

METHODS

In 68 consecutive nonselected patients (46 men; mean age 66 years) from three different institutions in two countries. dipyridamole stress echo and SPECT with 99mTc MIBI were compared. Continuous intravenous (IV) infusion of perfluorocarbon exposed sonicated dextrose albumin (PESDA) (2-5 cc/min) was administered for baseline myocardial perfusion using triggered harmonic end systolic frames. Real-time digitized images were used for wall motion analysis. Dipyridamole was then injected in two steps: (1) 0.56 mg/kg for 3 min, (2) 0.28 mg/kg for 1 min, if the first step was negative for an inducible wall motion abnormality. After dipyridamole injection, myocardial contrast enhancement and wall motion were analyzed again by the same methodology.

RESULTS

There were 35 patients with perfusion defects by SPECT. Wall motion was abnormal in 22, while MCE was abnormal in 32. Wall motion and MCE each had one false positive. The proportion of correctly assigned patients was significantly better with MCE than with wall motion (p = 0.03; chi square test).

CONCLUSIONS

Myocardial contrast echocardiography, using intermittent harmonic imaging and intravenous perfluorocarbon containing microbubbles, is a very effective method for detecting coronary artery disease during dipyridamole stress echo.

Coronary flow velocity reserve measurement in three major coronary arteries using transthoracic Doppler echocardiography

BACKGROUND

Measurement of the coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) has been reported to be useful for the noninvasive assessment of significant coronary artery stenosis or myocardial ischemia. The purpose of this study was to evaluate the value of this method in three major coronary arteries for detecting myocardial ischemia in the clinical setting.

METHODS

We studied 89 consecutive patients who were referred to our outpatient clinic because of chest pain. We measured CFVR using TTDE in three major coronary arteries. We defined CFVR<2.0 in at least one vessel as being positive for myocardial ischemia. The accuracy of CFVR measurements for detecting myocardial ischemia was determined in comparison with exercise thallium-201 (Tl-201) single photon emission computed tomography (SPECT) as a reference standard.

RESULTS

CFVR in at least one vessel was successfully measured in 87 of 89 patients (98%). The sensitivity and specificity of CFVR<2.0 in at least one coronary vessel, in any of the coronary territories, was 86% and 89%, respectively. In terms of assessing myocardial ischemia in each coronary artery territory, the agreement between CFVR<2.0 and Tl-201 SPECT for the left anterior descending coronary artery, the posterior descending coronary artery, and the left circumflex coronary artery territories was 95%, 81%, and 73%, respectively.

CONCLUSION

Noninvasive CFVR measurement by TTDE may be useful for detecting myocardial ischemia, as well as for identifying ischemic territories in the clinical setting.

Prognostic value of exercise stress technetium-99m-tetrofosmin myocardial perfusion imaging in patients with normal baseline electrocardiograms

Exercise stress electrocardiography is the recommended method for cardiac evaluation of patients with normal electrocardiograms (ECGs). There are no data to indicate an independent value of myocardial perfusion imaging (MPI) in predicting mortality in these patients. This study assessed the value of exercise stress MPI in predicting mortality in patients with normal baseline ECGs. We studied 319 patients (55 +/- 10 years of age; 180 men) with normal ECGs by exercise stress technetium-99m tetrofosmin MPI. End points during follow-up were cardiac and all-cause mortalities and hard cardiac events. A normal scan was detected in 190 patients (60%). Myocardial perfusion abnormalities were fixed in 59 patients (18%) and reversible in 70 (23%). During a mean follow-up of 7 +/- 1.2 years, 46 patients (14%) died. Death was considered cardiac in 28 patients (9%). Nonfatal myocardial infarction occurred in 12 patients (4%). Annual cardiac death rates were 0.4% in patients with normal perfusion, and 2.7% in patients with reversible defects. Annual total mortality rates were 1.1% in patients with normal perfusion and 3.4% in patients with reversible defects. In a multivariate analysis model, reversible perfusion abnormalities were associated with cardiac death (RR 2.8, 95% confidence interval 1.6 to 5.1) and hard cardiac events (RR 2.7, 95% confidence interval 1.5 to 4.5). Perfusion abnormalities in multivessel distribution were predictive of all-cause mortality (RR 2, 95% confidence interval 1.4 to 3.2). ST-segment depression was not significantly associated with events. In conclusion, stress technetium-99m tetrofosmin MPI provides independent information for predicting cardiac and overall mortalities in patients with normal ECGs. Reversible perfusion abnormalities, but not ischemic electrocardiographic changes, are predictive of outcome in these patients.

Diabetes mellitus: evaluation of patients with known or suspected coronary artery disease and the role played by myocardial perfusion imaging

Type 2 diabetes markedly increases cardiovascular risk, and patients often present with advanced and asymptomatic disease. The fact that diabetes is associated with an increased risk of acute coronary events and poor long-term survival makes a strong case for detecting coronary artery disease early, perhaps before clinical manifestation in this patient population. This article examines the role of myocardial perfusion scintigraphy in the diagnostic and prognostic evaluation of diabetic patients with suspected coronary artery disease and in screening high-risk asymptomatic diabetic patients.

The use of nuclear cardiology in clinical decision making

Extensive data exist to support the role of myocardial perfusion single-photon emission computed tomography (MPS) in risk stratification. Normal MPS studies usually are associated with very low risk, and patient risk increase significantly as a function of MPS results. Ventricular function measurements from gated single-photon emission computed tomography further augment risk stratification, particularly with respect to identifying patients at risk of cardiac death. Ancillary findings are prognostically important, particularly in the setting of normal or near-normal MPS results. Recent data suggest that MPS results can identify which patients will benefit from revascularization versus medical therapy and have expanded the understanding of how stress MPS is helpful in the identification of risk, enhanced the means of identifying risk, and improved its use as a means to identify optimal posttest treatment.

Prospective validation of a quantitative method for differentiating ischemic versus nonischemic cardiomyopathy by technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography

BACKGROUND

Myocardial perfusion single-photon emission computed tomography (SPECT) permits assessment of stress perfusion and resting left ventricular (LV) function. Quantitative analysis of perfusion patterns among patients with LV dysfunction offers an opportunity for developing criteria to differentiate ischemic from nonischemic cardiomyopathy.

HYPOTHESIS

Quantitative assessment of SPECT may allow differentiation between ischemic and nonischemic cardiomyopathy.

METHODS

We evaluated 144 patients with LV ejection fraction < or =40%, divided into 63 patients with nonischemic and 81 with ischemic cardiomyopathy. Mean relative myocardial counts were obtained for regions drawn over defect and normal zones on rest and stress polar perfusion maps.

RESULTS

Multivariate logistic regression analysis of significant univariate SPECT predictors of ischemic cardiomyopathy revealed that the stress defect severity ratio (SDSR) was the best predictor of ischemic cardiomyopathy (p < 0.0001). By receiver operator characteristic (ROC) curve analysis, an SDSR of < or =45% optimized prediction of ischemic cardiomyopathy (sensitivity 81%, specificity 96%). An SDSR of < or =45% occurred in 65 of 81 (80%) patients with ischemic cardiomyopathy, but in only 3 of the 63 (4%) patients with nonischemic cardiomyopathy (p < 0.0001). Applying the < or =45% SDSR threshold to a prospective group of 89 patients yielded a somewhat lower sensitivity (60%), but retained high specificity (91%) for identifying ischemic cardiomyopathy (p = NS vs. retrospective group).

CONCLUSIONS

Presence of a severe and extensive stress perfusion defect is a hallmark of ischemic cardiomyopathy. By contrast, a mild stress perfusion defect (SDSR of >45%) is commonly present among patients with ischemic and nonischemic cardiomyopathy. An SDSR of < or =45% is a reproducible specific marker for identifying the presence of ischemic cardiomyopathy.

Advances in nuclear imaging for preoperative risk assessment

Myocardial perfusion imaging (MPI) is frequently utilized for preoperative risk assessment. Results are pertinent for long-term risk. MPI, though most frequently applied in intermediate-risk patients, may also be valuable in selected low- and high-risk individuals. Coronary stenting may alter the timing of noncardiac surgery, which should be considered when performing preoperative risk assessment.

Utility of myocardial perfusion imaging in patients with low-risk treadmill scores

OBJECTIVES

The purpose of this study was to determine whether a previously validated clinical score (CS) could identify patients with a low-risk Duke treadmill score who had a higher risk of adverse events and, therefore, in whom myocardial perfusion imaging would be valuable for risk stratification.

BACKGROUND

Current American College of Cardiology/American Heart Association guidelines recommend using a standard exercise test without imaging as the initial test in patients who have an interpretable electrocardiogram and are able to exercise.

METHOD

We studied 1,461 symptomatic patients with low-risk Duke treadmill scores (> or =5) who underwent myocardial perfusion imaging. The CS was derived by assigning one point to each of the following variables: typical angina, history of myocardial infarction, diabetes, insulin use, male gender, and each decade of age over 40 years. A CS cutoff > or =5 or <5 was used to categorize patients as high risk (n = 303 [21%]) or low risk (n = 1,158 [79%]). Perfusion scans were categorized as low, intermediate, or high risk on the basis of the global stress score (GSS).

RESULTS

High-risk scans were more common in patients with a high-risk CS (26.4% vs. 9.5%, p < 0.0001). The CS and GSS were significant independent predictors of cardiac death. However, in patients with a low CS, seven-year cardiac survival was excellent, regardless of the GSS (99% for normal scans, 99% for mildly abnormal scans, and 99% for severely abnormal scans). In contrast, patients with a high CS had a lower seven-year survival rate (92%), which varied with GSS (94% for normal scans, 94% for mildly abnormal scans, and 84% for severely abnormal scans; p < 0.001).

CONCLUSIONS

In symptomatic patients with low-risk Duke treadmill scores and low clinical risk, myocardial perfusion imaging is of limited prognostic value. In patients with low-risk Duke treadmill scores and high clinical risk, annual cardiac mortality (>1%) is not low, and myocardial perfusion imaging has independent prognostic value.

Stress myocardial perfusion single-photon emission computed tomography is clinically effective and cost effective in risk stratification of patients with a high likelihood of coronary artery disease (CAD) but no known CAD

OBJECTIVES

We sought to evaluate the prognostic and cost implications of stress myocardial perfusion single-photon emission computed tomography (SPECT), or MPS, in patients with a high pretest likelihood (>0.85) of coronary artery disease (CAD) with no previous CAD.

BACKGROUND

Sparse data are available regarding the prognostic performance characteristics of MPS in this patient group.

METHOD

We followed up 1,270 consecutive patients with no previous revascularization or myocardial infarction (MI), with a pre-exercise tolerance test (ETT) likelihood of CAD > or =0.85, who underwent exercise or adenosine stress MPS (follow-up 94.4% complete; 2.2 +/- 1.2 years; 60 hard events [5.9%, 2.6%/year]). Risk adjustment of survival data was done using Cox proportional hazards analysis. Costs per reclassification of risk were calculated using assumed costs and threshold analyses.

RESULTS

In patients treated medically after MPS, normal MPS had a low risk of cardiac death and hard events (0.6% and 1.3% per year, respectively). With increasing extent and severity of MPS defects, the risk of both cardiac death and hard events increased significantly (p < 0.05). Cox models indicated that the addition of MPS data resulted in incremental prognostic value over pre-MPS data (chi-square increase 48 to 87, p < 0.0001). Compared with strategies of initial referral to ETT in patients able to exercise, initial referral to MPS appeared to be a more cost-effective strategy. Similarly, compared with a strategy of direct referral to catheterization in patients with a high likelihood of CAD, initial referral to MPS is a cost-saving approach.

CONCLUSIONS

In patients with a high likelihood of CAD but without known CAD, stress MPS yields incremental value and achieves risk stratification in a cost-effective manner. The current results support a strategy of initial stress imaging in this patient cohort, as a reasonable alternative to direct referral to catheterization or initial ETT.

Noninvasive assessment of myocardial ischemia in the left ventricular inferior regions by coronary flow reserve measurement using transthoracic doppler echocardiography

OBJECTIVE

The purpose of this study was to evaluate the potential of noninvasive measurement of coronary flow reserve (CFR) by transthoracic Doppler echocardiography (TTDE) for the assessment of myocardial ischemia in the left ventricular (LV) inferior regions.

BACKGROUND

Although coronary flow assessment by TTDE has been determined for the assessment of perfusion abnormality in the LV anterior regions, the usefulness of this method has not been well investigated in the LV inferior regions.

METHODS

We studied 50 patients (43 men; mean age 60 +/- 9 years) with suggested coronary artery disease. CFR in the posterodescending coronary artery (PDA) was calculated as a ratio of hyperemic to basal peak (peak CFR) and mean (mean CFR) flow velocities in the PDA, which were measured by TTDE. CFR values were compared with the results of exercise 201-thallium single photon emission computed tomography.

RESULTS

CFR was successfully measured in 43 of 50 patients (86%). Mean and peak CFR < 2 were shown in 10 of 12 patients with abnormal perfusion in the LV inferior regions, whereas CFR > or = 2 were shown in 30 of 31 patients with normal perfusion. Thus, CFR < 2 in the PDA by TTDE had a sensitivity of 83% and a specificity of 97% for the assessment of perfusion abnormality in the LV inferior regions by 201-thallium single photon emission computed tomography.

CONCLUSIONS

CFR in the PDA measured by TTDE provides data equivalent to those obtained by 201-thallium single photon emission computed tomography for myocardial ischemia in the LV inferior regions.

New frontiers in risk stratification using stress myocardial perfusion single photon emission computed tomography

PURPOSE OF REVIEW

The purpose of this review is to review the recent published literature since 2002 for studies using stress myocardial perfusion single photon emission computed tomography for determination of the prognostic value of testing.

RECENT FINDINGS

A series of manuscripts dealing with myocardial perfusion single photon emission computed tomography have been published over the past 2 years that have altered a number of the most basic concepts defining risk stratification. These studies may have redefined the manner in which noninvasive stress imaging results will be interpreted and applied.

SUMMARY

Recent studies have expanded the understanding of how stress myocardial perfusion single photon emission computed tomography is helpful in the identification of risk, enhanced the means of identifying risk, and improved its use as a means to identify optimal posttest treatment.

Determinants of risk and its temporal variation in patients with normal stress myocardial perfusion scans: what is the warranty period of a normal scan?

OBJECTIVES

The aim of this study was to determine the predictors of risk and the temporal characteristics of risk associated with normal myocardial perfusion single photon emission computed tomography (MPS).

BACKGROUND

No empiric data exist regarding predictors of risk after normal MPS and their temporal characteristics.

METHODS

Follow-up (mean: 665 +/- 200 days, 96% complete) of 7,376 consecutive patients with normal exercise or adenosine MPS identified 78 hard events (HE) (45 cardiac deaths, 33 non-fatal myocardial infarction; 1.1% cumulative HE rate, 0.6%/year). Cox proportional hazards analysis was used to identify predictors of HE. Parametric survival analysis was used to model predicted time to HE.

RESULTS

The HE rates were greater in patients with versus without previous coronary artery disease (CAD). The Cox proportional hazards model identified pharmacologic stress, known CAD, diabetes mellitus (DM), male gender, and increasing age, with interactions between stress type and previous CAD (lower risk in patients without previous CAD undergoing exercise stress vs. all others) and between DM and gender (higher risk in DM females vs. all others) as the model most predictive of HE. The highest risk subgroups had a maximal event rate of 1.4% to 1.8%/year. Parametric survival models revealed that in patients without previous CAD the level of risk was uniform with time, but in patients with known CAD, risk increased with time (e.g., risk in the first year was less than in the second year, hence, a dynamic temporal component of risk was present).

CONCLUSIONS

Multiple clinical factors add incremental prognostic value in patients with normal MPS, affecting their risk and its temporal pattern, and may alter the appropriate timing of repeat testing, hence establishing the existence of a "warranty" period for normal MPS studies.

Exercise echocardiography and thallium-201 single-photon emission computed tomography stress test for 5- and 10-year prognosis of mortality and specific cardiac events

Limited data suggest that stress myocardial perfusion imaging and stress echocardiography have similar prognostic value for composite cardiac events. However, it is not known whether exercise echocardiography and stress thallium are similar in their prediction of specific cardiac events, eg, death, sudden death, myocardial infarction, unstable angina, and congestive heart failure. A total of 206 patients undergoing stress echocardiography and thallium-201 single-photon emission computed tomography imaging during the same exercise test were followed-up for 5 and 10 years. Multivariate Cox regression analyses incorporating clinical, exercise stress test, echocardiographic, and nuclear imaging parameters were used to predict mortality and specific cardiac events. A moderate to large amount of ischemia (> or =4 segments on the basis of a 16-segment model) by exercise stress echocardiography was the strongest predictor of overall mortality (relative risk [RR] 6.2; P <.0001), cardiac death (RR 17.6; P =.01), congestive heart failure (RR 17.4; P =.0005) or sudden death (RR 26.8; P =.003), whereas a moderate to large fixed defect (> or =2 segments on the basis of a 6-segment model) by nuclear imaging was the strongest predictor of myocardial infarction (RR 8.1; P =.0002) or unstable angina (RR 3.0; P =.005) at 5 years. The heterogeneity in the prediction of these specific cardiac events by these 2 modalities was similarly observed at 10 years. The extent of ischemia by stress echocardiography is a better predictor of overall mortality, cardiac death, congestive heart failure, or sudden death, whereas the extent of a fixed defect by nuclear imaging is a better predictor of myocardial infarction or unstable angina.

Age-related determinants of outcome after acute myocardial infarction: a dobutamine-atropine stress echocardiographic study

OBJECTIVES

To investigate the cause of worse survival in older patients after myocardial infarction (MI).

DESIGN

Prospective 18-month and longer follow-up study of a cohort of 167 patients (mean age +/- standard deviation 58 +/- 12, including 71 aged >or=65) with acute MI for cardiac events, defined as cardiac death, recurrent MI, or resuscitated ventricular tachycardia or fibrillation (VT/VF).

SETTING

Milwaukee County Medical Complex and the Zablocki Veterans Affairs Medical Center, Milwaukee, WI.

PARTICIPANTS

One hundred sixty-seven patients who underwent dobutamine-atropine stress echocardiography (DASE) in the first week (2-7 days) after acute MI and were medically managed.

MEASUREMENTS

Comparison of event rates in older (>or=65 years) and younger (<65 years) patients and of clinical, resting echocardiographic, DASE, and angiographic findings in patients with and without events. Coronary angiography was performed in 141.

RESULTS

Older and younger patients tolerated DASE well. During follow-up, there were 29 cardiac events (cardiac death in 17, nonfatal MI in 10, and VT/VF in 2). Events were more common in older patients (26% vs 12%, P <.05), especially death (19% vs 5%, P <.05). Scar size in the infarct zone by DASE was larger (4.0 +/- 2.8 vs 3.0 +/- 2.7 segments, P <.05) and remote wall motion abnormalities more common (47 vs 29%, P <.05) in older patients. Univariate determinants of outcome (P <.05) in older patients were diabetes mellitus; remote wall motion abnormalities; angiographic multivessel disease; scar size; ejection fraction; and resting, low-, and peak-dose wall motion score. Univariate determinants in younger patients were similar, but diabetes mellitus was not. Multivariate analysis revealed that remote wall motion abnormalities and scar size by DASE were independently predictive of outcome in older and younger patients and diabetes mellitus only in older patients. Low- and peak-dose DASE data enhanced (P <.01) the prediction of outcome in all patients with acute MI relative to clinical data and resting echocardiography.

CONCLUSION

DASE was more predictive of outcome than clinical data and resting echocardiography in both age groups. Scar size and remote wall motion abnormalities were the primary determinants of outcome irrespective of age. The worse prognosis of older patients correlated with diabetes mellitus, greater scar size, and higher incidence of remote inducible ischemia.

Value of stress myocardial perfusion single photon emission computed tomography in patients with normal resting electrocardiograms: an evaluation of incremental prognostic value and cost-effectiveness

BACKGROUND

The incremental value and cost-effectiveness of stress single photon emission computed tomography (SPECT) is of unclear added value over clinical and exercise treadmill testing data in patients with normal resting ECGs, a patient subset known to be at relatively lower risk.

METHODS AND RESULTS

We identified 3058 consecutive patients who underwent exercise dual isotope SPECT, who on follow-up (mean, 1.6+/-0.5 years; 3.6% lost to follow-up) were found to have 70 hard events (2.3% hard-event rate). Survival analysis used a Cox proportional hazards model, and cost-effectiveness was determined by the cost per hard event identified by strategies with versus without the use of SPECT. In this cohort, a normal study was associated with an exceedingly low hard-event rate (0.4% per year) that increased significantly as a function of the SPECT result. After adjusting for pre-SPECT information, exercise stress SPECT yielded incremental value for the prediction of hard events (chi2 52 to 85, P<0.001) and significantly stratified patients. In patients with intermediate to high likelihood of coronary artery disease after exercise treadmill testing, a cost-effectiveness ratio of $25 134 per hard event identified and a cost of $5417 per reclassification of patient risk were found. Subset analyses revealed similar prognostic, and cost results were present in men, women, and patients with and without prior histories of coronary artery disease.

CONCLUSIONS

Stress SPECT yields incremental prognostic value and enhanced risk stratification in patients with normal resting ECGs in a cost-effective manner. These findings are opposite those of previous studies examining anatomic end points in this same population and thus, if confirmed, have significant implications for patient management.

Contemporary management of chronic stable angina

Chronic stable angina is a common condition with a prognosis that is less benign than is generally appreciated. The optimal treatment strategy of this disorder is unclear, and few anti-ischaemic agents have been rigorously tested in prospectively randomised mortality studies. The evidence base for the anti-ischaemic therapy of chronic angina draws upon data 'borrowed' from studies in acute coronary syndromes, and from studies in chronic angina using surrogate endpoints such as ambulatory silent ischaemia. Such evidence leads us to believe that anti-ischaemic therapy with beta-blockers offers a mortality benefit in chronic angina. In contrast, the mortality benefit of lipid lowering therapy and antiplatelet agents is well proven. Angioplasty offers no mortality benefit in the treatment of chronic angina, although it is more effective than medical therapy alone for the relief of symptoms. In a few patients with high order proximal coronary disease, coronary bypass surgery offers a distinct mortality advantage compared with medical treatment alone. Most patients, however, do not warrant such an approach, and only require surgery for when they remain symptomatic despite adequate medical therapy. Alternative strategies such as cardiac transplantation, transmyocardial laser revascularisation and spinal cord stimulation are now accepted in a subgroup of patients for the treatment of chronic angina refractory to standard therapy.

The cumulative effects of historical and physical examination findings on the prognostic value of the electrocardiogram

The electrocardiogram has been shown in epidemiologic studies to be an independent predictor of survival. These studies have adjusted for selected covariates simultaneously. This article assesses the value of the electrocardiogram as a predictor of survival when introduced at progressive stages of the common clinical encounter. Data collected from 4,518 patients ages of 60 to 96 years with isolated systolic hypertension who were followed-up for up to 6 years as part of the Systolic Hypertension in the Elderly Project were analyzed. Survival curves and 3- and 5-year survival rates (Cox regression methods) of groups with normal and abnormal resting electrocardiograms were compared. Blocks of covariates representing demographic information, risk factors for cardiovascular disease, clinical history, and physical examination findings were added to the survival models sequentially to mimic the sequence of the common clinical encounter, and the independent significance of the electrocardiogram as a predictor of survival was assessed at each step. An abnormal electrocardiogram was associated with reduced survival when no adjustment for covariates is made. Survival was also significantly (P <.05) different for groups with normal and abnormal electrocardiograms when demographic and risk factor variables were included in the statistical models, but not after findings from the clinical history and physical examination were added. The prognostic value of the electrocardiogram varies with the stage in the clinical encounter in which it is introduced.

Cardiac nuclear medicine in monitoring patients with coronary heart disease

Patient monitoring is a major indication for cardiac nuclear medicine procedures. Stress myocardial perfusion scintigraphy was initially used for diagnosis, but monitoring patients with coronary artery disease has become more common. Stress myocardial perfusion scintigraphy has been shown to provide a considerable amount of incremental prognostic information, which may be useful in selecting patients for therapy. In patients being considered for revascularization, fluorodeoxyglucose can be used to identify regions of dysfunctional but viable myocardium, even within regions that show fixed defects on stress perfusion imaging. It can be used to select a group of patients who will improve function with revascularization and who may have an improved outcome. Thus, cardiac nuclear medicine plays a pivotal role in monitoring patients with coronary artery disease.

Non-invasive investigations

The most commonly used techniques for imaging the effects of coronary artery disease (CAD) on the heart are myocardial perfusion scintigraphy (MPS) and echocardiography. Both tests have been validated during exercise and pharmacological stress and they are valuable for the diagnosis and aiding management decisions in patients with suspected or known CAD. In a proportion of these patients, repetitive episodes of myocardial ischaemia can lead to intracellular and extracellular changes so that myocytes, although viable, have insufficient energy to sustain contraction. This phenomenon is known as myocardial hibernation and it can be detected accurately by both MPS and stress echocardiography. The review that follows highlights the role of these techniques as powerful diagnostic and prognostic tools in clinical cardiology. In order to make the best use of them, attention to detail and planning are required to design the test to suit the clinical problem and to obtain the most accurate data possible.

Incremental prognostic value of myocardial perfusion single photon emission computed tomography in patients with diabetes mellitus

BACKGROUND

Previous studies have shown that myocardial perfusion single photon emission computed tomography (SPECT) provides incremental prognostic information in the general population, but the prognostic efficacy of nuclear testing in patients with diabetes mellitus is unclear.

METHODS

We conducted a study with 1271 consecutively registered patients with diabetes and 5862 patients without diabetes with known or suspected coronary artery disease undergoing rest thallium 201/stress technetium 99m sestamibi dual-isotope myocardial perfusion SPECT with exercise or adenosine pharmacologic testing. Patients were followed up for at least 1 year. The successful follow-up rate was 92.4% for patients with diabetes and 94.0% for subjects without diabetes. The mean follow-up period was 23.7 +/- 7.7 months for the former group and 21.5 +/- 6.1 months for the latter.

RESULTS

Over the follow-up period, patients with diabetes had significantly higher rates of hard events (cardiac death or nonfatal myocardial infarction) (4.3% per year versus 2.3% per year, P <.001) and higher total event rates (hard events and late revascularization) (9.0% per year versus 5.3% per year, P <. 001) compared with rates among patients without diabetes. Cox proportional hazards analysis revealed that nuclear testing added incremental value over clinical and historical variables among patients with diabetes (global chi(2) increased 46% for the exercise group [n = 619] and 88% for the adenosine group [n = 461]; both P <. 001). The event rates rose significantly as a function of summed stress score and summed difference score among both patients with diabetes and patients without diabetes (P <.001). The patients with diabetes with normal scans had relatively low hard event rates (1% to 2% per year), those with mildly abnormal scans had intermediate hard event rates (3% to 4% per year), and those with moderately to severely abnormal scans had relatively high hard event rates (>7% per year).

CONCLUSIONS

The results of this study indicated that exercise and adenosine stress myocardial perfusion SPECT are valuable for risk stratification and management of patients with diabetes.

Long-term additive prognostic value of thallium-201 myocardial perfusion imaging over clinical and exercise stress test in low to intermediate risk patients : study in 1137 patients with 6-year follow-up

BACKGROUND

The exercise treadmill test (ETT) and Tl201 single proton emission computed tomography (SPECT) are of short- to medium-term prognostic value in coronary heart disease. We assessed the long-term prognostic value of these tests in a large population of patients with low- to intermediate risk of cardiac events.

METHODS AND RESULTS

One thousand one hundred thirty-seven patients (857 men, age 55+/-9 years) referred for typical (62.1%) or atypical (22.4%) chest pain, or suspected silent ischemia (15.5%), were followed up for 72+/-18 months. Overall mortality was higher after strongly positive (ST depression >2 mm, or >1 mm for a workload </=75 W) (2. 36%/y) or nondiagnostic ETT (1.63%/y) than after normal (0.85%/y) or positive ETT (1.37%/y) (P=0.002), and after abnormal SPECT than after normal SPECT (1.60%/y versus 0.68%/y, P=0.001). The major cardiac event rate (cardiac death or myocardial infarction [MI]) was 0.88%, 1.59%, 2.10%, and 2.13%/y after negative, positive, strongly positive, and nondiagnostic ETT, respectively (P=0.003), and 0.56%, 1.43%, and 2.05%/y in patients with 0, 1 to 2, and >/=3 abnormal segments on SPECT, respectively (P<0.002). An abnormal SPECT was predictive of MI (P<0.001), whereas ETT was not. In multivariate analysis, SPECT was of incremental prognostic value over clinical and ETT data for predicting overall mortality and major cardiac events.

CONCLUSIONS

The incremental predictive value of SPECT is maintained over 6 years and is particularly relevant after positive, strongly positive, and nondiagnostic ETT.

The role of nuclear cardiology in clinical decision making

This review suggests that the field of nuclear cardiology is alive, well, and thriving, providing relevant information that aids in everyday clinical decision making for nuclear medicine and referring physicians alike. Despite the competition from other modalities, the clinically appropriate applications of nuclear cardiology techniques are likely to increase. The foundation of this optimism is based on the vast amount of data documenting cost-effective clinical applications for diagnosis, risk stratification, and assessing therapy in both chronic and acute coronary artery disease (CAD), the powerful objective quantitative analysis of perfusion and function provided by the technique, and the increasing general availability of the approach.