Prognostic implications of normal exercise tomographic thallium images in patients with angiographic evidence of significant coronary artery disease

The Role of Myocardial Perfusion Imaging in the Prediction of Major Adverse Cardiovascular Events at 1 Year Follow-Up: A Single Center's Experience

BACKGROUND

Myocardial perfusion imaging via single-photon emission computed tomography (SPECT MPI) is a well-established method of diagnosing coronary artery disease (CAD). The purpose of this study was to assess the role of SPECT MPI in predicting major cardiovascular events.

METHODS

The study population was composed of 614 consecutive patients (mean age: 67 years, 55% male) referred for SPECT MPI due to symptoms of stable CAD. The SPECT MPI was performed using a single-day protocol. We conducted a follow-up on all patients at 12 months via a telephone interview.

RESULTS

The majority of our patients (78%) presented findings suggestive of reversible ischemia, fixed defects or both. Extensive perfusion defects were found in 18% of the population, while LV dilation was found in 7%. During the 12-month follow-up, 16 deaths, 8 non-fatal MIs and 20 non-fatal strokes were recorded. There was no significant association of SPECT findings with the combined endpoint of all-cause death, non-fatal MI and non-fatal stroke. The presence of extensive perfusion defects was an independent predictor of mortality at 12 months (HR: 2.90, 95% CI: 1.05, 8.06, p = 0.041).

CONCLUSIONS

In a high-risk patient population with suspected stable CAD, only large reversible perfusion defects in SPECT MPI were independently associated with mortality at 1 year. Further trials are needed to validate our findings and refine the role of SPECT MPI findings in the diagnosis and prognosis of cardiovascular patients.

Hybrid anatomo-functional imaging of coronary artery disease: Beneficial irrespective of its core components

Coronary artery disease (CAD) is the most common and important cause of ischemic heart disease, with major implications on global morbidity and mortality. Non-invasive testing is crucial in the diagnostic and prognostic work-up of patients with or at risk of CAD, and also to guide decision making in terms of pharmacologic and revascularization therapy. The traditional paradigm is to view anatomic (i.e., coronary computed tomography) and functional imaging (e.g., myocardial perfusion scintigraphy) tests as opposing alternatives. Such approach is too reductionist and does not capitalize on the strengths of each type of test while risking to overlook the inherent limitations. The combination of anatomic and functional tests in a logic of hybrid imaging holds the promise of overcoming the limitations inherent to anatomic and functional testing, enabling more accurate diagnosis, prognosis, and guidance for revascularization in patients with CAD.

[Prognostic value of normal myocardial perfusion scintigraphy with 201Tl in post-acute myocardial infarction]

OBJECTIVE

The purpose of this work has been to determine the prognostic value of normal thallium-201 myocardial perfusion scintigraphy (MPS) in patients who had suffered myocardial infarction in the three months prior to the examination.

MATERIAL AND METHODS

A stress test followed by (201)Tl Gated SPECT was performed. A follow-up was made of 63 patients with normal perfusion scintigraphy. According to the MPS results, the patients were divided into 2 groups. Group I (n=63; 57% males, age 65±12), patients with normal MPS, and group II (n=60; 81% males, age 64±10), patients with abnormal MPS. The appearance of a new infarction or cardiac death occurring during this period (63±3 months) was analyzed. The appearance of events was related with the cardiovascular risk factors, perfusion study and ventricular function.

RESULTS

Five events occurred in group I in 4 patients: 3 new infarctions and 2 cardiac deaths. In group II, there were 18 events in 14 patients: 8 new infarctions and 10 cardiac deaths (p<0,0001). The events were related with age, time from MPS, diabetes, size of perfusion defect and post stress ventricular ejection fraction. Mean survival en group I was 108 months (103-112) and in group II 97 (88-107) (p=0,01).

CONCLUSION

Patients with normal MPS had fewer major events than patients with abnormal MPS. The size of MPS has been related with the appearance of events. A depressed post-stress left ventricular ejection fraction has a poor prognosis.

Integrated imaging of cardiac anatomy, physiology, and viability

Technologic developments in imaging will have a significant impact on cardiac imaging over the next decade. These advances will permit more detailed assessment of cardiac anatomy, complex assessment of cardiac physiology, and integration of anatomic and physiologic data. The distinction between anatomic and physiologic imaging is important. For assessing patients with known or suspected coronary artery disease, physiologic and anatomic imaging data are complementary. The strength of anatomic imaging rests in its ability to detect the presence of disease, whereas physiologic imaging techniques assess the impact of disease, such as whether a coronary atherosclerotic lesion limits myocardial blood flow. Research indicates that physiologic data are more prognostically important than anatomic data, but both may be important in patient management decisions. Integrated cardiac imaging is an evolving field, with many potential indications. These include assessment of coronary stenosis, myocardial viability, anatomic and physiologic characterization of atherosclerotic plaque, and advanced molecular imaging.

Women with high exercise tolerance and the role of myocardial perfusion imaging

BACKGROUND

Myocardial perfusion imaging (MPI) provides incremental diagnostic and prognostic information, even in patients with high exercise tolerance.

HYPOTHESIS

Myocardial perfusion imaging provides significant diagnostic value, specifically in women with high exercise tolerance.

METHODS

Our study population consisted of all women who underwent exercise MPI in our Department from January 1992 to June 1996 and reached at least Stage IV in the Bruce protocol. Patients were divided into those with known and those with possible coronary artery disease (CAD). All patients were followed for 3 years from the performance of MPI.

RESULTS

Of 4,803 women who underwent myocardial perfusion imaging, 3,183 had exercise stressing, and of those, 311 reached at least Stage IV in the Bruce protocol. Of these 311 MPI scans, only 23 (7.4%) were abnormal (reversible, fixed, or mixed) and the remaining 288 (92.6%) were normal. Of the 82 patients with known CAD, 13 (15.8%) had an abnormal MPI, while only 10 (4.4%) of the 229 patients with possible CAD. No myocardial infarction or cardiac death occurred within 3 years; one patient with normal MPI needed revascularization.

CONCLUSION

In women with high exercise tolerance, especially in those without already known CAD, the yield of MPI is very low. Women with high exercise tolerance have an excellent prognosis.

Angina, "normal" coronary angiography, and vascular dysfunction: risk assessment strategies

The authors discuss how to stratify risk in patients with chest pain and a normal coronary angiogram.

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.

Myocardial perfusion imaging in the elderly: a review

Coronary artery disease is a major cause of morbidity and mortality in the elderly population. As a result of ageing of the population and better medical, interventional and surgical treatment of patients with coronary artery disease, more and more elderly patients are referred to the cardiology department for diagnostic work-up. Stress testing, in combination with myocardial perfusion imaging, is routinely used in elderly patients, a population in which the diagnosis of significant coronary artery disease is often challenging because of atypical symptomatology. Since the introduction of technetium-99m ligands for myocardial perfusion imaging, it is possible to perform electrocardiogram-gated perfusion imaging. This not only improves the specificity of the test for coronary artery disease detection, but also enables the simultaneous assessment of left ventricular functional parameters. This article briefly overviews the possible stress modalities, diagnostic accuracy and prognostic value of myocardial perfusion imaging in elderly patients.

Prognostic value of normal exercise 99mTc-sestamibi myocardial tomography in patients with angiographic coronary artery disease

BACKGROUND AND AIM

Previous studies have documented the prognostic value of normal exercise Tl myocardial perfusion imaging in patients with angiographic coronary artery disease (CAD). However, data on exercise Tc-sestamibi myocardial single photon emission computed tomography (SPECT) are scant. Accordingly, the purpose of this study was to investigate the prognostic value of normal exercise Tc-sestamibi SPECT in patients with angiographic CAD.

METHODS

We retrospectively investigated 90 consecutive patients who had a normal exercise Tc-sestamibi myocardial SPECT but angiographic CAD. A group of 69 consecutive patients with both normal exercise Tc-sestamibi myocardial SPECT and coronary arteries were included as control.

RESULTS

During a mean follow-up of 50+/-19 months, a total of three hard cardiac events (non-fatal myocardial infarction) and seven soft cardiac events (late revascularization) were observed. The annual hard cardiac event rate between the two groups was not significantly different (0.6% vs. 0.3%, chi=0.47, P=NS), nevertheless the annual soft cardiac event rate was higher in patients with angiographic CAD (1.9% vs. 0, chi=5.74, P=0.02). Moreover, the annual hard cardiac events rate in patients with angiographic CAD who were treated medically was also not significantly different from that of the control group (0.8% vs. 0.3%, chi=0.77, P=NS). Among patients with angiographic CAD, the annual hard cardiac event rate was not statistically different between those treated medically and those who underwent revascularization (0.8% vs. 0, chi=0.53, P=NS).

CONCLUSIONS

Our data demonstrate that normal exercise Tc-sestamibi myocardial SPECT despite angiographic CAD suggests a low rate of cardiac death or non-fatal myocardial infarction but a relatively high rate of late revascularization during an intermediate term of follow-up.

[Positive exercise test and normal exercise myocardial perfusion SPECT. Clinical significance]

OBJECTIVE

To establish, in our area, the clinical significance of a normal exercise myocardial perfusion study, in patients with an ischemic response of the exercise test.

MATERIAL AND METHODS

A retrospective study was carried out in our Service for the last four years. We studied 45 patients (41 women and 4 men) with an ischemic response of the exercise test and normal myocardial perfusion SPECT, during a mean follow-up of 13,2 months. We considered the final clinical diagnosis according to clinical evolution, therapy outcome and coronary angiography results.

RESULTS

The presence of positive exercise test and normal SPECT was predominant in women (93.3%). In 35 patients (77.8%), the final diagnosis was chest pain of probable non-coronary origin (not secondary to coronary artery disease): 18 patients were diagnosed of hypertensive cardiomyopathy, 3 of valvulopathy, 2 of vasospastic angina, 1 of hypertrophic obstructive cardiomyopathy, 1 of microvascular angina, 1 of angina due to arrhythmia, and 9 patients diagnosed of atypical chest pain due to functional or non-cardiac origin. In 10 patients (22.2%), the final diagnosis was chest pain of probable coronary origin. We did not observe any major cardiac events (cardiac death and nonfatal myocardial infarction) during the follow-up period.

CONCLUSIONS

Patients with chest pain, positive exercise test and normal SPECT have an excellent prognosis within an intermediate follow-up period. 77.8% of patients were diagnosed of chest pain of non-coronary origin. The most common cause of non-coronary chest pain was hypertensive cardiomyopathy (51.4%), followed by functional or non-cardiac chest pain (28.6%).

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.

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.

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.

Long-term prognostic value of 201Tl single-photon emission computed tomographic myocardial perfusion imaging after coronary stenting

BACKGROUND

The prognostic value of (201)Tl myocardial imaging has been demonstrated in several studies concerning patients with a known significant coronary artery disease. However, the evolution of a coronary stenosis after stenting is difficult to predict. This study was designed to assess the prognostic value of (201)Tl single-photon emission computed tomography (thallium SPECT) perfusion imaging in patients after intracoronary stenting.

METHODS

One hundred fifty-two patients were studied. They were followed up during 40 +/- 13 (mean +/- SD) months after thallium SPECT. Stent-related events were studied after thallium stress testing and included cardiovascular death, myocardial infarction, and revascularization. Stress thallium imaging was performed 5 +/- 2 months after stenting, and ischemia was considered to be present if at least 2 contiguous segments were showing reversible defects.

RESULTS

Only 3 (3%) among the 105 nonischemic patients had major cardiac events during the follow-up versus 13 (28%) of the 47 ischemic patients (P < .001) after thallium SPECT. The relative risk of major cardiac events for patients with significant ischemia was 10.5 compared with nonischemic patients (P < .001). Fourteen (30%) of the ischemic patients and 8 (8%) among the nonischemic patients underwent iterative revascularization (P < .001). Therefore, only 11 (10%) of the nonischemic patients had major cardiac events or revascularization compared with 24 (51%) of the ischemic patients (P < .001).

CONCLUSIONS

Absence of ischemia on thallium SPECT imaging at 5 months after coronary stenting indicates a low risk for cardiovascular events or interventional procedure. These results may have important clinical implications in patient treatment.

Predicting plaque rupture: enhancing diagnosis and clinical decision-making in coronary artery disease

Atherosclerosis is the process underlying coronary artery disease, myocardial infarction and cerebrovascular disease and is a leading cause of morbidity and mortality in industrialized countries. The atherosclerotic plaque is often indolent and progressive and may destabilize without warning. Components of the atherosclerotic plaque, including structural, cellular and molecular characteristics, determine its vulnerability to rupture. The imaging techniques currently available utilize invasive and non-invasive methods to characterize coronary artery stenoses. Detection, however, usually occurs late in the course of disease after symptoms have presented. Much effort has recently been directed at early detection and in defining markers of atherosclerotic disease. Our challenge for the future is to find non-invasive imaging modalities that can predict plaque vulnerability before irreversible damage has occurred. Through early detection and a targeted treatment strategy we hope to reduce the burden of ischemic heart disease.

Principal uses of myocardial perfusion scintigraphy in the management of patients with known or suspected coronary artery disease

The use of myocardial perfusion single photon emission computed tomography (SPECT) has undergone considerable expansion and evolution over the past 2 decades. Although myocardial perfusion imaging was first conceived as a noninvasive diagnostic tool for determining the presence or absence of coronary artery disease, its prognostic value is now well established. Thus, identification of patients at risk for future cardiac events has become a primary objective in the noninvasive evaluation of patients with chest pain syndromes and among patients with known coronary artery disease. In particular, the ability of myocardial perfusion SPECT to identify patients at low (< 1%), intermediate (1% to 5%) or high (> 5%) risk for future cardiac events is essential to patient management decisions. Moreover, previous studies have conclusively shown the incremental prognostic value of myocardial perfusion SPECT over clinical and treadmill exercise data in predicting future cardiac events. This report addresses the current role and new developments, with respect to the use of myocardial perfusion imaging, in determining patient risk for cardiac events and the cost-effective integration of such information into patient management decisions.

Stress nuclear myocardial perfusion imaging versus stress echocardiography: prognostic comparisons

The use of noninvasive stress cardiac imaging for stratifying risk in patients with known or suspected coronary artery disease is growing as a tool for identification of the subgroup most likely to benefit from the expense and risk of more invasive procedures, including cardiac catheterization and coronary revascularization. In this setting, it is especially important that a test be able to identify patients with sufficiently low risk that clinicians are comfortable in deferring such interventions, especially in those with other markers of increased risk. Previous data have shown that cardiac risk is most closely related to the presence and extent of jeopardized viable myocardium on noninvasive stress cardiac imaging. Although stress echocardiography may have comparable ability to detect coronary artery disease, current data suggest that stress echocardiography detects significantly less jeopardized viable myocardium than stress nuclear myocardial perfusion imaging and consequently fewer patients at risk for cardiac events. Stress nuclear myocardial perfusion imaging may therefore have important advantages for risk stratification and the direction of future care of patients with known or suspected coronary artery disease.

Prognostic value of myocardial perfusion tomographic imaging in patients after percutaneous transluminal coronary angioplasty

PURPOSE

The authors assessed the prognostic value of stress myocardial perfusion tomographic imaging (SPECT) in patients with recurrent angina or inconclusive results of exercise electrocardiographic tests after successful percutaneous transluminal coronary angioplasty (PTCA).

MATERIALS AND METHODS

After PTCA, 70 patients (54 men, 16 women; 41 after myocardial infarction; mean age, 56 +/- 9 years) underwent TI-201 or Tc-99m sestamibi SPECT studies. SPECT patterns were divided into normal (n = 25), fixed defects (n = 15), and reversible or combined fixed plus reversible defects (n = 30). A cardiac event was defined as either cardiac death, nonfatal myocardial infarction, or unstable angina requiring further revascularization.

RESULTS

During an average follow-up of 25 +/- 10 months, two patients had severe outcomes (one cardiac death and one nonfatal myocardial infarction), and revascularization was required in 13 patients. In patients with normal SPECT or fixed defects, the annual event rate was low (1.2%), with only one revascularization. In patients with reversible or combined defects, the annual event rate was significantly greater (22.4%; chi square = 17.32, P = 0.00003).

CONCLUSIONS

Normal perfusion or fixed defects predict a benign prognosis in patients after successful PTCA. The presence of stress-induced reversible defects appears to be the best predictor of future cardiac events.

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.

Effects of medical therapy on outcome assessment using exercise thallium-201 single photon emission computed tomography imaging: evidence of a protective effect of beta-blocking antianginal medications

OBJECTIVES

The purpose of this study was to determine whether antianginal medications modify the prognostic significance of exercise single photon emission computed tomography (SPECT) ischemia.

BACKGROUND

Antianginal medications (especially beta-adrenergic blocking agents) limit exercise SPECT ischemia, but it is not known whether such medications also modify the prognostic effect of exercise SPECT ischemia.

METHODS

We included 352 patients with coronary heart disease, who had exercise Tl-201 SPECT and coronary angiography, and who were initially treated medically. Survival Cox models were applied in patients for whom classes of antianginal medications taken at exercise SPECT were the same as those prescribed for follow-up (GI; n = 136), and in patients for whom new classes of antianginal medications, including beta-blockers (GII; n = 79) or not including beta-blockers (GIII; n = 113), were added for follow-up.

RESULTS

During a mean 5.3+/-1.6 years of follow-up, 45 patients had cardiac death or myocardial infarction. Variables reflecting necrosis (irreversible defect extent, left ventricular ejection fraction) and those from coronary angiography provided equivalent prognostic information in the three groups. In contrast, the SPECT variable reflecting ischemia (reversible defect extent), which provided comparable prognostic information in GI (p = 0.005) and GIII (p = 0.004), lost its prognostic significance (p = 0.54) in GII, and was associated with a lower relative risk in GII than in GI or GIII (both p < 0.05).

CONCLUSIONS

In patients with coronary heart disease, the introduction of antianginal medications, when including beta-blockers, appears to have a favorable effect on the deleterious prognostic effect of exercise ischemia.

Ischemia detection in women: the diagnostic value of exercise QRS duration changes

AIM

To compare the diagnostic accuracy of exercise electrocardiographic (ECG) ST-T changes and QRS duration changes as a means of ischemia detection in a female population.

METHODS AND RESULTS

A total of 101 women from a pool of 318 referred for ECG stress testing underwent standard testing using ST-T criteria with the additional measurement of QRS duration before and at peak exercise using a new computerized optic scanner for precise QRS duration measurement. The diagnostic accuracy of the test was determined using planar thallium stress testing as a "gold standard." For the overall population, the sensitivity of ST-T criteria was 47% with a specificity of 58%. The sensitivity of QRS duration changes was 91% with a specificity of 89%. For Group 1 (age 27-50) the sensitivity of the ST-T criteria was 40% with a specificity of 58%. The sensitivity of the QRS duration changes was 80% with a specificity of 83%. For Group 2 (age 51-83), the sensitivity of the ST-T criteria was 43% with a specificity of 56%. The sensitivity of the QRS duration changes was 94% with a specificity of 90%.

CONCLUSION

In our female population exercise, QRS duration changes using our computerized method were better markers of ischemia than standard ST-T criteria.

Usefulness of exercise echocardiography in predicting cardiac events in an outpatient population

The prognostic value of exercise echocardiography in an outpatient population is not well defined. A total of 1,020 consecutive patients referred for exercise echocardiography in an ambulatory care setting were studied by reviewing their medical records and exercise echocardiographic data. Of these, 71 (7%) were excluded due to technically inadequate tests, leaving 949 patients who were included in the analysis. A positive exercise echocardiogram (EE) was defined as an appearance of a new wall motion abnormality or worsening of a baseline abnormality. Cardiac events, defined as myocardial infarction, coronary angioplasty, coronary bypass surgery, and death, were documented during a 12-month follow-up period. Cardiac events occurred in 17% of patients (26 of 152) with a positive exercise echocardiogram (EE) and in 2.5% (20 of 797) with a negative EE (p <0.001). The incidence of myocardial infarction (2.6% vs 0.4%, p <0.02), coronary angioplasty (7% vs 1%, p <0.001), and coronary bypass surgery (9% vs 1%, p <0.001) were higher in patients with a positive versus a negative EE. There was 1 death in the positive study group and none in the negative group. Significant independent variables (p <0.05) that predicted cardiac events included a positive exercise electrocardiogram, history of coronary angioplasty, nonspecific ST-T changes on the baseline electrocardiogram, double product <25,000, men, chest pain on exercise test, and a positive exercise electrocardiogram. On a stepwise logistic regression model, exercise echocardiography emerged as an independent predictor of future cardiac events in an outpatient population. This predictive value was enhanced in the presence of a positive exercise electrocardiogram compared with a negative exercise electrocardiogram (24.2% vs 7.9%, p <0.03). Our study suggests that exercise echocardiography is an independent predictor of future cardiac events in an outpatient population.

Clinical and angiographic significance of a normal thallium-201 tomographic study in patients with a strongly positive exercise electrocardiogram

Among 23,059 patients who underwent exercise myocardial tomography between 1985 and 1994 at our institution, there were 817 (3.5%) with a strongly positive exercise electrocardiogram and normal myocardial tomograms. Among these, 52 patients had no conditions known to be associated with a false-positive exercise electrocardiogram and no previous coronary revascularization, and underwent coronary angiography. Of the 32 patients with significant coronary stenoses, 50% had 1-vessel disease and only 22% had 3-vessel disease (p < 0.05). Among 55 stenosed arteries, 56% were of moderate severity (50 to 74%), whereas only 9% had subtotal or total occlusion (95 to 100%) (p < 0.001). There was a significant gender difference in the prevalence of significant coronary stenoses (80% in male vs 24% in female patients, p < 0.0001). A strongly positive exercise electrocardiogram coupled with normal exercise myocardial tomograms is a rare clinical finding. In women, this finding is usually associated with normal coronary arteries, whereas in men it often denotes coronary artery disease, usually of mild to moderate degree.

Prognostic value of simultaneous perfusion and function assessment using technetium-99m sestamibi

This study examines the prognostic value of simultaneous perfusion and function assessment in 412 patients. The exercise perfusion pattern was a stronger predictor of events (mostly acute nonfatal myocardial infarcts) than resting ejection fraction.

Prognostic significance of normal dobutamine-atropine stress sestamibi scintigraphy in women with chest pain

To evaluate the prognostic value of normal dobutamine-atropine technetium-99m sestamibi single-photon emission computed tomography (SPECT) perfusion imaging in women with chest pain and inability to perform an adequate exercise test, 80 women with a normal scintigram were followed up for 23 +/- 13 months. Mean age of the patients was 61 +/- 12 years. Nine patients (11%) had a low probability (< 10%) of coronary artery disease, 43 (54%) had an intermediate probability (10% to 80%) of disease, and 28 (35%) had a high probability (>80%) of disease (including 19 patients with known coronary artery disease). During follow-up, no major cardiac events (cardiac death or nonfatal myocardial infarction) occurred. One patient with known coronary disease underwent coronary bypass surgery after 3 months, and 1 patient with a 91% pretest likelihood of coronary disease underwent coronary angioplasty after 7 months. Thus, the overall incidence of (soft) cardiac events during the follow-up period was 2 of 80 patients, or 1.3%/year. It is concluded that normal dobutamine-atropine technetium-99m sestamibi SPECT perfusion imaging in women with chest pain implies an excellent prognosis, even in women with high pretest likelihood of coronary disease.

Incremental value of prognostic testing in patients with known or suspected ischemic heart disease: a basis for optimal utilization of exercise technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography

OBJECTIVES

This study assessed the incremental prognostic implications of normal and equivocal exercise technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) and sought to determine its incremental prognostic value, impact on patient management and cost implications.

BACKGROUND

The prognostic implications of Tc-99m sestamibi SPECT are not well defined, and risk stratification using this test has not been explored.

METHODS

We studied 1,702 patients referred for exercise Tc-99m sestamibi SPECT who were followed up for a mean (+/- SD) of 20 +/- 5 months. Patients with previous percutaneous transluminal coronary angioplasty or coronary artery bypass surgery were excluded. The SPECT studies were assessed using semiquantitative visual analysis. Cardiac death and myocardial infarction were considered "hard" events, and coronary angioplasty and bypass surgery > 60 days after testing were considered "soft" events.

RESULTS

Of the 1,702 patients studied, 1,131 had normal or equivocal scan results. A total of 10 events occurred in this group (1 cardiac death and 1 myocardial infarction [0.2% hard events]; 4 coronary angioplasty and 4 bypass surgery procedures [0.7% soft events]). The rates of hard events and referral to catheterization after SPECT were similarly low in patients with a low (< 0.15), intermediate (0.15 to 0.85) and high (> 0.85) post-exercise treadmill test (ETT) likelihood of coronary artery disease. With respect to scan type, patients with normal, probably normal or equivocal scan results had similarly low hard event rates. In the 571 patients with abnormal scan results, there were 43 hard events (7.5%) and 42 soft events (7.4%) (p < 0.001 vs. 1,131 patients with normal scan results for both). When the complete spectrum of scan responses was considered, SPECT provided incremental prognostic value in all patient subgroups analyzed. However, the nuclear scan was cost-effective only in patients with interpretable exercise ECG responses and an intermediate to high post-ETT likelihood of coronary artery disease and in those with uninterpretable exercise ECG responses and an intermediate to high pre-ETT likelihood of coronary artery disease.

CONCLUSIONS

Normal or equivocal exercise Tc-99m sestamibi study results are associated with a benign prognosis, even in patients with a high likelihood of coronary artery disease. Although incremental prognostic value is added by nuclear testing in all patient subgroups, a testing strategy incorporating nuclear testing proved to be cost-effective only in the groups with an intermediate to high likelihood of coronary artery disease before scanning.