Use of exercise thallium-201 imaging for risk stratification of elderly patients with coronary artery disease

Preoperative nuclear stress testing in the very old patient population

BACKGROUND

Elderly patients awaiting moderate to high-risk surgery may undergo nuclear stress testing (NST) in order to evaluate their cardiovascular risk. The prognostic utility of such testing in the very elderly (≥ 85 years) has yet to be fully evaluated. Octogenarians and nonogenarians frequently have a number of concurrent conditions including a high rate of coronary disease, and therefore the prognostic value of NST for their preoperative risk assessment has been questioned. Our evaluation assesses the ability of nuclear stress testing to predict peri-operative cardiac outcomes in this patient population.

AIM

To investigate the ability of NST to predict peri-operative cardiac outcomes in elderly patients awaiting moderate to high-risk surgery.

METHODS

Patients ≥ 85 years undergoing pre-operative NST were retrospectively evaluated. Patients undergoing low-risk surgery were excluded. Major adverse cardiac events (MACE) were considered any adverse event that occurred prior to discharge and included acute heart failure, arrhythmia, acute myocardial infarction, unstable angina, or death. Associations between patient risk factors, MACE, and the obtained results of the pre-operative stress testing, ejection fraction (< 40% or ≥ 40%), summed stress score (≤ 8, ≥ 9), and the summed difference score (≤ 0, > 0) were analyzed.

RESULTS

A total of 69 patients (mean age 88 ± 2.6 years, 31 males) underwent nuclear stress testing prior to surgery. There were 41 (60%) patients found to have an abnormal NST. Sixteen (23%) patients were noted to experience post-operative MACE. No significant associations between risk factors and MACE were noted. Patients with an abnormal NST and/or a summed stress score ≥ 9 were significantly (P < 0.01) more likely to develop peri-operative MACE.

CONCLUSION

Indicated preoperative NST is useful to assess pre-operative risk in elderly patients ≥ 85 years undergoing moderate to high-risk surgery.

Value of Exercise ECG for Risk Stratification in Suspected or Known CAD in the Era of Advanced Imaging Technologies

Exercise stress electrocardiography (ExECG) is underutilized as the initial test modality in patients with interpretable electrocardiograms who are able to exercise. Although stress myocardial imaging techniques provide valuable diagnostic and prognostic information, variables derived from ExECG can yield substantial data for risk stratification, either supplementary to imaging variables or without concurrent imaging. In addition to exercise-induced ischemic ST-segment depression, such markers as ST-segment elevation in lead aVR, abnormal heart rate recovery post-exercise, failure to achieve target heart rate, and poor exercise capacity improve risk stratification of ExECG. For example, patients achieving ≥10 metabolic equivalents on ExECG have a very low prevalence of inducible ischemia and an excellent prognosis. In contrast, cardiac imaging techniques add diagnostic and prognostic value in higher-risk populations (e.g., poor functional capacity, diabetes, or chronic kidney disease). Optimal test selection for symptomatic patients with suspected coronary artery disease requires a patient-centered approach factoring in the risk/benefit ratio and cost-effectiveness.

Long-term prognostic value of myocardial perfusion imaging in octogenarians able to undergo treadmill exercise stress testing

BACKGROUND

Although the use of myocardial perfusion imaging (MPI) for prognostic purposes in general population is well understood, its role in very elderly patients is not extensively studied.

METHODS

247 octgogenarians (79% male, 56% previous myocardial infarction-MI or revascularization) who underwent treadmill exercise testing (TET) with MPI were studied. TET and MPI-related data were registered per patient and prospective follow-up was performed to document all cause death (ACD), cardiac death (CD), non-fatal MI, and late revascularization (LR). Kaplan-Meier and Cox-regression analysis were used to compute event-free survival and identify significant predictors of these events.

RESULTS

After 7.3 years there were 48 deaths, 17 CDs, 8 MIs, and 21 LRs. 69 patients were classified as high and 103 as low risk by SSS with annual cardiac mortality rates of 5% and 0.9%, respectively. Differences between survival curves of SSS-based risk groups were significant for ACD, CD, CD/MI, and CD/MI/LR. Summed stress (SSS) and difference scores were the only significant predictors of all endpoints. LVEF and transient ischemic LV dilatation were significant predictors of CD and CD/MI. LVEF and all MPI variables were associated with the CD, MI, and LR endpoint while only Duke treadmill score and angina severity demonstrated such a relationship among TET variables.

CONCLUSIONS

In octogenarians, MPI provides effective long-term risk stratification for both hard (ACD, CD, CD/MI) and soft (CD/MI/LR) endpoints and should be preferred over simple TET.

Pathological 99mTc-sestamibi myocardial perfusion scintigraphy is independently associated with emerging cardiac events in elderly patients with known or suspected coronary artery disease

BACKGROUND

Only few data are available regarding the prognostic impact of myocardial perfusion scintigraphy with (99m)Tc-sestamibi (MPS) regarding emerging cardiac events in elderly patients

PURPOSE

To evaluate the prognostic value of MPS regarding emerging cardiac events in patients aged ≥70 years with known or suspected coronary artery disease (CAD).

MATERIAL AND METHODS

One hundred and thirty-three patients (74.6 ± 3.7 years) who underwent exercise or pharmacological stress/rest MPS were included in this analysis. Semi-quantitative visual interpretation of MPS images was performed and Summed-Stress- (SSS), Summed-Difference- (SDS), and Summed-Rest Scores (SRS) were calculated. Multivariate logistic regression analyses were calculated for evaluation of the independent prognostic impact of MPS results and several cardiac-related patient characteristics with regard to emerging cardiac events. Kaplan-Meier survival- and log rank analyses were calculated for assessment of cardiac event-free survival.

RESULTS

Pathological SSS (OR: 3.3), angina (OR: 2.7) and ischemic ECG (OR: 3.0) were independently associated with cardiac events. Patients with pathological SSS (p=0.005) and ischemic ECG (p=0.012) had a significantly lower incidence of cardiac event-free survival.

CONCLUSION

Pathological MPS is independently associated with emerging cardiac events predicting a significantly lower incidence of cardiac event-free survival in patients aged ≥70 years.

Value of exercise echocardiography for predicting mortality in elderly patients

BACKGROUND

Elderly patients with suspected or known coronary artery disease are often referred for pharmacological stress testing. Data on the value of exercise echocardiography (ExEcho) for predicting outcome (particularly all-cause mortality) in these patients are scarce.

METHODS

Peak treadmill ExEcho was performed in 2159 patients ≥ 70 years of age with known or suspected coronary artery disease. Left ventricular wall motion was evaluated at baseline and with exercise, and the increase in wall motion score index from rest to peak exercise (ΔWMSI) was calculated. Ischaemia was diagnosed when new or worsening wall motion abnormalities developed with exercise. The end points were all-cause mortality and major cardiac events (cardiac death or myocardial infarction).

RESULTS

Ischaemia developed in 844 patients (38·6%) during exercise. Over a mean follow-up of 3·5 ± 3·1 years, 439 deaths occurred. The cumulative 5-year mortality rate was 29·3% in patients with ischaemia versus 16·8% in those without ischaemia (P < 0·001). After covariate adjustment, ΔWMSI remained an independent predictor of mortality [hazard ratio (HR) 2·37, 95% confidence interval (CI) 1·66-3·39, P < 0·001] and major cardiac events (HR 3·48, 95% CI 2·11-5·74, P < 0·001). These results remained significant even in patients with chronotropic incompetence. When added to a model with clinical, resting echocardiographic and exercise electrocardiogram variables, ExEcho results provided incremental value for the prediction of both end points (P < 0·001).

CONCLUSIONS

ExEcho is feasible in elderly patients with suspected or known coronary artery disease and provides useful information for risk stratification in these patients.

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.

Incremental prognostic value of combined perfusion and function assessment during myocardial gated SPECT in patients aged 75 years or older

BACKGROUND

Perfusion and functional data obtained during gated single photon emission computed tomography (SPECT) have proven prognostic value in the middle-aged patient population. The aim of this study was to investigate whether perfusion and functional cardiac gated SPECT data have prognostic value in patients aged 75 years or older.

METHODS AND RESULTS

We studied clinical and gated SPECT predictors of cardiac and all-cause death in 294 patients aged 75 years or older with known or suspected coronary artery disease who were referred for tetrofosmin cardiac gated SPECT imaging. Summed perfusion scores were calculated in a 17-segment model by use of commercially available software (4D-MSPECT). Left ventricular functional data were calculated by use of QGS gated SPECT software. The median age of the study population was 78 years (range, 75-91 years). There were 160 men (54%) and 134 women (46%). During a median follow-up of 25.9 months (range, 1.8-36 months), 47 patients (16%) died (27 cardiac deaths). In a multivariate Cox proportional hazards regression analysis, the summed rest score (chi2 gain = 8.0, P = .009), transient ischemic dilatation index (chi2 gain = 6.3, P = .012), and resting left ventricular ejection fraction (chi2 gain = 7.0, P = .030) were independent predictors of all-cause death. The summed rest score (chi2 gain = 8.2, P = .004) and resting end-systolic volume (chi2 gain = 13.7, P = .005) were independent predictors of cardiac death.

CONCLUSIONS

This study showed that gated SPECT left ventricular functional data assessed during myocardial gated SPECT provide independent and incremental information above clinical and perfusion SPECT data for the prediction of cardiac and all-cause death in patients aged 75 years or older referred for myocardial SPECT imaging.

Clinical correlation between increased lung to heart ratio of tecnetium-99m sestamibi and multivessel coronary artery disease

BACKGROUND

An increased lung to heart ratio (LHR) on thallium-201 (Tl-201) stress myocardial perfusion imaging (MPI) is a predictor of adverse cardiac events and identifies people with extensive coronary artery disease (CAD). The implications of increased LHR in patients undergoing stress technetium-99m (tc-99m) sestamibi are developing. Our aim is to evaluate the relationship between increased LHR and extent of CAD in patients undergoing tc-99m sestamibi MPI.

METHODS

We reviewed the records and images of 530 consecutive subjects who underwent exercise or adenosine tc-99 m sestamibi MPI. One hundred thirty-two had transient or partially reversible myocardial perfusion defects and 79 (exercise=34, adenosine=45, male=43, female=36, mean age=61 years) of these underwent coronary angiography (study population). The average LHR of these 79 subjects was compared to 79 patients (control population) with normal scans (exercise=50, adenosine=29, male=34, female=45, mean age=60 years).

RESULTS

The mean LHR (+/-SE) in subjects with normal scans was 0.30+/-0.01. The mean LHR for those with abnormal scans and single vessel CAD who underwent exercise was 0.32+/-0.01 and pharmacological stress was 0.31+/-0.01. There was no statistically significant difference between the LHR of those with a normal scan and those with single vessel disease and an abnormal scan. However, there was a statistically significant association between the elevated LHR and multi-vessel CAD. The mean LHR for subjects with multi-vessel CAD with exercise was 0.39+/-0.01 (p=0.000) and for adenosine was 0.39+/-0.02 (p=0.000).

CONCLUSION

An elevated LHR in patients undergoing exercise or pharmacological tc-99m MPI correlates with multi-vessel CAD.

Exercise Single-Photon Emission Computed Tomography Provides Effective Risk Stratification of Elderly Men and Elderly Women

Background— In a recent study, we reported that the Duke treadmill score was unable to effectively stratify elderly patients according to risk. The purpose of this study was to evaluate the prognostic value of exercise single-photon emission computed tomography (SPECT) in this same population and to examine results by gender.

Methods and Results— A cohort of 247 elderly (age ≥75 years) patients (108 women, 139 men, age 77±3 years) who underwent exercise thallium-201 SPECT were followed up for a median duration of 6.4 years. SPECT variables were significantly associated with cardiac death: summed stress score (SSS) χ 2 =19.5, P <0.001; summed difference score χ 2 =12.3, P <0.001; increased lung uptake χ 2 =9.6, P =0.002; and left ventricular enlargement χ 2 =8.3, P =0.004. The Duke score was not significantly associated with cardiac death (χ 2 <1, P =NS). The SSS classified most patients as low risk (49%) or high risk (35%); the Duke score classified the majority (68%) as intermediate risk. Annual cardiac mortality rates for patients categorized by SSS as low risk and high risk were 0.8% and 5.8%, respectively. Cardiac survival rates according to SSS risk categories were significantly different for both women ( P =0.012) and men ( P =0.003).

Conclusions— SPECT classified most elderly patients into clinically useful low- and high-risk categories and accurately predicted outcomes in both genders. If these results can be validated in future studies, exercise SPECT rather than standard treadmill testing may emerge as the initial noninvasive testing strategy in elderly patients who are able to exercise.

Medium- to long-term prognostic impact of dipyridamole thallum-201 myocardial single-photon emission computed tomography in elderly patients

Dipyridamole thallium-201 single-photon emission computed tomography (SPECT) has not been extensively evaluated for risk stratification and the medium- to long-term prognostic value in elderly cardiac patients who are unable to exercise. The present study group comprised 210 consecutive patients aged at least 70 years with known or suspected coronary artery disease (CAD). The SPECT findings were classified as a reversible, fixed, or combined (reversible and fixed) defect. Of the 210 patients, 201 (77+/-5 years, 85 male) were successfully followed for 49+/-26 months. Thirteen (7%) patients had cardiac events: cardiac death (n=10), non-fatal myocardial infarction (n=1), or coronary artery bypass grafting (n=2). Cardiac events occurred in 3 of 112 patients with normal SPECT and in 10 of 89 patients with an abnormal scan (0.7% /year vs 2.8% /year, p=0.01). Stepwise Cox regression analysis revealed that the significant predictors of cardiac events were combined defects (relative risk 7.3) and the number of defect areas (relative risk 4.4). The predictive value of dipyridamole thallium-201 SPECT is maintained over 4 years in mixed populations of elderly CAD patients who are unable to exercise.

Incremental prognostic value of myocardial perfusion 99m-technetium-sestamibi SPECT in the elderly

Coronary artery disease (CAD) is the main cause of death in elderly patients. Single-photon emission computed tomography (SPECT) with technetium-99m ((99m)Tc)-labeled agents is extremely useful for the diagnosis and risk stratification of CAD in the general population. However, its prognostic value for the elderly has not been established. This study examined disease outcome in 328 patients aged 74 or older, with suspected CAD who were submitted to either pharmacological (dipyridamole) or exercise stress SPECT with (99m)Tc-sestamibi, seven of whom were completely lost to follow-up. Endpoints were defined as hard (myocardial infarction or cardiac death) or total events (myocardial infarction, cardiac death or myocardial revascularization). Mean follow-up was 34+/-15 months. During this period 24 cardiac deaths, 11 myocardial infarctions and 21 cases of revascularization were observed. Perfusion defects were found in 27.1% of patients (12.8% reversible, 6.2% partially reversible and 8.1% fixed). Abnormal studies were predominant in men, patients with chest pain and those with ST-T abnormalities in the baseline electrocardiogram (ECG) or in the exercise treadmill test. An abnormal scan was significantly associated with cardiac events (P<0.0001). Multivariate analysis revealed that a abnormal scan was the most important independent predictor of hard or total cardiac events. Event rates increased according to myocardial perfusion scintigraphy (MPS): <1.0% of hard events per year in patients with normal MPS versus 14.3% per year in those with abnormal MPS. (99m)Tc-sestamibi SPECT was demonstrated to be a powerful tool for the prognostic evaluation of elderly patients with suspected CAD.

Exercise myocardial perfusion imaging in elderly patients

BACKGROUND

Exercise myocardial perfusion imaging (MPI) has significant value for risk stratification, but most patients studied have been middle-aged. In particular, the value of exercise MPI in elderly patients with interpretable electrocardiographic (ECG) stress test results has not been well defined. MEHODS AND RESULTS: Clinical, ECG stress test, MPI, and follow-up data for 626 outpatients aged 65 years or older with interpretable electrocardiograms undergoing symptom-limited exercise MPI between 1992 and 1996 were analyzed. Follow-up was 97% complete after 4.4 +/- 1.3 years. After exclusion of the 27 patients who underwent revascularization within 90 days of MPI, there were 361 men and 217 women, aged 70.7 +/- 4.4 years. By univariate analysis, male sex, increasing age, an abnormal rest ECG result, lower exercise tolerance and lower peak exercise heart rates, exercise ST-segment depression, left ventricular dilatation, and the number of ischemic regions predicted death or myocardial infarction. By multivariable modeling, only increasing patient age, male sex, limitation of exercise tolerance, and the number of ischemic segments by MPI were predictive of subsequent death or myocardial infarction.

CONCLUSIONS

In elderly patients referred for exercise MPI, age, sex, exercise tolerance, and MPI ischemia provide significant prognostic information.

Stress testing in the elderly

The ever-increasing number of older patients requiring diagnostic and prognostic assessment for coronary artery disease has necessitated accurate, noninvasive techniques applicable to this age group. Exercise testing, either alone or with radionuclide or echocardiographic imaging, remains a useful tool in elderly patients capable of performing vigorous treadmill or cycle exercise. Fortunately, for the large elderly subset incapable of such exercise, pharmacologic stress testing with dipyridamole, adenosine, or dobutamine offers an excellent alternative. Choosing the most appropriate stress testing modality for a given patient from among the many choices available remains the clinician's challenge.

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.

[Nuclear cardiology: technical bases and clinical applications]

Although the role of nuclear cardiology is currently well consolidated, the addition of new radiotracers and modern techniques makes it necessary to continuously update the requirements, equipment and clinical applications of these isotopic tests. The characteristics of the radioisotopic drugs and examinations presently used are explained in the first part of this text. In the second, the indications of them in diagnostic and prognostic evaluation of the different coronary diseases are presented.

Coronary heart disease. Stable and unstable syndromes

CHD in the elderly population will continue to be a source of major concern because of the increasing costs entailed and uncertainties about how the widespread array of diagnostic and therapeutic interventions, often expensive and sometimes hazardous, should be applied. Financial, political, and health policy decisions will continue to occupy much attention, but it is likely that philosophic considerations about aging and death, both from the individual and the societal perspective, will be of paramount importance of deciding how the substantial resources available to the elderly will be used. Randomized, controlled trials are unlikely to play a major role in resolution of management dilemmas in the elderly because of the extraordinary heterogeneity in this population. Registries (databases) involving carefully prospectively collected key variables are likely to be a more effective approach. Critical characterization of complications of procedures, adverse drug reactions, and collection of follow-up data on functional status are among the critical questions, and these can be answered by registry studies. Algorithms and clinical rules developed in younger cohorts are not directly transferable to the elderly cardiovascular patients, further emphasizing the need for prospectively collected, syndrome-specific data. Treatments convincingly demonstrated to reduce mortality in absolute terms more in the elderly than in the young are underused. The heterogeneity of aging emphasizes the wide variability in patients' ability to withstand the stress of procedures and complications of disease and makes clear the need to consider physiologic reserve and biologic age rather than chronology. With better characterization of biologic age and physiologic reserve, more precise estimates of outcomes of therapies and interventions can be made, and patients can be given better information and with their families have more realistic expectations. Better-informed decisions will result. Biologic age will be multifactorial, involving cognitive, emotional, physical, and nutritional attributes as well as specific organ function (lung, kidney, liver) because no single feature can characterize the total elderly patient. The concept of competing risks among the cardiovascular disease being treated, comorbidity, risks of study, and life expectancy will evolve because even the most successful therapy will have limited effect on longevity in the very old. Although important research at the cellular and molecular level will characterize and provide better understanding of the aging process, it is not likely that this basic information will be immediately useful in the management of the large number of elderly patients with major cardiovascular disease. Preventive measures, including physical exercise, mental stimulation, avoidance of depression, good nutrition, and abstinence from tobacco use, are useful approaches to postpone or ameliorate the consequences of aging and allow patients to tolerate cardiovascular diseases better when they become manifest.

Evaluation of exercise thallium scintigraphy versus exercise electrocardiography in predicting survival outcomes and morbid cardiac events in patients with single- and double-vessel disease. Findings from the Angioplasty Compared to Medicine (ACME) Study

OBJECTIVES

We sought to evaluate the prognostic ability of cardiac exercise stress tests in predicting cardiac mortality and morbidity in a low risk group of patients with established coronary artery disease (CAD).

BACKGROUND

Although previous studies have demonstrated the superior value of stress nuclear cardiac scintigraphy in the prognosis of patients with CAD, none of these studies have focused on patients with a proven angiographic low risk profile (i.e., single- and double-vessel CAD).

METHODS

Three hundred twenty-eight patients with documented single- and double-vessel disease were treated by random assignment to percutaneous transluminal coronary angioplasty or medical therapy in the Angioplasty Compared to Medicine (ACME) trial. Six months after randomization, maximal symptom-limited exercise tests were performed with electrocardiography (n = 300) and thallium scintigraphy (n = 270). Patients were followed up for a minimum of 5 years thereafter.

RESULTS

A reversible thallium perfusion deficit documented after 6 months of either therapy was associated with an adverse mortality outcome (18% mortality rate with a reversible thallium perfusion defect and 8% mortality rate with no reversible thallium perfusion deficit, p = 0.02). Moreover, an important mortality gradient was demonstrated in relation to the number of reperfusing defects (0 = 7%, 1 to 2 = 15%, >3 = 20%, p = 0.04). Exercise electrocardiography did not predict this mortality outcome.

CONCLUSIONS

A reversible thallium perfusion deficit demonstrated 6 months after medical therapy or coronary angioplasty is a valuable prognostic marker in patients with angiographically documented single- and double-vessel disease and is superior to exercise electrocardiography in this regard.

Comparison of defect size between thallium-201 and technetium-99m tetrofosmin myocardial single-photon emission computed tomography in patients with single-vessel coronary artery disease

Defect size on exercise-rest technetium (Tc)-99m tetrofosmin myocardial perfusion imaging was compared with that on exercise-reinjection thallium-201 imaging with 20 patients with 1-vessel coronary artery disease. In each patient, exercise-reinjection thallium-201 single-photon emission computed tomography (SPECT) and exercise-rest Tc-99m tetrofosmin SPECT imaging were performed. For visual analysis of the obtained SPECT images, the left ventricular myocardium was divided into 20 segments based on 3 short-axis slices from the apical, middle, and basal ventricular levels. For quantitative analysis, a square region of interest was placed on the center of each segment which was used for visual analysis, and relative regional activity to the normal reference region was calculated for each segment. By visual interpretation of the images, exercise Tc-99m tetrofosmin imaging showed a smaller defect size than exercise thallium-201 imaging (6.9 +/- 3.9 vs 8.8 +/- 3.0 segments, p <0.01). In contrast, rest Tc-99m tetrofosmin imaging showed a defect size similar to that on reinjection thallium-201 imaging (5.9 +/- 3.6 vs 5.6 +/- 3.9 segments, p = NS). Similarly, the mean defect sizes during exercise determined by quantitative analysis were smaller on Tc-99m tetrofosmin SPECT than those on thallium-201 SPECT at all tested threshold cutoff points ranging from 50% to 70%, whereas there were no significant differences in defect sizes between rest Tc-99m tetrofosmin and reinjection thallium-201 imaging. These data indicate that exercise Tc-99m tetrofosmin SPECT defect size determined either by visual analysis or by quantitative analysis may be smaller than on exercise thallium-201 SPECT.

Assessment of myocardial perfusion and viability with technetium-99m methoxyisobutylisonitrile and thallium-201 rest redistribution in chronic coronary artery disease

We compare thallium-201 rest redistribution and fluorine-18 fluorodeoxyglucose ([18F]FDG) for the assessment of myocardial viability within technetium-99m methoxyisobutylisonitrile (MIBI) perfusion defects in 27 patients with chronic stable coronary artery disease. The following studies were performed: (1) stress 99mTc-MIBI, (2) rest 99mTc-MIBI, (3) 201Tl rest-redistribution single-photon emission tomography, (4) [18F]FDG positron emission tomography. The left ventricle was devided into 11 segments on matched tomographic images. The segment with the highest activity at stress was taken as the reference (activity=100%). Perfusion defects at 99mTc-MIBI rest were classified as severe (activity<50%), moderate (activity 50%-60%) or mild (activity 60%-85%). Uptakes of [18F]FDG and rest-redistributed 201Tl were recognized as significant if they exceeded 50% of that in the reference segment. Among the 33 segments with severe 99mTc-MIBI rest perfusion defects, 21 had significant [18F]FDG and 10 significant rest-redistributed 201Tl uptake. As regards the 37 segments with moderate defects, [18F]FDG was present in 29 and 201Tl in 31, while of the 134 segments with mild defects, 128 showed [18F]FDG uptake, and 131, 201Tl uptake. In conclusion, there is an inverse relationship between the severity of 99mTc-MIBI perfusion defects and the uptake of rest-redistributed 201Tl and [18F]FDG. Both tracers are adequate markers of viability in mild and moderate defects; in severe defects 201Tl might underestimate the presence of viability as assessed by [18F]FDG.

Implications of increased lung thallium uptake during exercise single photon emission computed tomography imaging

Increased lung thallium uptake during exercise is an important marker of patients who are at high risk and have CAD; however, most previous studies were done with planar imaging, and therefore it is unclear whether this conclusion is also true with SPECT imaging. This study examined the lung thallium uptake during exercise SPECT imaging in 1031 patients who also underwent coronary angiography. The lung thallium uptake was increased in 309 patients (group 1) and normal in 722 patients (group 2). Compared with patients in group 2, those in group 1 had more ST segment depression (44% vs 28%, p = 0.01), previous Q-wave myocardial infarction (28% vs 17%, p = 0.0001), larger perfusion defects (24% +/- 11% vs 10% +/- 11%, p = 0.0001), and multivessel CAD by angiography (75% vs 47%, p = 0.0001). Multivariate discriminant analysis identified left ventricular dilation, reversible defects, the size of perfusion abnormality, and the extent of CAD as independent predictors of increased lung thallium uptake. Increased lung thallium uptake was more common in men than women regardless of the extent of CAD: 26% versus 11% in patients with one-vessel, 38% versus 18% in patients with two-vessel, and 51% versus 31% in patients with three-vessel disease (p < 0.001 each). Thus increased lung thallium uptake by SPECT identifies patients with more severe anatomic and functional evidence of CAD. The sex-related difference suggests the need for a sex-specific normal file for quantitative analysis.

Diagnostic and prognostic value of stress testing in older persons

OBJECTIVE

To review the diagnostic and prognostic utility of exercise and pharmacologic stress testing in older individuals.

DATA SOURCE

A computer-assisted search of the literature, followed by a manual reference review of pertinent articles.

STUDY SELECTION

Studies addressing the use of exercise and pharmacologic stress testing for coronary artery disease (CAD) detection and prognosis were reviewed. Emphasis was placed on those studies applying these procedures to older populations.

DATA EXTRACTION

Pertinent data were extracted regarding the diagnostic and prognostic accuracy and safety of exercise and nonexercise stress testing techniques in older patients.

DATA SYNTHESIS

Available data from relevant articles were summarized and the merits and limitations of the available techniques discussed.

CONCLUSIONS

Numerous studies over the past 2 decades support the usefulness of the exercise ECG and exercise thallium-201 perfusion scan for detecting CAD in older populations. Although exercise echocardiography generally appears to have diagnostic and prognostic accuracy similar to thallium-201 imaging, greater technical difficulty with this technique is frequently encountered in older patients. Non-exercise forms of stress testing, particularly those employing pharmacologic agents such as dipyridamole, adenosine, or dobutamine, combined with either thallium-201 scintigraphy or echocardiography, allow accurate CAD diagnostic and prognostic assessment in even very frail older patients. Additional studies are needed to compare the accuracy and cost-benefit ratio of the many stress testing modalities now available for older patients.

Prognostic value of adenosine single-photon emission computed tomographic thallium imaging in medically treated patients with angiographic evidence of coronary artery disease

BACKGROUND

This study examined the prognostic value of adenosine single-photon emission computed tomographic thallium imaging in medically treated patients with angiographic evidence of coronary artery disease (CAD).

METHODS AND RESULTS

Patients who underwent coronary revascularization within 3 months of this study were excluded. There were 177 patients aged 64 +/- 11 years; 74 had one-vessel, 57 had two-vessel, and 46 had three-vessel CAD (> or = 50% diameter stenosis). During a mean follow-up of 22 +/- 13 months, there were 14 events (cardiac death or nonfatal myocardial infarction). Cox survival analysis with important clinical, catheterization, and scintigraphic variables identified the size of perfusion abnormality as the strongest predictor of events (chi 2 = 9). Life-table analysis showed that patients with perfusion defects of 15% or greater of the myocardium had a worse prognosis than had patients with no or smaller defects (Mantel-Cox statistic = 13; p < 0.001).

CONCLUSIONS

Thus adenosine single-photo emission computed tomographic thallium imaging provides important prognostic data in medically treated patients with CAD. The extent of thallium abnormality is the most important predictor of events.

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment

BACKGROUND

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD).

METHODS AND RESULTS

The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both).

CONCLUSIONS

Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

Prognostic value of thallium-201 myocardial perfusion imaging in three primary patient populations

Knowledge of a patient's coronary anatomy alone is often insufficient to predict who will benefit from revascularization. Risk of cardiac events is related more to the presence of viable myocardium supplied by coronary arteries that are hemodynamically significant. Myocardial perfusion imaging with thallium-201 has been shown to reveal the presence and extent of jeopardized viable myocardium. In addition, thallium-201 imaging can demonstrate exercise-induced left ventricular dysfunction, manifested by increased thallium-201 myocardial imaging has important prognostic value in a wide spectrum of patients with coronary artery disease. The use of thallium-201 to predict cardiac events in patients with known or suspected coronary artery disease, in patients following myocardial infarction, and in patients undergoing noncardiac surgery is reviewed.

Prognostic value of dipyridamole thallium-201 imaging in elderly patients

The prognostic value of intravenous dipyridamole myocardial perfusion imaging has not been studied in a large series of elderly patients. Patients greater than or equal to 70 years of age with known or suspected coronary artery disease were evaluated to determine the predictive value of intravenous dipyridamole thallium-201 imaging for subsequent cardiac death or nonfatal myocardial infarction. Of the 348 patients, 207 were symptomatic and 141 were asymptomatic; 52% of the asymptomatic group had documented coronary artery disease. During 23 +/- 15 months of follow-up, there were 52 cardiac deaths, 24 nonfatal myocardial infarctions and 42 revascularization procedures (percutaneous transluminal coronary angioplasty in 20; coronary artery bypass surgery in 22). Clinical univariate predictors of a cardiac event included previous myocardial infarction, congestive heart failure symptoms, hypercholesterolemia and diabetes (all p less than 0.05). The presence of a fixed, reversible or combined thallium-201 defect was significantly associated with the occurrence of cardiac death or myocardial infarction during follow-up (p less than 0.05). Cardiac death or nonfatal myocardial infarction occurred in only 7 (5%) of 150 patients with a normal dipyridamole thallium-201 study (p less than 0.001). Stepwise logistic regression analysis of clinical and radionuclide variables revealed that an abnormal (reversible or fixed) dipyridamole thallium-201 study was the single best predictor of cardiac events (relative risk 7.2, p less than 0.001). As has been demonstrated in younger patients, previous myocardial infarction (relative risk 1.8, p less than 0.001) and symptoms of congestive heart failure at presentation (relative risk 1.6, p = 0.02) were also significant independent clinical predictors of cardiac death or myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of dipyridamole thallium-201 scintigraphy in patients with stable chest pain

The usefulness of dipyridamole testing with planar thallium-201 scintigraphy for assessing risk of subsequent cardiac events was evaluated in 373 patients with stable chest pain. Follow-up information was complete in 362 patients (mean age 64 +/- 9 years). During an average follow-up period of 18 months, cardiac events occurred in 59 patients--unstable angina in 27, nonfatal acute myocardial infarction in 11, and death from cardiac causes in 21. A history of previous myocardial infarction, congestive heart failure, or coronary bypass surgery before the study, or the presence of an abnormal scan or one with a fixed perfusion defect was associated with a significantly increased frequency of subsequent cardiac events (p less than 0.05). However, the presence of a reversible perfusion defect was not associated with increased risk (p = 0.1872). Stepwise logistic regression showed that a history of coronary artery bypass surgery before the study and the presence of a fixed perfusion defect were the only variables with independent predictive value for occurrence of a subsequent cardiac event (p less than 0.05). Survival analysis revealed a significantly increased cardiac event rate in patients with abnormal scans compared with those with normal scans over a 30-month follow-up period (p less than 0.01). We conclude that dipyridamole testing with thallium-201 scintigraphy can provide prognostic information concerning risk of future cardiac events in patients with stable chest pain. The presence of a fixed perfusion defect in particular identifies patients at increased risk.

Nuclear medicine

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Prognostic significance of exercise thallium-201 testing in patients aged greater than or equal to 70 years with known or suspected coronary artery disease

The prognostic value of exercise thallium-201 myocardial perfusion imaging has not been studied in an elderly (aged greater than or equal to 70 years) population. Retrospective analysis of 120 consecutive elderly patients undergoing Bruce protocol exercise stress with quantitative planar thallium-201 scintigraphy, followed clinically for a mean of 36 +/- 12 months after testing, revealed a 10% cardiac event rate (6 cardiac deaths from arrhythmia or congestive heart failure, and 5 fatal and 1 nonfatal myocardial infarction). There were no exercise stress-related complications. Survival without cardiac events was associated with greater exercise duration (5.6 +/- 2.4 vs 3.1 +/- 2.4 minutes; p less than 0.0007) and peak exercise heart rate (131 +/- 18 vs 120 +/- 19 beats/min; p less than 0.05). Univariate variables associated with higher cardiac event rates included: (1) peak exercise less than or equal to stage I (18 vs 6%; p = 0.04); (2) maximal ST-segment depression greater than or equal to 2 mm (27 vs 6%; p = 0.003); and (3) presence of a fixed or reversible thallium-201 perfusion defect (18 vs 2%; p = 0.004). Multivariate stepwise logistic regression analysis identified the combination of peak exercise less than or equal to stage I and any thallium-201 perfusion defect as the most powerful predictor of subsequent cardiac events (relative risk = 5.3 at 1 year). Thus, exercise thallium-201 scintigraphy in elderly patients is safe and provides important prognostic information.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise thallium scintigraphy in aortitis syndrome (Takayasu's arteritis)

It is important for patient management to evaluate coronary arterial involvement in aortitis syndrome. Twenty one cases of aortitis syndrome who experienced chest pain were examined using exercise thallium scintigraphy. The patients were divided into four groups according to the angiographic findings. There were: five patients with left main coronary arterial involvement (group A), four with left or right coronary arterial involvement (group B), nine with aortic regurgitation (group C), and three with pulmonary arterial involvement (group D). In group A and B, all patients had positive ECGs and thallium perfusion defects. Group A patients showed extensive anterolateral perfusion defects, which were compatible with left main coronary arterial involvement. Group C and D patients, who had normal coronary arteries, showed no remarkable perfusion defects although five had positive ECG findings. Thus, the sensitivity and specificity of exercise scintigraphy for detection of myocardial ischemia were 9/9 and 12/12, while those of stress ECG were 9/9 and 7/12 (58%), respectively. It is recommended that exercise thallium scintigraphy be used for detecting clinically occult but significant coronary arterial involvement in aortitis syndrome with chest pain.