Preoperative risk stratification with myocardial perfusion imaging in intermediate and low-risk non-cardiac surgery.

BACKGROUND: Perioperative cardiac risk in high risk surgery is often stratified with myocardial perfusion single-photon emission computed tomography (SPECT). However, little and no data are available about intermediate and low-risk surgery, respectively. METHODS AND RESULTS: A total of 1,220 consecutive patients underwent electrocardiography-gated dipyridamole stress SPECT to evaluate myocardial perfusion and cardiac function before intermediate or low risk non-cardiac surgery. Variables predictive of perioperative cardiac events were determined and the usefulness of combining pretest information and the incremental prognostic value of SPECT was estimated. The frequency of all cardiac events depended on clinical risk factors and type of surgical procedures. After sorting the patients with clinical risk factors and surgical risk, assessment of myocardial perfusion or cardiac function yielded significant risk stratification in intermediate, but not in low-risk surgery. Adding functional data to perfusion variables offered an incremental prognostic value for patients with an intermediate clinical risk and scheduled intermediate risk surgery. CONCLUSIONS: Integrating information about clinical risk factors, type of surgery, myocardial perfusion and cardiac function allows detailed preoperative risk stratification. Preoperative SPECT provides an incremental prognostic value in intermediate, but not in low-risk surgery.     

Incremental value of exercise technetium-99m tetrofosmin myocardial perfusion single-photon emission computed tomography for the prediction of cardiac events

Technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomography (SPECT) is a useful alternative to thallium-201 scintigraphy for the assessment of myocardial perfusion. This study assessed the incremental value of exercise Tc-99m tetrofosmin SPECT for the prediction of cardiac events in patients with known or suspected coronary artery disease. Exercise Tc-99m tetrofosmin SPECT imaging was performed in 655 consecutive patients. Follow-up was successful in 648 patients (98.9%). Ten patients underwent early coronary revascularization and were excluded. End points were cardiac death, nonfatal infarction, and late (>60 days) coronary revascularization. An abnormal study was defined as the presence of fixed and/or reversible perfusion defects. A summed stress score (SSS) was derived to estimate the extent and severity of perfusion defects. An abnormal scan was detected in 344 patients (54%). During a mean follow-up period of 4 +/- 1.3 years, 56 patients (9%) died (22 cardiac deaths). Nonfatal myocardial infarction occurred in 19 patients (3%), and 89 patients (14%) underwent late coronary revascularization. An abnormal scan was an independent predictor of cardiac death (hazard ratio 3.5, confidence intervals [CI] 1.1 to 12.2) and provided incremental information over clinical and exercise test data (log-likelihood -133 to -125, p <0.05). The SSS provided incremental prognostic information over clinical data as well (log-likelihood -133 to -127, p <0.05) (hazard ratio 1.23, CI 1.10 to 1.38). An abnormal scan (hazard ratio 3.3, CI 1.1 to 12.2)) and the SSS (hazard ratio 1.25, CI 1.07 to 1.45)) were powerful independent predictors of the combined end point of any cardiac event. Thus, exercise Tc-99m tetrofosmin myocardial perfusion SPECT provides information incremental to clinical data for the prediction of cardiac events in patients with known or suspected coronary artery disease.     

Incremental prognostic power of single-photon emission computed tomographic myocardial perfusion imaging in patients with known or suspected coronary artery disease

Noninvasive stress testing provides prognostic information in patients who have suspected coronary artery disease, but limited data are available on the incremental value of myocardial perfusion testing in high-risk patients. We studied 3,275 patients who underwent cardiac catheterization and single-photon emission computed tomographic (SPECT) perfusion imaging. Median follow-up was 3.1 years for death, cardiovascular death, and a composite of cardiovascular death or nonfatal myocardial infarction. Using Cox's proportional hazards regression models, we examined the relation of SPECT summed stress score (SSS) to each outcome. A 1-unit change in SSS was associated with increased risks of 4%, 7%, and 5% for death, cardiovascular death, and death or nonfatal myocardial infarction, respectively (all p <0.0001). To examine the prognostic utility of SPECT, after baseline adjustments, SSS and angiographic results provided incremental prognostic information for each outcome. Thus, SPECT SSS provides information beyond clinical and angiographic data in patients who have known or suspected coronary artery disease. This information may be useful for stratifying patients into multiple risk categories for future cardiovascular events and potentially guiding therapy.     

Validation of an algorithm for predicting cardiac events in renal transplant candidates

A 2-tiered noninvasive cardiac risk stratification algorithm was first evaluated in a test population with planar thallium myocardial perfusion imaging and subsequently in a validation population using single-photon emission computed tomographic (SPECT) thallium myocardial perfusion imaging. This study examines if SPECT imaging was as predictive of cardiac death as planar imaging and also if SPECT imaging predicted nonfatal cardiac events in the patient population. Renal transplant candidates were evaluated using a 2-tiered noninvasive cardiac risk stratification algorithm. The first tier of risk assessment utilized 5 variables: age >50 years, insulin-dependent diabetes mellitus, abnormal electrocardiogram, and a history of either angina or congestive heart failure. Patients without risk factors were considered low risk and underwent no further cardiac evaluation. Patients with > or =1 risk factor were considered high risk and underwent a second tier of risk assessment with planar (n = 95) or SPECT (n = 112) imaging. In the test population, 13 of 16 cardiac deaths (81%) occurred in high-risk patients with abnormal planar studies. In the validation group, all cardiac deaths (5 of 60) and nonfatal cardiac events (13 of 60) occurred in high-risk patients with abnormal SPECT studies. SPECT imaging was at least as predictive as planar imaging and also predicted nonfatal as well as fatal cardiac events. Pretransplant risk stratification by clinical variables identified low-risk patients who may not require further cardiac evaluation and high-risk patients with normal SPECT imaging who may not require angiography.     

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.     

Prognostic value of dobutamine stress technetium-99m-sestamibi single-photon emission computed tomography myocardial perfusion imaging: stratification of a high-risk population.

OBJECTIVES: This work was undertaken to define the intrinsic cardiac risk of the patient population referred for dobutamine stress perfusion imaging and to determine whether dobutamine technetium-99m ((99m)Tc)-sestamibi single-photon emission computed tomography (SPECT) imaging is capable of risk stratification in this population. BACKGROUND: In animal models, dobutamine attenuates the myocardial uptake of (99m)Tc-sestamibi resulting in underestimation of coronary stenoses. Therefore, we hypothesized that the prognostic value of dobutamine stress (99m)Tc-sestamibi SPECT myocardial perfusion imaging might be impaired, owing to reduced detection of coronary stenoses. METHODS: We reviewed the clinical outcome of 308 patients (166 women, 142 men) who underwent dobutamine stress SPECT (99m)Tc-sestamibi imaging at our institution from September 1992 through December 1996. RESULTS: During an average follow-up of 1.9 +/- 1.1 years, there were 33 hard cardiac events (18 myocardial infarctions [MI] and 15 cardiac deaths) corresponding to an annual cardiac event rate of 5.8%/year, which is significantly higher than the event rate for patients referred for exercise SPECT imaging at our institution (2.2%/year). Event rates were higher after an abnormal dobutamine (99m)Tc-sestamibi SPECT study (10.0%/year) than after a normal study (2.3%/year) (p < 0.01), even after adjusting for clinical variables. In the subgroup (n = 29) with dobutamine-induced ST-segment depression and abnormal SPECT imaging, the prognosis was poor, with annual cardiac death and nonfatal MI rates of 7.9% and 13.2%, respectively. CONCLUSIONS: Patients referred for dobutamine perfusion imaging are a high-risk population, and dobutamine stress (99m)Tc-sestamibi SPECT imaging is capable of risk stratification in these patients.     

Comparative prognostic value of automatic quantitative analysis versus semiquantitative visual analysis of exercise myocardial perfusion single-photon emission computed tomography

Objectives. The purpose of this study was to determine the prognostic value of automatic quantitative analysis in exercise dual-isotope myocardial perfusion single-photon emission computed tomography (SPECT) and to compare the prognostic value of quantitative analysis to semiquantitative visual SPECT analysis.

Background. Extent, severity and reversibility of exercise myocardial perfusion defects have been shown to correlate with prognosis. However, most studies examining the prognostic value of SPECT in chronic coronary artery disease (CAD) have been based on visual analysis by experts.

Methods. We studied 1,043 consecutive patients with known or suspected CAD who underwent rest Tl-201/exercise Tc-99m sestamibi dual-isotope myocardial perfusion SPECT and were followed up for at least 1 year (mean 20.0 ± 3.7 months). After censoring 59 patients with early coronary artery bypass grafting or percutaneous transluminal coronary angioplasty, <60 days after nuclear testing, the final population consisted of 984 patients (36% women, mean age 63 ± 12 years).

Results. During the follow-up period, 28 hard events (14 cardiac deaths, 14 nonfatal myocardial infarctions) occurred. Patients with higher defect extent (>10%), severity (>150) and reversibility (>5%) by quantitative SPECT defect analysis, as well as those with an abnormal scan (>2 abnormal segments, summed stress score >4 and summed difference score >2) by semiquantitative visual SPECT analysis, had a significantly higher hard event rate compared to patients with a normal scan (p < 0.001). With both visual and quantitative analyses, hard event rates of approximately 1% with normal scans and 5% with abnormal scans (p > 0.05) were observed over the 20-month follow-up period. A Cox proportional hazards regression model showed that chi-square increased similarly with the addition of quantitative defect extent and visual summed stress score variables after considering both clinical and exercise variables (improvement chi-square = 11 for both, p < 0.0007). There were no significant differences in the areas under receiver operating characteristic curves between quantitative and visual analysis (p > 0.70). Linear regression analysis also indicated that quantitative assessments correlated well with visual semiquantitative assessments.

Conclusions. The findings of this study indicate that automatic quantitative analysis of exercise stress myocardial perfusion SPECT is similar to semiquantitative expert visual analysis for prognostic stratification. These findings may be of particular clinical importance in laboratories with less experienced visual interpreters.     

Prediction of cardiac death in hypertensive patients with suspected or known coronary artery disease by stress technetium-99m tetrofosmin myocardial perfusion imaging

BACKGROUND: There are currently insufficient data to indicate a role for stress myocardial perfusion imaging as a prognostic tool in hypertensive patients. OBJECTIVES: To assess the incremental value of stress myocardial perfusion imaging for the prediction of cardiac death in hypertensive patients relative to clinical data. PATIENTS: We studied 601 hypertensive patients (aged 59 +/- 10 years, 387 men) who underwent exercise bicycle or dobutamine (up to 40 microg/kg per min) stress technetium-99m tetrofosmin single photon emission computed tomography (SPECT) for evaluation of coronary artery disease. OUTCOME: Cardiac death during follow-up. RESULTS; An abnormal scan (reversible or fixed perfusion abnormalities) was detected in 293 (49%) patients (134 had reversible abnormalities). During a mean follow-up period of 3.1 +/- 1.3 years, 109 (18%) patients died; of whom, 42 patients (39%) died due to cardiac causes. Independent predictors of cardiac death were age [hazard ratio = 1.04, 95% confidence interval (CI) 1.01-1.08], history of previous myocardial infarction (hazard ratio = 2, CI 1.1-3.7), stress rate-pressure product (hazard ratio = 0.94, CI 0.87-0.98) and abnormal scan (hazard ratio = 4.7 CI 1.9-11.4). Both reversible and fixed abnormalities were predictive of death. The annual cardiac death rate was 5.3% in patients with an abnormal and 0.5% in patients with a normal perfusion scan. CONCLUSION: Stress technetium-99m tetrofosmin myocardial perfusion imaging provides prognostic information incremental to clinical data for the prediction of cardiac death in hypertensive patients with known or suspected coronary artery disease.     

Quantitative gated single-photon emission computed tomography with (99m)Tc sestamibi predicts major cardiac events in elderly patients with known or suspected coronary artery disease: the QGS-Prognostic Value in the Elderly (Q-PROVE) Study.

BACKGROUND: Although electrocardiogram-gated single-photon emission computed tomography (SPECT) may be useful in risk stratification of elderly patients with coronary artery disease (CAD), few studies have prospectively evaluated its prognostic value in this patient population. METHODS AND RESULTS: A total of 175 patients aged 75 years or more with known or suspected CAD were prospectively evaluated by stress gated SPECT using a 20-segment model and an automatic functional analysis. Patients with acute coronary syndrome within the previous 3 months, and those who underwent coronary revascularization within 3 months after the SPECT study were excluded. Outcome assessment included prespecified cardiac events and noncardiac deaths. During a mean follow-up of 3.4 years, there were 18 cardiac events: 2 cardiac deaths, 1 nonfatal myocardial infarction, 3 coronary artery bypass grafting, 5 percutaneous coronary interventions, 1 unstable angina, 4 heart failures, and 2 malignant arrhythmias. Kaplan-Meier survival estimation indicated an event-free survival rate of 98.1% at 3 years in patients without myocardial ischemia, but 79.9% in those with ischemia as documented by gated SPECT (p=0.0001). Multivariate analysis using the Cox proportional hazard model demonstrated that stress-induced myocardial ischemia was the only independent predictor for subsequent cardiac events (p<0.01). CONCLUSIONS: Stress gated SPECT predicts cardiac events in patients aged 75 years or more with known or suspected CAD and may have a role in risk stratification of this patient population.     

Prognostic significance of myocardial ischemia during dobutamine stress echocardiography in asymptomatic patients with diabetes mellitus and no prior history of coronary events

The prognostic significance of myocardial ischemia assessed by dobutamine stress echocardiography in asymptomatic patients with diabetes mellitus who have no previous coronary artery disease remains unclear. We assessed the value of dobutamine stress echocardiography for risk stratification in 161 asymptomatic patients with type 2 diabetes (mean 62 +/- 12 years of age; 96 men) who had no previous myocardial infarction or revascularization. End point during follow-up was hard cardiac events (cardiac death and nonfatal myocardial infarction). Ischemia was detected in 45 patients (28%). During a median follow-up of 5 years, 40 patients (25%) died (18 cardiac deaths) and 7 patients had nonfatal myocardial infarction (25 hard cardiac events). An abnormal dobutamine stress echocardiogram was associated with a higher mortality compared with a normal dobutamine stress echocardiogram (p = 0.03). In an incremental multivariate analysis model, clinical predictors of hard cardiac events were age and hypercholesterolemia. Ischemia was incremental to the clinical parameters. In conclusion, myocardial ischemia is an independent predictor of cardiac events in asymptomatic diabetic patients with no previous coronary artery disease.     

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.     

Prognostic value of dobutamine stress echocardiography in patients with systemic hypertension and known or suspected coronary artery disease

Currently, there are no outcome data to suggest an incremental value of stress echocardiography in the risk stratification of patients who have hypertension after controlling for the left ventricular mass index (LVMI). This study assessed the incremental value of dobutamine stress echocardiography (DSE) for the prediction of mortality rate and cardiac events in patients who have hypertension. We studied 596 patients who had hypertension (mean age 62 +/- 12 years; 382 men) and who underwent DSE for evaluation of known or suspected coronary artery disease. End points during follow-up were hard cardiac events (cardiac death and nonfatal myocardial infarction) and total mortality rate. Left ventricular hypertrophy was detected by echocardiography in 119 patients (20%). During a median follow-up of 3 years, 101 patients (17%) died (43 cardiac deaths) and 19 patients had nonfatal myocardial infarction. In an incremental multivariate analysis model, clinical predictors of hard cardiac events were age, history of congestive heart failure, and LVMI. The percentage of abnormal myocardial segments examined with DSE was incremental to the clinical model (chi square 41 vs 27, p <0.001). Clinical predictors of total mortality rate were age, smoking, hypercholesterolemia, history of congestive heart failure, and LVMI. The peak wall motion score index was incremental to the clinical model (chi square 45 vs 40, p <0.05). DSE provides incremental data for the prediction of mortality rate and hard cardiac events in patients who have hypertension after adjustment for clinical data and LVMI.     

Incremental prognostic value of technetium-99m-tetrofosmin exercise myocardial perfusion imaging for predicting outcomes in patients with suspected or known coronary artery disease.

Technetium-99m (Tc-99m)-tetrofosmin is a radio isotope that has been shown to be an accurate alternative to thallium-201 for detecting coronary artery disease. However, its prognostic value is less well determined. To this end, 459 consecutive patients (mean age 58 +/- 10 years) with suspected or known coronary artery disease underwent exercise single-photon emission tomography Tc-99m-tetrofosmin scintigraphy. Follow-up, defined as the time from scanning until a soft event (revascularization procedures), a hard event (myocardial infarction and cardiac death), or patient response, lasted up to 78 months (median 38). An ischemic scintigraphic perfusion score, which takes into account both the extent and severity of reversible perfusion defects, was calculated to estimate the severity of perfusion abnormalities. Patients with normal scans were at low risk of events (yearly hard event rate 0.5% and soft event rate 0.9%). The rate of outcomes increased significantly with abnormal scans (yearly hard event rate 4.9% and soft event rate 10.3%). Statistical analysis using the Kaplan-Meyer survival curves showed a significant difference in event-free survival between patients with normal and abnormal scans. With use of Cox proportional-hazards analysis, after adjusting for prescan information, nuclear data provided incremental prognostic value for hard events (clinical and exercise data vs nuclear data; chi-square = 15.5 vs 33.4, p <0.001). Exercise single-photon emission tomographic scintigraphy using Tc-99m-tetrofosmin provides significant independent information on the subsequent risk of hard and soft events. The annual event rate for hard and soft events is <1% for patients with a normal scan. Furthermore, this tracer yields incremental prognostic information in addition to that provided by clinical and exercise data for hard events.     

Long-term prognostic value of dobutamine stress echocardiography compared with myocardial perfusion scanning in patients unable to perform exercise tests

PURPOSE: To compare the long-term prognostic value of dobutamine stress echocardiography and dobutamine stress single photon emission computed tomography (SPECT) in patients unable to perform an exercise test. METHODS: We assessed the prognostic value of dobutamine stress technetium 99m ((99m)Tc)-sestamibi SPECT and dobutamine stress echocardiography in 301 patients who were unable to perform exercise tests. Outcomes during a mean (+/- SD) follow-up of 7.3 +/- 2.8 years were overall death, cardiac death, nonfatal myocardial infarction, and late (>60 days) coronary revascularization. RESULTS: Abnormal myocardial perfusion was detected in 66% of patients (n = 198), while 60% (n = 182) had an abnormal stress echocardiogram; agreement was 82% (kappa = 0.62). During the follow-up period, 100 deaths (33%) occurred, of which 43% were due to cardiac causes. Nonfatal myocardial infarction occurred in 23 patients (8%), and 29 (10%) underwent late revascularization. With stress SPECT, annual event rates were 0.7% for cardiac death and 3.6% for all cardiac events after a normal scan, and 2.6% for cardiac death and 6.5% for all cardiac events after an abnormal scan (P <0.0001). For stress echocardiography, annual event rates were 0.6% for cardiac death and 3.3% for all cardiac events after a normal test, and 2.8% for cardiac death and 6.9% for all cardiac events after an abnormal test (P <0.0001). CONCLUSION: Dobutamine stress (99m)Tc-sestamibi SPECT and dobutamine stress echocardiography provide comparable long-term prognostic information in addition to that afforded by clinical data.     

Prognostic value of combined perfusion and function by stress technetium-99m sestamibi gated SPECT myocardial perfusion imaging in patients with suspected or known coronary artery disease

The incremental prognostic value of combined regional wall motion and perfusion over perfusion alone by gated single-photon emission computed tomographic myocardial perfusion scintigraphy has not been evaluated. Of the 402 consecutive patients who underwent stress single-photon emission computed tomographic myocardial perfusion scintigraphy for suspected myocardial ischemia, we identified 333 patients (217 men, mean age 63 +/- 10 years; exercise in 249 and dipyridamole adminstered to 84). Visual scoring of perfusion images and regional wall motion used 20 segments and a scale of 0 to 4. Resting and poststress left ventricular ejection fraction was automatically generated. On follow-up (median 13 months), 30 hard cardiac events (17 cardiac deaths, 13 nonfatal acute myocardial infarctions) and 66 total cardiac events (including hard events, 26 with unstable angina, and 10 who underwent late revascularization) occurred. After adjustment for prescan information, the best independent predictors of hard events were summed stress score for wall motion (Wald's chi-square 8.3, p <0.004) and several vascular territories with ischemia by perfusion/function (Wald's chi-square 6.2, p <0.01). The strongest predictors of all cardiac events were the number of ischemias (Wald's chi-square 32.1, p <0.0001) and the number of ischemic vascular territories by perfusion (Wald's chi-square 13.1, p <0.0001). Addition of function data to the combined model of perfusion data yielded an incremental value of 26% for predicting hard events but not for all events. In conclusion, the assessment of combined perfusion/function provides incremental prognostic information for further hard events with perfusion data alone; perfusion data best predict all cardiac events.     

Technetium 99m sestamibi myocardial perfusion imaging predicts clinical outcome in the community outpatient setting. The Nuclear Utility in the Community (NUC) Study

OBJECTIVES: The purpose of this study was to evaluate the prognostic value of community-based myocardial perfusion imaging (MPI) and to assess the incremental value of individual components of (99m)Tc-sestamibi single photon emission computed tomography (SPECT). BACKGROUND: Although the most rapid growth of MPI has been in community outpatient laboratories, its prognostic value has not been validated in this setting. METHOD: We prospectively followed 1,612 consecutive patients undergoing stress (99m)Tc-sestamibi SPECT in an outpatient community laboratory who experienced 71 hard events over 24 +/- 7 months (0.2% lost to follow-up). RESULTS: Patients whose scans were normal incurred an annualized event rate of 0.4%, compared with 2.3% for those with abnormal scans (p < 0.0001). Subset analysis demonstrated comparable risk stratification for women and men, diabetics, patients with normal resting ECGs, and those referred for pharmacologic and exercise stress. After adjusting for pre-test variables, multivariable Cox regression analysis found the most potent independent components of MPI to be, in order of importance, transient ischemic dilation, extent of reversibility, post-stress ejection fraction, extent and severity of the stress perfusion defect, and the overall test result (normal or abnormal). Each 1% decrement of ejection fraction predicted a 3% increase in risk (p = 0.0009). Post-MPI angiography and revascularization increased commensurate with the extent and severity of MPI result. CONCLUSIONS: The prognostic value of perfusion imaging is portable and transferable to the outpatient community setting, with multiple components of MPI providing incremental prognostic information.     

Value of gated SPECT myocardial perfusion imaging for individual cardiac risk assessment

Myocardial perfusion imaging enables not only accurate diagnosis of disease but also entails prognostic value. Myocardial perfusion SPECT contributes to assessment of future cardiac events independently of other clinical parameters. A normal stress myocardial perfusion scan is associated with a favorable prognosis independent of history, symptoms, and exercise electrocardiography test variables. Cardiac risk and benefit from invasive therapeutic strategies increase in relation to the severity of the abnormality of perfusion and function assessed by gated myocardial perfusion SPECT. Thus, stress myocardial perfusion imaging may serve as a gatekeeper for referral to coronary angiography enabling effective risk stratification in patients with suspected or documented coronary artery disease.     

Prognostic value of thallium-201 single-photon emission computed tomographic myocardial perfusion imaging according to extent of myocardial defect: Study in 1,926 patients with foilow-up at 33 months

Objectives. This study was designed to assess the prognostic value of thallium-201 single-photon emission computed tomographic (thallium SPECT) perfusion imaging in patients evaluated for stable angina pectoris and to examine the relation, if any, between the preface and extent of myocardial defect and future fatal or nonfatal cardiovascular events (revascularization, secondary myocardial infarction).Background. Compared with planar scintigraphy, thallium SPECT enables better evaluation of the extent of mayocardial perfusion defect. However, its prognostic value has not yet been studied in a large population of patients.Methods. Between 1987 and 1989 we studied 3,193 patients. After exclusion of patients with unstable angina, myocardial infarction during the previous month or earlier revascularization, 1,926 patients were followed up for 33 ± 10 (mean ± SD) months after stress thallium SPECT imaging (performed after exercise in 1,121 patients or during dipyridamole infusion in 805 patients). Thallium SPECT imaging of the left ventricle was divided into six segments.Results. After normal thallium SPECT imaging (715 patients), the annual total and cardiovascular mortality rates were, respectively, 0.42%/year and 0.10%/year and were significantly higher after abnormal thallium SPECT imaging (respectively, 2.1%, relative risk 5, p = 0.012; 1.5%, relative risk 15, p < 0.0001 [log-rank test]). There was a significant relation between the number of abnormal segments and cardiovascular mortality during follow-up (p < 0.02) or the occurrence of nonfatal events (p < 0.001). The extent of defect on the initial scan provided the best SPECT variable for long-term prognosis. Thallium SPECT imaging provided additive prognostic information compared with other clinical variables (gender, previous myocardial infarction) and exercise electrocardiogram.Conclusions. In patients with stable angina, normal thallium SPECT imaging indicates a low risk patient, and the extent of myocardial defect is an important prognostic predictive factor.     

Incremental prognostic value of exercise thallium-201 myocardial single-photon emission computed tomography late after coronary artery bypass surgery

Objectives.This study assessed the incremental prognostic value of exercise thallium-201 myocardial perfusion single-photon emission computed tomography (SPECT) performed ≥5 years after coronary artery bypass surgery.Background.Thallium-201 scintigraphy has shown significant prognostic value in a variety of populations with suspected and known coronary artery disease. However, its value in patients with previous bypass surgery remains unknown.Methods.We studied 294 patients who were prospectively followed up. Cox proportional hazards models for prediction of “hard” events (cardiac death and nonfatal infarctions) were constructed, with variables considered for inclusion in hierarchic order: clinical and exercise data first, followed by scintigraphic information.Results.Mean (± SD) follow-up duration after scintigraphy was 31 ± 11 months. There were 20 cardiac deaths and 21 monfatal acute myocardial infarctions. Twenty-nine patients had late (>60) days after thallium-201 SPECT) revascularization procedures or underwent repeat bypass surgery or percutaneous transluminal angioplasty. Shortness of breath and peak exercise heart rate were the most important clinical predictors of hard events. Two scintigraphic variables added significant prognostic information to the clinical model: the thallium-201 summed reversibility score (summation of segmental differences between stress and redistribution scores) and the presence of increased lung uptake of the radiotracer. The global chi-square statistic for this model was twice as high as that for the clinical/exercise model alone (49.7 vs. 24.2). When a second multivariate Cox model was build adding “soft” events (i.e., late revascularization procedures) as outcomes of interest, the summed reversibility score was selected as an independent scintigraphic predictor of events. The global chi-square statistic for this model was 50.7, three times as high as that for the clinical/exercise model alone.Conclusions.After evaluation of treadmill and exercise data, thallium-201 myocardial perfusion SPECT provided incremental prognostic information in patients late after bypass.     

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.