Prognostic value of myocardial perfusion imaging in patients with high exercise tolerance

BACKGROUND: Although high exercise tolerance is associated with an excellent prognosis, the significance of abnormal myocardial perfusion imaging (MPI) in patients with high exercise tolerance has not been established. This study retrospectively compares the utility of MPI and exercise ECG (EECG) in these patients. METHODS AND RESULTS: Of 388 consecutive patients who underwent exercise MPI and reached at least Bruce stage IV, 157 (40.5%) had abnormal results and 231 (59.5%) had normal results. Follow-up was performed at 18+/-2.7 months. Adverse events, including revascularization, myocardial infarction, and cardiac death, occurred in 40 patients. Nineteen patients had revascularization related to the MPI results or the patient's condition at the time of MPI and were not included in further analysis. Seventeen patients (12.2%) with abnormal MPI and 4 (1.7%) with normal MPI had adverse cardiac events (P<0.001). Cox proportional-hazards regression analysis showed that MPI was an excellent predictor of cardiac events (global chi2=13.2; P<0.001; relative risk=8; 95% CI=3 to 23) but EECG had no predictive power (global chi2=0.05; P=0.8; relative risk=1; 95% CI=0.4 to 3.0). The addition of Duke's treadmill score risk categories did not improve the predictive power of EECG (global chi2=0.17). The predictive power of the combination of EECG (including Duke score categories) and MPI was no better than that of MPI alone (global chi2=13.5). CONCLUSIONS: Unlike EECG, MPI is an excellent prognostic indicator for adverse cardiac events in patients with known or suspected CAD and high exercise tolerance.     

Relationship between noninvasive coronary angiography with multi-slice computed tomography and myocardial perfusion imaging.

OBJECTIVES: The aim of this study was to perform a head-to-head comparison between multi-slice computed tomography (MSCT) and myocardial perfusion imaging (MPI) in patients with an intermediate likelihood of coronary artery disease (CAD) and to compare non-invasive findings to invasive coronary angiography. BACKGROUND: Multi-slice computed tomography detects atherosclerosis, whereas MPI detects ischemia; how these 2 techniques compare in patients with an intermediate likelihood of CAD is unknown. METHODS: A total of 114 patients, mainly with intermediate likelihood of CAD, underwent both MSCT and MPI. The MSCT studies were classified as having no CAD, nonobstructive (<50% luminal narrowing) CAD, or obstructive CAD. Myocardial perfusion imaging examinations were classified as showing normal or abnormal (reversible and/or fixed defects). In a subset of 58 patients, invasive coronary angiography was performed. RESULTS: On the basis of the MSCT data, 41 patients (36%) were classified as having no CAD, of whom 90% had normal MPI. A total of 33 patients (29%) showed non-obstructive CAD, whereas at least 1 significant (> or =50% luminal narrowing) lesion was observed in the remaining 40 patients (35%). Only 45% of patients with an abnormal MSCT had abnormal MPI; even in patients with obstructive CAD on MSCT, 50% still had a normal MPI. In the subset of patients undergoing invasive angiography, the agreement with MSCT was excellent (90%). CONCLUSIONS: Myocardial perfusion imaging and MSCT provide different and complementary information on CAD, namely, detection of atherosclerosis versus detection of ischemia. As compared to invasive angiography, MSCT has a high accuracy for detecting CAD in patients with an intermediate likelihood of CAD.     

The prognostic value of normal exercise myocardial perfusion imaging and exercise echocardiography: a meta-analysis.

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.     

Accuracy of stress Tc-99m tetrofosmin myocardial perfusion tomography for the diagnosis and localization of coronary artery disease in women.

BACKGROUND: Earlier studies have suggested a modest accuracy of stress thallium 201 myocardial perfusion imaging (MPI) for the diagnosis of coronary artery disease (CAD) in women. The accuracy of stress MPI with technetium 99m tetrofosmin has not been studied in women. The aim of this study was to assess the accuracy of stress Tc-99m tetrofosmin MPI for the diagnosis and localization of CAD in women. METHODS AND RESULTS: We studied 88 women who underwent exercise or dobutamine stress Tc-99m tetrofosmin tomography and coronary angiography within 3 months. Significant CAD was defined as a stenosis 50% or greater in diameter in at least 1 major epicardial coronary artery. Myocardial perfusion abnormalities were detected in 44 of 53 patients with significant CAD and in 7 of 35 patients without significant CAD (overall sensitivity, 83% [95% confidence interval (CI), 73%-93%]; specificity, 80% [95% CI, 67%-93%]; and accuracy, 82% [95% CI, 74%-90%]). The sensitivity was 72% (18/25) in patients with single-vessel CAD and 93% (26/28) in patients with multivessel CAD. Perfusion abnormalities were detected in 2 or more vascular distributions in 20 of 28 patients with multivessel CAD and in 4 of 60 patients without multivessel CAD (sensitivity for the identification of multivessel CAD, 71% [95% CI, 55%-88%]; specificity, 93% [95% CI, 86%-98%]; and accuracy, 86% [95% CI, 79%-93%]). The sensitivity, specificity, and accuracy were 82%, 84%, and 83%, respectively, for the diagnosis of CAD in the left anterior descending artery; 77%, 84%, and 81%, respectively, for CAD in the right coronary artery; and 74%, 80%, and 78%, respectively, for CAD in the left circumflex artery. CONCLUSION: Stress Tc-99m tetrofosmin MPI is an accurate noninvasive technique for the diagnosis and localization of CAD in women.     

Real-time dobutamine stress myocardial perfusion echocardiography predicts outcome in the elderly.

AIMS: Although there is an increasing number of studies showing the value of perfusion imaging with real-time contrast echocardiography (RTCE) for detecting coronary artery disease (CAD), no data exist regarding the value of this technique for detecting CAD and predicting outcome in the elderly. METHODS AND RESULTS: We examined the outcome of 399 patients > or =70 years old who underwent dobutamine stress RTCE for known or suspected CAD. Myocardial perfusion imaging (MPI) was performed using low mechanical index pulse sequence schemes following intravenous small bolus injections of ultrasound contrast. Quantitative coronary angiography (QCA) was performed within 1 month of the stress test in 60 patients. Events were defined as cardiac death or non-fatal myocardial infarction (MI). Sensitivity of MPI for detecting CAD by QCA was 94% [confidence interval (CI) 91-99], specificity was 67% (CI 36-74), and accuracy was 90% (CI 82-95). During a median follow-up of 21 months, 46 events occurred (31 cardiac deaths, 15 non-fatal MI). Univariate predictors of outcome were diuretic use (P = 0.03), abnormal stress wall motion (P < 0.0001), and abnormal stress MPI (P < 0.0001). Abnormal stress MPI, however, was the most significant predictor of outcome (chi(2) 7.5; P = 0.006). CONCLUSION: Myocardial perfusion analysis during dobutamine stress RTCE provides incremental predictive value in determining the outcome of elderly patients being evaluated for the presence of CAD.     

Safety of dobutamine stress real-time myocardial contrast echocardiography

OBJECTIVES: The aim of this study was to determine the safety of dobutamine stress myocardial perfusion imaging (MPI) obtained by real-time contrast echocardiography (RTCE) and intravenous ultrasound contrast in a large cohort of patients with suspected coronary artery disease (CAD). BACKGROUND: Despite the increasing number of studies showing the potential clinical utility of myocardial contrast perfusion imaging with commercially available contrast agents, the safety of this technique in a clinical setting has not been demonstrated. METHODS: Over a four-year period, 1,486 patients underwent dobutamine stress RTCE with low mechanical index pulse sequence schemes after intravenous injections of commercially available contrast agents (35% Definity, Bristol Myers Squibb Medical Imaging Inc., North Billerica, Massachusetts; 65% Optison, GE-Amersham, Princeton, New Jersey). The hemodynamic and adverse effects of RTCE were compared with 1,012 patients who underwent conventional dobutamine stress echocardiography (DSE) without contrast. The feasibility of image analysis was defined as the ability to analyze MPI in at least two of the three standard segments in each left ventricular wall. RESULTS: No myocardial infarction or death occurred during dobutamine stress. There was no difference in the incidence of nonsustained ventricular tachycardia, sustained ventricular tachycardia, or supraventricular tachycardia during dobutamine infusion between RTCE and DSE. Myocardial perfusion imaging was considered feasible for analysis in 94% of the walls at baseline and 95% at peak stress. The anterior, lateral, and posterior walls were the most common regions in which MPI was not feasible. Myocardial perfusion imaging with RTCE had a higher accuracy for detecting patients with angiographically significant CAD than the analysis of wall motion (84% vs. 66%, respectively; p < 0.001). CONCLUSIONS: Dobutamine stress RTCE appears to be a safe and feasible technique for evaluating patients with known or suspected CAD.     

Underestimation of extent of ischemia by gated SPECT myocardial perfusion imaging in patients with left main coronary artery disease.

BACKGROUND: There have been limited data regarding the value of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the detection of left main coronary artery disease (CAD). METHODS AND RESULTS: We studied 101 patients with angiographic left main CAD (> or = 50% stenosis) and no prior myocardial infarction or coronary revascularization who underwent gated exercise or adenosine stress technetium 99m sestamibi SPECT MPI. By perfusion assessment alone, high-risk disease with moderate to severe defects (> 10% myocardium at stress) was identified in only 56% of patients visually and 59% quantitatively. Absence of significant perfusion defect (> or = 5% myocardium) was seen in 13% of patients visually and 15% quantitatively. However, by combining visual perfusion data and nonperfusion variables, especially transient ischemic dilation, 83% of patients were identified as high risk. CONCLUSIONS: The findings of this study demonstrate that assessment of perfusion data alone by visual or quantitative SPECT MPI analysis underestimates the magnitude of left main CAD. The combination of perfusion and nonperfusion abnormalities on gated MPI identifies high risk in most patients with left main CAD.     

Evaluation of the patient with diabetes mellitus and suspected coronary artery disease

Coronary artery disease (CAD) is the leading cause of morbidity and mortality in patients with diabetes mellitus. In fact, patients with diabetes have the same risk of myocardial infarction as do nondiabetic subjects with a history of infarction. For this reason, diabetes has been designated by the American College of Cardiology (ACC) and the American Heart Association (AHA) as a CAD equivalent. For women, data indicate a substantially elevated risk of cardiovascular disease (CVD) even before a clinical diagnosis of type 2 diabetes has been made. Identifying patients with diabetes who have CAD and who will benefit from medical and/or invasive intervention to prevent cardiovascular events is a challenge in both symptomatic and asymptomatic patients. The decision to evaluate patients with diabetes who are asymptomatic for CAD presents the greatest challenge; investigation will reveal 10% to 15% of these patients to have CAD. Current diagnostic tools include exercise tolerance testing, stress echocardiography, stress myocardial perfusion imaging (MPI), and cardiac catheterization. Few guidelines are available to aid in the choice of testing modalities for a given patient. Although cardiac catheterization is useful, it is generally reserved for patients in whom invasive intervention is suitable. The American Diabetes Association (ADA) recommends exercise tolerance testing alone in symptomatic patients with > or = 2 CAD risk factors or an abnormal resting electrocardiogram (ECG). However, that recommendation is not based on data; it is the consensus of an expert panel. Stress echocardiography is a useful, noninvasive procedure; however, there is limited experience with this technology in the diabetic population. Recently accumulated data support both diagnostic and prognostic roles for stress MPI, particularly with ECG-gated single-photon emission computed tomographic imaging. In symptomatic patients with diabetes, the presence and extent of abnormal stress MPI findings have been found to be highly accurate independent predictors of subsequent cardiac events: 18% to 26% of asymptomatic patients with diabetes have perfusion defects consistent with CAD. However, CVD risk factors are not predictive of abnormal MPI findings even though duration of diabetes and abnormal ECGs are. The results of future studies may be helpful in guiding the selection of asymptomatic patients to undergo myocardial perfusion and function studies. In conclusion, MPI provides clinicians with an important diagnostic tool, because it offers perfusion as well as functional information for diagnosis and risk stratification in patients with diabetes. These capabilities facilitate decision making regarding the appropriateness of medical therapy or surgical intervention in these individuals.     

A hypertensive response to exercise is associated with transient ischemic dilation on myocardial perfusion SPECT imaging.

BACKGROUND: A hypertensive response to exercise (HRE) is associated with false-positive stress echocardiograms and myocardial perfusion single photon emission computed tomography (myocardial perfusion imaging [MPI]) defects even in the absence of coronary artery disease (CAD). Transient ischemic dilation (TID) of the left ventricle on stress MPI is a marker of severe CAD and future cardiac events. This study evaluated the association between an HRE and TID. METHODS AND RESULTS: Blinded quantitative TID assessment was performed in 125 patients who had an HRE and a summed stress score (SSS) of less than 4, as well as 125 control patients with an SSS of less than 4 and without an HRE matched for age, gender, and resting systolic blood pressure. Cardiac comorbidities, pretest Framingham risk, and exercise results were recorded. TID was defined as a stress-to-rest volume ratio of 1.22 or greater. An HRE was associated with a high prevalence of TID and significantly more TID than no HRE (25.6% vs 11.2%; odds ratio, 3.00 [95% confidence interval, 1.41-6.38]). TID was more prevalent even in subgroups with a low pretest probability CAD, including those without diabetes mellitus or angina. On conditional logistic regression analysis, an HRE was found to be independently associated with TID after consideration of other clinical and exercise MPI variables (odds ratio, 2.72 [95% confidence interval, 1.01-7.31]). CONCLUSION: An HRE is associated with a high prevalence of TID in patients without other significant perfusion defects, possibly as a result of global subendocardial ischemia induced by the HRE.     

201Tl运动负荷心肌显像、运动负荷心电图在冠心病诊断中的价值

目的:评价201Tl运动负荷心肌灌注显像(MPI),运动负荷心电图(ES-ECG)诊断冠心病(CAD)的临床价值。方法:首先以冠状动脉造影术(CAG)为标准(将冠脉管腔狭窄≥50%定为病变血管),96例做过CAG的患者被分为CAD组(n=55)和非CAD组(n=41)。所有患者均行运动负荷MPI和ES-ECG检查。对比分析运动负荷MPI和ES-ECG诊断CAD的灵敏度、特异性、准确性、阳性预测值。结果:运动负荷MPI和ES-ECG诊断CAD的敏感性分别为0.98、0.82;特异性分别为0.85、0.39;准确性分别为0.92、0.64;阳性预测值分别为0.90、0.64;阴性预测值分别为0.97、0.62。结论:运动负荷MPI与CAG有较好的一致性,而ES-ECG是一种较好的筛查方法。     

Clinical correlation between increased lung to heart ratio of technetium-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.     

Myocardial perfusion imaging in patients with a recent,normal exercise test

AIM: To investigate the added value of myocardial perfusion scintigraphy imaging (MPI) in consecutive patients with suspected coronary artery disease (CAD) and a recent, normal exercise electrocardiography (ECG). METHODS: This study was a retrospective analysis of consecutive patients referred for MPI during a 2-year period from 2006-2007 at one clinic. All eligible patients were suspected of suffering from CAD, and had performed a satisfactory bicycle exercise test (i.e. , peak heart rate > 85% of the expected, age-predicted maximum) within 6 mo of referral, their exercise ECG was had no signs of ischemia, there was no exercise-limiting angina, and no cardiac events occurred between the exercise test and referral. The patients subsequently underwent a standard 2-d, stress-rest exercise MPI. Ischemia was defined based on visual scoring supported by quantitative segmental analysis (i.e. , sum of stress score > 3). The results of cardiac catheterizationwere analyzed, and clinical follow up was performed by review of electronic medical files. RESULTS: A total of 56 patients fulfilled the eligibility criteria. Most patients had a low or intermediate ATPⅢ pretest risk of CAD (6 patients had a high pre-test risk). The referral exercise test showed a mean Duke score of 5 (range: 2 to 11), which translated to a low postexercise risk in 66% and intermediate risk in 34%. A total of seven patients were reported with ischemia by MPI. Three of these patients had high ATPⅢ pre-test risk scores. Six of these seven patients underwent cardiac catheterization, which showed significant stenosis in one patient with a high pre-test risk of CAD, and indeterminate lesions in three patients (two of whom had high pre-test risk scores). With MPI as a gate keeper for catheterization, no significant, epicardial stenosis was observed in any of the 50 patients (0%, 95% confidence interval 0.0 to 7.1) with low to intermediate pre-test risk of CAD and a negative exercise test. No cardiac events occurred in any patients within a median follow up period of > 1200 d. CONCLUSION: The added diagnostic value of MPI in patients with low or intermediate risk of CAD and a recent, normal exercise test is marginal.     

Exercise <Superscript>18</Superscript>FDG Imaging for the Detection of CAD: What Are the Clinical Hurdles?

Myocardial perfusion imaging (MPI) has been in clinical use for over 30 years, providing an effective, reliable, and relatively simple tool for diagnosis, risk stratification, and follow-up of patients with suspected or know coronary artery disease (CAD). The unique strength of nuclear imaging is its ability to provide tools for imaging biochemical and metabolic processes, and receptor and transporter functions at molecular and cellular levels in intact organisms under various physiologic conditions. Metabolic imaging using radiolabeled glucose analogues (¹⁸F-fluorodeoxyglucose [¹⁸FDG]) provides a unique ability to image myocardial ischemia directly (“hot spot” imaging) in patients with known or suspected CAD. Exercise ¹⁸FDG imaging can potentially overcome some of the limitations of currently used stress-rest MPI. In this article, we describe recent studies using exercise ¹⁸FDG for imaging myocardial ischemia and its potential use in routine clinical practice.     

Anatomic correlates of a normal perfusion scan using 64-slice computed tomographic coronary angiography

Both myocardial perfusion imaging (MPI) and multislice computed tomography (MSCT) are currently used to detect coronary artery disease (CAD). However, MSCT permits early detection of atherosclerosis while myocardial perfusion is still normal. In addition, MPI results can be normal despite the presence of high-risk CAD (left main and balanced 3-vessel CAD). In this study, the range of anatomic findings using MSCT in patients with normal MPI results was evaluated. In 180 patients presenting with chest pain, MPI (with gated single-photon emission computed tomography) and 64-slice MSCT were performed. In patients with normal MPI results, prevalences of completely normal coronary arteries, nonobstructive CAD, and obstructive CAD were determined using MSCT. The occurrence of high-risk CAD, including left main and 3-vessel disease, was also evaluated. Normal MPI and adequate MSCT findings were obtained in 97 patients (54%; 50% women; average age 58 +/- 12 years; 5% with known CAD). A total of 38 patients (39%) showed normal coronary anatomy, whereas nonsignificant and significant CAD were observed in 37 (38%) and 18 patients (19%), respectively. Importantly, only 4 patients (4%) presented with high-risk CAD using 64-slice MSCT, 2 with left main and 2 with 3-vessel disease. In conclusion, a normal MPI result can be associated with a wide range of anatomic observations and cannot exclude the presence of both nonobstructive and obstructive CAD. However, importantly, the prevalence of high-risk CAD was rare.     

Relation of exercise capacity and body mass index to mortality in patients with intermediate to high risk of coronary artery disease

The relative impact of body mass index (BMI) and exercise capacity on mortality in patients with an intermediate to high likelihood of coronary artery disease (CAD) is not clear. Thus, the effect of BMI and exercise capacity on all-cause mortality in patients referred for stress myocardial perfusion imaging was investigated. The outcome of 2,119 patients undergoing exercise stress myocardial perfusion imaging from 1995 to 1999 was assessed. Patients lacked known CAD, but were at intermediate to high risk. Mortality outcome data were obtained from the Social Security Administration Death Master File. There were 183 deaths during an average follow-up of 8.4 +/- 1.4 years. A Cox proportional hazards model identified age, Bruce protocol exercise time, BMI, male gender, and diabetes mellitus as significant predictors of all-cause mortality. In multivariate analysis, both exercise capacity and BMI correlated inversely with mortality, with higher chi-squared impact related to exercise capacity than BMI. In conclusion, both increased exercise capacity and BMI were associated with lower mortality in patients with an intermediate to high likelihood of CAD after controlling for confounding variables, supporting an inverse impact of BMI on mortality. The origin for this "obesity paradox" is unclear.     

Comparison of treadmill exercise versus dipyridamole stress with myocardial perfusion imaging using rubidium-82 positron emission tomography

OBJECTIVES: This study assessed the feasibility of treadmill exercise rubidium-82 ((82)Rb) positron emission tomography (PET) and compared image quality and diagnostic content with dipyridamole (82)Rb PET in patients referred for evaluation of coronary artery disease (CAD). BACKGROUND: Dipyridamole stress (82)Rb PET myocardial perfusion imaging (MPI) is an accurate imaging modality used to diagnose CAD and determine prognosis. Although pharmacologic stress is used routinely, exercise treadmill stress may be an alternative and provide clinical information helpful to decision making, particularly for patients unwilling or unable to tolerate pharmacologic stress. METHODS: Fifty patients (mean age, 60 +/- 10 years; 47 men) underwent treadmill exercise and dipyridamole (82)Rb PET. Images were assessed: 1) qualitatively using a 17-segment model and a semiquantitative visual score on a five-point scale and with calculation of summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS); and 2) quantitatively with a 70% threshold for abnormal perfusion and expressed as extent of abnormal perfusion (% left ventricular). RESULTS: Treadmill exercise was preferred by 74% of patients (37 of 50, p < 0.001). The exercise and dipyridamole (82)Rb PET summed scores and quantitative extent of abnormal perfusion were very similar and highly correlated. Results of Bland-Altman analysis showed no significant bias. Image quality was superior with exercise stress with greater myocardial uptake and higher target to background ratios. CONCLUSIONS: Treadmill exercise (82)Rb PET is feasible and provides imaging results of similar diagnostic content and superior image quality compared with dipyridamole stress. Treadmill exercise is a reasonable alternative to pharmacologic stress with (82)Rb PET MPI.     

Prognostic implications of stress Tc-99m tetrofosmin myocardial perfusion imaging in patients with left ventricular hypertrophy.

BACKGROUND: Left ventricular hypertrophy (LVH) is associated with an increased risk of cardiac death. Data on the prognostic value of myocardial perfusion imaging (MPI) in patients with LVH are limited. The aim of this study is to assess the independent value of stress technetium 99m tetrofosmin MPI in predicting the long-term mortality rate in patients with LVH. METHODS AND RESULTS: We studied 177 patients (mean age, 59 +/- 12 years; 134 men) with LVH by electrocardiographic criteria who underwent dobutamine or exercise stress Tc-99m tetrofosmin MPI. Endpoints during follow-up were cardiac and all-cause death and hard cardiac events. A normal scan was detected in 42 patients (24%). Myocardial perfusion abnormalities were fixed in 59 patients (33%) and reversible in 76 (43%). Perfusion abnormalities were observed in a single-vessel distribution in 79 patients and in a multivessel distribution in 56. During a mean follow-up period of 5.5 +/- 2 years, 60 patients (34%) died. Death was considered cardiac in 42 patients (24%). Nonfatal myocardial infarction occurred in 10 patients (6%). The annual mortality rate was 1.4% in patients with normal perfusion, 3.2% in those with perfusion abnormalities in a single-vessel distribution, and 8% in those with a multivessel distribution. In a multivariate analysis independent predictors of death were age (risk ratio [RR], 1.05; 95% confidence interval [CI], 1.02-1.07), male gender (RR, 1.9; 95% CI, 1.1-3.6), hypercholesterolemia (RR, 1.7; 95% CI, 1.0-2.9), and abnormal perfusion (RR, 2.7; 95% CI, 1.5-4.8). CONCLUSION: In patients referred for stress MPI, LVH is associated with a high mortality rate, with approximately one third of patients dying over a period of 5 years. Stress Tc-99m tetrofosmin MPI provides independent information for predicting death in these patients.     

Single photon emission computed tomography dual isotope myocardial perfusion imaging in women with systemic lupus erythematosus. II. Predictive factors for perfusion abnormalities

OBJECTIVE: We have reported that 40% of patients with systemic lupus erythematosus (SLE) had abnormal myocardial perfusion studies. Here we investigated risk factors for abnormal myocardial perfusion in a cohort of women with SLE without history of coronary artery disease. METHODS: Consecutive women with SLE followed at a large lupus clinic underwent single photon emission computed tomography dual isotope myocardial perfusion imaging (DIMPI) following pharmacological stress using dipyridamole. At the time of study each patient had a clinical and laboratory assessment performed by a standard protocol. We compared traditional risk factors as well as disease and therapy related factors in those with and without perfusion abnormalities. RESULTS: A total of 129 patients were studied. The mean +/- SD age was 44.8 +/- 10.9 yrs, and mean SLE Disease Activity Index was 4.2 +/- 5.1. Forty-nine (38%) patients had an abnormality of myocardial perfusion. Factors associated with an abnormal DIMPI included current hypertension (OR 2.11, p = 0.05), elevated cholesterol ever (OR 2.51, p < 0.05), and total cholesterol:high density lipoprotein-cholesterol ratio (OR 1.96 for each increase of 1.0, p < 0.008). CONCLUSION: Myocardial perfusion abnormalities are common in women with SLE without known coronary artery disease (CAD), suggesting a high burden of subclinical CAD. Several metabolic and therapy related factors appear to be associated with the process of atherogenesis in SLE. These results suggest that SLE should be considered a predisposing factor for atherosclerosis.     

Evaluating the Prognostic Value of Positron‐Emission Tomography Myocardial Perfusion Imaging Using Automated Software to Calculate Perfusion Defect Size

Background:

Myocardial perfusion imaging by positron‐emission tomography (PET MPI) is regarded as a valid technique for the diagnosis of coronary artery disease (CAD), but the incremental prognostic value of PET MPI among individuals with known or suspected CAD is not firmly established.

Hypothesis:

Myocardial perfusion defect sizes as measured by PET MPI using automated software will provide incremental prognostic value for cardiac and all‐cause mortality.

Methods:

This study included 3739 individuals who underwent rest‐stress rubidium‐82 PET MPI for the evaluation of known or suspected CAD. Rest, stress, and stress‐induced myocardial perfusion defect sizes were determined objectively by automated computer software. Study participants were followed for a mean of 5.2 years for cardiac and all‐cause mortality. Cox proportional hazards models were developed to evaluate the incremental prognostic value of PET MPI.

Results:

A strong correlation was observed between perfusion defect sizes assessed visually and by automated software (r = 0.76). After adjusting for cardiac risk factors, known CAD, noncoronary vascular disease, and use of cardioprotective medications, stress perfusion defect size was strongly associated with cardiac death (P < 0.001). Rest perfusion defects demonstrated a stronger association with cardiac death (P < 0.001) than stress‐induced perfusion defects (P = 0.01), yet both were highly significant. Similar patterns held for all‐cause death.

Conclusions:

The current study is the largest to date demonstrating PET MPI provides incremental prognostic value among individuals with known or suspected CAD. Automated calculation of perfusion defect sizes may provide valuable supplementary information to visual assessment. This work was partially funded by a predoctoral fellowship grant awarded to the first author by the American Heart Association's Founders' Affiliate. Additional funding was provided by Niagara Falls Memorial Medical Center, Positron Corporation, the University at Buffalo, and Niagara University. The authors have no other funding, financial relationships, or conflicts of interest to disclose.     

The clinical role of stress myocardial perfusion imaging in women with suspected coronary artery disease

Cardiovascular disease remains the number one cause of mortality for women in the United States, with coronary artery disease (CAD) accounting for 54% of all cardiovascular deaths. CAD claims the lives of more than 250,000 women each year and is therefore the single largest killer of American women. For several decades, the underrepresentation of women in clinical trials led to both a lack of available sex-specific evidence and a generalized misconception that CAD was a “man's disease.” In actuality, not only are women vulnerable to CAD, they typically develop it 10 to 15 years later than men. Furthermore, sex differences exist in the mortality rates of women and men with CAD, such that once CAD is present in women, they have worse outcomes than their male counterparts. Consequently, early and accurate diagnosis of CAD is crucial for reducing mortality rates in women. Stress myocardial perfusion imaging (MPI) using contemporary techniques has been shown to have significant value in the diagnosis and prognosis of CAD in women. In the risk assessment of women with an intermediate clinical pretest likelihood of CAD, using MPI with exercise or pharmacologic stress has been shown to add incremental value to clinical variables or exercise electrocardiogram stress testing alone. This review discusses the clinical role of stress MPI in the management of women with suspected CAD.