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.     

Combined protocols for myocardial perfusion imaging in patients with hypertension

OBJECTIVE: Patients diagnosed previously with hypertension submitted to exercise testing for myocardial scintigraphy often respond with excessive elevation of the blood pressure, even when baseline blood pressure is normal, resulting in interruption of the test or false positive results for coronary artery disease. The aim of this study was to evaluate the haemodynamic changes and the safety of the combined examination protocols of dipyridamole plus handgrip exercise and of dipyridamole plus symptom-limited exercise testing on a treadmill in patients with hypertension. METHODS AND RESULTS: We performed scintigraphic myocardial single photon emission computed tomography in 240 patients with hypertension as follows: in 27 patients who were administered dipyridamole alone, in 126 patients who were administered dipyridamole and were also submitted to isometric handgrip exercise and in 87 patients who were administered dipyridamole and were also submitted to treadmill, symptom-limited exercise (modified Bruce protocol). Mean systolic blood pressure, mean diastolic blood pressure and heart rate did not rise excessively in patients submitted to exercise testing (192 +/- 18 mm Hg, 106 +/- 14 mm Hg and 111 +/- 21 bpm for the dipyridamole plus handgrip group and 180 +/- 28 mm Hg, 104 +/- 10 mm Hg and 149 +/- 19 bpm for the dipyridamole plus treadmill group, respectively), with two patients from each exercise group presenting a maximum systolic blood pressure higher than 220 mm Hg and no subsequent major cardiac complications (such as death, myocardial infarction, unstable angina or life-threatening arrhythmia). Moreover, patients in these exercise groups experienced fewer non-cardiac side effects than with dipyridamole alone, while attaining a good level of exercise stress. CONCLUSIONS: Both combined dipyridamole and exercise protocols for scintigraphic myocardial single photon emission computed tomography in patients with hypertension are safe and increase heart rate without an excessive elevation in blood pressure. Consequently, they can be recommended for clinical use. Dipyridamole combined with treadmill, symptom-limited exercise would be the first choice, with dipyridamole and isometric handgrip exercise reserved for patients with physical handicaps.     

Myocardial salvage in patients with non-ST-elevation myocardial infarction determined by myocardial perfusion imaging

We compared acute and late myocardial perfusion imaging using technetium-99m isotopes in 69 patients who had non-ST-elevation myocardial infarction. Among these patients, we found that the ischemic risk area was often large (19% of the left ventricle), and that 67% had significant myocardial salvage, defined as a >25% decrease in risk area, which was associated with an improved ejection fraction.     

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

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

Thallium-201 myocardial perfusion imaging in patients with systemic lupus erythematosus

The cardiovascular system is frequently affected in systemic lupus erythematosus (SLE). The observation of clinical manifestations related to the presence of coronary artery disease has not been frequently documented in young SLE patients. In these patients, the presence of inflammatory or thrombotic vascular lesions is often documented by anatomo-histological studies in the absence of previous clinical manifestations. The purpose of this study was to evaluate the presence of myocardial perfusion defects in SLE patients. The study was carried out in 15 patients without clinical signs of myocardial ischemia, 1 male and 14 females, 24 to 64 years old, with a mean SLE duration of 10.2 +/- 7.5 years. All the patients had normal blood pressure; electrocardiogram and Doppler-echocardiographic analysis showed values in the normal range. All the patients underwent thallium-201 exercise stress imaging repeated 3 hours later at rest, with tomographic SPECT analysis. Exercise test was carried out until submaximal load, without induction of ST segment alterations or symptoms. Scintigraphic scan showed normal thallium-201 SPECT imaging in 11/15 patients, while the other 4 patients had a slight perfusion defect, 3 of them in the inferior segment, in 2 non reversible and in 1 reversible; 1 patient had a non reversible defect in the septal segment. These slight perfusion defects, prevalently non reversible, may sometimes be a false positive imaging. Our results are in contrast with the literature observations concerning the frequent incidence of thallium-201 perfusion defects in SLE patients. In young asymptomatic SLE patients, our study does not report very important data indicating myocardial ischemia and suggesting the presence of significant coronary obstruction or vasculitis.     

Single-photon emission computed tomography myocardial perfusion imaging in patients with diabetes

Diabetes mellitus has reached epidemic proportions, creating a large population of people at increased risk for cardiac events. Single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) provides an effective tool to accurately diagnose and risk stratify patients with diabetes, similar to patients without diabetes. Diabetics, however, are at increased risk for coronary events. Diabetics with normal MPI have increased late cardiac events, and even those with mild perfusion defects have increased event rates compared with nondiabetics with similar perfusion abnormalities. Stress MPI can provide valuable risk stratification data for both sexes, with or without diabetes. However, diabetes appears to exert a greater relative impact in women than in men. Despite the absence of symptoms, the incidence and prevalence of coronary artery disease is increased in patients with diabetes. Further studies and research will be needed to define the eventual role of SPECT MPI in asymptomatic diabetics.     

Comparative value of maximal treadmill testing, exercise thallium myocardial perfusion scintigraphy and exercise radionuclide ventriculography for distinguishing high- and low-risk patients soon after acute myocardial infarction

The prognostic value of symptom-limited treadmill exercise electrocardiography, exercise thallium myocardial perfusion scintigraphy and rest and exercise radionuclide ventriculography was compared in 117 men, aged 54 +/- 9 years, tested 3 weeks after a clinically uncomplicated acute myocardial infarction (MI). During a mean follow-up period of 11.6 months, 8 men experienced "hard" medical events (cardiac death, nonfatal ventricular fibrillation or recurrent MI) and 14 were hospitalized for unstable angina pectoris, congestive heart failure or coronary bypass surgery (total of 22 combined events). By multivariate analysis (Cox proportional hazards model), peak treadmill work load and the change in left ventricular ejection fraction (EF) during exercise were significant (p less than 0.01) predictors of hard medical events; these 2 risk factors and recurrent ischemic chest pain in the coronary care unit were also significantly predictive (p less than 0.001) for combined events. A peak treadmill work load of 4 METs or less or a decrease in EF of 5% or more below the value at rest during submaximal effort distinguished 22 high-risk patients (20% of the study population) from 89 low-risk patients. The rate of hard medical events within 12 months was 23% (5 of 22 patients), vs 2% (2 of 89 patients) in the high- and low-risk patient subsets, respectively (p less than 0.001). Thus, in patients who underwent evaluation 3 weeks after a clinically uncomplicated MI, exercise radionuclide ventriculography contributed independent prognostic information to that provided by symptom-limited treadmill testing and was superior to exercise thallium scintigraphy for this purpose.     

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.     

Impaired myocardial perfusion reserve in patients with Fatty liver disease assessed by quantitative myocardial perfusion magnetic resonance imaging

Background:?The purpose of this study was to determine whether the presence of fatty liver is associated with an alteration in myocardial perfusion reserve (MPR). Methods and Results:?A retrospective analysis of 65 asymptomatic subjects who underwent both plain abdominal computed tomography and cardiac magnetic resonance imaging (MRI), and who had normal left ventricular wall motion, no regional myocardial ischemia and no myocardial scar on MRI was performed. Stress and rest myocardial perfusion MRI were analyzed by Patlak plot method to quantify myocardial blood flow (MBF) and MPR in 16 myocardial segments. Fatty liver was detected in 18 (28%) of the 65 subjects. No significant difference was found in rest-MBF between subjects with and without fatty liver (1.2±0.75 vs. 1.1±0.67ml·min(-1)·g(-1), P=0.59). However, MPR was significantly lower in subjects with fatty liver than the non-fatty liver subjects (2.3±0.74 vs. 3.3±1.4, P<0.001). Subjects with fatty liver had a higher prevalence of MPR <2.5 (78% vs. 38%, P<0.005) and higher triglyceride levels (206±61 vs. 92±37mg/dl, P<0.001). Multivariate analysis revealed the presence of fatty liver as a significant predictor of reduced MPR with an odds ratio of 8.2 (P<0.01). Conclusions:?Nonalcoholic fatty liver disease is related to reduced MPR, suggesting impaired coronary microcirculation. (Circ J?2012; 76: 2234-2240).     

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.     

冠状动脉慢血流患者的腺苷负荷心肌灌注显像研究

目的:评价腺苷负荷心肌灌注单光子发射计算机断层扫描(SPECT)在诊断冠状动脉慢血流(CSF)中的临床价值。方法:根据冠状动脉造影(CAG)结果不同,分为CSF组、正常血流(NCF)组和CAG阳性组。使用校正的TIMI血流分级方法评价冠状动脉血流速度。3组均行CAG、静息心电图(ECG)、腺苷负荷ECG、静息及腺苷负荷SPECT检查,评价其心肌血流灌注情况。结果:CSF组腺苷负荷SPECT诊断心肌缺血阳性率(84%),明显高于平静ECG(20%)及腺苷负荷ECG(52%)。CSF组在腺苷负荷SPECT中显示心肌缺血的范围和程度高于NCF组,低于CAG阳性组。结论:CSF与心肌缺血关系密切,腺苷负荷SPECT可以作为检测CSF者心肌缺血的一种有效的无创性检查方法。     

Outcomes in patients with abnormal myocardial perfusion imaging and normal coronary angiogram

A subset of subjects undergoing myocardial perfusion imaging has perfusion abnormalities that are subsequently labeled false positive based on coronary angiography. We evaluated the long-term prevalence of cardiovascular events in these patients. We retrospectively identified 48 patients who had reversible perfusion abnormalities with myocardial perfusion imaging and normal coronary angiography. Patients with known coronary artery disease, left ventricular dysfunction, valvular disease, and cardiomyopathy were excluded. Patient follow-up, conducted for at least 3 (mean interval, 7.4) years from the index myocardial perfusion imaging, was accomplished by a review of medical records and telephone interviews. Study endpoints were cardiovascular events defined as sudden cardiac death, myocardial infarction, percutaneous coronary revascularization, coronary artery bypass grafting, and cerebrovascular or peripheral revascularization. Thirty-one percent (15 of 48) of the patients had cardiovascular events. Six of the 48 patients had coronary events. These patients had abnormal myocardial perfusion imaging and normal coronary angiogram. The time between myocardial perfusion imaging and coronary event was 0.5 to 8.67 years. There was a strong correlation between the regions of original perfusion abnormality and the ultimate coronary ischemia or revascularization. Abnormal findings on myocardial perfusion imaging may predict a higher prevalence of coronary and peripheral vascular events than suggested by a normal coronary angiogram.     

Prognostic value of exercise stress myocardial perfusion imaging in patients with permanent pacemakers

One hundred eight patients with single- or dual-chamber pacemakers underwent exercise myocardial perfusion imaging with thallium-201 or technetium-99m sestamibi. A high-risk scan (a large fixed defect, a large reversible defect, or evidence of cardiomyopathy) identified patients at high risk for cardiac death on both a univariate and multivariate basis.     

心肌灌注核素显像、平板运动心电图及动态心电图在冠心病中的意义

目的：探讨心肌灌注核素显像（ECT）,平板运动心电图（TET）及动态心电图（DEG）对冠心病的诊断价值。方法：以冠状动脉造影为冠心病诊断的金标准,对80例冠心病患同步进行ECT,TET及DEG,并作对比分析,结果：ECT的阳性率（91．3％）明显高于TET（77．5％）,DEG（62．5％）,TET的阳性率明显高于DEG,而DEG的特异性（86．5％）,明显高于TET能较好地反映心肌缺血的程度和部位,DEG有较高的特异性。     

Utility of cardiac computed tomography angiography to exclude clinically significant obstructive coronary artery disease in patients after myocardial perfusion imaging

Patients with mildly abnormal or equivocal results on myocardial perfusion imaging (MPI) typically undergo diagnostic angiography or receive medical management for coronary artery disease. Catheterization is often required for either appropriate diagnosis or management. With its very high negative predictive rate, coronary computed tomographic angiography (CCTA) has great potential to rule out clinically significant coronary artery disease in this setting. The aim of this study was to analyze the clinical utility and cost implications of CCTA before invasive angiography in patients with abnormal or equivocal results on MPI. Consecutive patients referred by their physicians to our center with abnormal or equivocal results on MPI were reviewed. Patients with histories of myocardial infarction or of revascularization (coronary artery bypass grafting or percutaneous coronary intervention) were excluded. All patients underwent CCTA. Of 241 participants, only 66 (27%) of the studies with abnormal or equivocal nuclear findings revealed obstructive disease on CCTA (>50% stenosis). Fifty-five of 241 patients had normal coronary arteries, 97 patients had nonsignificant disease (<30%), and 23 patients had mild disease (30% to 50% stenosis) on CCTA, leading to diagnoses of noncardiac chest pain. Selective catheterization (for >50% stenosis on CCTA) demonstrated an average cost reduction of $1,295 per patient. Sensitivity analysis revealed cost savings to be preserved even if up to 70% of the patient cohort underwent catheterization after CCTA and across a wide range of procedural costs. In conclusion, CCTA after equivocal or mild or moderate abnormal MPI findings results in significant cost savings and a robust reduction in the need for cardiac catheterization and excludes obstructive coronary artery disease in almost 75% of patients.     

核素心肌显像的临床应用现状

核素心肌显像(MPI)是核心脏病学的最主要内容,它是美国常用的冠心病诊断处理技术.循证医学证明,在冠心病危险度分层和预后判断方面MPI的价值优于心电图运动试验和冠脉造影.MPI与冠脉造影在冠心病诊断处理方面优势互补.     

Planar myocardial perfusion imaging for evaluation of patients with acute chest pain

BACKGROUND: Rest single-photon emission computed tomographic (SPECT) perfusion imaging identifies acute myocardial ischemia in patients with chest pain in the emergency department; however, the costs are high and radioisotopic services are usually not available 24 h a day. Planar imaging through a portable gamma camera may be useful in this setting. However, planar imaging might be associated with less predictive values in comparison with a gated SPECT imaging. We sought to evaluate rest planar myocardial perfusion imaging for evaluation and triage of patients with suspected acute cardiac ischemia. METHODS: Patients within 6 h of chest pain onset and nondiagnostic electrocardiograms (ECGs) underwent planar myocardial perfusion imaging. Studies showing perfusion defects were considered suggestive of acute coronary syndromes. The results of planar scintigraphy were compared with the clinical diagnosis and outcomes. All patients were followed up and monitored for the occurrence of major cardiac events 120 days after hospital discharge. RESULTS: 71 patients underwent scintigraphy. Twenty-one (30%) patients had acute coronary syndromes, 15 (21%) had major cardiac events (8 had myocardial infarction and 7 underwent myocardial revascularization). Planar scintigraphy demonstrated perfusion defects in 21 patients, 16 (76%) patients with acute coronary syndromes, 12 (80%) patients who had major cardiac events and in 7 (88%) patients with myocardial infarction. The negative predictive value of planar scintigraphy was 90% for diagnosis of acute coronary syndromes and 94% for detecting major cardiac events. CONCLUSION: Early planar myocardial perfusion imaging allowed rapid and accurate risk stratification of emergency departments patients with possible myocardial ischemia and nondiagnostic ECGs.