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

Diagnosing Coronary Artery Disease in the Patient Presenting with Stable Ischemic Heart Disease: The Role of Anatomic versus Functional Testing

There are unique advantages and disadvantages to functional versus anatomic testing in the work-up of patients who present with symptoms suggestive of obstructive coronary artery disease. Evaluation of these individuals starts with an assessment of pre-test probability, which guides subsequent testing decisions. The choice between anatomic and functional testing depends on this pre-test probability. In general, anatomic testing has particular utility among younger individuals and women; while functional testing can be helpful to rule-in ischemia and guide revascularization decisions. Ultimately, selection of the most appropriate test should be individualized to the patient and clinical scenario.

Long-term prognostic value of low-dose normal stress-only myocardial perfusion imaging by wide beam reconstruction: A competing risk analysis

BACKGROUND

A normal stress myocardial perfusion single-photon emission computed tomography (MPS) is associated with a good clinical outcome. New iterative algorithms, such as wide beam reconstruction (WBR), which improve image interpretation with half-dose or half-time acquisition, have been proposed for cardiac MPS. The aim of this study was to assess the long-term predictive value of a low-dose normal stress-only MPS with WBR using conventional Anger camera in patients with known or suspected coronary artery disease (CAD).

METHODS AND RESULTS

A total of 2106 patients with known or suspected CAD and normal perfusion at half-dose stress-only MPS protocol were followed for a mean of 6.6 ± 2.7 years. MPS data were reconstructed with WBR iterative algorithm. End-point events were cardiac death or nonfatal myocardial infarction. Noncardiac death was considered the competing event. During follow-up, 149 cardiac events occurred with an annualized event rate of 1.2%. Independent predictors of cardiac events at Cox analysis were age, male gender, diabetes mellitus, previous myocardial infarction and the need for pharmacologic stress testing. At Fine-Gray analysis the cumulative incidence of cardiac events progressively increases with age and in the presence of diabetes for any combination of gender and stress type. Survival tree analysis confirmed that long-term prognosis considerably varies according of risk factors profile.

CONCLUSIONS

Low-dose normal stress-only WBR MPS has a reliable long-term prognostic value in patients with suspected or known CAD. This finding supports the introduction of such a method into clinical practice with a consistent dose optimization in the interest of patients and exposed staff.

The success of opening single chronic total occlusion lesions to improve myocardialviabilitytrial (SOS-COMEDY): Study protocol of a prospective multicenter study

AIMS

Success of opening single (SOS)-comedy is a prospective multicenter study to compare the improvement in the decrease of myocardial viability by percutaneous coronary intervention (PCI) with that by optimal medical therapy (OMT) alone in patients with chronic total occlusion (CTO) of a single coronary artery.

METHODS AND RESULTS

The risks and the benefits of both options (PCI and OMT) were listed in a CTO decision aid (DA). Eligible participants detected by invasive coronary angiography (ICA) or coronary computed tomography angiography (CCTA) were divided into PCI or OMT groups according to patients' choice after shared-decision making process with DA. Participants will undergo positron emission tomography/computed tomography (PET/CT), cardiac magnetic resonance (CMR) and transthoracic echocardiography (TTE), and proceed to ICA and revascularization if possible. Blinded core laboratory interpretation will be performed for ICA, CCTA, PET/CT, CMR, and TTE. All participants will be followed up for 12 months. The primary endpoint is the improvement to the decrease of myocardial viability from baseline assessed with the use of PET/CT after 12-month follow-up.

CONCLUSIONS

All of the patients are appropriately consented before enrolling in this study, which has been approved by the Ethics Committee. Results of SOS-COMEDY will be helpful to develop a strategy for single CTO patients.

Prognosis in patients with suspected or known ischemic heart disease and normal myocardial perfusion: long-term outcome and temporal risk variations

BACKGROUND

The prognostic value of a normal myocardial perfusion scintigraphy (MPS) may be well described, but long-term follow-up data are sparse, and temporal variations in risk are insufficiently elucidated.

METHODS AND RESULTS

During long-term follow-up (mean 6.2 years) of 1,327 consecutive Danish patients with normal MPS, the rate of all-cause death (ACD) was 1.9%/year (differing by gender) and of cardiac death (CD)/myocardial infarction (MI) 0.8%/year (differing by coronary artery disease, CAD). Female gender (HR: 0.60), age (HR: 1.07 per-year increment), and known CAD without prior revascularization (HR: 2.17) were statistically significant factors for ACD, whereas diabetes and previous MI per se were not. Known CAD with previous revascularization carried a low risk of ACD when adjusted for gender and age (HR: 0.56). For CD/MI, risk increased with age and threefold with known CAD, previous MI, and previous percutaneous coronary intervention. Judged from smoothed hazard functions, mortality risk increased further with time for men, elderly, and diabetics and markedly further with known CAD without prior revascularization.

CONCLUSIONS

Following a normal MPS, rates of death and hard cardiac events were low. Risk varied with age, gender, and disease history. Novel aspects of temporal risk variation suggested a general warranty period of 5 years, but less in risk groups.

The utility and prognostic value of dipyridamole technetium-99m sestamibi myocardial perfusion imaging SPECT in predicting perioperative cardiac events following non-cardiac surgery

OBJECTIVE

A perioperative cardiac events is one of the most important medical concerns for both surgeons and patients. The purpose of the current study was to determine the prognostic value of myocardial perfusion imaging (MPI), using dipyridamole 99m Tc-MIBI, for the prediction of perioperative cardiac events.

MATERIALS AND METHODS

This study included 253 patients who were candidates for non-cardiac elective surgery and underwent scanning with dipyridamole 99m Tc-MIBI. Based on normal or abnormal MPI, patients were divided into two groups and all preoperative cardiac events were recorded. Risk factors, including diabetes mellitus, dyslipidemia, hypertension, smoking and age ≥70 years, were compared between patients with normal and abnormal MPI and, also, in patients with or without cardiac events.

RESULTS

There were 197 patients with normal and 56 patients with abnormal MPI. In total, 14 patients had perioperative cardiac events, which included myocardial infarction (MI), hypotension, arrhythmia and death; of the 14 patients with perioperative cardiac events, 12 had abnormal and two had normal MPI. There were statistically meaningful differences between the two groups (p<0.001). Based on these findings, we determined that MPI had a sensitivity of 85.7%, a specificity of 81.6%, an accuracy of 81.8%, a positive predictive value of 21.4 % and a negative predictive value of 98.9%.

CONCLUSION

The incidence of perioperative cardiac events is higher in patients with abnormal MPI. Dipyridamole 99m Tc-MIBI myocardial perfusion imaging can accurately detect the preoperative cardiac risk of patients undergoing major non-cardiac surgery. Based on these findings, the occurrence of perioperative cardiac events in patients with abnormal MPI should be considered, especially in the older age population (age ≥70).

Prognostic value of stress echocardiogram in patients with angiographically significant coronary artery disease

The purpose of this study was to evaluate the prognostic value of stress echocardiography in patients with angiographically significant coronary artery disease (CAD). Two hundred sixty patients (mean age 63 ± 10 years, 58% men) who underwent stress echocardiography (41% treadmill, 59% dobutamine) and coronary angiography within 3 months and without intervening coronary revascularization were evaluated. All patients had significant CAD as defined by coronary stenosis ≥70% in major epicardial vessels or branches (45% had single-vessel disease, and 55% had multivessel disease). The left ventricle was divided into 16 segments and scored on a 5-point scale of wall motion. Patients with abnormal results on stress echocardiography were defined as those with stress-induced ischemia (increase in wall motion score of ≥1 grade). Follow-up (3.1 ± 1.2 years) for nonfatal myocardial infarction (n = 23) and cardiac death (n = 6) was obtained. In patients with angiographically significant CAD, stress echocardiography effectively risk stratified normal (no ischemia, n = 91) in contrast to abnormal (ischemia, n = 169) groups for cardiac events (event rate 1.0%/year vs 4.9%/year, p = 0.01). Multivariate logistic regression analysis identified multivessel CAD (hazard ratio 2.53, 95% confidence interval 1.16 to 5.51, p = 0.02) and number of segments in which ischemia was present (hazard ratio 4.31, 95% confidence interval 1.29 to 14.38, p = 0.01) as predictors of cardiac events. A Cox proportional-hazards model for cardiac events showed small, significant incremental value of stress echocardiography over coronary angiography (p = 0.02) and the highest global chi-square value for both (p = 0.004). In conclusion, in patients with angiographically significant CAD, (1) normal results on stress echocardiography conferred a benign prognosis (event rate 1.0%/year), and (2) stress echocardiographic results (no ischemia vs ischemia) added incremental prognostic value to coronary angiographic results, and (3) stress echocardiography and coronary angiography together provided additive prognostic value, with the highest global chi-square value.

Assessment of myocardial ischemia with cardiovascular magnetic resonance

Assessment of myocardial ischemia in symptomatic patients remains a common and challenging clinical situation faced by physicians. Risk stratification by presence of ischemia provides important utility for both prognostic assessment and management. Unfortunately, current noninvasive modalities possess numerous limitations and have limited prognostic capacity. More recently, ischemia assessment by cardiovascular magnetic resonance (CMR) has been shown to be a safe, available, and potentially cost-effective alternative with both high diagnostic and prognostic accuracy. Cardiovascular magnetic resonance has numerous advantages over other noninvasive methods, including high temporal and spatial resolution, relatively few contraindications, and absence of ionizing radiation. Furthermore, studies assessing the clinical utility and cost effectiveness of CMR in the short-term setting for patients without evidence of an acute myocardial infarction have also demonstrated favorable results. This review will cover techniques of ischemia assessment with CMR by both stress-induced wall motion abnormalities as well as myocardial perfusion imaging. The diagnostic and prognostic performance studies will also be reviewed, and the use of CMR for ischemia assessment will be compared with other commonly used noninvasive modalities.

Additive Value of B-Type Natriuretic Peptide on Rest Tl-Dipyridamole Stress Tc-Sestamibi Gated Myocardial SPECT in Patients with Normal Left Ventricular Systolic Function

We evaluated whether BNP has additive value to SPECT in patients with normal left ventricular (LV) systolic function. Data from 224 consecutive patients who underwent rest (201)Tl-dipyridamole stress (99m)Tc-sestamibi gated SPECT and coronary angiography due to chest pain were analyzed. Patients with true positive SPECT showed significant higher BNP level than those with false positive defect (38.5 (19.0-79.8) versus 19.0 (9.3-35.8), P = .01). Patients with true negative SPECT also showed significantly lower BNP level than those with false negative SPECT (39.0 (23.0-77.0) versus 22.0 (15.0-43.0), P = .002). In multivariate analyses, elevated BNP level (using a cut-off value of 23.0 pg/mL) was the strongest and independent predictor of CAD in overall patients (OR 2.75, 95% CI: 1.50-5.023, P = .001) and patients with positive SPECT (OR 3.34, 95% CI: 1.51-7.37, P = .003). The area under the receiver-operating characteristic curve for CAD in overall patients and patients with positive SPECT was 0.673 (95% CI: 0.603-0.743, P < .001) and 0.694 (95% CI: 0.602-0.786, P < .001), respectively. This study suggests that BNP level has additive diagnostic value to SPECT findings in predicting CAD in patients with normal LV systolic function.

Myocardial perfusion study of panic attacks in patients with coronary artery disease

Panic disorder (PD) and panic-like anxiety have been associated with an increased risk of cardiovascular death. No study has specifically examined the association between panic attacks and ischemia in patients who have coronary artery disease (CAD). We hypothesized that panic attacks would induce myocardial perfusion defects in patients who have CAD and PD. Sixty-five patients who had CAD and positive results with nuclear exercise stress testing (35 with PD and 30 without PD served as controls) underwent a well-established panic challenge test (1 vital capacity inhalation of a gas mixture containing 35% carbon dioxide and 65% oxygen) and were injected with technetium-99m sestamibi at inhalation. Single-photon emission computed tomography was used to assess per-panic challenge perfusion defects, and heart rate, blood pressure, and 12-lead electrocardiogram were continuously measured during the procedure. Patients were not withdrawn from their cardiac medications. Patients who had PD were significantly younger than the controls; otherwise groups did not differ with respect to gender, cardiac medications, nuclear exercise test results, and baseline heart rate and blood pressure. Seventy-four percent of patients (26 of 35) who had PD had a panic attack at inhalation versus 6.7% of controls (2 of 30, p <0.001). As hypothesized, patients who had PD and demonstrated a panic attack were more likely to develop a reversible myocardial perfusion defect than were controls who did not have an attack (80.9% vs 46.4% p = 0.009). Thus, despite being on their cardiac medications, panic attacks preferentially induced significant perfusion defects in patients who had CAD and PD. In conclusion, panic attacks in patients who have CAD appear to be bad for the heart.

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 under-representation 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.

Stress Myocardial Perfusion Imaging in the Diagnosis and Prognosis of Women with Suspected Coronary Artery Disease

Coronary artery disease is the single largest killer of women in the United States and claims the lives of more than 250,000 women each year. For several decades, there was the misperception that coronary artery disease was a "man's disease." The fact is that women are indeed vulnerable to coronary artery disease; however, they typically develop the disease 10 to 15 years later than men. Once coronary artery disease is evident, women have worse outcomes as compared with men.Therefore, early and accurate diagnosis of coronary artery disease is crucial for reducing heart disease mortality in women. Stress myocardial perfusion imaging using contemporary techniques has been shown to have significant value in the diagnosis and prognosis of coronary artery disease in women. Myocardial perfusion imaging with exercise or pharmacologic stress has been shown to add incremental value to the use of clinical variables or exercise electrocardiogram stress testing alone in the risk stratification of women with an intermediate clinical pretest likelihood of coronary artery disease. This review provides an overview of the role of stress myocardial perfusion imaging in the clinical evaluation of women with suspected coronary artery disease.

Practical applications in stress echocardiography

OBJECTIVES

The purpose of this study was to define appropriate parameters for risk stratification and prognosis in patients undergoing stress echocardiography.

BACKGROUND

Stress echocardiography is an established technique for the diagnosis of coronary artery disease. However, current data on risk stratification of patients undergoing stress echocardiography are limited.

METHODS

We evaluated 1,500 patients (59 +/- 13 years old; 51% male) undergoing stress echocardiography (34% with treadmill exercise and 66% with dobutamine). Resting left ventricular ejection fraction (EF) and regional wall motion were assessed by the consensus of two echocardiographers. Follow-up (mean 2.7 +/- 1.0 years) for confirmed non-fatal myocardial infarction (n = 31) and cardiac death (n = 44) were performed.

RESULTS

By univariate analysis, both the peak wall motion score index (WMSI) (p < 0.0001) and EF (p < 0.0001) were significant predictors of cardiac events. Peak WMSI effectively risk stratified patients into low (0.9%/year), intermediate (3.1%/year), and high (5.2%/year) risk groups (p < 0.0001). A threshold of 45% EF provided further risk stratification of all WMSI groups. By multivariate logistic regression analysis, peak WMSI (relative risk [RR] 2.1, 95% confidence interval [CI] 1.0 to 4.4; p = 0.04) and EF (RR 1.0, 95% CI 0.9 to 1.0; p = 0.01) were both predictors of cardiac events.

CONCLUSIONS

Stress echocardiography yields prognostic information for risk stratification of patients with known or suspected ischemic heart disease. A normal stress echocardiographic study (peak WMSI = 1.0) confers a benign prognosis (0.9%/year cardiac event rate). Peak WMSI >1.7 and EF < or =45% are independent markers of patients at high risk of an adverse clinical outcome.

Risk assessment by myocardial perfusion imaging for coronary revascularization, medical therapy, and noncardiac surgery

Stress myocardial perfusion imaging (MPI) has become an important tool in risk stratification of patients with known coronary artery disease. A normal myocardial perfusion scan has a high negative predictive value and is associated with low annual mortality rate (< 1%). Patients with extensive ischemia (> 20% of the left ventricle), defects in more than 1 coronary vascular territory, transient or persistent left ventricular cavity dilation, and ejection fraction less than 45% have a high annual mortality rate (> 3%). Those patients should undergo coronary revascularization whenever feasible, as the cardiac event rate increases in proportion to the magnitude of the jeopardized myocardium. Stress MPI can be used to demonstrate ischemia in patients with symptoms early after coronary artery bypass surgery (< 5 years) or in those without symptoms late (>/= 5 years) after coronary artery bypass surgery. With respect to patients who underwent percutaneous interventions, stress MPI can help detect in-stent restenosis early after the intervention (3-6 months) or assess the progression of native coronary disease afterward. Since preliminary data suggest that a reduction in the perfusion defect size may translate to a reduction of coronary events, stress MPI can help assess the efficacy of medical management of coronary disease. Finally, stress MPI is indicated for perioperative cardiac risk stratification for noncardiac surgery in patients with intermediate risk predictors (mild angina, prior myocardial infarction or heart failure symptoms, diabetes mellitus, renal insufficiency) and poor functional capacity or in those who undergo high-risk surgery with significant implications in further preoperative management.

Use of pharmaceuticals in noninvasive cardiovascular diagnosis

A number of pharmaceuticals are employed as diagnostic agents for cardiovascular diseases. Four groups of agents are reviewed here: 1) vasoactive substances employed as adjuncts to physical maneuvers in diagnosis of structural heart disease; 2) vasodilators used to produce heterogeneity of coronary flow; 3) sympathomimetic agents simulating the effects of exercise on the heart for the purpose of detection of coronary artery stenosis; and 4) ultrasonic contrast agents used to enhance myocardial imaging for the assessment of segmental wall motion. In the first group are amyl nitrate, a vasodilator, and methoxamine and phenylephrine, both vasopressors. The vasodilators of the second group are dipyridamole and adenosine. When combined with scintigraphic perfusion imaging or with echocardiographic assessment of segmental wall motion, these agents can detect single- or multiple-vessel coronary artery disease with sensitivity and specificity comparable to submaximal exercise. They are especially useful for preoperative risk assessment before noncardiac surgery. The sympathomimetic agents of the third group, dobutamine and arbutamine, increase myocardial contractility and heart rate, and dilate the peripheral vasculature. As with the vasodilators, when combined with nuclear or echocardiographic techniques they are equivalent to exercise in detection of coronary disease. They are especially useful in patients with bronchospastic disease and for assessment of myocardial viability. Agents from groups 2 and 3 have acceptable side-effect and safety profiles. The last group reviewed includes echocardiographic contrast agents that, in this investigative setting, are employed to enhance detection of segmental wall motion when used with agents from groups 2 and 3.

Cardiac catheterization in morbidly obese patients

The safety and findings of cardiac catheterization and coronary angiography in morbidly obese patients with suspected coronary heart disease (CHD) have not been fully examined in the modern era. From a database of 4,978 patients undergoing diagnostic cardiac catheterization, we identified 110 with morbid obesity (body mass > or = 145 kg and body mass index > or = 40 kg/m(2)). Relative to all the other patients in this database, morbidly obese patients had a lower prevalence of CHD (45% vs. 72%; P < 0.05), reflecting a higher prevalence of false positive noninvasive tests. Overall, noninvasive tests were only 75% sensitive and 39% specific for CHD in this group. Use of radial access (66%) and femoral closure devices (24%) was much more frequent in the morbidly obese cohort. Complications were no more frequent in the morbidly obese group, with major (0 vs. 0.9%) and minor (4.7% vs. 3.5%) adverse outcomes being similar to the rest of the database. We conclude that cardiac catheterization using the radial artery or a femoral closure device is a safe and effective method of evaluating CHD in morbidly obese patients. In contrast, noninvasive testing is frequently not definitive and may be misleading.

Stress radionuclide imaging versus stress echocardiography: a framework for comparisons

Comparisons of stress-imaging procedures require analyses based on their 2 principal applications: diagnostic and prognostic assessments. Besides comparing results reported in the literature--in which differences have been reported in the ability of stress nuclear versus stress echocardiographic imaging to predict a low risk of cardiac events-other factors often not reported may be important in discerning the relative efficacy of these tests. These include consideration of how these tests perform in specific, individualized patient scenarios; the effect of on-going technical advances on test usefulness; and evaluation of test worthiness according to such factors as cost-effectiveness and the magnitude of incremental test information that is provided. Furthermore, it is important to distinguish between a test's efficacy (ie, its intrinsic accuracy) and its effectiveness (ie, how it performs in the real world of clinical practice).