Impact of diabetes on the risk stratification using stress single-photon emission computed tomography myocardial perfusion imaging in patients with symptoms suggestive of coronary artery disease

Comparison between multiple logistic regression and machine learning methods in prediction of abnormal thallium scans in type 2 diabetes

BACKGROUND

The prevalence of type 2 diabetes (T2D) has been increasing dramatically in recent decades, and 47.5% of T2D patients will die of cardiovascular disease. Thallium-201 myocardial perfusion scan (MPS) is a precise and non-invasive method to detect coronary artery disease (CAD). Most previous studies used traditional logistic regression (LGR) to evaluate the risks for abnormal CAD. Rapidly developing machine learning (Mach-L) techniques could potentially outperform LGR in capturing non-linear relationships.

AIM

To aims were: (1) Compare the accuracy of Mach-L methods and LGR; and (2) Found the most important factors for abnormal TMPS.

METHODS

556 T2D were enrolled in the study (287 men and 269 women). Demographic and biochemistry data were used as independent variables and the sum of stressed score derived from MPS scan was the dependent variable. Subjects with a MPS score ≥ 9 were defined as abnormal. In addition to traditional LGR, classification and regression tree (CART), random forest, Naïve Bayes, and eXtreme gradient boosting were also applied. Sensitivity, specificity, accuracy and area under the receiver operation curve were used to evaluate the respective accuracy of LGR and Mach-L methods.

RESULTS

Except for CART, the other Mach-L methods outperformed LGR, with gender, body mass index, age, low-density lipoprotein cholesterol, glycated hemoglobin and smoking emerging as the most important factors to predict abnormal MPS.

CONCLUSION

Four Mach-L methods are found to outperform LGR in predicting abnormal TMPS in Chinese T2D, with the most important risk factors being gender, body mass index, age, low-density lipoprotein cholesterol, glycated hemoglobin and smoking.

Correlation Between Coronary Artery Calcium Score and Triglyceride-Glucose Index in Post-menopausal Women

INTRODUCTION

To clarify the correlation between coronary artery calcium score (CACS) and triglyceride-glucose (TyG) index in post-menopausal women.

METHODS

Post-menopausal women who underwent computed tomography angiography with the suspicion of acute coronary syndrome were included in the study. Patients were categorized into three groups (CACS < 100 as group 1, CACS = 100-300 as group 2, and CACS > 300 as group 3). Groups were compared with regard to demographic characteristics, laboratory test outcomes, electrocardiogram findings, and the TyG index.

RESULTS

The study was conducted by examining the data of 228 patients. Median TyG index was 9.0 and median CACS was 79.5. The median age was significantly lower in group 1 (p = 0.001). Diabetes mellitus rate and smoking rate were higher in group 3 compared to the other groups (p = 0.037 and p = 0.032). The glucose level was significantly higher for group 3 (p = 0.001). Additionally, the TyG index was 9.3 in group 3 and was statistically significantly higher than the values in group 1 and group 2 (8.9 and 9.1, respectively) (p = 0.005). There was a moderate correlation between CACS and age (correlation coefficient (CC): 0.241, p = 0.001). Also, there was a significant correlation between glucose level and CACS (CC: 0.307, p = 0.001). A high correlation was found between the TyG index and CACS (CC: 0.424, p = 0.001).

CONCLUSION

Our study demonstrated for the first time that there was a strong correlation between the TyG index and CACS in post-menopausal patients. In addition, patients with increased age, patients with higher glucose levels, and diabetic patients had significantly higher CACS.

Long-term Survival Benefit From Revascularization Compared With Medical Therapy in Patients With or Without Diabetes Undergoing Myocardial Perfusion Single Photon Emission Computed Tomography

OBJECTIVE

To explore the long-term association of survival benefit from early revascularization with the magnitude of ischemia in patients with diabetes compared with those without diabetes using a large observational cohort of patients undergoing single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI).

RESEARCH DESIGN AND METHODS

Of 41,982 patients who underwent stress and rest SPECT-MPI from 1998 to 2017, 8,328 (19.8%) had diabetes. A propensity score was used to match 8,046 patients with diabetes to 8,046 patients without diabetes. Early revascularization was defined as occurring within 90 days after SPECT-MPI. The percentage of myocardial ischemia was assessed from the magnitude of reversible myocardial perfusion defect on SPECT-MPI.

RESULTS

Over a median 10.3-year follow-up, the annualized mortality rate was higher for the patients with diabetes compared with those without diabetes (4.7 vs. 3.6%; P < 0.001). There were significant interactions between early revascularization and percent myocardial ischemia in patients with and without diabetes (all interaction P values <0.05). After adjusting for confounding variables, survival benefit from early revascularization was observed in patients with diabetes above a threshold of >8.6% ischemia and in patients without diabetes above a threshold of >12.1%. Patients with diabetes receiving insulin had a higher mortality rate (6.2 vs. 4.1%; P < 0.001), but there was no interaction between revascularization and insulin use (interaction P value = 0.405).

CONCLUSIONS

Patients with diabetes, especially those on insulin treatment, had higher mortality rate compared with patients without diabetes. Early revascularization was associated with a mortality benefit at a lower ischemic threshold in patients with diabetes compared with those without diabetes.

Comparison between Machine Learning and Multiple Linear Regression to Identify Abnormal Thallium Myocardial Perfusion Scan in Chinese Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) patients have a high risk of coronary artery disease (CAD). Thallium-201 myocardial perfusion scan (Th-201 scan) is a non-invasive and extensively used tool in recognizing CAD in clinical settings. In this study, we attempted to compare the predictive accuracy of evaluating abnormal Th-201 scans using traditional multiple linear regression (MLR) with four machine learning (ML) methods. From the study, we can determine whether ML surpasses traditional MLR and rank the clinical variables and compare them with previous reports.In total, 796 T2DM, including 368 men and 528 women, were enrolled. In addition to traditional MLR, classification and regression tree (CART), random forest (RF), stochastic gradient boosting (SGB) and eXtreme gradient boosting (XGBoost) were also used to analyze abnormal Th-201 scans. Stress sum score was used as the endpoint (dependent variable). Our findings show that all four root mean square errors of ML are smaller than with MLR, which implies that ML is more precise than MLR in determining abnormal Th-201 scans by using clinical parameters. The first seven factors, from the most important to the least are:body mass index, hemoglobin, age, glycated hemoglobin, Creatinine, systolic and diastolic blood pressure. In conclusion, ML is not inferior to traditional MLR in predicting abnormal Th-201 scans, and the most important factors are body mass index, hemoglobin, age, glycated hemoglobin, creatinine, systolic and diastolic blood pressure. ML methods are superior in these kinds of studies.

Atherosclerotic plaque characteristics on quantitative coronary computed tomography angiography associated with ischemia on positron emission tomography in diabetic patients

Patients with diabetes mellitus (DM) may show diffuse coronary artery atherosclerosis on coronary computed tomography angiography (CTA). The present study aimed at quantification of atherosclerotic plaque with CTA and its association with myocardial ischemia on positron emission tomography (PET) in DM patients. Of 922 symptomatic outpatients without previously known coronary artery disease who underwent CTA, 115 with DM (mean age 65 ± 8 years, 58% male) who had coronary atherosclerosis and underwent both quantified CTA (QCTA) and PET were included in the study. QCTA analysis was performed on a per-vessel basis and the most stenotic lesion of each vessel was considered. Myocardial ischemia on PET was based on absolute myocardial blood flow at stress ≤ 2.4 ml/g/min. Of the 345 vessels included in the analysis, 135 (39%) had flow-limiting stenosis and were characterized by having longer lesions, higher plaque volume, more extensive plaque burden and higher percentage of dense calcium (37 ± 22% vs 28 ± 22%, p = 0.001). On univariable analysis, QCTA parameters indicating the degree of stenosis, the plaque extent and composition were associated with presence of ischemia. The addition of the QCTA degree of stenosis parameters (x2 36.45 vs 88.18, p < 0.001) and the QCTA plaque extent parameters (x2 88.18 vs 97.44, p = 0.01) to a baseline model increased the association with ischemia. In DM patients, QCTA variables of vessel stenosis, plaque extent and composition are associated with ischemia on PET and characterize the hemodynamic significant atherosclerotic lesion.

Added Prognostic Value of Plaque Burden to Computed Tomography Angiography and Myocardial Perfusion Imaging in Patients with Diabetes

BACKGROUND

We aimed to compare the added prognostic value of plaque burden to cardiac computed tomographic angiography (CCTA) anatomic assessment and single-photon emission computed tomography (SPECT) physiologic assessment in patients with diabetes undergoing both tests.

METHODS

Consecutive patients with diabetes who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected coronary artery disease were included. Stenosis severity and segment involvement score (SIS) were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed from date of imaging for major adverse cardiovascular events (MACE).

RESULTS

A total of 778 patients were included (mean age 60.6 ± 14.4 years, 55% males). After a median follow-up of 31 months, 87 (11%) patients experienced a MACE. In multivariable Cox regression models, SIS significantly predicted outcomes in models including obstructive stenosis and ischemia (hazard ratio 1.17, 95% confidence interval 1.10-1.24, P < .001; hazard ratio 1.16, 95% confidence interval 1.10-1.23, P < .001, respectively), and improved discrimination (Harrel's C 0.75, P = .006; 0.76, P = .006 in models with CCTA obstructive stenosis and SPECT ischemia, respectively). Results were consistent using subgroups of summed scores by composition of plaque (calcified vs noncalcified) and alternate definitions of obstructive stenosis.

CONCLUSION

Our results suggest that in high-risk patients with diabetes and suspected coronary disease, SIS has incremental prognostic value over ischemia by SPECT or stenosis by CCTA in predicting incident cardiovascular outcomes.

ACR Appropriateness Criteria® Chronic Chest Pain-High Probability of Coronary Artery Disease: 2021 Update

Management of patients with chronic chest pain in the setting of high probability of coronary artery disease (CAD) relies heavily on imaging for determining or excluding presence and severity of myocardial ischemia, hibernation, scarring, and/or the presence, site, and severity of obstructive coronary lesions, as well as course of management and long-term prognosis. In patients with no known ischemic heart disease, imaging is valuable in determining and documenting the presence, extent, and severity of obstructive coronary narrowing and presence of myocardial ischemia. In patients with known ischemic heart disease, imaging findings are important in determining the management of patients with chronic myocardial ischemia and can serve as a decision-making tool for medical therapy, angioplasty, stenting, or surgery. This document summarizes the recent growing body of evidence on various imaging tests and makes recommendations for imaging based on the available data and expert opinion. This document is focused on epicardial CAD and does not discuss the microvascular disease as the cause for CAD. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The Value of Stress Echocardiography in a Young Female Patient With a Negative Stress Electrocardiogram

Stress echocardiography remains a steadfast noninvasive diagnostic test used to determine the presence of obstructive coronary artery disease, along with defining the severity of other disease states (i.e., hypertrophic obstructive cardiomyopathy, regurgitant valve lesions, and right ventricular systolic pressure). Due to its high sensitivity and specificity, stress echocardiographic imaging is advantageous when stress electrocardiography, alone, is not enough to discover true ischemic findings, on a standard Bruce protocol. Even then, false positive and false negative electrocardiogram (EKG) results occur all too frequently. Furthermore, because women may more commonly present with atypical signs of ischemia, additional echocardiographic imaging is beneficial when added to a treadmill stress test to visualize ischemic areas of the myocardium. This case study illustrates the importance of using stress echocardiographic imaging, on a female patient, with false negative EKG findings and atypical chest pain in the presence of coronary artery disease.

Nuclear Cardiology in Women and Underrepresented Minority Populations

PURPOSE OF REVIEW

To outline sex-specific features of coronary artery disease (CAD) that should be considered in the assessment of women, including those from ethnic minority populations with suspected stable ischemic heart disease (IHD). Second, to determine the latest nuclear imaging tools available to assess microvascular CAD.

RECENT FINDINGS

Latest studies indicate that women are more likely to have ischemia with no obstructive coronary arteries (INOCA) and paradoxically have worse outcomes. Therefore, the evaluation of women with suspected IHD should include assessing microvascular and epicardial coronary circulation. The prevalence of CAD is increasing in younger women due to the increased cardiovascular disease (CVD) risk burden. CAD is often underrecognized in these patients. There is increasing recognition that INOCA is not benign and should be accurately diagnosed and managed. Nuclear imaging assesses the full spectrum of CAD from microvascular CAD to multivessel obstructive epicardial CAD. Further research on myocardial blood flow (MBF) assessment with PET MPI is needed.

Multimodality imaging approach to left ventricular dysfunction in diabetes: an expert consensus document from the European Association of Cardiovascular Imaging

Heart failure (HF) is among the most important and frequent complications of diabetes mellitus (DM). The detection of subclinical dysfunction is a marker of HF risk and presents a potential target for reducing incident HF in DM. Left ventricular (LV) dysfunction secondary to DM is heterogeneous, with phenotypes including predominantly systolic, predominantly diastolic, and mixed dysfunction. Indeed, the pathogenesis of HF in this setting is heterogeneous. Effective management of this problem will require detailed phenotyping of the contributions of fibrosis, microcirculatory disturbance, abnormal metabolism, and sympathetic innervation, among other mechanisms. For this reason, an imaging strategy for the detection of HF risk needs to not only detect subclinical LV dysfunction (LVD) but also characterize its pathogenesis. At present, it is possible to identify individuals with DM at increased risk HF, and there is evidence that cardioprotection may be of benefit. However, there is insufficient justification for HF screening, because we need stronger evidence of the links between the detection of LVD, treatment, and improved outcome. This review discusses the options for screening for LVD, the potential means of identifying the underlying mechanisms, and the pathways to treatment.

Diagnostic Value of Single-Photon Emission Tomography Stress Test in Patients With Suspected Coronary Artery Disease in Saudi Arabia

Background

Invasive coronary angiography (ICA) is the gold standard procedure for the diagnosis of coronary artery disease (CAD). ICA allows for clear visualization of the coronary arterial blood flow. Single-photon emission computed tomography (SPECT) is currently in widespread use to non-invasively evaluate patients known or suspected of coronary artery disease (CAD). This study aimed to examine the association between (SPECT) stress test and elective ICA in terms of diagnostic value in patients suspected of coronary artery disease at the King Faisal Cardiac Center (KFCC), Jeddah, Saudi Arabia.

Methods

This study is a retrospective diagnostic validation study using a consecutive sampling technique to select the study sample at KFCC. The study included all patients who presented with chest pain that were investigated with either exercise or pharmacologic myocardial perfusion SPECT study followed by elective ICA within six months from January 2015 to January 2020.

Results

A total of 207 patients met the inclusion criteria, where 43% (n = 90) of patients were females and 57% (n = 117) were males; 68% (n = 141) of the patients had both test results concordant (both SPECT and ICA results were in agreement). In 32% of the patients (n = 66), there was a discordant result (discrepant result between SPECT and ICA). SPECT had a sensitivity of 92.4% and a specificity of 26.3%. SPECT had a negative predictive value of 0.68 and a positive predictive value of 0.66 compared to ICA. There was a low degree of reliability between SPECT and ICA.

Conclusion

Reliability between the SPECT and ICA in exclusion of significant CAD is high. The rate of false-positive tests was high while the accuracy of SPECT in detecting CAD in patients with diabetes and hypertension was high. The overall reliability of SPECT to ICA in the Saudi population was low.

Severe myocardial ischemia in a patient with diabetes mellitus and left bundle branch block

We present the case of a 69-year-old woman with diabetes mellitus, left bundle branch block, and obesity who develops cardiogenic shock after undergoing myocardial perfusion imaging and diagnostic left heart catheterization, but prior to coronary revascularization. This case highlights the risk of cardiac decompensation awaiting surgery in patients with multivessel coronary artery disease. It also emphasizes the subtleties involved in imaging patients with diabetes mellitus and left bundle branch block, as well as the risk of developing complete heart block in the setting of ischemia with underlying conduction disease.

Incremental prognostic value of coronary flow reserve determined by phase-contrast cine cardiovascular magnetic resonance of the coronary sinus in patients with diabetes mellitus

BACKGROUND

Although non-invasive assessment of coronary flow reserve (CFR) by cardiovascular magnetic resonance (CMR) provides prognostic information for patients with diabetes mellitus (DM), the incremental prognostic value of CMR-derived CFR remains unclear.

PURPOSE

To evaluate the incremental prognostic value of CMR-derived CFR for patients with DM who underwent stress CMR imaging.

MATERIALS AND METHODS

A total of 309 patients with type 2 DM [69 ± 9 years; 244 (78%) male] assessed between 2009 and 2019 were retrospectively reviewed. Coronary sinus blood flow (CSBF) was measured using phase contrast (PC) cine CMR. CFR was calculated as the CSBF during adenosine triphosphate infusion divided by that at rest. Major adverse cardiac events (MACE) were defined as death, acute coronary syndrome, hospitalization due to heart failure exacerbation, or sustained ventricular tachycardia. The incremental prognostic value of CFR over clinical and CMR variables was assessed by calculating the C-index and net reclassification improvement (NRI).

RESULTS

During a median follow-up of 3.8 years, 42 patients (14%) experienced MACE. The annualized event rate was significantly higher among patients with CFR < 2.0, regardless of the presence of late gadolinium enhancement (LGE) (1.4% vs. 9.8%, p = 0.011 in the LGE (-) group; 1.8% vs. 16.9%, p < 0.001 in the LGE (+) group). In addition, this trend was maintained in the subgroups stratified by presence or absence of ischemia (0.3% vs. 6.7%, p = 0.007 in the ischemia (-) group; 3.9% vs. 17.1%, p = 0.001 in the ischemia (+) group). Adding CFR to the risk model (age + gender + left ventricular ejection fraction + %LGE + %ischemia) resulted in a significant increase of the C-index from 0.838 to 0.870 (p = 0.038) and an NRI of 0.201 (0.004-0.368, p = 0.012).

CONCLUSION

PC cine CMR-derived CFR of the coronary sinus may be useful as a prognostic marker for DM patients, incremental to common clinical and CMR parameters. Due to the high prevalence of coronary microvascular dysfunction, the addition of CFR to conventional vasodilator stress CMR imaging may improve risk stratification for patients with DM.

Predictors of abnormality in thallium myocardial perfusion scans for type 2 diabetes

Type 2 diabetes mellitus (T2DM) increases coronary artery disease (CAD) risk. In this study, we used T2DM clinical variables to predict abnormality in thallium-201 myocardial perfusion scans (Th-201 scans). These clinical variables were summed stress score (SSS), summed rest score, and summed difference score (SDS), with data obtained from 368 male and 428 female participants with T2DM. Multiple linear regression results were as follows. In male participants, body mass index (BMI) and creatinine (Cr) were associated with SSS (β = 0.224, p < 0.001; β = 0.140, p = 0.022, respectively), and only BMI was associated with SDS (β = 0.174, p = 0.004). In female participants, BMI and high-density lipoprotein cholesterol level were associated with SSS (β = 0.240, p < 0.001; β =  - 0.120, p = 0.048, respectively), and only BMI was correlated with SDS (β = 0.123, p = 0.031). Our multivariate logistic regression indicated that in male and female participants, BMI was the only independent indicator of high SSS (SSS ≥ 9). In this study, we demonstrated that male patients have a higher SSS and SDS than female patients do in Th-201 scans for T2DM in a Chinese population. For male and female patients, BMI was the strongest predictor of abnormality in Th-201 scans. Our results can help clinicians identify patients with T2DM at high risk of CAD.

Myocardial Ischemic Burden and Differences in Prognosis Among Patients With and Without Diabetes: Results From the Multicenter International REFINE SPECT Registry

OBJECTIVE

Prevalence and prognostic impact of cardiovascular disease differ between patients with or without diabetes. We aimed to explore differences in the prevalence and prognosis of myocardial ischemia by automated quantification of total perfusion deficit (TPD) among patients with and without diabetes.

RESEARCH DESIGN AND METHODS

Of 20,418 individuals who underwent single-photon emission computed tomography myocardial perfusion imaging, 2,951 patients with diabetes were matched to 2,951 patients without diabetes based on risk factors using propensity score. TPD was categorized as TPD = 0%, 0% < TPD < 1%, 1% ≤ TPD < 5%, 5% ≤ TPD ≤ 10%, and TPD >10%. Major adverse cardiovascular events (MACE) were defined as a composite of all-cause mortality, myocardial infarction, unstable angina, or late revascularization.

RESULTS

MACE risk was increased in patients with diabetes compared with patients without diabetes at each level of TPD above 0 (P < 0.001 for interaction). In patients with TPD >10%, patients with diabetes had greater than twice the MACE risk compared with patients without diabetes (annualized MACE rate 9.4 [95% CI 6.7-11.6] and 3.9 [95% CI 2.8-5.6], respectively, P < 0.001). Patients with diabetes with even very minimal TPD (0% < TPD < 1%) experienced a higher risk for MACE than those with 0% TPD (hazard ratio 2.05 [95% CI 1.21-3.47], P = 0.007). Patients with diabetes with a TPD of 0.5% had a similar MACE risk as patients without diabetes with a TPD of 8%.

CONCLUSIONS

For every level of TPD >0%, even a very minimal deficit of 0% < TPD < 1%, the MACE risk was higher in the patients with diabetes compared with patients without diabetes. Patients with diabetes with minimal ischemia had comparable MACE risk as patients without diabetes with significant ischemia.

Differential association of diabetes mellitus and female sex with impaired myocardial flow reserve across the spectrum of epicardial coronary disease

Aims 

Diabetes mellitus (DM) affects the macro- and microvasculature, leading to impairment in coronary vascular reactivity. Microvascular dysfunction is more prevalent in females compared to males, leading to increased cardiovascular risk in women. The purpose of this study was to quantify the association between diabetes and female sex on myocardial flow reserve (MFR) across the spectrum of epicardial coronary artery disease (CAD).

Methods and results 

In 222 patients with known or suspected CAD (63.7 ± 10.7 years, 66 females, 85 with diabetes) who had rubidium-82 positron emission tomography (PET) and invasive coronary angiography within 6 months, a multiple linear regression model was developed to predict MFR based on clinical risk factors and imaging results across a spectrum of regional epicardial disease. A significant interaction effect suggested that impairment of MFR is accelerated in diabetics with increasing severity of epicardial disease. Furthermore, female sex (−13%), decade of age (−6%), ischaemia on electrocardiogram (−10%), resting rate-pressure product (−3%), and rest end-diastolic volume (−0.2%) were associated with reductions in MFR independent of the combined extent and severity of epicardial disease.

Conclusion

In the presence of significant obstructive epicardial disease, MFR decreases more rapidly in patients with DM compared to those without. Additional patient demographics and risk factors such as female sex and older age, and stress PET functional parameters should also be considered in the clinical interpretation of MFR. This has implications for the diagnosis and management of CAD patients with these and other risk factors for microvascular disease.

Stress Myocardial Perfusion PET Provides Incremental Risk Prediction in Patients with and Patients without Diabetes

PURPOSE

To evaluate the prognostic value of myocardial perfusion PET in patients with and patients without diabetes mellitus.

MATERIALS AND METHODS

The authors performed a retrospective analysis of prospectively acquired data from a multicenter registry cohort of 7061 patients, including 1966 with diabetes mellitus, who underwent clinically indicated rest-stress rubidium 82 (⁸²Rb) myocardial perfusion PET. The mean patient age (±standard deviation) was 63.3 years ± 13. Of the 7061 patients, 3348 were women (47.4%), 2296 (32.5%) had known coronary artery disease, and 1895 (26.8%) had previously undergone revascularization. The primary end point was cardiac death (n = 169) assessed at a mean of 2.5 years ± 1.5. The authors used Cox proportional hazards models and risk reclassification measures stratified according to diabetes status.

RESULTS

In multivariable models adjusting for established clinical predictors, increasing magnitude of stress myocardial perfusion abnormality was associated with greater risk of cardiac death in patients with diabetes (hazard ratio [HR]: 7.2; 95% confidence interval [CI]: 3.1, 16.8) for severely abnormal myocardium compared with normal myocardium. The addition of stress myocardial perfusion imaging results significantly improved the fit of a clinical model for predicting cardiac death in patients with and patients without diabetes. Myocardial perfusion PET improved risk reclassification for cardiac death in patients with diabetes (category-based net reclassification index: 0.39; 95% CI: 0.15, 0.60, P < .001). Among diabetic patients, an abnormal myocardial perfusion PET scan was associated with increased risk of cardiac death (HR: 4.4; 95% CI: 2.0, 9.7) in all important clinical subgroups based on age, sex, obesity, or prior revascularization.

CONCLUSION

In a large cohort of patients referred for clinical ⁸²Rb stress PET, myocardial perfusion imaging results provided incremental risk prediction of cardiac death in patients with and patients without diabetes mellitus.© RSNA, 2019Supplemental material is available for this article.

[The Clinical use of Stress Echocardiography in Ischemic Heart Disease Cardiovascular Ultrasound (2017)15:7. Translation authors: Arystan A.Zh., Fettser D.V.]

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows detecting myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependence on operator expertise, the lack of outcome data (a widespread problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

Imaging to Stratify Coronary Artery Disease Risk in Asymptomatic Patients with Diabetes

Coronary artery disease (CAD) is the leading cause of morbidity and mortality in patients with diabetes mellitus. Patients with diabetes have a higher prevalence of CAD and a larger magnitude of ischemia, and they are more likely to have silent myocardial ischemia and myocardial infarction. However, recent large cohort studies demonstrate that diabetic patients are not a homogenous group with similar high risk for cardiac events. In fact, more than 30% of asymptomatic diabetic patients do not have evidence of coronary atherosclerosis and have a very low annual cardiac event rate. Accordingly, there has been a recent paradigm shift as to whether the detection of subclinical coronary atherosclerosis through imaging can best guide therapeutic decision making. This review discusses the role of various cardiac imaging techniques for stratifying cardiovascular risk and optimizing therapy in asymptomatic diabetic patients.

Noninvasive Imaging of Endothelial Damage in Patients With Different HbA1c Levels: A Proof-of-Concept Study

The aim of this study was to compare endothelial permeability, which is considered a hallmark of coronary artery disease, between patients with different HbA_1c levels using an albumin-binding magnetic resonance (MR) probe. This cross-sectional study included 26 patients with clinical indication for X-ray angiography who were classified into three groups according to HbA_1c level (<5.7% [<39 mmol/mol], 5.7-6.4% [39-47 mmol/mol], and ≥6.5% [48 mmol/mol]). Subjects underwent gadofosveset-enhanced coronary magnetic resonance and X-ray angiography including optical coherence within 24 h. Contrast-to-noise ratios (CNRs) were assessed to measure the probe uptake in the coronary wall by coronary segment, excluding those with culprit lesions in X-ray angiography. In the group of patients with HbA_1c levels between 5.7 and 6.4%, 0.30 increased normalized CNR values were measured, compared with patients with HbA_1c levels <5.7% (0.30 [95% CI 0.04, 0.57]). In patients with HbA_1c levels ≥6.5%, we found 0.57 higher normalized CNR values compared with patients with normal HbA_1c levels (0.57 [95% CI 0.28, 0.85]) and 0.26 higher CNR values for patients with HbA_1c level ≥6.5% compared with patients with HbA_1c levels between 5.7 and 6.4% (0.26 [95% CI -0.04, 0.57]). Additionally, late atherosclerotic lesions were more common in patients with high HbA_1c levels (HbA_1c ≥6.5%, n = 14 [74%]; HbA_1c 5.7-6.4%, n = 6 [60%]; and HbA_1c <5.7%, n = 10 [53%]). In conclusion, coronary MRI in combination with an albumin-binding MR probe suggests that both patients with intermediate and patients with high HbA_1c levels are associated with a higher extent of endothelial damage of the coronary arteries compared with patients with HbA_1c levels <5.7%.

Coronary Atherosclerosis Assessment by Coronary CT Angiography in Asymptomatic Diabetic Population: A Critical Systematic Review of the Literature and Future Perspectives

The prognostic impact of diabetes mellitus (DM) on cardiovascular outcomes is well known. As a consequence of previous studies showing the high incidence of coronary artery disease (CAD) in diabetic patients and the relatively poor outcome compared to nondiabetic populations, DM is considered as CAD equivalent which means that diabetic patients are labeled as asymptomatic individuals at high cardiovascular risk. Lessons learned from the analysis of prognostic studies over the past decade have challenged this dogma and now support the idea that diabetic population is not uniformly distributed in the highest risk box. Detecting CAD in asymptomatic high risk individuals is controversial and, what is more, in patients with diabetes is challenging, and that is why the reliability of traditional cardiac stress tests for detecting myocardial ischemia is limited. Cardiac computed tomography angiography (CCTA) represents an emerging noninvasive technique able to explore the atherosclerotic involvement of the coronary arteries and, thus, to distinguish different risk categories tailoring this evaluation on each patient. The aim of the review is to provide a wide overview on the clinical meaning of CCTA in this field and to integrate the anatomical information with a reliable therapeutic approach.

The elusive role of myocardial perfusion imaging in stable ischemic heart disease: Is ISCHEMIA the answer?

The assessment of ischemia through myocardial perfusion imaging (MPI) is widely accepted as an index step in the diagnostic evaluation of stable ischemic heart disease (SIHD). Numerous observational studies have characterized the prognostic significance of ischemia extent and severity. However, the role of ischemia in directing downstream SIHD care including coronary revascularization has remained elusive as reductions in ischemic burden have not translated to improved clinical outcomes in randomized trials. Importantly, selection bias leading to the inclusion of many low risk patients with minimal ischemia have narrowed the generalizability of prior studies along with other limitations. Accordingly, an ongoing randomized controlled trial entitled ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) will compare an invasive coronary revascularization strategy vs a conservative medical therapy approach among stable patients with moderate to severe ischemia. The results of ISCHEMIA may have a substantial impact on the management of SIHD and better define the role of MPI in current SIHD pathways of care.

Prognostic implications of myocardial perfusion imaging and coronary calcium score in a Macedonian cohort of asymptomatic patients with type 2 diabetes

AIM

Type 2 diabetes is a risk factor for coronary artery disease; however, a number of studies have shown that patients are asymptomatic for coronary artery disease. The presence of coronary artery disease in asymptomatic patients with type 2 diabetes was evaluated to determine its impact on management decision and prognosis.

METHODS

A total of 75 patients underwent single-photon emission computed tomography myocardial perfusion imaging for detection of suspected coronary artery disease. We used 17-segment model for perfusion and function analysis. Multislice computed tomography was performed in 45 patients to assess coronary artery calcium. Complete laboratory analyses with lipid values and standard risk factors were analysed. Forward logistic regression analysis was used to assess predictive parameters for myocardial ischaemia during the follow-up period of 20 ± 4 months.

RESULTS AND CONCLUSION

Silent myocardial ischaemia and subclinical coronary artery disease can be detected in a significant proportion of asymptomatic patients with type 2 diabetes. Diabetic patients with normal myocardial perfusion imaging had an excellent 2-year prognosis with optimal medical therapy and intensive risk factor control. In comparison, an abnormal myocardial perfusion imaging led to an increased risk of cardiovascular events. Myocardial perfusion imaging and coronary artery calcium are valuable tools for risk stratification and optimal treatment decision in this asymptomatic diabetic cohort of Macedonian patients.

Is ischemia the only factor predicting cardiovascular outcomes in all diabetes mellitus patients?

Diabetes mellitus (DM) is associated with an excess in cardiovascular morbidity and mortality, and is characterized by increased rates of coronary artery disease. Furthermore, once atherosclerosis is established, this is associated with an increased extent, complexity and a more rapid progression than seen in non-DM patients. Ischemia is the single most important predictor of future hard cardiac events and ischemia correction remains the cornerstone of current revascularization strategies. However recent data suggests that, in DM patients, coronary atherosclerosis despite the absence of ischemia, detected by either invasive or non-invasive methods, may not be associated with the same low risk of future cardiac events as seen in non-DM patients. This review seeks to examine the current evidence supporting an ischemia driven revascularization strategy, and to challenge the notion that ischemia is the only clinically relevant factor in the prediction of cardiovascular outcomes in all-comer DM patients. Specifically, we examine whether in DM patients certain characteristics beyond ischemia, such as microvascular disease, coronary atherosclerosis burden, progression and plaque composition, may need to be considered for a more refined risk stratification in these high-risk patients.

The clinical use of stress echocardiography in ischemic heart disease

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows to detect myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician.

The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependance on operator expertise, the lack of outcome data (a widesperad problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

Cardiovascular Screening for the Asymptomatic Patient with Diabetes: More Cons Than Pros

Diabetes mellitus is associated with an increased risk of coronary heart disease (CHD) morbidity and mortality. Although it frequently coexists with other cardiovascular disease (CVD) risk factors, it confers an increased risk for CVD events on its own. Coronary atherosclerosis is generally more aggressive and widespread in people with diabetes (PWD) and is frequently asymptomatic. Screening for silent myocardial ischaemia can be applied in a wide variety of ways. In nearly all asymptomatic PWD, however, the results of screening will generally not change medical therapy, since aggressive preventive measures, such as control of blood pressure and lipids, would have been already indicated, and above all, invasive revascularization procedures (either with percutaneous coronary intervention or coronary artery bypass grafting) have not been shown in randomized clinical trials to confer any benefit on morbidity and mortality. Still, unresolved issues remain regarding the extent of the underlying ischaemia that might affect the risk and the benefit of revascularization (on top of optimal medical therapy) in ameliorating this risk in patients with moderate to severe ischaemia. The issues related to the detection of coronary atherosclerosis and ischaemia, as well as the studies related to management of CHD in asymptomatic PWD, will be reviewed here.

Noninvasive Cardiovascular Risk Assessment of the Asymptomatic Diabetic Patient: The Imaging Council of the American College of Cardiology

Increased cardiovascular morbidity and mortality in patients with type 2 diabetes is well established; diabetes is associated with at least a 2-fold increased risk of coronary heart disease. Approximately two-thirds of deaths among persons with diabetes are related to cardiovascular disease. Previously, diabetes was regarded as a "coronary risk equivalent," implying a high 10-year cardiovascular risk for every diabetes patient. Following the original study by Haffner et al., multiple studies from different cohorts provided varying conclusions on the validity of the concept of coronary risk equivalency in patients with diabetes. New guidelines have started to acknowledge the heterogeneity in risk and include different treatment recommendations for diabetic patients without other risk factors who are considered to be at lower risk. Furthermore, guidelines have suggested that further risk stratification in patients with diabetes is warranted before universal treatment. The Imaging Council of the American College of Cardiology systematically reviewed all modalities commonly used for risk stratification in persons with diabetes mellitus and summarized the data and recommendations. This document reviews the evidence regarding the use of noninvasive testing to stratify asymptomatic patients with diabetes with regard to coronary heart disease risk and develops an algorithm for screening based on available data.

Imaging Atherosclerosis in Diabetes: Current State

Cardiovascular events, including myocardial infarction and stroke, are the primary causes of mortality in both type 1 and type 2 diabetes. Affected patients frequently have asymptomatic coronary artery disease. Studies have shown heterogeneity in cardiovascular risk among patients with diabetes. Imaging can help categorize risk of future cardiovascular events by identifying those patients with atherosclerosis, rather than relying on risk prediction based on population-based studies. In this article, we will review the evidence regarding use of atherosclerosis imaging in patients with diabetes to predict risk of coronary heart disease and mortality.

Stress Perfusion Cardiac Magnetic Resonance Imaging Effectively Risk Stratifies Diabetic Patients With Suspected Myocardial Ischemia

BACKGROUND

Diabetics remain at high risk of cardiovascular disease and mortality despite advancements in medical therapy. Noninvasive cardiac risk profiling is often more difficult in diabetics owing to the prevalence of silent ischemia with unrecognized myocardial infarction, reduced exercise capacity, nondiagnostic electrocardiographic changes, and balanced ischemia from diffuse epicardial coronary atherosclerosis and microvascular dysfunction.

METHODS AND RESULTS

A consecutive cohort of 173 patients with diabetes mellitus (mean age, 61.7±11.9 years; 37% women) with suspected myocardial ischemia underwent stress perfusion cardiac magnetic resonance imaging. Patients were evaluated for adverse cardiac events after cardiac magnetic resonance imaging with mean follow-up time of 2.9±2.5 years. Mean hemoglobin A1c for the population was 7.9±1.8%. Primary end point was a composite of cardiac death and nonfatal myocardial infarction. Diabetics with no inducible ischemia (n=94) experienced an annualized event rate of 1.4% compared with 8.2% (P=0.0003) in those with inducible ischemia (n=79). Diabetics without late gadolinium enhancement or inducible ischemia had a low annual cardiac event rate (0.5% per year). The presence of inducible ischemia was the strongest unadjusted predictor (hazard ratio, 4.86; P<0.01) for cardiac death and nonfatal myocardial infarction. This association remained robust in adjusted stepwise multivariable Cox regression analysis (hazard ratio, 4.28; P=0.02). In addition, categorical net reclassification index using 5-year risk cutoffs of 5% and 10% resulted in reclassification of 43.4% of the diabetic cohort with net reclassification index of 0.38 (95% confidence interval, 0.20-0.56; P<0.0001).

CONCLUSIONS

Stress perfusion cardiac magnetic resonance imaging provided independent prognostic utility and effectively reclassified risk in patients with diabetes mellitus referred for ischemic assessment. Further evaluation is required to determine whether a noninvasive imaging strategy with cardiac magnetic resonance imaging can favorably affect downstream outcomes and improve cost-effectiveness of care in diabetics.

Dobutamine stress myocardial perfusion imaging: 8-year outcomes in patients with diabetes mellitus

AIMS

Many studies have examined the prognostic value of myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) for the prediction of short- to medium-term outcomes. However, the long-term prognostic value of MPI in patients with diabetes mellitus remains unclear. Therefore, this study assessed the long-term prognostic value of MPI in a high-risk cohort of patients with diabetes mellitus.

METHODS AND RESULTS

A high-risk cohort of 207 patients with diabetes mellitus who were unable to undergo exercise testing underwent dobutamine stress MPI. Follow-up was successful in 206 patients; 12 patients were excluded due to early revascularization. The current data are based on the remaining 194 patients. Follow-up end points were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction. The Kaplan-Meier survival curves were constructed, and univariable and multivariable analyses were performed to identify predictors of long-term outcome. During a mean follow-up of 8.1 ± 5.9 years, 134 (69%) patients died of which 68 (35%) died due to cardiac causes. Nonfatal myocardial infarction occurred in 24 patients (12%), and late (>60 days) coronary revascularization was performed in 61 (13%) patients. Survival analysis showed that MPI provided optimal risk stratification up to 4 years after testing. After that period, the outcome was comparable in patients with normal and abnormal MPI. Multivariable analyses showed that MPI provided incremental prognostic value up to 4 years after testing.

CONCLUSION

In high-risk patients with diabetes mellitus, dobutamine MPI provides incremental prognostic information in addition to clinical data for a 4-year period after testing.

Holter monitoring for the screening of cardiac disease in diabetes mellitus: The non-invasive Holter monitoring observation of new cardiac events in diabetics study

We investigated the usefulness of Holter monitoring to detect cardiac disease and predict future cardiovascular risk in asymptomatic diabetic patients. This is a multi-centre, prospective study in 406 asymptomatic diabetic patients. They were categorized into three groups based on findings of Holter monitoring. A total of 377 met inclusion criteria and were classified as low (n = 172), moderate (n = 136) and high risk (n = 69). In total, 86 in moderate and 53 in high risk receive further evaluation. In total, 29 in moderate and 25 in high risk were diagnosed as cardiac disease and 12 required additional treatment, including coronary intervention. Over 1.8 years of mean follow-up, 11 (16.5 per 1000 person-years) experienced cardiovascular events. The cumulative incidence in moderate and high risk was higher than that in low risk (p = 0.029 and p = 0.014, respectively). Our study suggests that Holter monitoring may be a useful screening tool to detect cardiac disease and predict future cardiovascular risk in asymptomatic diabetic patients.

Temporal trends of stress myocardial perfusion imaging: Influence of diabetes, gender and coronary artery disease status

INTRODUCTION

Temporal trends of myocardial perfusion imaging (MPI) among diabetics and non-diabetics and the influence of gender and prior coronary artery disease (CAD) status has not been previously investigated.

MATERIALS AND METHODS

Consecutive patients who underwent clinically indicated stress-MPI over a 17-year period (1996 through 2012) were studied. Data were collected prospectively as a part of the ongoing clinical databases. Study patients were divided into 4 temporal subgroups (1996 to 2000, 2001 to 2004, 2005 to 2008 and 2009 to 2012) to compare the trends of cardiac risk factors and the frequency of abnormal and ischemic MPI.

RESULTS

Of 78,344 total stress MPI studies, 30.2% were in diabetics. The frequency of abnormal MPI studies, while substantially higher in diabetics, significantly declined over time both in diabetics (53.6% in 1996 to 39.8% in 2012) and non-diabetics (37% in 1996 to 27.4% in 2012), despite an increase in the cardiac risk factor profile. Furthermore, among patients with no known CAD, the temporal prevalence of abnormal MPI was highest in diabetic men (57.5% in 1996 to 31.9% in 2012), lowest in non-diabetic women (18.8% in 1996 to 11% in 2012), and both intermediate and comparable in non-diabetic men and diabetic women (36.4% and 35.7% in 1996 and 20.7% and 17.5% in 2012, respectively).

CONCLUSIONS

Despite a temporal reduction in the prevalence of abnormal studies from 1996 through 2012, stress MPI continues to play an important clinical role, particularly in diabetics, men and patients with known-CAD.

Warranty periods for normal myocardial perfusion stress SPECT

BACKGROUND

To assess different warranty periods following a normal myocardial perfusion SPECT based on patients' clinical characteristics and the type of stress performed.

METHODS AND RESULTS

A study was done of 2,922 consecutive patients (62.9 ± 13 years; 53.4% women) with a normal stress-rest SPECT. The warranty period was defined as the period during which patients remained at a low risk (<1% events/year) of total mortality (TM), or hard events (HE) (cardiac death or non-fatal myocardial infarction). Of these patients, 2,051 were given an exercise myocardial perfusion imaging (Ex-MPI); 461 submaximal exercise plus dipyridamole (Ex+Dipy-MPI); and 410 dipyridamole (Dipy-MPI). During a mean follow-up of 5 ± 3.3 years, a significant reduction (P < .05) of the warranty period for TM (13.5, 9.6 and 8 months) and HE (34.8, 20.5 and 8.2 months) was observed, for Ex-MPI, Ex+Dipy-MPI and Dipy-MPI, respectively. Other warranty period determinants were the clinical variables of age, sex, diabetes and known coronary artery disease. An abnormal left ventricular ejection fraction on gated-SPECT also significantly shortened the warranty period for HE in patients undergoing Ex+Dipy-MPI (P = .001) or Dipy-MPI alone (P = .007).

CONCLUSIONS

The warranty period for a normal stress-rest SPECT is highly variable since it is primarily determined by the type of stress, the patient's clinical characteristics and LVEF.

Cardiovascular risk stratification in diabetic patients following stress single-photon emission-computed tomography myocardial perfusion imaging: the impact of achieved exercise level

BACKGROUND

Previous studies have demonstrated that diabetic patients undergoing exercise stress single-photon emission-computed tomography (SPECT) myocardial perfusion imaging (MPI) have significantly lower cardiac events when compared to the diabetic patients undergoing pharmacologic stress SPECT MPI across all perfusion categories. However, there are limited data on the level of exercise achieved during exercise SPECT MPI among diabetic patients and its impact on cardiovascular outcomes.

METHODS

We retrospectively analyzed 14,849 consecutive patients (3,654 diabetics and 11,195 non-diabetics) undergoing exercise stress, combined exercise and pharmacologic stress, and pharmacologic stress SPECT MPI from 1996 to 2005 at a single tertiary care center. Diabetic and non-diabetic patients were categorized into 3 groups based on the metabolic equivalents (METs) achieved: ≥5 METs, <5 METs, and pharmacologic stress groups. All studies were interpreted using the 17-segment ASNC model. The presence, extent, severity of perfusion defects were calculated using the summed stress score (SSS), and patients were classified into normal (SSS < 4), mildly abnormal (SSS 4-8), and moderate-severely abnormal (SSS > 8) categories. Annualized event rates (AER) for the composite end point of non-fatal myocardial infarction and cardiac death were calculated over a mean follow-up period of 2.4 ± 1.4 years with a maximum of 6 years.

RESULTS

In moderate-severe perfusion abnormality (SSS > 8) category, diabetic patients who were able to achieve ≥5 METs had significantly lower AER compared to diabetic patients who were unable to achieve ≥5 METs (3% vs 5.5%, P = .04), and non-diabetic patients unable to achieve ≥5 METs (3% vs 4.8%, P < .001). Diabetic patients who achieved a high workload of ≥10 METs had a very low AER of 0.9%. Diabetic patients, who attempted exercise but were unable to achieve ≥5 METs, still had significantly lower AER than diabetics undergoing pharmacologic stress MPI across all perfusion categories [1.5% vs 3.2%, P = .006 (SSS < 4); 2.5% vs 4.9%, P = .032 (SSS 4-8); 5.5% vs 10.3%, P = .003 (SSS > 8)]. After adjustment for cardiovascular risk factors, the percentage decrease in cardiac event rate for every 1-MET increment in exercise capacity was 10% in the overall cohort, 12% in diabetic group, and 8% in non-diabetic group.

CONCLUSIONS

Despite significant perfusion defects, diabetic patients who achieve ≥5 METs during stress SPECT MPI have significantly reduced risk for future cardiac events. Diabetic patients who achieve ≥10 METs have a very low annualized event rate. These findings support that exercise capacity obtained during SPECT MPI is a surrogate for outcomes among diabetic patients undergoing nuclear stress testing.

Prognostic value of normal stress myocardial perfusion imaging in diabetic patients: a meta-analysis

BACKGROUND

The prognostic value of normal stress myocardial perfusion single-photon emission computed tomography (MPS) in patients with diabetes has only been evaluated in single-center studies of relatively limited sample size. We performed a meta-analysis of published studies, including diabetic patients with known or suspected coronary artery disease (CAD), to assess the predictive value for adverse cardiac ischemic events of normal stress MPS.

METHODS AND RESULTS

Studies published between January 1990 and December 2013 were identified by database search. We included studies using stress MPS to evaluate diabetic patients with known or suspected CAD and providing data on clinical outcomes of non-fatal myocardial infarction or cardiac death with a follow-up time ≥12 months. A total of 14 studies were finally included, recruiting 13,493 patients. The negative predictive value (NPV) for non-fatal myocardial infarction and cardiac death of normal MPS was 94.92% (95% confidence interval 93.67-96.05), during a weighted mean follow-up of 36.24 months, resulting in estimated event rate after a negative test equal to 5.08% (95% confidence interval 3.95-6.33). The corresponding annualized event rate after a negative test was 1.60% (95% confidence interval 1.21-2.04).

CONCLUSIONS

Stress MPS has a high NPV for adverse cardiac events in diabetic patients with known or suspected CAD leading to define a "relatively low-risk" patients category.

Impact of SPECT myocardial perfusion imaging on cardiac care

Single photon emission computed tomography myocardial perfusion imaging is a powerful modality for the assessment of coronary artery disease. It is useful in the diagnosis of CAD, prognostication of CAD and the determination of viability. It acts as guide for therapy and has the ability to assess effectiveness of therapy. The use of SPECT myocardial perfusion imaging has also been shown to be cost-effective compared to other modalities in cardiology.