Incremental prognostic value of myocardial perfusion single photon emission computed tomography in patients with diabetes mellitus

Prediction of 2-year major adverse cardiac events from myocardial perfusion scintigraphy and clinical risk factors

BACKGROUND

We developed CRAX2MACE, a new tool derived from clinical and SPECT myocardial perfusion imaging (MPI) variables, to predict 2-year probability of major adverse cardiac event (MACE) comprising death, hospitalized acute myocardial infarction or coronary revascularization.

METHODS

Consecutive individuals with SPECT MPI 2001-2008 had two-year MACE determined from population-based health services data. CRAX2MACE included age, sex, diabetes, recent cardiac hospitalization, pharmacologic stress, stress total perfusion deficit (TPD), ischemic (stress-rest) TPD, left ventricular ejection fraction and transient ischemic dilation ratio. Two-year event rates were classified as low (< 5%), moderate (5.0-9.9%), high (10-19.9%) and very high (20% or greater).

RESULTS

The study population comprised 3896 individuals for the development and 1946 for the validation subgroups with subsequent MACE in 589 (15.1%) and 272 (14.0%), respectively. CRAX2MACE, derived from the development subgroups, accurately stratified MACE risk in the validation subgroup (area under the receiver operating characteristics curve 0.79) with stepwise increase in the observed event rate with increasing predicted risk category (low, 2.3%; moderate, 5.5%; high, 18.8%; very high 33.2%; P-trend < 0.001).

CONCLUSIONS

A simple tool based upon clinical risk factors and MPI variables predicts 2-year cardiac events. Risk stratification between the low and very high groups was greater than tenfold.

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.

The application of artificial intelligence in nuclear cardiology

A decade of unprecedented progress in artificial intelligence (AI) has demonstrated a lot of interest in medical imaging research including nuclear cardiology. AI has a potential to reduce cost, save time and improve image acquisition, interpretation, and decision-making. This review summarizes recent researches and potential applications of AI in nuclear cardiology and discusses the pitfall of AI.

Comparing left ventricular mechanical dyssynchrony between diabetic and non-diabetic patients with normal gated SPECT MPI

The aim of this study was to employ phase analysis to diagnose left ventricular mechanical dyssynchrony (LVMD) in asymptomatic patients with diabetes mellitus type 2 and normal perfusion study which may help prevent diabetic cardiomyopathy. Ninety-three consecutive patients with known type 2 diabetes and 81 age- and gender- matched patients without diabetes who were candidates for SPECT-MPI were considered as the control group. The presence of LVMD as an possible risk factor for cardiomyopathy- was determined using phase analysis for each scan with quantitative gated SPECT (QGS) and corridor4DM (4DM) software. All outcomes such as phase bandwidth (PBW) and phase standard deviation (PSD) were compared between the two groups. A total of 174 patients were included in the study. There were no statistically significant difference regarding demographic factors between the two groups (P > 0.05). PBW showed statistically significant differences (increased in diabetics) between the control and diabetic patients (P < 0.05). Kruskal Wallis analysis revealed that as the duration of diabetes is prolonged, especially more than 15 years, the probability of LVMD is increased as well (P = 0.021). Fraction of asymptomatic diabetic patients with normal ejection fraction and gated SPECT MPI-especially those with prolonged diabetes- might have some degrees of LVMD. Phase analysis can detect this which in turn may prevent progress into heart failure.

Prognostic value of SPECT myocardial perfusion entropy in high-risk type 2 diabetic patients

PURPOSE

Risk stratification of patients with type 2 diabetes mellitus (T2D) remains suboptimal. We hypothesized that myocardial perfusion entropy (MPE) quantified from SPECT myocardial perfusion images may provide incremental prognostic value in T2D patients independently from myocardial ischemia.

METHODS

T2D patients with very high and high cardiovascular risk were prospectively included (n = 166, 65 ± 12 years). Stress perfusion defect was quantified by visual evaluation of SPECT MPI. SPECT MPI was also used for the quantification of rest and stress MPE. The primary end point was major adverse cardiac events (MACEs) defined as cardiac death, myocardial infarction (MI), and myocardial revascularization > 3 months after SPECT.

RESULTS

Forty-four MACEs were observed during a 4.6-year median follow-up. Significant differences in stress MPE were observed between patients with and without MACEs (4.19 ± 0.46 vs. 3.93 ± 0.40; P ≤ .01). By Kaplan-Meier analysis, the risk of MACEs was significantly higher in patients with higher stress MPE (log-rank P ≤ 01). Stress MPE and stress perfusion defect (SSS ≥ 4) were significantly associated with the risk of MACEs (hazard ratio 2.77 and 2.06, respectively, P < .05 for both) after adjustment for clinical and imaging risk predictors as identified from preliminary univariate analysis. MPE demonstrated incremental prognostic value over clinical risk factors, stress test EKG and SSS as evidenced by nested models showing improved Akaike information criterion (AIC), reclassification (global continuous net reclassification improvement [NRI]: 63), global integrated discrimination improvement (IDI: 6%), and discrimination (change in c-statistic: 0.66 vs 0.74).

CONCLUSIONS

Stress MPE provided independent and incremental prognostic information for the prediction of MACEs in diabetic patients.

TRIAL REGISTRATION NUMBER

NCT02316054 (12/12/2014).

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.

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.

Non-Invasive Imaging in Diabetic Cardiomyopathy

There is increasing recognition of a specific diabetic cardiomyopathy beyond ischemic cardiomyopathy, which leads to structural and functional myocardial abnormalities. The aim of this review is to summarize the recent literature on diagnostic findings and prognostic significance of non-invasive imaging including echocardiography, nuclear imaging, computed tomography and cardiovascular magnetic resonance in diabetic cardiomyopathy.

Assessment of myocardial blood flow and coronary flow reserve with positron emission tomography in ischemic heart disease: current state and future directions

Positron emission tomography (PET) is a versatile imaging technology that allows assessment of myocardial perfusion, both at a spatially relative scale and also in absolute terms, thereby enabling noninvasive evaluation of myocardial blood flow (MBF) and coronary flow reserve (CFR). Assessment of MBF using FDA-approved PET isotopes, such as ⁸²Rb and ¹³N-ammonia, has been well validated, and several software packages are currently available, thereby allowing for MBF evaluation to be incorporated into routine workflow in contemporary nuclear laboratories. Incremental diagnostic and prognostic information provided with the knowledge of MBF has the potential for widespread applications. Improving the ability to identify the true burden of obstructive epicardial coronary stenoses and allowing for noninvasive assessment of coronary micro circulatory function can be achieved with MBF assessment. On the other hand, attenuated CFR has been shown to predict adverse cardiovascular prognosis in a variety of clinical settings and patient subgroups. With expanding applications of MBF, this tool promises to provide unique insight into the integrity of the entire coronary vascular bed beyond what is currently available with relative perfusion assessment. This review intends to provide an in-depth discussion of technical and clinical aspects of MBF assessment with PET as it relates to patients with ischemic heart disease.

Machine learning for prediction of all-cause mortality in patients with suspected coronary artery disease: a 5-year multicentre prospective registry analysis

Aims

Traditional prognostic risk assessment in patients undergoing non-invasive imaging is based upon a limited selection of clinical and imaging findings. Machine learning (ML) can consider a greater number and complexity of variables. Therefore, we investigated the feasibility and accuracy of ML to predict 5-year all-cause mortality (ACM) in patients undergoing coronary computed tomographic angiography (CCTA), and compared the performance to existing clinical or CCTA metrics.

Methods and results

The analysis included 10 030 patients with suspected coronary artery disease and 5-year follow-up from the COronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicenter registry. All patients underwent CCTA as their standard of care. Twenty-five clinical and 44 CCTA parameters were evaluated, including segment stenosis score (SSS), segment involvement score (SIS), modified Duke index (DI), number of segments with non-calcified, mixed or calcified plaques, age, sex, gender, standard cardiovascular risk factors, and Framingham risk score (FRS). Machine learning involved automated feature selection by information gain ranking, model building with a boosted ensemble algorithm, and 10-fold stratified cross-validation. Seven hundred and forty-five patients died during 5-year follow-up. Machine learning exhibited a higher area-under-curve compared with the FRS or CCTA severity scores alone (SSS, SIS, DI) for predicting all-cause mortality (ML: 0.79 vs. FRS: 0.61, SSS: 0.64, SIS: 0.64, DI: 0.62; P< 0.001).

Conclusions

Machine learning combining clinical and CCTA data was found to predict 5-year ACM significantly better than existing clinical or CCTA metrics alone.

Prognostic Value of Combined Clinical and Myocardial Perfusion Imaging Data Using Machine Learning

OBJECTIVES

This study evaluated the added predictive value of combining clinical information and myocardial perfusion single-photon emission computed tomography (SPECT) imaging (MPI) data using machine learning (ML) to predict major adverse cardiac events (MACE).

BACKGROUND

Traditionally, prognostication by MPI has relied on visual or quantitative analysis of images without objective consideration of the clinical data. ML permits a large number of variables to be considered in combination and at a level of complexity beyond the human clinical reader.

METHODS

A total of 2,619 consecutive patients (48% men; 62 ± 13 years of age) who underwent exercise (38%) or pharmacological stress (62%) with high-speed SPECT MPI were monitored for MACE. Twenty-eight clinical variables, 17 stress test variables, and 25 imaging variables (including total perfusion deficit [TPD]) were recorded. Areas under the receiver-operating characteristic curve (AUC) for MACE prediction were compared among: 1) ML with all available data (ML-combined); 2) ML with only imaging data (ML-imaging); 3) 5-point scale visual diagnosis (physician [MD] diagnosis); and 4) automated quantitative imaging analysis (stress TPD and ischemic TPD). ML involved automated variable selection by information gain ranking, model building with a boosted ensemble algorithm, and 10-fold stratified cross validation.

RESULTS

During follow-up (3.2 ± 0.6 years), 239 patients (9.1%) had MACE. MACE prediction was significantly higher for ML-combined than ML-imaging (AUC: 0.81 vs. 0.78; p < 0.01). ML-combined also had higher predictive accuracy compared with MD diagnosis, automated stress TPD, and automated ischemic TPD (AUC: 0.81 vs. 0.65 vs. 0.73 vs. 0.71, respectively; p < 0.01 for all). Risk reclassification for ML-combined compared with visual MD diagnosis was 26% (p < 0.001).

CONCLUSIONS

ML combined with both clinical and imaging data variables was found to have high predictive accuracy for 3-year risk of MACE and was superior to existing visual or automated perfusion assessments. ML could allow integration of clinical and imaging data for personalized MACE risk computations in patients undergoing SPECT MPI.

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.

Insulin resistance, endothelial function, angiogenic factors and clinical outcome in non-diabetic patients with chest pain without myocardial perfusion defects

Background

Patients with angina-like symptoms without myocardial perfusion scintigram (MPS)-verified abnormality may still be at risk for cardiovascular events. We hypothesized that insulin resistance could play a role in this population even without diagnosed diabetes. We further explored physiological and blood biomarkers, as well as global gene expression patterns that could be closely related to impaired glucose homeostasis to deepen our mechanistic understanding.

Methods

A total of 365 non-diabetic patients with suspected myocardial ischemia referred to MPS were enrolled and followed up regarding event-free survival with a median time of 5.1 years. All patients underwent endothelial function assessment by reactive hyperemic index (RHI) using EndoPAT and extensive biomarker analysis. Whole blood global gene expression pathway analysis was performed in a subset of patients.

Results

Homeostasis model assessment of insulin resistance (HOMA-IR) added independent prognostic value in patients without myocardial perfusion defects. In a multivariable analysis, HOMA-IR was inversely associated with low RHI. Furthermore, elevated HOMA-IR was associated with decreased levels of vascular endothelial growth factor D, stem cell factor and endocan as well as to increased level of interleukin-6. Global gene expression pathway analysis of whole blood cells showed that high HOMA-IR and impaired endothelial function were associated with upregulated pro-inflammatory pathways and down-regulated eukaryotic initiation factor-2 pathway.

Conclusions

Insulin resistance measured by HOMA-IR is associated with endothelial dysfunction and confers independent prognostic information in non-diabetic patients with chest pain without myocardial perfusion defects. Increased systemic pro-inflammatory state and decreased levels of pro-angiogenic vascular growth factors may be important underlying molecular mechanisms.

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.

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.

Atypical presentation of acute and chronic coronary artery disease in diabetics

In patients with diabetes mellitus, cardiovascular disease is the principal cause of mortality and chest pain is the most frequent symptom in patients with stable and acute coronary artery disease. However, there is little knowledge concerning the pervasiveness of uncommon presentations in diabetics. The symptomatology of acute coronary syndrome, which comprises both pain and non-pain symptoms, may be affected by traditional risk factors such as age, gender, smoking, hypertension, diabetes, and dyslipidemia. Such atypical symptoms may range from silent myocardial ischemia to a wide spectrum of non-chest pain symptoms. Worldwide, few studies have highlighted this under-investigated subject, and this aspect of ischemic heart disease has also been under-evaluated in the major clinical trials. The results of these studies are highly diverse which makes definitive conclusions regarding the spectrum of atypical presentation of acute and even stable chronic coronay artery disease difficult to confirm. This may have a significant impact on the morbidity and mortality of coronary artery disease in diabetics. In this up-to-date review we will try to analyze the most recent studies on the atypical presentations in both acute and chronic ischemic heart disease which may give some emphasis to this under-investigated topic.

Prognostic Value of Normal Perfusion but Impaired Left Ventricular Function in the Diabetic Heart on Quantitative Gated Myocardial Perfusion SPECT

PURPOSE

This study aimed at identifying the predictive parameters on quantitative gated myocardial perfusion single-photon emission computed tomography (QG-SPECT) in diabetic patients with normal perfusion but impaired function.

METHODS

Among the 533 consecutive diabetic patients, 379 patients with normal perfusion on rest Tl-201/dipyridamole-stress Tc-99m sestamibi Gated SPECT were enrolled. Patients were grouped into those with normal post-stress left ventricular function (Group I) and those with impaired function (EF <50 or impaired regional wall motion, Group II). We investigated cardiac events and cause of death by chart review and telephone interview. Survival analysis and Cox proportional hazard model analysis were performed.

RESULTS

Between the Group I and II, cardiac events as well as chest pain symptoms, smoking, diabetic complications were significantly different (P < 0.05). On survival analysis, event free survival rate in Group II was significantly lower than in Group I (P = 0.016). In univariate Cox proportional hazard analysis on overall cardiac event, Group (II over I), diabetic nephropathy, summed motion score (SMS), summed systolic thickening score (STS), numbers of abnormal segmental wall motion and systolic thickening predicted more cardiac events (P < 0.05). Multivariate analysis showed that STS was the only independent predictor cardiac event.

CONCLUSION

The functional parameter, especially summed systolic thickening score on QG-SPECT had prognostic values, despite normal perfusion, in predicting cardiac events in diabetic patients, and QG-SPECT provides clinically useful risk stratification in diabetic patients with normal perfusion.

Warranty period of normal stress myocardial perfusion imaging in diabetic patients: a propensity score analysis

BACKGROUND

We evaluated the relationship between diabetes and temporal characteristics of cardiac risk at long-term follow-up in a propensity score-matched cohort of diabetic and non-diabetic patients with normal stress myocardial perfusion single-photon emission computed tomography (MPS).

METHODS AND RESULTS

We studied 828 consecutive patients with suspected or known coronary artery disease and normal perfusion at stress MPS. To account for differences in baseline characteristics between diabetics and non-diabetics, we created a propensity score-matched cohort considering clinical variables and stress type. After matching, clinical characteristics were comparable in 260 diabetic and 260 non-diabetic patients. All patients were followed for at least 1 year (median 53 months). End-point events were cardiac death or nonfatal myocardial infarction. At Cox analysis, diabetes (hazard ratio 3.9, P < .01) and post-stress left ventricular ejection fraction (LVEF) ≤45% (hazard ratio 4.1, P < .01) were independent predictors of events. At parametric analysis, non-diabetic patients with post-stress LVEF >45% remained at low risk for the entire length of follow-up, while the highest probability of events and the major risk acceleration was observed in patients with diabetes and post-stress LVEF ≤45%.

CONCLUSIONS

After a normal stress MPS, diabetic patients are at higher risk for cardiac events than non-diabetic subjects also after balancing clinical characteristics and stress type by propensity score analysis. The warranty period of a normal stress MPS varies according to diabetic status and post-stress LVEF.

Prognostic value of normal stress echocardiography in obese patients

BACKGROUND

Chest pain is a common problem in obese patients. Because of the body habitus, the results of noninvasive evaluation for CAD may be limited in this group.

METHODS

We reviewed the records of 1446 consecutive patients who had undergone clinically indicated stress echocardiography (SE). We compared major adverse cardiac events (MACE; myocardial infarction, cardiac intervention, cardiac death, subsequent hospitalization for cardiac events, and emergency department visits) at 1 year in normal weight, overweight, and obese subjects with normal SE.

RESULTS

Excluding patients with an abnormal and indeterminate SE and those who were lost to follow-up, a retrospective analysis of 704 patients was performed. There were 366 obese patients (BMI ≥ 30), 196 overweight patients (BMI 25-29.9), and 142 patients with normal BMI (18.5-24.9). There was no MACE in the groups at 1-year follow-up after a normal SE.

CONCLUSIONS

In obese patients including those with multiple risk factors and symptoms concerning for cardiac ischemia, stress echocardiography is an effective and reliable noninvasive tool for identifying those with a low 1-year risk of cardiac events.

Evaluating gender differences in prognosis following SPECT myocardial perfusion imaging among patients with diabetes and known or suspected coronary disease in the modern era

BACKGROUND

Previous data suggested that diabetic women were at greater risk for future cardiac events than diabetic men. Increasing awareness of coronary artery disease (CAD) in women and advances in the management of CAD may have changed this paradigm.

OBJECTIVE

To investigate gender differences in prognosis among patients with diabetes who were clinically referred for single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI).

METHODS

Patients with diabetes undergoing SPECT-MPI from 1996 to 2006 were followed for 5 years or until cardiac death or non-fatal myocardial infarction. Clinical characteristics and nuclear parameters were compared with χ (2) and t tests. Multivariable Cox regression controlled for baseline differences and tested the impact of gender on survival.

RESULTS

A total of 4,628 SPECT-MPI patients with diabetes (50% women, mean age 63 ± 12 years) were analyzed. There were 380 events, with rates higher in men (10% vs 7%, P < .001). Patients of either gender with abnormal scans had higher event rates than patients with normal scans. There were fewer cardiac events in diabetic females with no known CAD and normal scans compared to similar males (P = .044). However, diabetic males and females with known CAD had similar event rates for all degrees of perfusion abnormalities. Only age, history of heart failure, nuclear perfusion defect, and LVEF predicted survival; gender did not. LVEF ≤ 50% had the strongest association with cardiac events (hazard ratio = 2.518, 95% confidence interval, 1.922-3.298).

CONCLUSION

Cardiovascular outcomes among patients with diabetes, regardless of a history of CAD, were similar in women and men. The size and severity of stress-induced perfusion abnormalities predicted outcomes equally in both genders.

Myocardial Perfusion SPECT Utility in Predicting Cardiovascular Events Among Indonesian Diabetic Patients

Background:

Indonesia has the fourth largest number of diabetes patients after India, China and the USA. Coronary artery disease (CAD) is the most common cause of death in diabetic patients. Early detection and risk stratification is important for optimal management. Abnormal myocardial perfusion imaging (MPI) is an early manifestation in the ischemic cascade. Previous studies have demonstrated the use of MPI to accurately diagnose obstructive CAD and predict adverse cardiac events. This study evaluated whether MPI predicts adverse cardiac event in an Indonesian diabetic population.

Method:

The study was undertaken in a consecutive cohort of patients with suspected or known CAD fulfilling entry criteria. All had adenosine stress MPI. The end point was a major adverse cardiac event (MACE) defined as cardiac death or nonfatal myocardial infarction (MI).

Results:

Inclusion and exclusion criteria were satisfied by 300 patients with a mean follow-up of 26.7 ± 8.8 months. The incidence of MACEs was 18.3% among diabetic patients, versus 9% in the non-diabetic population (p < 0.001). A multivariable Cox proportional hazard model demonstratedin dependent predictors for a MACE as abnormal MPI [HR: 9.30 (3.01 – 28.72), p < 0.001], post stress left ventricular ejection fraction (LVEF) ≤30% [HR:2.72 (1.21 – 6.15), p = 0.016] and the patients diabetic status [HR:2.28 (1.04 – 5.01), p = 0.04]. The Kaplan Meier event free survival curve constructed for the different subgroups based on the patients’ diabetic status and MPI findings demonstrated that diabetic patients with an abnormal MPI had the worst event free survival (log rank p value < 0.001).

Conclusions:

In an Indonesian population with suspected or known CAD abnormal adenosine stress MPI is an independent and potent predictor for adverse cardiovascular events and provides incremental prognostic value in cardiovascular risk stratification of patients with diabetes.

Risk stratification among diabetic patients undergoing stress myocardial perfusion imaging

BACKGROUND

Previous studies have suggested that diabetic patients undergoing single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) are at greater risk for cardiac events than non-diabetic patients with both normal and abnormal imaging results. However, the impact of stress modality on outcomes in this patient group has not been examined.

METHODS

The data on all patients undergoing exercise stress or vasodilator stress SPECT MPI from 1996 to 2005 were reviewed. After excluding patients based on our predefined criteria, we subcategorized the study population into diabetic patients and non-diabetic patients. Among the diabetic patients, we identified patients with known coronary artery disease (CAD) and no known CAD. All studies were interpreted using the 17-segment ASNC model. The presence, extent, and 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. The annualized cardiac event rate including cardiac death and non-fatal myocardial infarction was calculated over a mean follow-up period of 2.4 ± 1.4 years with a maximum of 6 years.

RESULTS

The cardiac event rate was statistically significantly lower in diabetic patients undergoing exercise stress MPI when compared to the diabetic patients undergoing pharmacological stress MPI across all three perfusion categories (1.3% vs 3.4%, 2.3% vs 5.7%, 4.2% vs 10.7%, respectively). Diabetic patients with no known CAD, who underwent exercise stress MPI had significantly lower cardiac events across all three perfusion categories as compared to the remainder of the diabetic population. Ability to perform exercise stress test was the strongest multivariate predictor of favorable outcome, whereas ejection fraction < 50%, abnormal perfusion imaging on SPECT MPI, and increasing age stood out as independent predictors of adverse outcome in the diabetic patients. Within the abnormal perfusion category, the annualized cardiac event rate among patients undergoing exercise stress SPECT MPI was not statistically different between the diabetic and non-diabetic cohorts.

CONCLUSION

Diabetic patients undergoing exercise SPECT MPI have a significantly better prognosis than those undergoing pharmacological stress, more similar to patients without diabetes. In patients with diabetes exercise stress test MPI identifies low risk patients and provides precise risk stratification.

Prognostic value of myocardial perfusion imaging for cardiovascular events among asymptomatic Japanese patients with type 2 diabetes and mild renal dysfunction

BACKGROUND

Diabetes is frequently accompanied by chronic kidney disease, and both diabetes and chronic kidney disease are risk factors for ischemic heart disease; however, cardiac risk among diabetic patients with mild renal dysfunction has not been analyzed in detail. The present study investigates how myocardial perfusion imaging (MPI) contributes to the risk stratification of diabetic patients with mild renal dysfunction who are asymptomatic for cardiac diseases.

PATIENTS AND METHODS

Among 513 asymptomatic patients with type 2 diabetes in the Japanese Assessment of Cardiac Events and Survival Study 2 (J-ACCESS) database, we selected 286 with estimated glomerular filtration rates (eGFR) of at least 45 ml/min/1.73 m and assigned them to groups on the basis of eGFR of at least 60 without (group A, n=66) or with microalbuminuria or eGFR 45 to less than 60 (group B, n=220). The 3-year incidence of cardiac events and the value of MPI were evaluated.

RESULTS

Cardiac events developed in 1.52 and 4.55% of patients in groups A and B, respectively. Event-free survival did not differ according to summed stress scores in group A but was significantly lower among patients with summed stress scores of at least 9 in group B.

CONCLUSION

Routine MPI might be useful for stratifying risk among diabetic patients with mild renal dysfunction but is unnecessary for those with good renal function.

Major adverse cardiac events and the severity of coronary atherosclerosis assessed by computed tomography coronary angiography in an outpatient population with suspected or known coronary artery disease

PURPOSE

To investigate the predictive value of 64-slice computed tomography coronary angiography (CTCA) for major adverse cardiac events (MACEs) in patients with suspected or known coronary artery disease (CAD).

MATERIALS AND METHODS

Seven hundred and sixty-seven consecutive patients (496 men, age 62±11 y) with suspected or known heart disease referred to an outpatient clinic underwent 64-slice CTCA. The patients were followed for the occurrence of MACE (ie, cardiac death, nonfatal myocardial infarction, unstable angina).

RESULTS

Eleven thousand five hundred and sixty-four coronary segments were assessed. Of these, 178 (1.5%) were not assessable because of insufficient image quality. Overall, CTCA revealed the absence of CAD in 219 (28.5%) patients, nonobstructive CAD (coronary plaque ≤50%) in 282 (36.8%) patients, and obstructive CAD in 266 (34.7%) patients. A total of 21 major cardiac events (4 cardiac deaths, 12 myocardial infarctions, and 5 unstable angina) occurred during a mean follow-up of 20 months. One noncardiac death occurred. Seventeen events occurred in the group of patients with obstructive CAD, and 4 events occurred in the group with nonobstructive CAD. The event rate was 0% among patients with normal coronary arteries at CTCA. In multivariate analysis, the presence of obstructive CAD and diabetes were the only independent predictors of MACE.

CONCLUSIONS

Coronary plaque evaluation by CTCA provides an independent prognostic value for the prediction of MACE. Patients with normal CTCA findings have an excellent prognosis at follow-up.

Relationship between vascular stiffness and stress myocardial perfusion imaging in asymptomatic patients with diabetes

Purpose

Vascular stiffness may potentially be used as a screening tool to identify asymptomatic patients with diabetes with abnormal myocardial perfusion. The purpose of this study was therefore to determine the association between vascular stiffness, measured in term of pulse wave velocity (PWV) and augmentation index (AIx), and abnormal myocardial perfusion imaging (MPI) in asymptomatic patients with diabetes.

Methods

Prospectively, 160 asymptomatic patients with diabetes (mean age 51 years, 87 men) underwent MPI with adenosine stress. The summed stress score (SSS) was determined in each patient according to a 17-segment and five-point score. Abnormal MPI (SSS ≥3) was classified as moderate (SSS 3–7) or severe (SSS ≥8) MPI defects. Using applanation tonometry, the carotid–femoral PWV and the radial AIx corrected to 75 beats per minute were determined noninvasively.

Results

MPI was abnormal in 61 patients (38%), with severe MPI defects in 22 patients (14%). Mean PWV increased with deteriorating MPI from 8.4 ± 2.2 m/s in normal MPI to 9.0 ± 2.2 m/s in moderate MPI defects (p = 0.11) and to 11.1 ± 2.5 m/s in severe MPI defects (p < 0.01). Likewise, mean AIx increased from 18.4 ± 13.4% to 19.4 ± 10.7% (p = 0.66) and to 25.4 ± 9.0% (p = 0.03). After adjustment for age and other risk factors, PWV remained a significant predictor of severe MPI defects (p = 0.01, OR 1.50, 95% CI 1.11–2.00), whereas AIx was no longer significant (p = 0.20).

Conclusion

Vascular stiffness measured by PWV is associated with severe MPI defects in asymptomatic patients with diabetes.

Correlation of the severity of diabetic retinopathy and the heart muscle perfusion in patients with type 2 diabetes

OBJECTIVE

The objective was to investigate whether microvascular disturbances in patients with type 2 diabetes (DM) as defined by retinal examination predict the existence of macrovascular disturbances found on radioisotopic perfusion examinations of the heart muscle.

MATERIALS AND METHODS

A total of 100 patients with type 2 DM and an additional cardiovascular risk factor were enrolled in the study. All patients underwent comprehensive ophthalmologic examination, including fundus color photography and fluorescein angiography, and were divided into three groups: group 1 (NoDR): met the inclusion criteria but had no diabetic retinopathy; group 2 (NPDR): had signs of nonproliferative diabetic retinopathy; group 3 (PDR): had signs of preproliferative or proliferative diabetic retinopathy. After collecting general medical history and clinical data, patients underwent heart muscle perfusion studies. All patients followed a 48-h protocol heart muscle perfusion examination in the rest state as well as after the standardized exercise test. Single photon emission computed tomography examination was performed.

RESULTS

In the PDR group, the impairment of the heart muscle perfusion at stress and rest was more frequent than in the NPDR and NoDR groups. Analysis of the heart muscle perfusion results for the three groups showed a significant relationship with the severity of microvascular complications observed in eye fundus examinations.

CONCLUSIONS

Comprehensive ophthalmologic assessment of the progression of diabetic retinopathy in patients with type 2 DM may be an indicator of heart muscle perfusion disturbance.

Multimodality imaging in diabetic heart disease

Diabetic heart disease is currently defined as left ventricular dysfunction that occurs independently of coronary artery disease and hypertension. Its underlying etiology is likely to be multifactorial, acting synergistically together to cause myocardial dysfunction. Multimodality cardiac imaging, such as echocardiography, nuclear, computed tomography, and magnetic resonance imaging, can provide invaluable insight into different aspects of the disease process, from imaging at the cellular level for altered myocardial metabolism to microvascular and endothelial dysfunction, autonomic neuropathy, coronary atherosclerosis, and finally, interstitial fibrosis with scar formation. Furthermore, cardiac imaging is pivotal in diagnosing diabetic heart disease. Thus, the aim of the present review is to illustrate the role of multimodality cardiac imaging in elucidating the underlying pathophysiologic mechanisms of diabetic heart disease.

Duration and type of therapy for diabetes: impact on cardiac risk stratification with stress electrocardiographic-gated SPECT myocardial perfusion imaging

BACKGROUND

Stress electrocardiogram(ECG)-gated single photon emission computed tomography (SPECT) imaging is highly effective in risk stratification of diabetic patients for adverse cardiac events. While patients with diabetes are predisposed to a more aggressive progression of vascular disease, the impact of its duration and type of therapy on risk stratification are unknown.

METHODS

From the Hartford Hospital Nuclear Cardiology clinical database, 886 diabetic patients who underwent exercise or pharmacologic stress ECG-gated SPECT were identified, with complete follow-up regarding the occurrence of adverse cardiac events and information regarding the duration of diabetes and the type of therapy (insulin vs oral medication only) at the time of testing. Images were interpreted using the American College of Cardiology/ASNC standard 17-segment scoring model.

RESULTS

Of the 886 diabetic patients, 98 (11%) suffered cardiac death or non-fatal myocardial infarction during follow-up (2.5 ± 1.6 years). A receiver operator characteristics curve demonstrated that diabetes ≥10 years in duration provided the maximal sum of sensitivity and specificity for the prediction of adverse cardiac outcomes. Multivariate analysis identified the following as independent predictors of adverse outcome: Post-stress ejection fraction (EF) <40% (P = .001), age (P = .004), insulin therapy (P = .031), diabetes duration >10 years (P = .038), summed stress score (SSS) >8 (P = .046). For patients with an SSS >8, diabetes duration and type of therapy significantly enhanced risk stratification. Similar findings emerged for patients with a post-stress EF <40%.

CONCLUSION

For diabetic patients undergoing stress ECG-gated SPECT myocardial perfusion imaging, disease duration and type of therapy provide independent and incremental prognostic information. Integration of these variables with this cardiovascular imaging technology significantly enhances cardiac risk stratification.

Diabetes: prognostic value of CT coronary angiography--comparison with a nondiabetic population

PURPOSE

To evaluate the prognostic value of multidetector computed tomographic (CT) coronary angiography in a diabetic population known to have or suspected of having coronary artery disease (CAD) compared with that in nondiabetic individuals.

MATERIALS AND METHODS

Institutional review board approval and patient informed consent were obtained. Three hundred thirteen patients with type 2 diabetes mellitus (DM) and 303 patients without DM underwent unenhanced 64-detector row CT, at which a calcium score was obtained, followed by CT angiography. Multidetector CT coronary angiograms were retrospectively classified as normal, showing nonobstructive CAD (<or=50% luminal narrowing), or showing obstructive CAD (>50% luminal narrowing). During follow-up after CT angiography, major events (cardiac death, nonfatal myocardial infarction, and unstable angina requiring hospitalization) and total events (major events plus coronary revascularizations) were recorded for each patient. Cox proportional hazards analysis and Kaplan-Meier analysis were used to compare survival rates.

RESULTS

In the group of 313 patients with DM, there were 213 men, and the mean age was 62 years +/- 11 (standard deviation). In the group of 303 patients without DM, there were 203 men, and the mean age was 63 years +/- 11. The mean number of diseased segments (5.6 vs 4.4, P = .001) and the rate of obstructive CAD (51% vs 37%, P < .001) were higher in patients with DM. Patients were followed up for a mean of 20 months +/- 5.4 (range, 6-44 months). At multivariate analysis, DM (P < .001) and evidence of obstructive CAD (P < .001) were independent predictors of outcome. Obstructive CAD remained a significant multivariate predictor for both patients with DM and patients without DM. In both patients with DM and patients without DM with absence of disease, the event rate was 0%. The event rate increased to 36% in patients without DM but with obstructive CAD and was highest (47%) in patients with DM and obstructive CAD.

CONCLUSION

In both patients with DM and patients without DM, multidetector CT coronary angiography provides incremental prognostic information over baseline clinical variables, and the absence of atherosclerosis at CT coronary angiography is associated with an excellent prognosis. Multidetector CT coronary angiography might be a clinically useful tool for improving risk stratification in both patients with DM and patients without DM.

Identification of asymptomatic type 2 diabetes mellitus patients with a low, intermediate and high risk of ischaemic heart disease: is there an algorithm?

AIMS/HYPOTHESIS

The leading cause of death in type 2 diabetes is cardiovascular disease (CVD). We examined the prevalence of myocardial ischaemia in type 2 diabetes patients and tried to establish an algorithm to identify patients with a high risk of ischaemic heart disease.

METHODS

Type 2 diabetes patients who had no known or suspected CVD, and had been referred consecutively to a diabetes clinic for the first time (n=305; age 58.6+/-11.3 years; diabetes duration 4.5+/-5.3 years) were screened for myocardial ischaemia using myocardial perfusion scintigraphy (MPS).

RESULTS

The univariate predictors of myocardial ischaemia were: atypical or typical angina pectoris, two or more traditional risk factors for CVD, BMI >32 kg/m2, systolic blood pressure >140 mmHg, HbA1c >8.5%, high-sensitivity C-reactive protein >4.0 mg/l, N-terminal pro-brain natriuretic peptide >300 pg/ml, left atrial volume index >32 ml/m2, left ventricular ejection fraction <50%, and carotid and peripheral arterial disease. The algorithm identified low (n=96), intermediate (n=65) and high risk groups (n=115), in which the prevalence of myocardial ischaemia was 15%,23% and 43%, respectively. Overall the algorithm reduced the number of patients referred to MPS from 305 to 144.However, the sensitivity and specificity of the algorithm was just 68% and 62%, respectively.

CONCLUSIONS/INTERPRETATION

Our algorithm was able to stratify which patients had a low, intermediate or high risk of myocardial ischaemia based on MPS. However, the algorithm had low sensitivity and specificity, combined with high cost and time requirements.

TRIAL REGISTRATION

clinicaltrials.gov NCT00298844 FUNDING: The study was funded by the Danish Cardio vascular Research Academy (DaCRA), The Danish Diabetes Association and The Danish Heart Foundation.

Perspectives of nuclear diagnostic imaging in diabetic cardiomyopathy

Diabetic cardiomyopathy is a ventricular dysfunction in the absence of coronary artery disease, valvular or hypertensive heart disease. The mechanisms underlying diabetic cardiomyopathy may involve metabolic disturbances, myocardial fibrosis, small vessel disease, microcirculation abnormalities, cardiac autonomic neuropathy and insulin resistance. Diagnostic problems emerge because no specific disease pattern characterizes the disease and because there may be coexistence in diabetes of coronary artery disease and hypertension as independent but compounding causes of biochemical, anatomical and functional alterations impairing cardiac function. In this paper we will review the role of nuclear imaging today, concentrating on the diagnostic capabilities of radionuclide ventriculography, to study the effect of insulin resistance and, more extensively, gated-single photon emission computed tomography with Tc-99m labelled agents. A broad analysis will be dedicated to: 1) positron emission tomography using perfusion agents, with the potential to quantify resting and stress blood flow and coronary flow reserve; 2) radionuclide procedures evaluating aerobic and anaerobic cardiac metabolism; and 3) cardiac neurotransmission imaging, studying the autonomic neuropathy.

Diagnostic and prognostic testing to evaluate coronary artery disease in patients with diabetes mellitus

Coronary artery disease (CAD) continues to be the most common cause of morbidity and mortality in patients with diabetes mellitus (DM). In recent years, the strategies for treatment of CAD in DM have undergone much evolution. Currently, all patients with DM, regardless of symptoms or diagnosed CAD, are treated aggressively for CAD risk factor reduction. In this clinical climate, the ability to specifically identify patients with disease that will benefit from more aggressive and invasive therapies remains a challenge. In this article we review the current literature on diagnostic and prognostic utility of conventional non-invasive modalities for assessment of CAD in patients with DM, as well as on novel and emerging methods for CAD risk stratification.

Increased carotid intima-media thickness as a predictor of the presence and extent of abnormal myocardial perfusion in type 2 diabetes

OBJECTIVE

Identification of asymptomatic patients with type 2 diabetes at increased risk for coronary artery disease (CAD) remains a challenge. We evaluated the potential of carotid intima-media thickness (CIMT) for prediction of abnormal myocardial perfusion in this population.

RESEARCH DESIGN AND METHODS

CIMT and SPECT myocardial perfusion imaging were assessed in 98 asymptomatic patients with type 2 diabetes. An increased CIMT was defined as > or =75th percentile of reference values. RESULTS Increased CIMT was an independent predictor of the extent of abnormal perfusion (P < 0.001). In patients with increased CIMT as compared with patients with normal CIMT, abnormal perfusion (75 vs. 9%) and severely abnormal perfusion (28 vs. 3%) were observed more frequently.

CONCLUSIONS

Increased CIMT was significantly related to the presence and extent of abnormal myocardial perfusion. Assessment of CIMT may be useful to identify asymptomatic patients with type 2 diabetes at higher risk for CAD.

The evolving roles of nuclear cardiology

The use of cardiac imaging modalities has grown steadily, and cardiac nuclear studies constitute a large part of this number. Nuclear Cardiology is often mistakenly considered a synonym of myocardial perfusion imaging (MPI), but has broader applications, including metabolic imaging, innervation imaging, among other technologies. MPI has been a powerful diagnostic and prognostic tool in the assessment of patients for known or suspected CAD for decades, and is now increasingly used for the evaluation of the anti-ischemic effects of various therapies, according to changes in left ventricular perfusion defect size defined by sequential MPI. Neuronal dysfunction identified with iodine-123-metaiodobenzylguanidine may give information on prognosis in different disease conditions, such as after myocardial infarction, in diabetes and dilated cardiomyopathy. Molecular imaging may identify the predominant cellular population in the atherosclerotic plaque and help predict the likelihood of clinical events. Therefore, although its usefulness is well established, Nuclear Cardiology remains a moving science, whose roles keep in pace with evolving clinical needs and expectations.

Myocardial ischemia, carotid, and peripheral arterial disease and their interrelationship in type 2 diabetes patients

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in type 2 diabetes mellitus (T2DM) patients. We examined the relationship between CVD in different vascular territories.

METHODS

T2DM patients without known or suspected CVD (n = 305) referred consecutively to a diabetes clinic for the first time and age-matched nondiabetic reference subjects (n = 40) were screened for myocardial ischemia, carotid, and peripheral arterial disease by means of myocardial perfusion scintigraphy, carotid artery ultrasonography, and peripheral ankle and toe systolic blood pressure measurements.

RESULTS

In the T2DM patients, the prevalence of myocardial ischemia, carotid, and peripheral arterial disease was 30%, 42%, and 15%, respectively, almost three times higher than in the reference subjects (P = 0.007, P = 0.001, and P = 0.09, respectively). T2DM patients with myocardial ischemia, carotid, or peripheral arterial disease had a significantly increased risk of CVD in other vascular territories as well (OR: 1.99, 2.09, and 3.09, respectively). However, 40%, 52%, and 22% of the T2DM patients with myocardial ischemia, carotid, or peripheral arterial disease demonstrated exclusively this particular type of CVD manifestation.

CONCLUSIONS

In T2DM patients, signs of CVD in one vascular territory carry a significantly increased risk of CVD in other territories, although many patients only presented one manifestation.

Pre-exercise cardiology screening guidelines for asymptomatic patients with diabetes

Coronary heart disease is a major cause of morbidity and mortality in persons with diabetes mellitus. Exercise is an important cornerstone in the treatment and management of diabetes but is also associated with a heightened risk of sudden cardiac death in those with occult coronary heart disease. Before beginning a physical activity program that involves anything greater than moderate intensity exercise, consideration should be given to screening asymptomatic persons with diabetes for silent myocardial ischemia.

Prognostic value of myocardial perfusion scintigraphy in type 2 diabetic patients with mild, stable angina pectoris

AIM

To determine the prognostic value of reversible myocardial perfusion defects on myocardial perfusion scintigraphy (MPS) in patients with type 2 diabetes mellitus and mild anginal complaints.

METHODS AND RESULTS

In the MERIDIAN trial, patients with diabetes mellitus type 2, stable, mild anginal symptoms (Canadian Cardiovascular Society classification (CCS) I-II/IV) and reversible perfusion defects were randomized to either continued pharmacological treatment or early invasive treatment. In this sub analysis, the severity of the myocardial perfusion defect was related to the occurrence of cardiac death and non-fatal myocardial infarction, in 319 patients (63% male, 65 +/- 9 years). During follow-up (2.2 +/- 0.6 years), 14 patients had a cardiac event: 3 in 171 patients without myocardial ischemia and 11 in 148 patients with myocardial ischemia. Annual event rates rose from 0.8% to 5.8% with increasing severity of myocardial ischemia. Multivariable analysis identified the presence of severe myocardial ischemia (hazard ratio (HR) 5.45, 95%CI 1.89-15.71) and insulin use (HR 4.00, 95%CI 1.25-12.75) as independent predictors of cardiac events.

CONCLUSIONS

Type 2 diabetics with mild anginal symptoms with no or moderate myocardial ischemia have a low annual cardiac event rate. In patients with severe myocardial ischemia event rate increased 3-6 fold.