The role of non-invasive imaging in the risk stratification of asymptomatic diabetic subjects

Non-traditional risk factors for coronary calcification and its progression in patients with type 2 diabetes: The impact of postprandial glycemia and fetuin-A

Objective

This study was performed to assess the impact of risk factors on the presence and progression of coronary calcification in patients with type 2 diabetes.

Methods

We prospectively enrolled 45 patients without cardiovascular or kidney disease. Coronary calcification was measured with multidetector computed tomography at baseline and 18 months. We also measured blood pressure; body mass index; serum levels of calcium, phosphate, and 25-hydroxyvitamin D; mineral bone density; and levels of alkaline phosphatase, parathormone, fetuin-A, high-sensitivity C-reactive protein, fibrinogen, albumin, homocysteine, lipids, HbA1c, and average preprandial and postprandial blood glucose at 18 months. Information about severe hypoglycemia and smoking was recorded. Spearman’s correlation coefficients were calculated. Multiple linear regression was used for the multivariate analysis.

Results

The median baseline calcium score was 63, and that at 18 months was 100. In the univariate analysis, albumin was significantly correlated with the baseline calcium score. Fetuin-A and postprandial glycemia were correlated with calcium score progression. In the multivariate model, postprandial glycemia and fetuin-A were independently associated with calcium score progression.

Conclusions

Fetuin-A and postprandial glycemia influence coronary calcification progression in patients with type 2 diabetes. The absence of some correlations could be due to pharmacological treatments for cardiovascular risk reduction.

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.

Screening for asymptomatic coronary artery disease in patients with type 2 diabetes mellitus

Diabetes is a very frequent disease and it is estimated that its prevalence will continuously increase during the next two decades. The arteriosclerotic process in diabetic patients progresses earlier and more diffusely, and it is more accelerated in the diabetic patient than in the overall population. In diabetic subjects, acute myocardial infarction (AMI) and stroke are the leading causes of death, but the presence of arterial disease is not always detected before the development of the acute arterial event. Several times, AMI is asymptomatic or present nonspecific symptoms, and it is the initial form of presentation of coronary artery disease causing an important delay in initiating cardiovascular treatment in these patients. The purpose of this review article is to discuss how to screen and early diagnose the presence of coronary artery disease in asymptomatic diabetic patients, based on new available diagnostic resources. Currently, the most recommended technique used for screening coronary artery disease in these patients is myocardial perfusion scintigraphy or stress echocardiography because of greater sensitivity and specificity in relation to the exercise test. However, technological advances have enabled the development of new imaging diagnostic methods that are less invasive than conventional coronary angiography, and which gradually gain importance in the diagnosis of coronary artery disease as they show higher effectiveness with lower invasiveness and risk. Arch Endocrinol Metab. 2016;60(2):143-51.

Relationship between glycemic control and coronary artery disease severity, prevalence and plaque characteristics by computed tomography coronary angiography in asymptomatic type 2 diabetic patients

Evaluate whether glycemic control in type 2 diabetes (DM2) asymptomatic for coronary artery disease (CAD) affects not only the presence and magnitude of CAD but also the characteristics of plaque vulnerability using multidetector row computed coronary tomography (MDCT). Acute coronary syndrome (ACS) is frequently observed in asymptomatic DM2 patients. Positive vessel remodeling (PR) and low-attenuation plaques (LAP) identified by MDCT have been demonstrated to be characteristics of subsequent culprit lesions of ACS. However, little is known regarding plaque characteristics in asymptomatic diabetic patients and their relationship with glycemic control. Ninety asymptomatic DM2 patients, aged 40-65 years old, underwent MDCT. The presence of atherosclerotic obstruction, defined as coronary stenosis ≥50 %, and plaque characteristics were compared between two groups of patients with A1c < 7 and A1c ≥ 7 %. Of the 90 patients, 38 (42.2 %) presented with coronary atherosclerotic plaques, 11 had A1c < 7 % and 27 had A1c ≥ 7 % (p = 0.0006). Fourteen patients had significant lumen obstruction higher than 50 %: 3 in the A1c < 7 % group and 11 in the A1c ≥ 7 % group (p = 0.02). Non-calcified plaque was more prevalent in the A1c ≥ 7 % group (p = 0.005). In eleven patients, the simultaneous presence of two vulnerability plaque characteristics (PR and LAP) were observed more frequently in the A1c ≥ 7 group (n = 8) than in the A1c < 7 group (n = 3) (p = 0.04). Asymptomatic DM2 patients with A1c ≥ 7 % have a higher frequency of CAD and a higher proportion of vulnerable atherosclerotic coronary plaque by MDCT compared to patients with DM2 with A1c < 7 in our study.

Value of Coronary Computed Tomography Angiography in Tailoring Aspirin Therapy for Primary Prevention of Atherosclerotic Events in Patients at High Risk With Diabetes Mellitus

Aspirin use for primary prevention in patients at high risk with diabetes mellitus (DM) is often recommended under the assumption that most patients with DM have coronary artery disease (CAD). However, not all patients may have CAD. The present study evaluated, in 425 patients at high risk with DM (without chest pain syndrome or a history of cardiac disease), the prevalence of CAD on coronary computed tomography angiography (CTA). Moreover, the association between the presence and number of traditional cardiovascular (CV) risk factors and CAD (on coronary CTA) was evaluated. The median coronary artery calcium score was 29 (interquartile range 0 to 298). On coronary CTA, 116 patients (27%) had no CAD (defined as <30% stenosis). Of the 309 patients (73%) with any CAD (≥30% stenosis), 35% had obstructive CAD (≥50% stenosis). The number of traditional CV risk factors was not associated with the presence of any CAD (≥30% stenosis; p = 0.18) or obstructive CAD (≥50% stenosis; p = 0.13). Hypertension was the only traditional CV risk factor associated with a higher frequency of any CAD (≥30% stenosis; odds ratio = 2.21, 95% CI 1.43 to 3.41, p <0.001) and obstructive CAD (≥50% stenosis; odds ratio 2.03, 95% CI 1.33 to 3.11, p = 0.001). In conclusion, in patients at high risk with DM without chest pain syndrome, any CAD was ruled out by coronary CTA in 27%, whereas 65% of the patients did not have obstructive CAD. The number of CV risk factors was not associated with the presence of CAD. Hypertension was the only traditional CV risk factor that was associated with a higher frequency of CAD. These observations support potential use of coronary CTA to tailor aspirin therapy in patients at high risk with DM.

Assessment of dipyridamole stress echocardiography for risk stratification of diabetic patients

BACKGROUND

Despite advances in medical therapy, cardiovascular disease, mainly coronary artery disease (CAD), remains the leading cause of mortality among patients with diabetes mellitus (DM). The objective of the present study was to assess the effectiveness of dipyridamole stress echocardiography in identify diabetic patients at high risk for cardiovascular events.

METHODS

Dipyridamole stress echocardiography was administered to 483 diabetic patients (294 women; mean age 63.41 ± 11.28 years) between July 2006 and December 2012.

RESULTS

Follow-up data were available for 264 patients (163 women; mean age 64.3 ± 10.5 years): 250 with a negative stress echocardiography and 14 with a positive stress echo. During a mean follow-up time of 18 ± 14 months, a cardiovascular event occurred in 18 (6.8%) patients, 12 (4.8%) in patients with a negative stress echo (n = 250) during a mean follow-up period of 20 ± 16 months and 6 (42%) in patients with positive stress echo (n = 14) during a mean follow-up of 13 ± 13 months. The positive and negative predictive values of stress echocardiography were 42% and 96% respectively. The accuracy value was 92%. A Cox regression model showed that CAD (hazard ratio [HR] 5.4, 95% confidence interval [CI] 1.9-15.4; p = 0.002) and positive stress echocardiography (HR 7.1, 95% CI 2.5-20.5; p < 0.001) were significant predictors of cardiovascular events.

CONCLUSIONS

For patients with diabetes, a negative dipyridamole stress echocardiogram predicts favorable outcome during the first year of follow-up. A new stress imaging test should be done after 12 months in diabetic patients.

[Percutaneous coronary intervention versus bypass surgery in patients with diabetes and multivessel coronary disease. Coronary revascularization after FREEDOM]

Is coronary revascularization required in a patient with chronic stable coronary artery disease or can optimized medical therapy (OMT) alone be a sufficient alternative? This question has been controversially discussed for non-diabetics as well as for diabetics since the COURAGE and BARI 2D trials. According to our present knowledge, a patient will benefit from coronary revascularization only when either a non-invasive test method, such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) myocardial scintigraphy, stress echocardiography or stress nuclear magnetic resonance imaging, can detect relevant, objective evidence of ischemia >10% of the left ventricular myocardium or when a pathological fractional flow reserve (FFR) <0.80 can be measured in an invasive procedure for an angiographically detectable coronary stenosis. If similar relevant ischemia can be non-invasively or invasively objectified in a patient with chronic stable multivessel coronary artery disease, the often controversially discussed question arises particularly in diabetics whether a percutaneous coronary intervention (PCI) with implantation of drug-eluting stents or coronary artery bypass surgery should be favored. The FREEDOM study (Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multivessel Disease), published in November 2012, was the first prospective randomized study to examine this issue in diabetic patients with multivessel coronary artery disease. Despite a higher rate of stroke in the surgical cohort, after an average follow-up time of 3.8 years a significant prognostic advantage in favor of bypass surgery was detected for a combined primary endpoint of all-cause mortality, nonfatal myocardial infarction and nonfatal stroke. Thus, in the new ESC guidelines on diabetes, pre-diabetes and cardiovascular diseases developed with the EASD of the European Society of Cardiology and published in 2013, coronary bypass surgery has a class I, level of evidence A recommendation for patients with diabetes mellitus, chronic stable multivessel coronary disease and a synergy between PCI with taxus and cardiac surgery (SYNTAX) score >22. The decision for or against a PCI/stent implantation or coronary bypass surgery in a diabetic patient with chronic stable multivessel coronary artery disease should therefore be made with the patient only after a detailed informed consent discussion and comprehensive explanation of both treatment options. In controversial cases, particularly with an equivocal SYNTAX score around 22, relevant comorbidities or anticipated method-specific complications, a one-stage ad hoc intervention during the diagnostic coronary angiography should be rejected in favor of a two-stage procedure with prior discussion of both treatment options in the heart team comprising noninvasive cardiologists, interventional cardiologists and cardiac surgeons.

Screening and treatment by the primary care provider of common diabetes complications

Diabetes is the leading cause of end-stage renal disease, blindness, and nontraumatic lower-limb amputation. The largest reductions in cardiovascular events are seen when multiple risk factors are addressed simultaneously. The benefit of aspirin as secondary prevention in patients with previous stroke or myocardial infarction has been well established. Regular, dilated eye examinations are effective in detecting sight-threatening diabetic retinopathy and have been shown to prevent blindness. The use of appropriate tools and clinical examination/inspection provides greater than 87% specificity in detecting diabetic peripheral neuropathy. Early treatment of risk factors, including hypertension, hyperglycemia, and dyslipidemia can delay or prevent diabetic nephropathy.

Post-stress left ventricular ejection fraction drop in patients with diabetes: a gated myocardial perfusion imaging study

BACKGROUND

To evaluate the relevance of stress-induced decrease in left ventricular ejection fraction (LVEF) in patients with type-2 diabetes.

METHODS

A total of 684 diabetic patients with available rest and post-stress gated myocardial perfusion single-photon emission computed tomography (MPS) data were enrolled. An automated algorithm was used to determine the perfusion scores using a 17-segment model. LVEF drop was considered significant if the post-stress LVEF was ≥5% below the rest value. Follow-up data were available in 587 patients that were followed for the occurrence of cardiac death, nonfatal myocardial infarction, or unstable angina requiring revascularization.

RESULTS

A post-stress LVEF drop ≥5% was observed in 167 (24%) patients. Patients with LVEF drop had higher summed stress score (p < 0.05), summed difference score (p < 0.001), and rest LVEF (p < 0.001) compared to patients without. Conversely, summed rest score, a measure of infarct size, was comparable between the two groups. At multivariable analysis, summed difference score and rest LVEF were independent predictors (both p < 0.001) of post-stress LVEF drop. Myocardial perfusion was abnormal in 106 (63%) patients with post-stress LVEF drop and in 296 (57%) of those without (p = 0.16). The overall event-free survival was lower in patients with post-stress LVEF drop than in those without (log rank χ2 7.7, p < 0.005). After adjusting for clinical data and MPS variables, the hazard ratio for cardiac events for post-stress LVEF drop was 1.52 (p < 0.01).

CONCLUSIONS

In diabetic patients stress-induced ischemia is an independent predictor of post-stress LVEF drop; however, a reduction in LVEF is detectable also in patients with normal perfusion. Finally, post-stress LVEF drop increases the risk of subsequent cardiac events in diabetic patients.

Coronary calcium score, albuminuria and inflammatory markers in type 2 diabetic patients: associations and prognostic implications

AIMS

To investigate the relationship of coronary artery calcium (CAC) scores with common carotid artery intima media thickness (CCA-IMT), albuminuria and inflammatory factors in type 2 diabetes.

METHODS AND RESULTS

128 asymptomatic type 2 diabetic patients, with at least one cardiovascular risk factor in addition to diabetes, were included in the study. CAC scores, carotid arteries plaque formation and CCA-IMT were assessed. The patients were followed for a mean period of 36.6 ± 3.3 months. Linear regression analysis identified the logarithmically transformed (Ln) albuminuria (β=0.32, P=0.007), age (β=0.04, P=0.001) and the uric acid (β=0.13, P=0.04) as independent determinants of the CAC score. During follow-up period, cardiovascular events occurred in 18 out of 46 patients with CAC score ≥100 compared with 5 out of 82 patients with CAC score <100 (log rank, P<0.0001). Multivariate Cox proportional hazards analysis identified LnCAC score (P<0.0001), LnAlbuminuria (P=0.01) and uric acid (P=0.03) as independent predictors for cardiovascular events.

CONCLUSIONS

There was a significant relationship between CAC score, albuminuria and inflammation in patients with type 2 diabetes. LnCAC score together with LnAlbuminuria and uric acid were identified as independent predictors of cardiovascular events in these patients.

Cardiac mitochondrial dysfunction during hyperglycemia--the role of oxidative stress and p66Shc signaling

Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or by the effects of insulin resistance. Insulin deficiency leads to hyperglycemia which is the major initiator of diabetic cardiovascular complications escalating with time and driven by many complex biochemical and molecular processes. Four hypotheses, which propose mechanisms of diabetes-associated pathophysiology, are currently considered. Cardiovascular impairment may be caused by an increase in polyol pathway flux, by intracellular advanced glycation end-products formation or increased flux through the hexosamine pathway. The latter of these mechanisms involves activation of the protein kinase C. Cellular and mitochondrial metabolism alterations observed in the course of diabetes are partially associated with an excessive production of reactive oxygen species (ROS). Among many processes and factors involved in ROS production, the 66 kDa isoform of the growth factor adaptor shc (p66Shc protein) is of particular interest. This protein plays a key role in the control of mitochondria-dependent oxidative balance thus it involvement in diabetic complications and other oxidative stress based pathologies is recently intensively studied. In this review we summarize the current understanding of hyperglycemia induced cardiac mitochondrial dysfunction with an emphasis on the oxidative stress and p66Shc protein. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.

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.

[Bypass surgery versus percutaneous coronary intervention in patients with diabetes mellitus]

At present, in patients with diabetes mellitus and coronary multivessel disease no fixed general recommendation can be given in favor or to the disadvantage of surgical revascularization or in favor or to the disadvantage of percutaneous coronary intervention (PCI). In cases with an evidence-based indication for coronary revascularization because of clinical symptoms and/or proven ischemia, both therapeutic alternatives of bypass surgery or PCI are electable. The decision, which method of revascularization to prefer, must be based on close analyses of individual risk profile, individual comorbidity, and individual coronary morphology. With correct indication, both therapeutic methods are equivalent regarding the prognostically important combined endpoint of death, nonfatal myocardial infarction, and stroke. For PCI, however, there is a higher probability of restenosis depending on the complexity of lesion morphology, requiring more often repeat interventions or revascularizations. Before deciding in subfavor of or against a surgical or nonsurgical revascularization procedure, the complexity of the coronary artery disease should be analyzed, for example using the SYNTAX Score. In patients with SYNTAX Scores > or = 33 and no contraindications to bypass surgery, a surgical revascularization should be preferred. In the intermediate group with SYNTAX Scores between 23 und 32, the advantages and disadvantages of bypass surgery or PCI, for instance, the increased probability of restenosis with a higher necessity of repeat revascularizations after PCI, should be extensively discussed with the patient. In patients with SYNTAX Scores between 0 and 22, the nonsurgical, interventional therapy using drug-eluting stents (DES) can be recommended as an equivalent alternative to bypass surgery. In meta-analyses of randomized controlled trials and meta-analyses of large registries with PCI in patients with diabetes mellitus, clear advantages of DES in comparison with bare-metal stents (BMS) could be shown. Especially for patients with diabetes mellitus, there is still no clear evidence in favor of or against a special DES type or in favor of or against a special stent covering. Further sufficiently powered randomized controlled trials with hard clinical endpoints comparing bypass surgery with PCI (e.g., FREEDOM trial) and comparing different types of DES in patients with diabetes mellitus and clear PCI indications must be awaited, before further recommendations can be given.

Calcification in atherosclerosis

Coronary calcification has long been known to occur as a part of the atherosclerotic process, although whether it is a marker of plaque stability or instability is still a topic of considerable debate. Coronary calcification is an active process resembling bone formation within the vessel wall and, with the advances in CT technology of the past decade, can be easily quantified and expressed as a coronary artery calcium (CAC) score. The extent of calcium is thought to reflect the total coronary atherosclerotic burden, which has generated interest in using CAC as a marker of risk of cardiovascular events. The current consensus is that large amounts of CAC identify a highly vulnerable patient rather than a vulnerable plaque or vulnerable vessel. Indeed, CAC has incremental prognostic value beyond traditional risk factors in various subsets of the population. Furthermore, whereas the presence of CAC is associated with increased risk, a zero CAC score predicts excellent short-term to mid-term prognosis, even in high-risk patients. The advent of CT angiography has perhaps clouded the importance of CAC as a long-term marker of risk, as opposed to the presence of luminal stenoses that are associated with a more immediate risk of events.

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.

Prognostic value of exercise echocardiography in diabetic patients

BACKGROUND

Coronary artery disease (CAD) is the leading cause of death in diabetic patients. Although exercise echocardiography (EE) is established as a useful method for diagnosis and stratification of risk for CAD in the general population, there are few studies on its value as a prognostic tool in diabetic patients. The purpose of this investigation was to evaluate the value of EE in predicting cardiac events in diabetics.

METHODS

193 diabetic patients, 97 males, 59.8 +/- 9.3 yrs (mean +/- SD) were submitted to EE between 2001 and 2006 and followed from 7 to 65 months with median of 29 months by phone calls and personal interviews with patients and their primary physician, and reviewing medical records and death certificates. The end points were cardiac events, defined as non-fatal myocardial infarction, late myocardial revascularization and cardiac death. Sudden death without another explanation was considered cardiac death. Survival free of end points was estimated by the Kaplan-Meier method.

RESULTS

Twenty-six cardiac events were registered in 24 individuals during the follow-up. The rates of cardiac events were 20.6 and 7% in patients with positive and negative EE, respectively (p < 0.001). Predictors of cardiac events included sedentary lifestyle, with RR of 2.57 95%CI [1.09 to 6.02] (P = 0.03) and positive EE, with RR 3.63, 95%CI [1.44 to 9.16] (P = 0.01). Patients with positive EE presented higher rates of cardiac events at 12 months (6.8% vs. 2.2%), p = 0.004.

CONCLUSION

EE is a useful method to predict cardiac events in diabetic patients with suspected or known CAD.

Cardiac radionuclide imaging in stable coronary artery disease and acute coronary syndromes

INTRODUCTION

The increasing number of available cardiac imaging techniques has made the investigation of coronary artery disease (CAD) more complex. Appropriate patient referral depends on an understanding of the pre-test likelihood of CAD and the information provided by each test.

SOURCES OF DATA

This article describes myocardial perfusion scintigraphy (MPS) and summarizes evidence for its role in stable CAD and acute coronary syndromes with particular reference to current guidelines.

AREAS OF AGREEMENT

MPS has been extensively validated for the cost-effective diagnosis and prognosis of functionally significant CAD in both the acute and chronic settings. Its use is emphasized in the current NICE, national and international guidelines.

AREAS OF CONTROVERSY

Although normal MPS is associated with good outcomes, assessments of subclinical atherosclerosis such as coronary artery calcium scoring and computed tomography coronary angiography (CTA) demonstrate that non-flow-limiting CAD remains prognostically important.

GROWING POINTS

Technological developments, such as attenuation correction to improve diagnostic accuracy or analysis of left ventricular phase to detect dyssynchrony, carry the possibility of increasing the information that can be usefully gained from a single MPS study.

AREAS TIMELY FOR DEVELOPING RESEARCH

Of particular importance will be the role of MPS in an integrated imaging strategy that involves both anatomical and functional cardiac assessments. The use of hybrid technology that combines techniques such as MPS and CTA into a single imaging unit requires careful consideration with regard to diagnostic usefulness and cost-effectiveness.

The clinical significance of microvascular impairment in patients with pure uncomplicated diabetes mellitus

Pure uncomplicated type 2 diabetes mellitus is 'coronary artery disease equivalent' in view of microvascular impairment in myocardium. We believe that the current study reemphasized clinical significance of coronary microvasculature assesment in patients with diabetes mellitus even though they had normal luminogram.

Heart rate adjustments and analysis of recovery patterns of ST-segment depression in type 2 diabetes

AIMS

To investigate the diagnostic value for coronary artery disease (CAD) detection of evaluating time- and heart rate (HR)-related ST-segment changes (the ST/HR-slope) and the post-exercise recovery pattern (the ST/HR-recovery loop) in patients with type 2 diabetes mellitus (T2DM).

METHODS AND RESULTS

Ninety-one patients (22 female, age 59+/-9 years) with T2DM (diabetes duration 6+/-6 years) performed an exercise ECG-test that was evaluated using the ST/HR slope (cut-off</=-2.4 microV/bpm) and -recovery loop patterns (abnormal versus normal) and compared to the conventional >/=1 mm ST-segment depression criterion and dobutamine stress echo-cardiography, all evaluated against coronary angiography irrespective of stress test results. Coronary angiography revealed CAD in 20 men and 3 women (25%). Sensitivity for the conventional exercise test and stress echocardiography was low (0.35 and 0.30), but increased significantly using the ST/HR-slope (0.45), the recovery loop (0.86) or the combined ST/HR slope and recovery loop criterion (0.91). The associations between angiographic CAD-detection and the different tests expressed by the Odds ratio demonstrated an added value of performing ST/HR analysis both over pre-test CAD risk profile and the established techniques.

CONCLUSION

T2DM patients capable of performing an exercise test could be assessed with the ST/HR-analysis for selecting patients to angiography. However, further studies including a higher number of patients are needed to confirm the diagnostic value of this approach.

Noninvasive Screening for Coronary Atherosclerosis and Silent Ischemia in Asymptomatic Type 2 Diabetic Patients

Coronary artery disease (CAD) accounts for 65% to 80% of deaths in diabetic patients. The merits of screening asymptomatic type 2 diabetic patients for either (A) the presence of coronary atherosclerosis by imaging of coronary calcification using cardiac computed tomography or (B) silent ischemia by stress myocardial perfusion imaging (MPI) remain controversial. Some observers have advocated for such noninvasive screening in at least the subset of the diabetic population who have significant clinical CAD risk factors, so that the highest risk patients for future cardiac events can be identified and offered more aggressive intensive medical therapy or coronary revascularization and optimum medical therapy. Computed tomography coronary calcium scanning could be the first noninvasive screening test in these clinically high-risk diabetic patients, followed by stress MPI to detect silent ischemia in those who exhibit high coronary calcium scores.

The potential of myocardial perfusion scintigraphy for risk stratification of asymptomatic patients with type 2 diabetes

Patients with diabetes, in particular patients with type 2 diabetes, are at a 2- to 4-fold higher risk of cardiovascular mortality compared with their nondiabetic peers. Patients with diabetes are also more likely to have silent ischemia and less likely to survive a myocardial infarction than nondiabetic patients. Recent studies with electron beam computed tomography (EBCT) have shown that subclinical atherosclerosis is common in patients with diabetes, and studies with myocardial perfusion scintigraphy (with single-photon emission computed tomography) or stress echocardiography have demonstrated that between 25% and 50% of asymptomatic diabetic patients have ischemia during exercise or pharmacological stress and that a substantial proportion of these patients go on to develop major cardiovascular events within several years. Clearly, asymptomatic diabetic patients include a subset of individuals at high risk of cardiovascular disease who would benefit from improved risk stratification beyond that possible with risk factor scoring systems alone. Single-photon emission computed tomography, stress echocardiography, and possibly EBCT or multi-slice computed tomography, are emerging as valuable diagnostic tools for identifying asymptomatic diabetic patients who might require early and aggressive intervention to manage their cardiovascular risk.