Silent myocardial ischemia screening in patients with diabetes mellitus

Identification of Silent Myocardial Ischemia in Patients with Long-Term Type 1 and Type 2 Diabetes

(1) Background: This study aimed to analyze epidemiological data to identify risk factors for silent myocardial ischemia in patients with long-term type 1 and type 2 diabetes. (2) Methods: An analysis was performed on 104 patients with long-term type 1 and type 2 diabetes who had not previously been diagnosed with cardiovascular disease. During hospitalization, patients were subjected to a standard ECG exercise test on a treadmill. If the test could not be performed or the result was uncertain, a pharmacological exercise test with dobutamine was performed. In the case of a positive exercise ECG test or a positive dobutamine test, the patient underwent coronary angiography. (3) Results: Atherosclerotic lesions were found in 24 patients. Patients with silent ischemia were significantly older and had a lower mean left ventricular ejection fraction and a higher incidence of carotid atherosclerosis. The presence of microvascular complications did not increase the risk of silent ischemia. (4) Conclusions: Silent heart ischemia is more common in type 2 than type 1 diabetes. Predisposing factors include older age, coexistence of carotid atherosclerosis, lower left ventricular ejection fraction, and smoking in patients with type 1 diabetes. Concomitant microvascular complications are not a risk factor.

Heterocyclic compounds as a magic bullet for diabetes mellitus: a review

Diabetes mellitus (DM) is a major metabolic disorder due to hyperglycemia, which is increasing all over the world. From the last two decades, the use of synthetic agents has risen due to their major involvement in curing of chronic diseases including DM. The core skeleton of drugs has been studied such as thiazolidinone, azole, chalcone, pyrrole and pyrimidine along with their derivatives. Diabetics assays have been performed in consideration of different enzymes such as α-glycosidase, α-amylase, and α-galactosidase against acarbose standard drug. The studied moieties were depicted in both models: in vivo as well as in vitro. Molecular docking of the studied compounds as antidiabetic molecules was performed with the help of Auto Dock and molecular operating environment (MOE) software. Amino acid residues Asp349, Arg312, Arg439, Asn241, Val303, Glu304, Phe158, His103, Lys422 and Thr207 that are present on the active sites of diabetic related enzymes showed interactions with ligand molecules. In this review data were organized for the synthesis of heterocyclic compounds through various routes along with their antidiabetic potential, and further studies such as pharmacokinetic and toxicology studies should be executed before going for clinical trials.

Diabetes mellitus (DM) is a major metabolic disorder due to hyperglycemia, which is increasing all over the world.

Risk stratification for coronary artery disease in multi-ethnic populations: Are there broader considerations for cost efficiency?

Coronary artery disease (CAD) screening and diagnosis are core cardiac specialty services. From symptoms, autopsy correlations supported reductions in coronary blood flow and dynamic epicardial and microcirculatory coronaries artery disease as etiologies. While angina remains a clinical diagnosis, most cases require correlation with a diagnostic modality. At the onset of the evidence building process much research, now factored into guidelines were conducted among population and demographics that were homogenous and often prior to newer technologies being available. Today we see a more diverse multi-ethnic population whose characteristics and risks may not consistently match the populations from which guideline evidence is derived. While it would seem very unlikely that for the majority, scientific arguments against guidelines would differ, however from a translational perspective, there will be populations who differ and importantly there are cost-efficacy questions, e.g., the most suitable first-line tests or what parameters equate to an adequate test. This article reviews non-invasive diagnosis of CAD within the context of multi-ethnic patient populations.

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.

Should adults with type 2 diabetes be screened for atherosclerotic cardiovascular disease?

Diabetes mellitus is associated with greater risks for cardiovascular diseases (CVD). Multiple noninvasive screening tools for CVD including cardiac CT, carotid intima-media thickness test, myocardial perfusion imaging have been examined in those with diabetes, but the prognostic value of these tests vary and issues remain regarding their cost-benefit ratios, potential harms of radiation, and how they fit into screening algorithms for CVD. We discuss in this report the needs and criteria for screening tests and summarize the evidence from observational studies and clinical trials. We also explore whether there should be more sensitive screening modalities to better detect both short and long-term cardiovascular risk among asymptomatic patients with diabetes.

Tele-nuclear medicine

This article presents a description of tele-nuclear medicine and, after outlining its history, a wide, representative range of its applications. Tele-nuclear medicine has benefited greatly from technological progress, which for several decades has provided greater data transfer rates and storage capacity at steadily decreasing cost. Differences in the practice of nuclear medicine between developed and developing countries arise mainly from disparities in their available infrastructure, funding and education levels of personnel involved. Consequently there are different emphases in their tele-nuclear medicine, which are elaborated. It is concluded that tele-nuclear medicine is important for all countries, but the emphasis on its application may differ between developed and developing nations, with an emphasis on distance learning in the latter.

Subclinical atherosclerosis and silent myocardial ischaemia in patients with type 2 diabetes: a protocol of a clinico-observational study

Introduction

Atherosclerotic cardiovascular disease is a significant modifiable complication in patients with diabetes and subclinical atherosclerosis is considered a surrogate marker of future vascular events. The clustering of cardiometabolic-risk factors in patients with diabetes and cardiovascular disease is increasingly being recognised. Recent evidence indicates that 20–50% of asymptomatic patients with diabetes may have silent coronary heart disease. However, the identification of subclinical atherosclerosis and silent myocardial ischaemia in patients with diabetes has been less well-explored, especially in low-resource population settings where cost-effective non-invasive clinical tools are available. The objective of this study is to identify patients with physician-diagnosed diabetes who are at risk of developing future cardiovascular events measured as subclinical atherosclerosis and silent myocardial ischaemia in an urban population of Eastern India.

Methods and analysis

This is a cross-sectional clinico-observational study. A convenience sampling of approximately 350 consecutive patients with type 2 diabetes based on predefined inclusion and exclusion criteria will be identified at an urban diabetes center. This estimated sample size is based on an expected prevalence of silent myocardial ischaemia of 25% (± 5%), we computed the required sample size using OpenEpi online software assuming an α level of 0.05 (95% CI) to be 289. On factoring 20% non-response the estimated sample size is 350. Previously validated questionnaire tools and well-defined clinical, anthropometric and biochemical measurements will be utilised for data collection. The two primary outcomes—subclinical atherosclerosis and silent myocardial ischaemia will be measured using carotid intima-media thickness and exercise tolerance testing, respectively. Descriptive and multivariate logistic regression statistical techniques will be employed to identify ‘at risk’ patients with diabetes, and adjusted for potential confounders.

Ethics and dissemination

Ethical approval was granted by the institutional review board of Kalinga Institute of Medical Sciences, Bhubaneshwar, India. Data will be presented at academic fora and published in peer-reviewed journals.

Silent myocardial ischemia detected by single photon emission computed tomography (SPECT) and risk of cardiac events among asymptomatic patients with type 2 diabetes: a meta-analysis of prospective studies

OBJECTIVE

To assess the value of detecting silent myocardial ischemia (SMI) by single photon emission computed tomography (SPECT) in predicting risk of cardiac events among patients with type 2 diabetes mellitus (T2DM) who do not have overt cardiac symptoms.

MATERIALS AND METHODS

Electronic databases (PubMed, Cochrane Library, EMBASE, and others) and original article references were systematically searched through February 1, 2013. A fixed-effects model was applied to pooled data to estimate relative risks (RR) and 95% confidence intervals (CI).

RESULTS

Ten prospective studies with follow-up ranging from 1 to 6 years were identified. Among the total of 1360 asymptomatic patients with T2DM screened by SPECT, the cumulative prevalence rate of SMI was 26.1%. Patients with SMI were at increased risk of experiencing endpoints relative to patients without SMI: RR (95% CI) for cardiac death, 4.60 (1.78-11.84); non-fatal cardiac events, 3.48 (2.30-5.28); total cardiac events, 3.48 (2.59-4.68); and all-cause mortality, 2.20 (1.14-4.25). The risk of cardiac death and non-fatal cardiac events increased with increasing severity of SPECT-detected abnormalities.

CONCLUSIONS

SMI detected by SPECT is associated with increased risk of cardiac death, all-cause mortality, and non-fatal cardiac events in T2DM patients without overt cardiac symptoms. Advanced intervention procedures including intensive drug management should be implemented to reduce the risk of cardiac events for SMI-positive T2DM patients.

Clinical value and severity of myocardial perfusion defects in asymptomatic diabetic patients with negative or weakly positive exercise treadmill test

Objective:

Although coronary artery disease (CAD) is the leading cause of death in type 2 diabetic patients, it is frequently asymptomatic. Myocardial perfusion imaging (MPI) is reported to show ischemia in a significant number of asymptomatic diabetic patients. We studied the prevalence and severity of myocardial perfusion defects in asymptomatic diabetic patients and its clinical impact.

Methods and patients:

One hundred thirty consecutive asymptomatic patients, aged 35-65 years with type 2 diabetes mellitus and with no history of CAD and no cardiac symptoms were recruited in the study. Echocardiography, electrocardiography (ECG), routine laboratory tests and exercise treadmill test (ETT) were performed and patients with weakly positive or negative ETT underwent Dipyridamole MPI. Patients with positive ETT were referred to coronary angiography. Patients were followed for at least 17 months (mean 21.7 months) and any cardiac event was recorded.

Results:

We studied 81 female and 49 male patients with mean age of 51.8 years. Negative, weakly positive and positive ETT result was noted in 74.3%, 15% and 10.7% respectively. 75% of patients with positive ETT had coronary artery disease in angiography. Gated myocardial perfusion SPECT was done in 106 patients. MPI showed reversible defect in 26.9% of the patients with a mean summed stress score of 3.3±1.8. Follow up completed in 112 patients and only one patient with abnormal MPI underwent coronary angiography followed by PTCA. No cardiac death, MI, UA or hospital admission occurred among our patients during follow up (17-26 months). Mean stress end diastolic volume (EDV) was significantly higher in patients with reversible defect compared to patients without reversible defect based on MPI findings (62.0±31.6 Vs 48.5±18.4 ml, P=0.04). Blood glucose and HbA1c were significantly higher in patients with ischemia compared to patients without ischemia (P<0.05). Meanwhile the ratio of TG to HDL was 6.06±3.2 in ischemic patients compared to 4.8±2.3 in normal subjects (P=0.03).

Conclusion:

Reversible defects are commonly seen in myocardial perfusion SPECT in asymptomatic diabetic patients and are mild in severity and not associated with adverse cardiac events. Routine approach for detection of CAD beginning with ETT seems to be appropriate in these patients.

Myocardial perfusion scintigraphy in the detection of silent ischemia in asymptomatic diabetic patients

OBJECTIVE: This study was aimed to evaluate myocardial perfusion in asymptomatic patients with type 1 (DM1) and type 2 diabetes mellitus (DM2) without previous diagnoses of coronary artery disease (CAD) or cerebral infarction. MATERIALS AND METHODS: Fifty-nine consecutive asymptomatic patients (16 DM1, 43 DM2) underwent myocardial perfusion scintigraphy with 99mTc-sestamibi (MPS). They were evaluated for body mass index, metabolic control of DM, type of therapy, systemic arterial hypertension, dyslipidemia, nephropathy, retinopathy, peripheral neuropathy, smoking, and familial history of CAD. RESULTS: MPS was abnormal in 15 patients (25.4%): 12 (20.3%) with perfusion abnormalities, and 3 with isolated left ventricular dysfunction. The strongest predictors for abnormal myocardial perfusion were: age 60 years and above (p = 0.017; odds ratio [OR] = 6.0), peripheral neuropathy (p = 0.028; OR = 6.1), nephropathy (p = 0.031; OR = 5.6), and stress ECG positive for ischemia (p = 0.049; OR = 4.08). CONCLUSION: Silent myocardial ischemia occurs in more than one in five asymptomatic diabetic patients. The strongest predictors of ischemia in this study were: patient age, peripheral neuropathy, nephropathy, retinopathy and a stress ECG positive for ischemia.

Screening for asymptomatic coronary artery disease can reduce cardiovascular mortality and morbidity in type 2 diabetic patients

The impact of the screening for asymptomatic coronary artery disease (CAD) on the cardiovascular prognosis in diabetes is controversial. The aim of the study was to investigate whether screening for asymptomatic CAD can have an impact on cardiovascular morbidity and mortality in diabetes. In this nonrandomized longitudinal study, 1,189 consecutive type 2 diabetic patients without a history of CAD were evaluated. They were subdivided into two groups according to whether they were screened (screening group, n = 921) or not (no-screening group, n = 268) for asymptomatic CAD. Among the screened patients, 386 had angiographically proven CAD (CAD group) and 535 did not have silent CAD (no-CAD group). During a mean follow-up period of 4.3 ± 1.9 years, 130 patients experienced major adverse cardiac events (MACE). The incidence of MACE was significantly greater in the no-screening than in the screening group (22.0 vs. 7.7%; p = 0.001). The Kaplan-Meier method showed that: (1) the screening was associated with a lower rate of MACE (log-rank test, 3-95; p = 0.047); (2) the no-screening group had a risk profile similar to that of CAD group (log-rank test, 2.02; p = 0.154); and (3) cardiovascular prognosis was significantly better in no-CAD than in no-screening group (log-rank test, 4.27; p = 0.039). Multivariate Cox regression analysis showed that screening for CAD (HR 0.2; 95% CI 0.2-0.3; p = 0.000) was significantly protective against the occurrence of MACE. Our data suggest that screening for asymptomatic CAD can significantly reduce cardiovascular morbidity and mortality in type 2 diabetic patients. This may be due to specific diagnostic and therapeutic interventions in diabetic patients with proven CAD at screening.

[Screening of silent myocardial ischemia in diabetic patients: Practical details and issues]

Silent myocardial ischemia is more frequent in diabetic patients. Nevertheless, its prevalence depends on global cardiovascular risk. Although this is a factor of overmortality, its screening is discussed. In fact, crucial issue is the demonstration of a benefit from revascularizing immediately any coronary stenosis in silent diabetic patients. Recent studies report no benefit of revascularization by endovascular treatment versus medical treatment in patients with stable coronary disease in general population and in diabetic patients. Screening of silent myocardial ischemia should be only proposed to diabetic patients with a very high probability of multivessel disease. Only these patients could benefit from surgical revascularization. For the other diabetic patients, it seems to be reasonable that only patients with cardiovascular risk factors not controlled by medical treatment should benefit from screening, whose optimal practical details stay discussed.

Significance of inflammatory markers in diabetic patients with stable coronary artery disease

BACKGROUND/AIMS

Patients with diabetes are prone to coronary artery disease (CAD); however, the majority of diabetic patients show normal coronary arteries. We examined differences in the clinical aspects of diabetic patients with insignificant and with significant stenosis of the coronary artery.

METHODS

A total of 418 consecutive diabetic patients with stable angina who had undergone coronary angiography from January 2004 to March 2007 were included in this study. Patients were subdivided into control and CAD groups and then clinical characteristics and CAD-associated factors were evaluated.

RESULTS

A total of 92 (22%) patients were assigned to the control group and 326 (78%) patients were assigned to the CAD group. Using univariate regression analysis, we found that patients with CAD were significantly older (control vs. CAD; 59+/-21 vs. 64.7+/-33.7, years, p<0.001), had a longer duration of diabetes (8.2+/-21.8 vs. 10.2+/-29.8, years, p=0.027), higher titers of high sensitivity C-reactive protein (hsCRP; 0.3+/-6.79 vs. 0.9+/-12.6, mg/dL, p=0.015), and increased hemoglobin A1c (HbA1c) levels (7.1+/-3.8 vs. 7.5+/-4.8, %, p=0.007) compared to control patients. Multivariate regression analysis showed that only differences in age, hsCRP, and HbA1c were statistically significant. When patients were subdivided into groups based on hsCRP levels (208 patients in the low group [49.8%], 210 patients in the high group [50.2%]), we found that patients with higher hsCRP levels showed more frequent multivessel disease.

CONCLUSIONS

In diabetic patients, age, hsCRP, and HbA1c were associated with stable CAD. Among these factors, hsCRP levels were significantly correlated with multivessel involvement in diabetic CAD. Therefore, high hsCRP levels may be a strong predictor for atherosclerotic progression of the coronary arteries in diabetic patients, suggesting that regular screening tests should be performed.

[Coronary artery disease in patients with diabetes]

Diabetes in patients with coronary artery disease multiplies the risk of a cardiovascular event by a factor of 2 to 3. The risk is still higher for patients with heart or kidney failure. The detection of silent ischemia makes it possible to identify patients with revascularizable stenosis of the coronary artery or three-vessel atheroma. The choice between angioplasty and coronary bypass for diabetes patients with multiple-vessel disease requires multidisciplinary discussion. The onset of acute coronary syndrome in a patient with diabetes justifies coronary angiography to attempt any possible revascularization. Coronary angioplasty with a drug-eluting stent reduces the risk of need for revascularization due to restenosis, without modifying the risk of death/infarction compared with a bare-metal stent. Prognosis is improved only if appropriate comprehensive management follows, including intensive correction of risk factors. The management of a patient with coronary artery disease and diabetes must be multidisciplinary, in a network of care coordinated by the general practitioner.