Stress myocardial scintigraphy and dobutamine echocardiography in the detection of coronary disease in asymptomatic patients with type 2 diabetes

Precision prognostics for cardiovascular disease in Type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Precision medicine has the potential to improve cardiovascular disease (CVD) risk prediction in individuals with Type 2 diabetes (T2D).

METHODS

We conducted a systematic review and meta-analysis of longitudinal studies to identify potentially novel prognostic factors that may improve CVD risk prediction in T2D. Out of 9380 studies identified, 416 studies met inclusion criteria. Outcomes were reported for 321 biomarker studies, 48 genetic marker studies, and 47 risk score/model studies.

RESULTS

Out of all evaluated biomarkers, only 13 showed improvement in prediction performance. Results of pooled meta-analyses, non-pooled analyses, and assessments of improvement in prediction performance and risk of bias, yielded the highest predictive utility for N-terminal pro b-type natriuretic peptide (NT-proBNP) (high-evidence), troponin-T (TnT) (moderate-evidence), triglyceride-glucose (TyG) index (moderate-evidence), Genetic Risk Score for Coronary Heart Disease (GRS-CHD) (moderate-evidence); moderate predictive utility for coronary computed tomography angiography (low-evidence), single-photon emission computed tomography (low-evidence), pulse wave velocity (moderate-evidence); and low predictive utility for C-reactive protein (moderate-evidence), coronary artery calcium score (low-evidence), galectin-3 (low-evidence), troponin-I (low-evidence), carotid plaque (low-evidence), and growth differentiation factor-15 (low-evidence). Risk scores showed modest discrimination, with lower performance in populations different from the original development cohort.

CONCLUSIONS

Despite high interest in this topic, very few studies conducted rigorous analyses to demonstrate incremental predictive utility beyond established CVD risk factors for T2D. The most promising markers identified were NT-proBNP, TnT, TyG and GRS-CHD, with the highest strength of evidence for NT-proBNP. Further research is needed to determine their clinical utility in risk stratification and management of CVD in T2D.

Precision Prognostics for Cardiovascular Disease in Type 2 Diabetes: A Systematic Review and Meta-analysis

Background Precision medicine has the potential to improve cardiovascular disease (CVD) risk prediction in individuals with type 2 diabetes (T2D). Methods We conducted a systematic review and meta-analysis of longitudinal studies to identify potentially novel prognostic factors that may improve CVD risk prediction in T2D. Out of 9380 studies identified, 416 studies met inclusion criteria. Outcomes were reported for 321 biomarker studies, 48 genetic marker studies, and 47 risk score/model studies. Results Out of all evaluated biomarkers, only 13 showed improvement in prediction performance. Results of pooled meta-analyses, non-pooled analyses, and assessments of improvement in prediction performance and risk of bias, yielded the highest predictive utility for N-terminal pro b-type natriuretic peptide (NT-proBNP) (high-evidence), troponin-T (TnT) (moderate-evidence), triglyceride-glucose (TyG) index (moderate-evidence), Genetic Risk Score for Coronary Heart Disease (GRS-CHD) (moderate-evidence); moderate predictive utility for coronary computed tomography angiography (low-evidence), single-photon emission computed tomography (low-evidence), pulse wave velocity (moderate-evidence); and low predictive utility for C-reactive protein (moderate-evidence), coronary artery calcium score (low-evidence), galectin-3 (low-evidence), troponin-I (low-evidence), carotid plaque (low-evidence), and growth differentiation factor-15 (low-evidence). Risk scores showed modest discrimination, with lower performance in populations different from the original development cohort. Conclusions Despite high interest in this topic, very few studies conducted rigorous analyses to demonstrate incremental predictive utility beyond established CVD risk factors for T2D. The most promising markers identified were NT-proBNP, TnT, TyG and GRS-CHD, with the highest strength of evidence for NT-proBNP. Further research is needed to determine their clinical utility in risk stratification and management of CVD in T2D.

Identification of coronary heart disease in asymptomatic individuals with diabetes mellitus: to screen or not to screen

Coronary heart disease (CHD) is highly prevalent in patients with diabetes mellitus (DM), and remains the single most common cause of death among this population. Regrettably, a significant percentage of diabetics fail to perceive the classic symptoms associated with myocardial ischemia. Among asymptomatic diabetics, the prevalence of abnormal cardiac testing appears to be high, ranging between 10% and 62%, and mortality is significantly higher in those with abnormal scans. Hence, the potential use of screening for CHD detection among asymptomatic DM individuals is appealing and has been recommended in certain circumstances. However, it was not until recently, that this question was addressed in clinical trials. Two studies randomized a total of 2,023 asymptomatic diabetics to screening or not using cardiac imaging with a mean follow up of 4.4 ± 1.4 years. In combination, both trials showed lower than expected annual event rates, and failed to reduce major cardiovascular events in the screened group compared to the standard of care alone. The results of these trials do not currently support the use of screening tools for CHD detection in asymptomatic DM individuals. However, these studies have important limitations, and potential explanations for their negative results that are discussed in this manuscript.

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.

Coronary artery disease screening in type II diabetic patients: prognostic value of rest and stress echocardiography

AIM

Presence of inducible ischemia in type II diabetic patients is associated with an adverse outcome, but less is known about prognostic value of resting wall motion abnormalities (WMA).

MATERIALS AND METHODS

From October 2006 to May 2008, 278 patients underwent to CAD screening, according to ADA criteria, by dobutamine stress echocardiography (DSE). Between July and September 2009, all patients were contacted to verify the occurrence of new cardiac events.

RESULTS

Resting-WMA were present in 63 patients; 88 subjects showed inducible ischemia. During the follow-up, we observed 24 new cardiac events; patients with a good outcome showed less frequently resting WMA (19 vs 50%). Inducible ischemia (71% vs 28%; p<0.001) and a more extensive area of inducible ischemia, expressed by a higher value of peak WMSI (1.63±0.45 vs 1.17±0.31; p<0.0001), were more frequent in patients with adverse outcome. A Cox regression analysis showed that only a higher peak WMSI (HR 6.645, 95% CI 2.782-15.874, p<0.0001) was associated with a bad outcome. Event-free survival was lower in presence of rest WMA (79% vs 94%, p<0.0001) and a higher peak WMSI (66% vs 95%, p<0.0001).

CONCLUSIONS

In diabetic patients presence of an extensive inducible ischemia was independently associated with a worst outcome; resting WMA were associated with reduced event-free survival.

Allelic variations of the vitamin D receptor (VDR) gene are associated with increased risk of coronary artery disease in type 2 diabetics: the DIABHYCAR prospective study

AIM

Vitamin D deficiency is associated with coronary artery disease (CAD), and the actions of vitamin D are mediated by binding to a specific nuclear vitamin D receptor (VDR). This study investigated the associations of VDR gene variants with CAD in two cohorts of type 2 diabetes patients.

METHODS

A cohort of 3137 subjects from the prospective DIABHYCAR study (CAD incidence: 14.8%; follow-up: 4.4 ± 1.3 years) and an independent, hospital-based population of 713 subjects, 32.3% of whom had CAD, were assessed. Three SNPs in the VDR gene were genotyped: rs1544410 (BsmI); rs7975232 (ApaI); and rs731236 (TaqI).

RESULTS

In the DIABHYCAR cohort, an association was observed between the A allele of BsmI and incident cases of CAD (HR: 1.16, 95% CI: 1.05-1.29; P = 0.002). Associations were also observed between BsmI (P = 0.01) and TaqI (P = 0.04) alleles and baseline cases of CAD. The AAC haplotype (BsmI/ApaI/TaqI) was significantly associated with an increased CAD prevalence at the end of the study compared with the GCT haplotype (OR: 1.12, 95% CI: 1.02-1.28; P = 0.04). In a cross-sectional study of the independent hospital-based cohort, associations of ApaI (P = 0.009) and TaqI (P = 0.03) alleles with CAD were observed, with similar haplotype results (OR: 1.33, 95% CI: 1.03-1.73; P = 0.03).

CONCLUSION

The haplotype comprising the minor allele of BsmI, major allele of ApaI and minor allele of TaqI of VDR (AAC) was associated with an increased risk of CAD in type 2 diabetes patients. This effect was independent of the effects of other known cardiovascular risk factors.

Silent myocardial infarction in women with type II diabetes mellitus and microalbuminuria

Introduction:

The aim of this study was to investigate whether asymptomatic women with diabetes mellitus (DM) without previous history of ischemic heart disease (IHD) and normal electrocardiogram (ECG) have suffered silent myocardial infarction (MI).

Methods:

The study population consisted of 64-years old women with DM and albuminuria (n = 15) and aged- and body mass index-matched controls (n = 16). The patients were selected after screening of 240 women with previously known or unknown DM. The individuals with previous history of IHD and ECG suggesting the presence of IHD were excluded. All subjects were investigated with magnetic resonance imaging (MRI).

Results:

MRI investigation has revealed the presence of subendocardial MI in the two DM women (13%). No MI was detected in the control group. MR coronary angiography detected the presence of significant stenosis in the proximal segment of left anterior descending (LAD) coronary artery in one DM woman. This patient developed unstable angina 1 week after the MRI investigation. The conventional angiography has confirmed the presence of significant stenosis in LAD demanding invasive revascularization by percutaneous coronary angioplasty. No difference was found in indices of left ventricular (LV) systolic function while diastolic function was disturbed in the DM group. There was a tendency for increased LV mass in the DM group. No difference was found in the LV volumes.

Conclusion:

Clinically significant proportion of the women with DM and albuminuria without previous history of IHD have had silent MI. MRI screening of these high risk female patient is valuable diagnostic tool which may increase diagnostic accuracy and improve prognosis in DM patients with IHD.

[Incidence and prognostic value of ischemic heart disease in high risk cardiovascular asymptomatic diabetic patients detected by gated myocardial perfusion SPECT study]

AIM

To determine the clinical utility of the gated myocardial perfusion SPECT to detect silent ischemia in asymptomatic diabetic patients without previous coronary events and to evaluate the prognosis of this population.

MATERIAL AND METHODS

A retrospective study of 56 asymptomatic diabetics referred for a gated myocardial perfusion SPECT for diagnosis of ischemic disease was performed. The criteria for ischemia were: mild SDS<4, moderate SDS 4-8, severe SDS>8. A multivariable statistical analysis was carried out to identify possible predictive variables of an abnormal SPECT. The cardiovascular events were recorded up to December-2010.

RESULTS

A high proportion of the 56 patients had an abnormal perfusion study (46.4%), there being moderate-severe ischemia in 10.7%, necrosis with ischemia in 5.4% and necrosis in 7.1%. We found no statistical differences in the type of stress used (treadmill or dipyridamole). The patients had a high combination of cardiovascular risk factors. In the multivariate analysis, diabetic nephropathy was the only factor related to an abnormal SPECT (p=0.043). The events recorded in the follow-up were: 2 early revascularizations, 5 cardiology admissions, 10 non-cardiac related deaths. The existence of ischemia in the SPECT was significantly related to the appearance of cardiovascular events (p<0.05).

CONCLUSION

A gated myocardial perfusion SPECT in asymptomatic diabetics with high combination of cardiovascular risk factors detects silent ischemia in a significant proportion and this seems to be related to future coronary events. Diabetic nephropathy implies a greater likelihood of abnormal studies. However, the screening criteria in this population still need to be established for better performance and lower cost.

Myocardial ischemia: a silent epidemic in Type 2 diabetes patients

The prevalence of diabetes mellitus is increasing consistently. Coronary artery disease (CAD) is the main cause of death; however, silent myocardial ischemia (SMI) is more frequent in diabetic patients. Early CAD diagnosis provided by SMI screening could lead to decreased cardiovascular complications and mortality. Current guidelines recommend screening for SMI in asymptomatic diabetic patients selected on a basis of high cardiovascular risk, followed by coronary angiogram in case of a positive stress test. However, the benefit of systematic SMI screening has not been demonstrated in diabetic patients with optimal treatment of risk factors. The benefit of revascularization in diabetic patients with SMI seems to be restricted to patients with severe CAD. Prospective studies are required to identify diabetic patients who may potentially benefit from SMI screening. These patients should have a high prevalence of severe CAD and potential benefit of revascularization, such as patients with renal failure, left ventricular dysfunction and peripheral or carotid occlusive arterial disease.

[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.

A randomized study comparing isotope and echocardiography stress testing in the screening of silent myocardial ischaemia in type 2 diabetic patients

AIMS

This study aimed to compare the positive predictive value (PPV) of stress myocardial scintigraphy (SPECT) and of dobutamine echocardiography (DE) in the diagnosis of significant coronary artery stenosis (CAD) in asymptomatic type 2 diabetic patients, and to assess long-term clinical outcomes according to silent myocardial ischaemia (SMI) screening.

METHODS

A total of 204 asymptomatic type 2 diabetic patients at high cardiovascular (CV) risk were prospectively randomized to undergo either SPECT (n=104) or DE (n=100). Coronary angiography was proposed in cases of SMI, with revascularization of suitable lesions. Intensive treatment of CV risk factors was prescribed for all patients. Death and myocardial infarction (MI) were recorded during the 3-year follow-up.

RESULTS

Clinical characteristics were similar in the two testing groups. The prevalence of SMI and significant CAD were 13% and 4%, respectively, in the SPECT group vs 11% and 5%, respectively, in the DE group (not significant [NS]). The PPV for the detection of significant CAD was 29% for SPECT and 45% for DE (NS). Seven patients (3%) underwent initial revascularization. The 3-year rate of CV death and MI was 2.5%, and similar in both groups.

CONCLUSION

Rates of SMI and significant CAD in asymptomatic high-risk type 2 diabetic patients receiving intensive care of risk factors are low, and SPECT and DE are similar in the detection of SMI and CAD. Coronary revascularization and intensive CV risk-factor therapy are associated with a low rate of adverse CV events at 3 years, whichever stress test was used.

Myocardial perfusion scintigraphy in asymptomatic diabetic patients: a critical review

The increasing prevalence of diabetes mellitus and the associated high cardiovascular risk has made the non-invasive identification of silent coronary heart disease in diabetic individuals an important issue. This strategy could identify higher risk asymptomatic patients with diabetes mellitus in whom coronary revascularization may improve the outcome beyond that achieved by currently recommended medical management. Stress myocardial perfusion imaging has been shown to be effective in detecting coronary heart disease and predicting adverse cardiac events in asymptomatic diabetic patients. However, the clinical utility of myocardial perfusion scintigraphy is debated intensively due to the paucity of prospective and outcome based evidence. The controversy stems from several observational studies, epidemiologic data and cost-effectiveness analyses. Thus, although several authors and professional organizations advocate the use of stress imaging for screening higher risk asymptomatic diabetic patients, others are cautious in recommending any kind of stress testing in that population. This review is based on a broad survey of the literature and discusses the potential role of stress myocardial perfusion scintigraphy in screening asymptomatic diabetic subjects for coronary heart disease in the current era and in relation with other non-invasive screening tools.

[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.

Silent myocardial ischemia screening in patients with diabetes mellitus

The prevalence of diabetes mellitus is fairly increasing, especially in the developing countries. Diabetes is a major cardiovascular risk factor; it often leads to severe cardiovascular complications, and coronary artery disease (CAD) is the main cause of death in diabetic patients. Silent myocardial ischemia (SMI) is more frequent in diabetic patients. The progress made in detection and treatment of CAD allows reconsidering the screening of SMI, in the hope that early CAD diagnosis leads to a more effective therapy and the decrease of cardiovascular complications and mortality. However, the benefit of systematic SMI screening remains discussed. Current guidelines recommend screening SMI in asymptomatic diabetic patients selected for high cardiovascular risk (i.e. with two or more other cardiovascular risk factors, or peripheral or carotid arterial disease, or proteinuria). ECG stress test can be recommended in first intention if maximal heart rate can be achieved. For patient with inconclusive ECG stress test, myocardial scintigraphy seems more accurate than stress echocardiography. Coronary angiogram should be performed in case of positive stress test. Further evaluations of systematic screening have to be conducted on broad randomized trial.

The common -866G>A variant in the promoter of UCP2 is associated with decreased risk of coronary artery disease in type 2 diabetic men

OBJECTIVE

Uncoupling protein 2 (UCP2) is a physiological downregulator of reactive oxygen species generation and plays an antiatherogenic role in the vascular wall. A common variant in the UCP2 promoter (-866G>A) modulates mRNA expression, with increased expression associated with the A allele. We investigated association of this variant with coronary artery disease (CAD) in two cohorts of type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

We studied 3,122 subjects from the 6-year prospective Non-Insulin-Dependent Diabetes, Hypertension, Microalbuminuria, Cardiovascular Events, and Ramipril (DIABHYCAR) Study (14.9% of CAD incidence at follow-up). An independent, hospital-based cohort of 335 men, 52% of whom had CAD, was also studied.

RESULTS

We observed an inverse association of the A allele with incident cases of CAD in a dominant model (hazard risk 0.88 [95% CI 0.80-0.96]; P = 0.006). Similar results were observed for baseline cases of CAD. Stratification by sex confirmed an allelic association with CAD in men, whereas no association was observed in women. All CAD phenotypes considered--myocardial infarction, angina pectoris, coronary artery bypass graft (CABG), and sudden death--contributed significantly to the association. Results were replicated in a cross-sectional study of an independent cohort (odds ratio 0.47 [95% CI 0.25-0.89]; P = 0.02 for a recessive model).

CONCLUSIONS

The A allele of the -866G>A variant of UCP2 was associated with reduced risk of CAD in men with type 2 diabetes in a 6-year prospective study. Decreased risk of myocardial infarction, angina pectoris, CABG, and sudden death contributed individually and significantly to the reduction of CAD risk. This association was independent of other common CAD risk factors.

[Cardiovascular assessment of diabetic patients]

INTRODUCTION

Type 2 diabetes is a cardiovascular disease. The morbidity and mortality among these patients are primarily due to cardiovascular diseases. There are many guidelines regarding clinical evaluation of cardiovascular disease in those patients. Implementation of these guidelines has been an argued subject. Our objective in this paper is to describe what basal cardiovascular evaluation has been carried out at a specialized university Diabetes Center.

SUBJECTS AND METHODS

Data were collected from February to October 2006 of 121 type 2 diabetes individuals who were enrolled at the Diabetes Center of Federal University of São Paulo. We analyzed the type of cardiovascular disease evaluation that they had been submitted in the year that preceded the consultation.

RESULTS

We have observed a high prevalence of several other cardiovascular risk factors in this population. The cardiovascular evaluations during this period has shown 36% of the patients had not been submitted to any cardiovascular test, 17% had been submitted to resting electrocardiogram and 27% of the patients had been submitted to exercise test. Rest echocardiogram, pharmacologic stress echocardiogram, myocardial perfusion scintigraphy, and coronary angiography have been carried out in a much lesser ratio.

CONCLUSION

Our data has shown the variability and limitations on boarding diagnosing of DAC in university environment patients and point us the necessity of constructing defined and directed directives for the peculiarities of the Brazilian population and health system.

The changing costs and benefits of screening for asymptomatic coronary heart disease in patients with diabetes

Aggressive medical therapy can be justified in most patients with diabetes, but there may be some higher-risk asymptomatic patients who could benefit from revascularization and/or medical therapy for myocardial ischemia. Silent myocardial ischemia (SMI) might be used to identify these high-risk individuals. In this Review we define SMI as objective evidence of ischemia from any noninvasive test occurring in an asymptomatic patient. We outline what is known about asymptomatic coronary heart disease (CHD) in diabetes and how this relates to SMI. We examine how SMI predicts angiographic CHD and CHD events, and we describe the changing role of CHD screening as reflected by various guidelines. We identify the recent research suggesting that there may be substantial numbers of high-risk asymptomatic patients who have diabetes with undiagnosed CHD and who could benefit from more-active intervention; however, with the recent advances in medical therapy, and the uncertain benefits of screening, current guidelines strongly discourage this practice, except in limited clinical situations, such as before major surgery. Carefully conducted clinical trails using state-of-the-art investigations and therapy in well-characterized patients with diabetes are urgently required to inform physicians on when and how to intervene.

Nuclear Cardiology: Present and Future

Nuclear cardiology has made significant advances since the first reports of planar scintigraphy for the evaluation of left ventricular perfusion and function. While the current "state of the art" of gated myocardial perfusion single-photon emission computed tomographic (SPECT) imaging offers invaluable diagnostic and prognostic information for the evaluation of patients with suspected or known coronary artery disease (CAD), advances in the cellular and molecular biology of the cardiovascular system have helped to usher in a new modality in nuclear cardiology, namely, molecular imaging. In this review, we will discuss the current state of the art in nuclear cardiology, which includes SPECT and positron emission tomographic evaluation of myocardial perfusion, evaluation of left ventricular function by gated myocardial perfusion SPECT and gated blood pool SPECT, and the evaluation of myocardial viability with PET and SPECT methods. In addition, we will discuss the future of nuclear cardiology and the role that molecular imaging will play in the early detection of CAD at the level of the vulnerable plaque, the evaluation of cardiac remodeling, and monitoring of important new therapies including gene therapy and stem cell therapy.