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

Screening for Coronary Artery Disease in Patients with Diabetes

PURPOSE OF REVIEW

The study aims to describe methods for detecting subclinical coronary artery disease (CAD) and their potential implications in asymptomatic patients with diabetes.

RECENT FINDINGS

Imaging tools can assess non-invasively the presence and severity of CAD, based on myocardial ischemia, coronary artery calcium score, and coronary computed tomography coronary angiography. Subclinical CAD is common in the general population ageing 50 to 64 years with any coronary atherosclerosis present in 42.1% and obstructive CAD in 5.2%. In patients with diabetes, an even higher prevalence has been noted. The presence of myocardial ischemia, obstructive CAD, and the extent of coronary atherosclerosis provide powerful risk stratification regarding the risk of cardiovascular events. However, randomized trials evaluating systematic screening in the general population or patients with diabetes have demonstrated only moderate impact on management and no significant impact on patient outcomes. Despite providing improved risk stratification, systematic screening of CAD is not recommended in patients with diabetes.

Silent coronary artery disease in type 2 diabetes: a narrative review on epidemiology, risk factors, and clinical studies

Silent coronary artery disease (CAD) is one of the manifestations of heart disease that particularly affects subjects with type 2 diabetes mellitus (T2DM). From a clinical point of view, silent CAD represents a constant challenge for the diabetologist, who has to decide whether a patient could or could not be screened for this disease. In the present narrative review, several aspects of silent CAD are considered: the epidemiology of the disease, the associated risk factors, and main studies conducted, in the last 20 years, especially aimed to demonstrate the usefulness of the screening of silent CAD, to improve cardiovascular outcomes in type 2 diabetes.

Diagnosis and Prognosis of Coronary Artery Disease with SPECT and PET

PURPOSE OF REVIEW

Radionuclide myocardial perfusion imaging (MPI) continues to be the most reliable modality for diagnosis of hemodynamically significant coronary artery disease (CAD). The application of radionuclide MPI using single photon emission computed tomography (SEPCT) and positron emission tomography (PET) for CAD is reviewed, with emphasis on diagnosis and risk stratification.

RECENT FINDINGS

Contemporary studies have reported the diagnostic and prognostic value of novel imaging protocols, employing stress-first or stress-only approach. In addition, the superior diagnostic value of PET has been established with a role of assessment of myocardial blood flow to improve risk stratification. The utility of MPI in special populations, such as the elderly, women, and diabetic patients has also been recently evaluated. Furthermore, multicenter studies have reported a similar diagnostic and prognostic value of radionuclide MPI compared with other functional and anatomical techniques for CAD. Radionuclide MPI with SPECT and PET are efficacious for diagnosis and prognosis of CAD. Its universal application in varied patient populations highlights its excellent clinical effectiveness.

Risk of silent myocardial ischemia detected by single photon emission computed tomography (SPECT) among asymptomatic Chinese patients with type 2 diabetes

To explore the prevalence and risk factors of silent myocardial ischemia (SMI) detected by using single photon emission computed tomography (SPECT) in Chinese asymptomatic patients with type 2 diabetes (T2D).In this hospital-based retrospective study, 821 T2D patients who were screened for SMI detected by stress myocardial perfusion imaging using SPECT between June 2014 and July 2016 were investigated. Clinical indicators were compared between the patients with SMI and controls without SMI. Risk factors for SMI were evaluated by univariate and multivariate analysis.In this study, there were 131 patients with SMI in asymptomatic diabetes and the prevalence of SMI was 21.3% of 614 individuals. Logistic regression analysis indicated that diabetic retinopathy (OR = 1.474, 95%CI: 1.113-1.951, P = .007), male gender (OR = 1.805, 95%CI: 1.183-2.747, P = .006), and low-density lipoprotein (LDL) cholesterol (OR = 1.298, 95%CI: 1.042-1.615, P = .02) were risk factors associated with SMI. Besides, the prevalence of SMI increased in associated with the progression of retinopathy (P = .041). The percentage of SMI diagnosed in patients with no diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR) were 18.5% (75/405), 25.2% (37/147), and 30.6% (19/62), respectively. The percentage of SMI in male (24.5%, 85/347) was higher than that in female (17.2%, 46/267), P = .029.Physicians should be aware of these conditions when examining male patients with type 2 diabetes, especially with DR and/or high level of low-density lipoprotein cholesterol (LDL cholesterol), even if otherwise asymptomatic. A routine screening for SMI may thus be considered advisable in these patients.

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.

The First Harmonic of Radial Pulse as an Early Predictor of Silent Coronary Artery Disease and Adverse Cardiac Events in Type 2 Diabetic Patients

Background

It has been reported that harmonics of radial pulse is related to coronary artery disease (CAD) in patients with type 2 diabetes mellitus (T2DM). It is still unclear whether or not the first harmonics of the radial pulse spectrum is an early independent predictor of silent coronary artery disease (SCAD) and adverse cardiac events (ACE).

Objectives

To measure the risk of SCAD in patients with T2DM and also to survey whether or not an increment of the first harmonic (C1) of the radial pulse increases ACE.

Methods

1968 asymptomatic individuals with T2DM underwent radial pulse wave measurement. First harmonic of the radial pressure wave, C1, was calculated. Next, the new occurrence of ACE and the new symptoms and signs of coronary artery disease were recorded. The follow-up period lasted for 14.7 ± 3.5 months.

Results

Out of 1968 asymptomatic individuals with T2DM, ACE was detected in 239 (12%) of them during the follow-up period. The logrank test demonstrated that the cumulative incidence of ACE in patients with C1 above 0.96 was greater than that in those patients with C1 below 0.89 (P < 0.01). By comparing the data of patients with C1 smaller than the first quartile and the patients with C1 greater than the third quartile, the hazard ratios were listed as follows: ACE (hazard ratio, 2.29; 95% CI, 1.55–3.37), heart failure (hazard ratio, 2.22; 95% CI, 1.21–4.09), myocardial infarction (hazard ratio, 2.44; 95% CI, 1.51–3.93), left ventricular dysfunction (Hazard ratio, 2.01; 95% CI, 0.86–4.70), and new symptoms and signs for coronary artery disease (hazard ratio, 2.03; 95% CI, 1.45–2.84). As C1 increased, the risk for composite ACE (P < 0.001 for trend) and for coronary disease (P < 0.001 for trend) also increased. The hazard ratio and trend for cardiovascular-cause mortality were not significant.

Conclusions

This study showed that C1 of the radial pulse wave is correlated with cardiovascular events. Survival analysis showed that C1 value is an independent predictor of ACE and SCAD in asymptomatic patients with T2DM. Thus, screening for the first harmonic of the radial pulse may improve the risk stratification of cardiac events and SCAD in asymptomatic patients although they had no history of coronary artery disease or angina-related symptom.

Serum cystatin C level is associated with carotid arterial wall elasticity in subjects with type 2 diabetes mellitus: A potential marker of early-stage atherosclerosis

AIMS

Detection of early-stage atherosclerosis in type 2 diabetes mellitus (T2DM) patients is important for preventing cardiovascular disease. A phased tracking method for evaluating arterial wall elasticity sensitively detects early-stage atherosclerosis. However, biochemical markers for early-stage atherosclerosis have yet to be established.

METHODS

This cross-sectional study enrolled 180 T2DM patients, who were classified as not having atherosclerosis according to the carotid intima-media thickness (IMT) criteria. We measured serum cystatin C, the estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR), and analyzed the associations between these markers and arterial wall elasticity (Eθ), IMT and the cardio-ankle velocity index.

RESULTS

Multiple linear regression analyses revealed that cystatin C was significantly associated with Eθ, while neither eGFR nor ACR showed an association. Furthermore, among the examined atherosclerotic markers, Eθ was most reliably associated with cystatin C. Additionally, the association between cystatin C and Eθ disappeared in the low elasticity subgroup, which included subjects in whom no atherosclerotic changes had yet been initiated.

CONCLUSIONS

In T2DM patients without apparent arterial wall thickening, cystatin C is strongly and independently associated with arterial wall elasticity, which reflects the degree of subclinical atherosclerosis. Thus, cystatin C is a potentially useful marker of early-stage atherosclerosis.

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

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

Ambulatory 24-h ECG monitoring and cardiovascular autonomic assessment for the screening of silent myocardial ischemia in elderly type 2 diabetic hypertensive patients

The aim of the study was to evaluate the usefulness of Holter monitoring for the detection of silent myocardial ischemia (SMI) in elderly type 2 diabetic patients with hypertension and the possible relationship between SMI and cardiovascular autonomic neuropathy (CAN). Two hundred and forty-three asymptomatic outpatients, aged 65-75 years, with type 2 diabetes and essential hypertension underwent 24-h ECG monitoring and 5 tests for the evaluation of both parasympathetic (heart rate variability, response to breath deeping, and Valsalva manoeuvre) and sympathetic (cold pressor test and orthostatic hypotension test) autonomic function. A total of 518 asymptomatic episodes of ST depression during Holter monitoring indicative of SMI were detected in 51 of the 243 studied patients (20.9 %). None of the patients with ST depression episodes exhibited a normal response to at least one of the evaluated autonomic function tests, whereas 22 of the 192 patients without ST changes (11.4 %) exhibited a normal response to all tests. Abnormality in both parasympathetic and sympathetic function test responses was found in 94.1 % of patients with ST depression episodes vs 26.1 % of those without ST changes (P < 0.001). Statistical evaluation of the relationship between the abnormal response to single autonomic function test and episodes of ST depression was highly significant for all the 5 tests (P < 0.001). These results indicate that: (a) Holter monitoring enables to detect ST segment changes indicative of SMI in 20.9 % of elderly diabetic patients with hypertension; (b) the presence of autonomic cardiac dysfunction in these patients suggests a role of diabetic neuropathy in the pathogenesis of SMI; and

Can myocardial performance index predict the presence of silent ischemia in asymptomatic type 2 diabetic patients?

BACKGROUND

Coronary artery disease (CAD) is an important cause of morbidity and mortality in patients with diabetes. Silent myocardial ischemia (SMI) is common in patients with diabetes and is associated with poorer prognosis. Myocardial performance index "Tei index" that reflects both left ventricular (LV) systolic and diastolic function. The aim of our study was to test the value of Tei index in prediction of SMI in asymptomatic patients with type 2 diabetes.

PATIENTS AND METHODS

Asymptomatic patients with type 2 diabetes were included in our study. We excluded patients with known CAD, previous revascularization, low ejection fraction, or abnormal ECG from the study. All patients had undergone history taking and clinical examination, ECG, echocardiography with measuring of Tei index and Holter monitoring for detecting silent ischemia.

RESULTS

A total of 200 patients were recruited. We divided our patients into two groups: Group I: 64 patients with SMI, Group II: 136 patients without SMI. There was no significant difference between the two groups regarding clinical and conventional echocardiographic data. Tei index was significantly higher in patients with silent ischemia (P<.00001). Sensitivity, specificity, positive, and negative predictive values of Tei index ≥0.6 in prediction of Holter detected silent ischemia were 85.9%, 90%, 78.6%, and 88.6%, respectively. We found a significant positive correlation between Tei index and number of ischemic episodes (r=.366, P=.0029).

CONCLUSION

Measuring Tei index is helpful in predicting the presence of silent ischemia in asymptomatic patients with type 2 diabetes.

Progression to overt or silent CAD in asymptomatic patients with diabetes mellitus at high coronary risk: main findings of the prospective multicenter BARDOT trial with a pilot randomized treatment substudy

OBJECTIVES

The purpose of this study was to evaluate prevalence, progression, treatment, and outcome of silent coronary artery disease (CAD) in asymptomatic patients with diabetes (DM) at high coronary risk.

BACKGROUND

Despite the close association of diabetes and CAD, general CAD screening in asymptomatic patients with DM is discouraged even though outcome data in patients at high coronary risk are lacking.

METHODS

Prospective multicenter outcome study-with a pilot randomized treatment substudy. The study comprised 400 asymptomatic patients with DM (type 2) without history or symptoms of CAD at high CAD risk. They underwent clinical evaluation and myocardial perfusion single-photon emission computed tomography (MPS) at baseline and after 2 years. Patients with normal MPS received usual care; those with abnormal MPS received medical or combined invasive and medical management.

RESULTS

An abnormal MPS was found in 87 of 400 patients (22%). In patients with normal MPS, MACE occurred in 2.9% and ischemia or new scar in 3.2%. Patients with abnormal MPS had more MACE (9.8%; hazard ratio: 3.44; 95% confidence interval [CI]: 1.32 to 8.95; p = 0.011) and ischemia or new scar (34.2%; odds ratio: 15.91; 95% CI: 7.24 to 38.03; p < 0.001) despite therapy, resulting in "overt or silent CAD progression" of 35.6% versus 4.6% (odds ratio: 11.53; 95% CI: 5.63 to 24.70; p < 0.001). Patients with abnormal MPS randomized to medical versus invasive-medical strategies had similar event rates (p = 0.215), but more ischemic or new scar findings (54.3% vs. 15.8%; p < 0.001).

CONCLUSIONS

High-risk asymptomatic patients with DM and normal MPS (78%) have a low rate of first manifestations of CAD. Patients with abnormal MPS at baseline (22%) have a 7-fold higher rate of progression to "overt or silent CAD," despite therapy. Randomized patients' outcomes suggest that a combined invasive and medical strategy for silent CAD may reduce scintigraphic but not symptomatic CAD progression versus medical therapy alone. (Trial of Invasive versus Medical therapy of Early coronary artery disease in Diabetes Mellitus ISRCTN87953632).