Does diabetes always confer coronary heart disease risk equivalent to a prior myocardial infarction?: implications for prevention

Strategy to identify subjects with diabetes mellitus more suitable for selective echocardiographic screening: The DAVID-Berg study

BACKGROUND

Despite the burden of pre-clinical heart failure (HF) among diabetes mellitus (DM) patients, routine screening echocardiography is not currently recommended. We prospectively assessed risk prediction for HF/death of a screening strategy combining clinical data, electrocardiogram, NTproBNP, and echocardiogram, aiming to identify DM patients more suitable for selective echocardiography.

METHODS

Among 4047 screened subjects aged≥55/≤80years, the DAVID-Berg Study prospectively enrolled 623 outpatients with DM, or hypertension, or known cardiovascular disease but with no HF history/symptoms. The present analysis focuses on data obtained during a longitudinal follow-up of the 219 patients with DM.

RESULTS

Mean age was 68years, 61% were men, and median DM duration was 4.9years. During a median follow-up of 5.2years, 50 subjects developed HF or died. A predictive model using clinical data demonstrated moderate predictive power, which significantly improved by adding electrocardiogram (C-statistic 0.75 versus 0.70; p<0.05), but not NTproBNP (C-statistic 0.72, p=0.20). Subjects with normal clinical variables or abnormal clinical variables but normal electrocardiogram had low events rate (1.3 versus 2.4events/100-person-years, p=NS). Conversely, subjects with both clinical and electrocardiogram abnormalities (47%) carried higher risk (9.0events/100-person-years, p<0.001). The predictive power for mortality/HF development increased when echocardiography was added (13.6events/100-person-years, C-statistic 0.80, p<0.05).

CONCLUSIONS

Our prospective study found that a selective echocardiographic screening strategy guided by abnormal clinical/electrocardiogram data can reliably identify DM subjects at higher risk for incident HF and death. This screening approach may hold promise in guiding HF prevention efforts among DM patients.

Long-term Prediction of Cardiovascular Outcomes by Circulating CD34+ and CD34+CD133+ Stem Cells in Patients With Type 2 Diabetes

OBJECTIVE

Cardiovascular risk varies substantially in the population with diabetes, and biomarkers can improve risk stratification. Circulating stem cells predict future cardiovascular events and death, but data for the population with diabetes are scant. In this study we evaluated the ability of circulating stem cell levels to predict future cardiovascular outcomes and improve risk discrimination in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A cohort of 187 patients with type 2 diabetes was monitored for a median of 6.1 years. The primary outcome was time to a first cardiovascular event, defined as 3-point major adverse cardiovascular event (cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke) plus hospitalization for cardiovascular causes. At baseline, we measured six stem/progenitor cell phenotypes in peripheral blood based on expression of CD34, CD133, and KDR.

RESULTS

The primary outcome occurred in 48 patients (4.5/100 patient-years). Patients with incident cardiovascular events had significantly lower CD34⁺ and CD34⁺CD133⁺ cells than those without. Higher rates of cardiovascular events occurred in patients with below median levels of CD34⁺ and CD34⁺CD133⁺. In Cox proportional hazards regression analyses, a reduced CD34⁺ (hazard ratio 2.21 [95% CI 1.14-4.29]) and CD34⁺CD133⁺ (2.98 [1.46-6.08]) cell count independently predicted future events. Addition of the CD34⁺ cell count to the reference model or the UK Prospective Diabetes Study risk engine improved C statistics, continuous net reclassification improvement, and/or integrated discrimination index.

CONCLUSIONS

In patients with type 2 diabetes, a reduced baseline level of circulating CD34⁺ stem cells predicts adverse cardiovascular outcomes up to 6 years later and improves risk stratification.

Diabetes, diabetes severity, and coronary heart disease risk equivalence: REasons for Geographic and Racial Differences in Stroke (REGARDS)

BACKGROUND

Evidence is mixed regarding whether diabetes confers equivalent risk of coronary heart disease (CHD) as prevalent CHD. We investigated whether diabetes and severe diabetes are CHD risk equivalents.

METHODS

At baseline, participants in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study (black and white US adults ≥45 years old recruited in 2003-2007) were categorized as having prevalent CHD only (self-reported or electrocardiogram evidence; n = 3,043), diabetes only (self-reported or elevated glucose; n = 4,012), diabetes and prevalent CHD (n = 1,529), and neither diabetes nor prevalent CHD (n = 17,155). Participants with diabetes using insulin and/or with albuminuria (urinary albumin-to-creatinine ratio ≥30 mg/g) were categorized as having severe diabetes. Participants were followed up through 2011 for CHD events (myocardial infarction or fatal CHD).

RESULTS

During a mean follow-up of 5 years, 1,385 CHD events occurred. The hazard ratios of CHD events comparing participants with diabetes only, diabetes, and prevalent CHD and neither diabetes nor prevalent CHD with those with prevalent CHD were 0.65 (95% CI 0.54-0.77), 1.54 (95% CI 1.30-1.83), and 0.41 (95% CI 0.35-0.47), respectively, after adjustment for demographics and risk factors. Compared with participants with prevalent CHD, the hazard ratio of CHD events for participants with severe diabetes was 0.88 (95% CI 0.72-1.09).

CONCLUSIONS

Participants with diabetes had lower risk of CHD events than did those with prevalent CHD. However, participants with severe diabetes had similar risk to those with prevalent CHD. Diabetes severity may need consideration when deciding whether diabetes is a CHD risk equivalent.

Natriuretic Peptide and High-Sensitivity Troponin for Cardiovascular Risk Prediction in Diabetes: The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

Cardiovascular disease (CVD) is the major cause of morbidity and mortality in diabetes; yet, heterogeneity in CVD risk has been suggested in diabetes, providing a compelling rationale for improving diabetes risk stratification. We hypothesized that N-terminal prohormone brain natriuretic peptide (NTproBNP) and high-sensitivity troponin T may enhance CVD risk stratification beyond commonly used markers of risk and that CVD risk is heterogeneous in diabetes.

RESEARCH DESIGN AND METHODS

Among 8,402 participants without prevalent CVD at visit 4 (1996-1998) of the Atherosclerosis Risk in Communities (ARIC) study there were 1,510 subjects with diabetes (mean age 63 years, 52% women, 31% African American, and 60% hypertensive).

RESULTS

Over a median follow-up of 13.1 years, there were 540 incident fatal/nonfatal CVD events (coronary heart disease, heart failure, and stroke). Both troponin T ≥14 ng/L (hazard ratio [HR] 1.96 [95% CI 1.57-2.46]) and NTproBNP >125 pg/mL (1.61 [1.29-1.99]) were independent predictors of incident CVD events at multivariable Cox proportional hazard models. Addition of circulating cardiac biomarkers to traditional risk factors, abnormal electrocardiogram (ECG), and conventional markers of diabetes complications including retinopathy, nephropathy, and peripheral arterial disease significantly improved CVD risk prediction (net reclassification index 0.16 [95% CI 0.07-0.22]). Compared with individuals without diabetes, subjects with diabetes had 1.6-fold higher adjusted risk of incident CVD. However, participants with diabetes with normal cardiac biomarkers and no conventional complications/abnormal ECG (n = 725 [48%]) were at low risk (HR 1.12 [95% CI 0.95-1.31]), while those with abnormal cardiac biomarkers, alone (n = 186 [12%]) or in combination with conventional complications/abnormal ECG (n = 243 [16%]), were at greater risk (1.99 [1.59-2.50] and 2.80 [2.34-3.35], respectively).

CONCLUSIONS

Abnormal levels of NTproBNP and troponin T may help to distinguish individuals with high diabetes risk from those with low diabetes risk, providing incremental risk prediction beyond commonly used markers of risk.

Comparison of different vascular risk engines in the identification of type 2 diabetes patients with high cardiovascular risk

Background

Some authors consider that secondary prevention should be conducted for all DM2 patients, while others suggest that the drug preventive treatment should start or be increased depending on each patient’s individual CVR, estimated using cardiovascular or coronary risk functions to identify the patients with a higher CVR. The principal objective of this study was to assess three different cardiovascular risk prediction models in type 2 diabetes patients.

Methods

Multicentre, cross-sectional descriptive study of 3,041 patients with type 2 diabetes and no history of cardiovascular disease. The demographic, clinical, analytical, and cardiovascular risk factor variables associated with type 2 diabetes were analysed. The risk function and probability that a cardiovascular disease could occur were estimated using three risk engines: REGICOR, UKPDS and ADVANCE. A patient was considered to have a high cardiovascular risk when REGICOR ≥ 10 % or UKPDS ≥ 15 % in 10 years or when ADVANCE ≥ 8 % in 4 years.

Results

The ADVANCE and UKPDS risk engines identified a higher number of diabetic patients with a high cardiovascular risk (24.2 % and 22.7 %, respectively) compared to the REGICOR risk engine (10.2 %). The correlation using the REGICOR risk engine was low compared to UKPDS and ADVANCE (r = 0.288 and r = 0.153, respectively; p < 0.0001). The agreement values in the allocation of a particular patient to the high risk group was low between the REGICOR engine and the UKPDS and ADVANCE engines (k = 0.205 and k = 0.123, respectively; p < 0.0001) and acceptable between the ADVANCE and UKPDS risk engines (k = 0.608).

Conclusions

There are discrepancies between the general population and the type 2 diabetic patient-specific risk engines. The results of this study indicate the need for a prospective study which validates specific equations for diabetic patients in the Spanish population, as well as research on new models for cardiovascular risk prediction in these patients.

Awareness, treatment, and control of LDL cholesterol are lower among U.S. adults with undiagnosed diabetes versus diagnosed diabetes

OBJECTIVE

Diabetes is often undiagnosed, resulting in incorrect risk stratification for lipid-lowering therapy. We conducted a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2005-2010 to determine the prevalence, awareness, treatment, and control of elevated LDL cholesterol (LDL-C) among U.S. adults with undiagnosed diabetes.

RESEARCH DESIGN AND METHODS

Fasting NHANES participants 20 years of age or older who had 10-year Framingham coronary heart disease (CHD) risk scores <20% and were free of CHD or other CHD risk equivalents (n = 5,528) were categorized as having normal glucose, impaired fasting glucose, undiagnosed diabetes, or diagnosed diabetes. High LDL-C was defined by the 2004 Adult Treatment Panel (ATP) III guidelines.

RESULTS

The prevalence of diagnosed and of undiagnosed diabetes was 8 and 4%, respectively. Mean LDL-C was 102 ± 2 mg/dL among those with diagnosed diabetes and 117 ± 3 mg/dL for those with undiagnosed diabetes (P < 0.001). The prevalence of high LDL-C was similar among individuals with undiagnosed (81%) and diagnosed (77%) diabetes. Among individuals with undiagnosed diabetes and high LDL-C, 38% were aware, 27% were treated, and 16% met the ATP III LDL-C goal for diabetes. In contrast, among individuals with diagnosed diabetes and high LDL-C, 70% were aware, 61% were treated, and 36% met the ATP III goal. Subjects with undiagnosed diabetes remained less likely to have controlled LDL-C after multivariable adjustment (prevalence ratio, 0.42; 95% CI, 0.23-0.80).

CONCLUSIONS

Improved screening for diabetes and reducing the prevalence of undiagnosed diabetes may identify individuals requiring more intensive LDL-C reduction.

Variability in the response to antiplatelet treatment in diabetes mellitus

Atherothrombosis is a leading cause of death in patients with diabetes mellitus. Among factors contributing to the diabetic prothrombotic state, platelet activation plays a pivotal role. Numerous studies have investigated the benefits of antiplatelet therapy for primary and secondary cardiovascular prevention in diabetic patients. However, there are limited evidences that low-dose aspirin may be effective in this clinical setting. Several disease-specific factors have been identified as potential determinants of aspirin treatment failure. In this review, the main determinants of interindividual variability in response to antiplatelet agents are discussed, with particular emphasis on the pharmacokinetic and pharmacodynamic mechanisms of clinical efficacy and safety of antiplatelet drugs in patients with diabetes mellitus.

Mortality rates in trials of subjects with type 2 diabetes

BACKGROUND

In randomized controlled trials (RCTs) of subjects with type 2 diabetes mellitus, mortality rates vary substantially. We sought to examine the inclusion and exclusion criteria of these RCTs to explore relationships with mortality.

METHODS AND RESULTS

MEDLINE database was searched from August 1980 through March 2011. Selection criterion included published RCTs of adults with type 2 diabetes mellitus of at least 1000 patients, reporting all-cause mortality and having follow-up duration of at least 1 year. Twenty-two trials were eligible. Annualized mortality rates were derived. Inclusion and exclusion criteria were tabulated for each trial. Trials were categorized in 4 groups according to annual mortality rates: <1, ≥1 to <2, ≥2 to <4, and ≥4 per 100 patient-years. The analysis cohort included 91842 patients and 6837 deaths. Mortality rates ranged from 0.28 to 8.24 per 100 patient-years. Patients enrolled in the highest mortality category were more likely to be older and had longer diabetes duration and higher blood pressure. The selection for hypertension was common in the low- as well as high-mortality trials. Although the mortality rates were higher in RCTs with prior cardiovascular morbidity, the selection for chronic kidney disease-defined by either higher serum creatinine or lower estimated glomerular filtration rate and/or the presence of proteinuria-was associated with the highest mortality rates.

CONCLUSIONS

In this analysis of RCTs of type 2 diabetes mellitus, a 29-fold difference in annualized mortality was observed. In these RCTs, selection for renal disease, defined by either decline in renal function or presence of proteinuria, portends important mortality risk. (J Am Heart Assoc. 2012;1:8-15.)

CLINICAL TRIAL REGISTRATION

URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00303979.