Non-invasive cardiac imaging techniques and vascular tools for the assessment of cardiovascular disease in type 2 diabetes mellitus.

Cardiovascular disease is the major cause of mortality in type 2 diabetes mellitus. The criteria for the selection of those asymptomatic patients with type 2 diabetes who should undergo cardiac screening and the therapeutic consequences of screening remain controversial. Non-invasive techniques as markers of atherosclerosis and myocardial ischaemia may aid risk stratification and the implementation of tailored therapy for the patient with type 2 diabetes. In the present article we review the literature on the implementation of non-invasive vascular tools and cardiac imaging techniques in this patient group. The value of these techniques as endpoints in clinical trials and as risk estimators in asymptomatic diabetic patients is discussed. Carotid intima-media thickness, arterial stiffness and flow-mediated dilation are abnormal long before the onset of type 2 diabetes. These vascular tools are therefore most likely to be useful for the identification of 'at risk' patients during the early stages of atherosclerotic disease. The additional value of these tools in risk stratification and tailored therapy in type 2 diabetes remains to be proven. Cardiac imaging techniques are more justified in individuals with a strong clinical suspicion of advanced coronary heart disease (CHD). Asymptomatic myocardial ischaemia can be detected by stress echocardiography and myocardial perfusion imaging. The more recently developed non-invasive multi-slice computed tomography angiography is recommended for exclusion of CHD, and can therefore be used to screen asymptomatic patients with type 2 diabetes, but has the associated disadvantages of high radiation exposure and costs. Therefore, we propose an algorithm for the screening of asymptomatic diabetic patients, the first step of which consists of coronary artery calcium score assessment and exercise ECG.

Vascular phenotype and subclinical inflammation in diabetic Asian Indians without overt cardiovascular disease.

Although Asian Indian (AI) patients with diabetes mellitus type 2 (DM2) are at high risk for cardiovascular disease (CVD), not all patients develop CVD. The vascular phenotype of AI-DM2 without CVD has not been elucidated and may point to protective features. Using baseline data from a clinical trial we provide an initial description of vascular parameters in AI-DM2 compared to Europid Caucasian controls (ECs) matched for age and gender. Endpoints of the study were endothelial function, low-grade systemic inflammation (CRP) and carotid intima-media thickness (cIMT). AIs had longer duration of diabetes, worse glycemic control and more microangiopathy. Both groups demonstrated marked endothelial dysfunction. CRP levels were similar: 1.7 (4.9) mg/L in AIs and 2.8 (3.6) mg/L in ECs. cIMT values were significantly lower in AI-DM2 than EC-DM2 (0.655mm (0.12) versus 0.711mm (0.15), p=0.03). Multiple regression analysis showed that variability in CRP was mainly determined by waist circumference, not by ethnicity. In contrast, ethnicity was a significantly explanatory variable for cIMT. Vascular phenotype of AI-DM2 without CVD was characterized by endothelial dysfunction and relatively low levels of CRP, comparable to EC-DM2 controls. In contrast, lower cIMT values were observed in AI-DM2 despite longer duration of diabetes and worse metabolic control. We propose that mechanisms slowing its progression may have atheroprotective potential in AI-DM2.

The metabolic syndrome: a vascular perspective.

The metabolic syndrome (MS) is a clustering of cardiovascular risk factors. Current definitions of MS use hypertension, waist circumference, fasting glucose, triglyceride and HDL-cholesterol levels as defining variables. The prevalence of MS is increasing in our society due to lifestyle changes that result in decreased physical activity and increased body weight. Patients with MS have a three times greater risk of coronary heart disease and stroke, and a two to four times greater risk of dying from atherosclerotic coronary heart disease than those without MS. Imaging studies have shown an increased burden and progression of atherosclerosis. Also, MS patients seem to be more vulnerable to events at comparable levels of atherosclerosis. First-line treatment for MS is therapeutic lifestyle intervention, including exercise and weight reduction. Medical intervention strategies using blood pressure-lowering medication, statins, fibrates and metformin seem the most appropriate to date. The effects of thiazolidinediones on cardiovascular endpoints have not been studied to a large extent in the setting of MS. Evidence regarding risk assessment and optimal medical strategies will be an important aspect of vascular research in the coming years.