Arun Natarajan

Platelet hyperactivity in type 2 diabetes: role of antiplatelet agents

Type 2 diabetes mellitus increases atherothrombotic risk. Platelets in individuals with diabetes show increased activity at baseline and in response to agonists, ultimately leading to increased aggregation. Increased expression of platelet surface adhesion molecules and receptors, enhanced production of thromboxane and thrombin and disturbances in platelet calcium homeostasis are well documented. As intra-arterial thrombi are initiated by platelets, strategies to limit acute thrombotic events have largely focused on antiplatelet agents. Aspirin remains the cornerstone of antiplatelet therapy but appears to have limited benefit in diabetes. Use of thienopyridines and platelet glycoprotein IIb/IIIa receptor inhibitors has been shown to benefit high-risk patient populations. This review summarises the different platelet abnormalities characterised in diabetes and the role of currently used antiplatelet agents.

Coronary artery bypass surgery in elderly people

An increasing number of elderly individuals are now undergoing coronary artery bypass surgery. Elderly patients, compared with patients of a younger age group, present for surgery with a greater burden of risk factors and reduced functional levels. Short-term outcomes are hence poorer in them. But symptom relief occurs in most survivors and is accompanied by excellent rates of long-term survival and a good quality of life. Therefore, an individualised risk–benefit profile must be carefully constructed by clinicians, taking into account several different factors and not just age alone. This review summarises the current concepts of coronary artery bypass surgery from the perspective of the very old.

The presence of coronary artery disease increases platelet-dependent thrombosis in patients with type 2 diabetes mellitus

Patients with type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD) die predominantly of thrombotic events [1] with poorer outcomes [2,3], even after treatment with invasive strategy than those without diabetes treated conservatively [4]. Reduction in macrovascular events is modest in these patients despite favorable glycemic indices [5,6]. Although in vitro abnormalities in platelet physiology exist in patients with diabetes mellitus [7], their impact on thrombogenesis remains poorly characterized. We assessed platelet-dependent thrombus formation in patients with T2DM using an ex vivo arterial injury model to simulate intracoronary conditions following plaque rupture. The local ethics committee and the Medicines and Healthcare Regulatory Agency, UK approved the study. Eighty-four patients in four groups were studied: 1 T2DM and stable CAD (n = 23); 2 T2DM without clinical macrovascular disease (n = 20); 3 CAD without T2DM (n = 21); 4 age and sex matched controls without history of T2DM or macrovascular disease (n = 20). Diabetic medications are given in Table 1. All participants (non-smokers) took 75 mg of aspirin daily for at least 1 week before the study. Compliance was confirmed by interview prior to the study. Stable CAD was defined as symptoms plus one of the following, in the absence of Canadian Cardiovascular Society class III/IV angina or acute coronary syndrome in the preceding 6 months: 1 Positive exercise tolerance test or myocardial perfusion scintigraphy; 2 angiographic evidence (> 50% stenosis of one vessel); or 3 previous coronary revascularization. Macrovascular disease was defined as clinically evident cerebrovascular, peripheral, renal or aortic atherosclerotic disease. Absence of macrovascular disease in groups 2 and 4 was confirmed by evaluating case records and the standardized Rose questionnaire [8]. T2DMwas defined usingWorldHealth Organization [9] criteria. Absence of diabetes mellitus was defined by the combination of: no prior history, no glucoselowering drug therapy, fasting blood glucose< 6.1 mmol L, and glycated hemoglobin (HbA1c) < 6.1%. The validated ex vivo Badimon perfusion chambers [10,11] incorporating two chambers with internal flow channels of different diameters were used. One simulated high-shear flow of 1690 s (Reynolds number 60, flow rate 10 mL min, average blood velocity 21.2 cm s) and the other simulated low-shear flow. The internal flow channels were lined with porcine aortic tunica media – the thrombogenic substrate. After perfusion with venous blood flowing at 10 mL min for 5 min, aortic segments were fixed in 10% formalin for 72 h. Total thrombus burden was measured using a validated computer-assisted planimetry using IMAGE-PRO PLUS software (Media Cybernetics, Inc., Bethesda, MD, USA) [10,11]. The results are the mean of the analyzed sections (lm mm). Statistical analysis was performed (SPSS 14.0; SPSS, Chicago, IL, USA) with variables expressed as mean ± standard deviation (SD) or median (range). Continuous variables, including thrombus areas in the groups, were compared using analysis of variance or appropriate non-parametric equivalents. Post hoc pairwise comparisons were calculated using Bonferroni adjustment. The two-tailed significance level was set at 0.05. Linear regression was performed using thrombus area as the dependent variable and metabolic parameters as independent variables. Univariate predictors were then entered into a

Non-invasive assessment of saphenous vein graft patency in asymptomatic patients

The development and progression of atherosclerotic disease in saphenous vein grafts (SVGs) following coronary artery bypass surgery (CABG) are often without symptoms. Four-slice CT is a non-invasive imaging technique reliable for assessing SVG patency. This study utilised CT to assess temporal progression of patency in asymptomatic patients. A four-slice CT scanner was used employing standard techniques. Analysis of the reconstructed images was performed offline by two experienced operators blinded to patient details. The primary aim was vein graft patency. 130 asymptomatic subjects were studied. The mean time from CABG was 7.3 years (range, 15 days to 21 years 9 months; standard deviation (SD), 4.4 years). 294 of the 305 SVGs were suitable for assessment of patency. The overall occlusion rate for assessable grafts was 23.5%. Occlusion rates for grafts <1 year old was 12.5% (2/16), 20.7% (42/203) for grafts 1-10 years old, and 33.3% (25/75) for grafts >10 years old. In conclusion, significant occlusion of SVGs occurs early after CABG in asymptomatic patients. Four-slice CT has the potential for the non-invasive assessment of individuals after surgery.

Coronary anomalies in Klippel–Trenaunay–Weber syndrome: multidetector computed tomography and cardiac magnetic resonance study of a rare association

A 38-year-old male with Klippel–Trenaunay–Weber syndrome presented with a non-ST-segment elevation myocardial infarction. He was a non-smoker, had skin capillary haemangiomas, a non-functioning kidney, and hypertension. He also suffered from recurrent leg cellulitis and had recently been discharged from intensive care after being treated for septicaemia from the same. Initial coronary assessment was done using 64-multidetector computed tomography (64-MDCT). Volume-rendered …