Thrombosis risk reduction

The available evidence suggests that n-6 fatty acid-derived eicosanoids are generally proinflamma-tory and prothrombotic. In contrast, eicosanoids derived from n-3 fatty acids have attenuated biological activity on cardiovascular risk factors. The effects of altering n-6 PUFA intake, in conjvmction with changes in other polyunsaturated fatty acids, as well as other classes of fatty acids, on endothelial function, thrombosis, and inflammation are not understood. The relative proportion of all the classes of fatty acids in the diet may well be more important and relevant to cardiovascular risk reduction than any single class of fatty acids. Clearly such research warrants further investigation. 

Supplements of 400 Ig/d of folate begun before conception result in a significant reduction in the incidence of neural mbe defects as found in spina bifida. Elevated blood homocysteine is an associated risk factor for atherosclerosis, thrombosis, and hypertension. The condition is due to impaired abihty to form methyl-tetrahydrofolate by methylene-tetrahydrofolate reductase, causing functional folate deficiency and resulting in failure to remethylate homocysteine to methionine. People with the causative abnormal variant of methylene-tetrahydrofolate reductase do not develop hyperhomocysteinemia if they have a relatively high intake of folate, but it is not yet known whether this affects the incidence of cardiovascular disease. 

The ACCP Conference on Antithrombotic Therapy recommended against the use of aspirin as the primary method of VTE prophylaxis.2 Antiplatelet drugs clearly reduce the risk of coronary artery and cerebrovascular events in patients with arterial disease, but aspirin produces a very modest reduction in VTE following orthopedic surgeries of the lower extremities. The relative contribution of venous stasis in the pathogenesis of venous thrombosis compared with that of platelets in arterial thrombosis likely explains the reason for this difference. 

Some polyphenols inhibit platelet aggregation reducing the risk of thrombosis [171-173]. This effect may be due to a series of interaction of flavonoids in different biochemical pathways, such as by inhibition of cyclooxygenase and lipoxygenase, that are involved in the arachidonic acid metabolism in the platelets, or by inhibition of the formation of tromboxane and of the receptor function of the same [173-176]. Regular consumption of wine, tea and chocolate has been associated to the reduction of platelet aggregation, cardio-vascular diseases and thrombosis [171,177-179]. 

In view of the perceived benefit of aspirin in the secondary prevention of stroke and myocardial infarction, two large trials involving physicians as subjects were initiated to study the effect of aspirin in the primary prevention of arterial thrombosis. In the American study, 22,000 volunteers (age 40 to 84 years) were randomly assigned to take 325 mg of aspirin every other day or placebo. The trial was halted early, after a mean follow-up of 5 years, when a 45% reduction in the incidence of myocardial infarction and a 72% reduction in the incidence of fatal myocardial infarction were noted with aspirin treatment. However, total mortality was reduced only 4% in the aspirin group, a difference that was not statistically significant, and there was a trend for a greater risk of hemorrhagic stroke with aspirin. Thus, the prophylactic use of aspirin in an apparently healthy population is not recommended at this time, unless there are risk factors for cardiovascular disease. 

This British trial (Thrombosis Prevention Trial - TPT) [11] allocated 5,499 men with increased risk of coronary heart disease to either aspirin 75 mg daily or placebo, observing a 20% reduction of all coronary heart disease events (p = 0.04), almost entirely due to a 32% reduction in non-fatal events (p = 0.004). Diabetes was not one of the factors upon which baseline risk was calculated, and this probably explains why subsequent subgroup analyses of the trial results did not report separate data on diabetics... 

FDA approves Pradaxa for treatment and reduction in risk of recurrent deep vein thrombosis (DVT) and pulmonary embolism (PE), http //www. 

Venous thrombosis Vitamin Be Homocysteine reduction RCT no reduction of risk in disease recurrence den Heijer et al. (2007)... 

Fistula banding or plication is aimed to increase the resistance of the fistula to divert flow below the fistula to the native artery [24-26]. This reduces flow in the fistula and threatens its survival. However, most of these techniques are empirical, not well codified and reproducible and pose many questions (1) It is not clear where the reduction should be placed, whether on the arteriovenous anastomosis or the vein or both. (2) What is the optimal percentage of surface reduction in order to satisfactorily reduce flow without taking the risk of having a fistula thrombosis For these reasons, many reports of banding show high rates of fistula thrombosis, and these techniques have been abandoned by most authors [1-8,16]. 

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