Aspirin, anticoagulant therapy

One drawback of thrombolytic therapy is a high incidence of reocclusion. In a report using a canine model, inclusion of heparin [9005-49-6] (anticoagulant therapy) in the treatment prevented this side effect (158). The combination of aspirin [50-78-2] (antiplatelet therapy) and streptokinase (thrombolytic therapy) has also shown significant therapeutic advantages (78). Although additional work is needed to estabUsh the thrombolytic advantage of various combinations, preliminary results in this area indicate promise in terms of increased efficacy and reduced side effects. 

This was largely influenced by the high-dose UFH group in 1ST (OR 1.38, 95% Cl 1.05-1.82). An interaction by UFH dose (p = 0.01) on recurrent stroke risk with combination UFH-aspirin therapy compared to aspirin monotherapy was observed, with a trend toward increased risk of recurrent stroke with high-dose UFH + aspirin (OR 1.22, 95% Cl 0.92-1.62) and a trend toward reduced risk with low-dose UFH + aspirin (OR 0.75, 95% Cl 0.56-1.03), equivalent to 10 fewer (95% Cl 0-20 fewer) recurrent strokes per 1000 patients treated. They found a small, but significant beneht of LMWH over aspirin in the prevention of symptomatic DVT, equivalent to 10 (95% Cl 0-30) fewer DVTs per 1000 patients treated. Compared with aspirin, anticoagulants were associated with nonsignificantly fewer symptomatic PEs (OR 0.85, 95% Cl 0.55-1.32). There were fewer PEs with the combination of UEH and aspirin (OR 0.58, 95% Cl 0.34—1.00), equivalent to 5 fewer (Cl 0-10) PEs per 1000 patients treated. However, the overall incidence of symptomatic DVT and PE was low (1.1% and 0.7%). 

Warfarin antagonists include vitamin K, barbiturates, glutethimide. rifampin, and cholestyramine. Warfarin potentiators include phenylbutazone. oxyphenbutazone, anabolic steroids, clofibrate, aspirin, hepatotoxins, disnlfirain, and metronidazole. In patients undergoing anticoagulation therapy with warfann, it has been found that cimetidine (used in therapy of duodenal ulcer) may increase anticoagulant blood levels and consequently prolong the prothrombin time. 

Rheumatic mitral valve disease is associated with thromboembolic complications at reported rates of 1.5 to 4.7% per year the incidence in patients with mitral stenosis is approximately 1.5 to 2 times that in patients with mitral regurgitation. The presence of atrial fibrillation is the single most important risk factor for thromboembolism in valvular disease, increasing the incidence of thromboembolism in both mitral stenosis and regurgitation four- to sevenfold. In current practice, patients with nonrheumatic atrial fibrillation at low risk for thromboembolism based on clinical characteristics frequently are treated with aspirin. Warfarin therapy is considered in higher-risk patients, especially those with previous thromboembolism and in whom anticoagulation is not contraindicated due to preexisting conditions. 

Patients in atrial fibrillation who have a TIA or stroke without other clear etiology should be given anticoagulation therapy if there are no contraindications (European Atrial Fibrillation Trial Study Group 1993, 1995). Recent studies have shown that warfarin is as safe as aspirin in elderly patients with atrial fibrillation (Rash et al. 2007 Mant et al. 2007). Patients with presumed cardioembolic TIA or stroke secondary to other causes should certainly receive antithrombotic therapy. Also they may benefit from anticoagulation in certain circumstances, such as intracardiac mural thrombosis after myocardial infarction, although there have been no randomized trials in situations other than non-valvular atrial fibrillation. 

European Atrial Fibrillation Trial Study Group (1995). Optimal oral anticoagulant therapy in patients with nonrheumatic atrial fibrillation and recent cerebral ischemia. New England Journal of Medicine 333 5-10 Halkes PH, van Gijn J For the ESPRIT Study Group (2006). Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT) randomised controlled trial. Lancet 367 1665-73 [Erratum in Lancet (2007) 369 274]... 

Watson RM, Pierson RN Jr. Effect of anticoagulant therapy upon aspirin-induced gastrointestinal bleeding. Circulation 1961 24 613-16. 

Aspirin potentiates the anticoagulant effect of warfarin and other coumarins because of its inhibitory effect on platelet aggregation and inhibition of vitamin K synthesis. Ibuprofen may also enhance the effect of anticoagulants. Patients on anticoagulant therapy should avoid over-the-counter (OTC) aspirin and ibuprofen. 

The optimal dose of aspirin and the intensity of anticoagulation therapy have not been well established, and clinicians will use various strategies for prevention of thrombosis in the presence of antiphospholipid antibodies. 

Anticoagulant therapy, chiefly warfarin, and platelet inhibitors, such as aspirin, are used prophylactically to prevent thromboembolic disease while fibrinolytic drugs can be used to destroy thrombi already formed and can be life saving after a myocardial infarction or stroke. 

Hi) anticoagulation therapy, in which the patient takes medication proidiylactically, such as low dosage aspirin in order to prevent clot formation ... 

Dong, M.R et al.. Anticoagulation therapy with combined low dose aspirin and warfarin following mechanical heart valve replacement. ThrombRes, 2011.128(5) e91-e94. 

Overall no evidence was found to support the claim that anticoagulants offer a net advantage over aspirin in patients with acute ischemic stroke. There was evidence, however, to suggest that combination anticoagulant and aspirin therapy was associated with a small increase in the number of deaths at the end of follow-up, equivalent to 20 more deaths per 1000 patients treated. This adverse effect can probably be attributed partly to the 10 extra sICHs, and the 5 extra major extracranial hemorrhages per 1000 patients treated with combination anticoagulant/ aspirin therapy. 

Warfarin has not been adequately studied in non-cardioembolic stroke, but it is often recommended in patients after antiplatelet agents fail. One small retrospective study suggests that warfarin is better than aspirin.30 More recent clinical trials have not found oral anticoagulation in those patients without atrial fibrillation or carotid stenosis to be better than antiplatelet therapy. In the majority of patients without atrial fibrillation, antiplatelet therapy is recommended over warfarin. In patients with atrial fibrillation, long-term anticoagulation with warfarin is recommended and is effective in both primary and secondary prevention of stroke.12 The goal International Normalized Ratio (INR) for this indication is 2 to 3. 

Clopidogrel may be substituted for aspirin when aspirin is absolutely contraindicated Long-acting nondihydropyridine calcium antagonists instead of /3-blockers as initial therapy ACEIs are recommended in patients with CAD or other vascular disease Low-intensity anticoagulation with warfarin, in addition to aspirin, is recommended but bleeding would be increased Therapies to be avoided include ... 

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