Stroke warfarin

Use of warfarin in the secondary prevention of noncardioem-bolic stroke was addressed in the Warfarin Aspirin Recurrent Stroke Study. In 2206 patients with recent stroke, warfarin (INR = 1.4—2.8) was not superior to aspirin 325 mg/day in the prevention of recurrent events. This led many clinicians to abandon the practice of using warfarin as an alternative agent in patients who suffered recurrent events while on antiplatelet therapy in favor of combination or alternate antiplatelet therapy. 

Coumarin/warfarin, given at a typical dosage of 4 to 5 mg/day, prevents the deleterious formation in the bloodstream of small blood clots and thus reduces the risk of heart attacks and strokes for individuals whose arteries contain sclerotic plaques. Taken in much larger doses, as for example in rodent poisons, Coumarin/warfarin can cause massive hemorrhages and death. 

Five randomized primary and secondary prevention trials " have demonstrated the efficacy and safety of warfarin in preventing AF-related stroke. Pooled data from these trials demonstrated a 68% reduction in ischemic stroke (95% Cl 50-79) and an intracerebral hemorrhage rate of <1% per year. The data for aspirin suggested that it had a lesser effect, with a 36% risk reduction (95% Cl 4—57). 

The majority of patients with AF should receive warfarin therapy (titrated to an International Normalized Ratio of 2 to 3) for stroke prevention, particularly if they have other risk factors for stroke. 

Stroke Prevention All patients with paroxysmal, persistent, or permanent AF should receive therapy for stroke prevention, unless compelling contraindications exist. A decision strategy for stroke prevention in AF is presented in Fig. 6-9.27 In general, most patients require therapy with warfarin in some patients with no additional risk factors for stroke, aspirin may be acceptable. For some patients, serious consideration of the benefits of warfarin versus the risks of bleeding associated with warfarin therapy is warranted. The potential bleeding risks associated with warfarin may outweigh the benefits in... 

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. 

The most prescribed drugs for blood-related disorders are also summarized in Table 1.17. Blood clots can occur in the veins at extremities (especially after a long period of immobility). Those clots can subsequently become lodged in the blood vessels, the atria, the heart valves, and within the lungs, causing embolism and shortness of breath. Under severe conditions, the clots can also obstruct the flow of blood to the brain, leading to a stroke and paralysis. Coumadin (warfarin see chemical structure below) is one of the main hematological compounds that has been widely prescribed to counter these conditions... 

Johnson CE, Lim WK, Workman BS. People aged over 75 in atrial fibrillation on warfarin the rate of major hemorrhage and stroke in more than 500 patient-years of follow-up. J Am Geriatr Soc 2005 53 655-659. 

In present times, because of early mobilization and shorter stays in hospital, venous thrombosis in the legs and resulting pulmonary embolism has declined to a large degree. In persons with acute myocardial infarction, prophylactic low-dose heparin has reduced the incidence of venous thrombosis in the legs. It is considered as a reasonable alternative to warfarin in selected patients. Preventive anlicoagulalion may be indicated in some cases to prevent strokes due to left ventricular mitral thrombi embolizing in tire brain. 

Poller, L. and F.R.C. Path The Effect of Low Dose Warfarin on the Risk of Stroke in Patients with Nonrheumatic Atrial Fibrillation, New Eng J. Med.. 129 (July 1L 1992),... 

More than 50% of patients with cerebral embolism have atrial fibrillation. In the majority of these patients, the underlying cardiac disease is nonvalvular. The risk of ischemic stroke and atrial fibrillation increases with age, reaching a cumulative risk of 35% during a patient s lifetime. Combined results from several randomized trials show that warfarin reduces the risk of stroke in patients with nonrheumatic atrial fibrillation by 68% (to 1.4% per year), with an excess incidence of major hemorrhage (including intracranial) of only 0.3% per year. 

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