Myocardial infarction, Stroke and deep vein thrombosis are all indications for anticoagulation therapy plus monitoring

Myocardial Infarction
The most frequent heart disease in western countries is coronary heart disease. Every second patient with coronary heart disease suffers acute myocardial infarction (12, 13).

Anticoagulation
Oral anticoagulation is indicated following major anterior-wall infarction with severely reduced left-ventricular function with or without atrial fibrillation. Also, thrombi in the heart require anticoagulation following infarction. Acute phase studies (WARIS-II study, ASPECT II) showed that combined administration of antiaggregants and oral anticoagulants can bring about up to almost 30% reduction in risks compared to the administration of antiaggregants alone (14, 15).

Deep Vein Thrombosis and Pulmonary Embolism
Thrombosis is the blockage of a blood vessel by a blood clot (thrombus). Various risk factors such as immobilization, cardiac insufficiency, age, pregnancy, hypercoagulability, oral contraceptive medication, adiposity and varicose veins favor occurrence (Virchow’s triad).

Various risk factors favor thrombotic events mainly in the deep veins of the leg and pelvis. Effective medications are available to prevent the spread of thrombosis and the consecutive occurrence of potentially fatal pulmonary embolism.

Anticoagulation
The aim of treatment is to prevent the occurrence of pulmonary embolism and the spread of thrombosis.

Various medications are available:

  • Heparin acts immediately to inactivate mainly factor Xa and thrombin. It has to be administered parenterally and is thus not suitable for long-term therapy.
  • The action of Vitamin K antagonists is based on reducing the activity of factors IX, VII, X and prothrombin (II). Several days are required for the onset of the anticoagulant effect of coumarin preparations, so that heparin and coumarins must be used in combination to treat acute thrombosis (16). Once the therapeutic range of anticoagulation (INR) has been reached, parenteral treatment with heparin may be terminated (16).

The length of time for which anticoagulants are given for thrombosis depends on various factors and risk assessments. The “optimum duration of anticoagulation” is the subject of on-going studies.

Acute Ischemic Stroke
Ischemic cerebral stroke is the third most frequent cause of death in Europe. Its incidence is approximately 120,000 cases annually in Germany, and approximately 78,000 cases in France. Around 5.5 million people in USA suffered a stroke (2003, American Heart Association)

Stroke is caused by an acute circulatory disturbance in a defined region of the brain. In 20% of cases a hemorrhagic insult is involved, in 80% of cases an ischemic insult.

Improved management of risk factors such as arterial hypertension, atrial fibrillation, diabetes mellitus, hypercholesterolemia, nicotine abuse and excessive alcohol consumption can reduce the incidence of stroke considerably.

Anticoagulation
Anticoagulation in patients with ischemic cerebral insult should not be used in every case, as there is no proof so far that any improvement in prognosis nor any lowering of the relapse risk can be achieved thereby (17). On the other hand, patients with proven cardiological pathology can benefit from anticoagulation therapy. Thrombocyte aggregation inhibitors administered within the first 48 h after the event reduce mortality and relapse occurrences minimally, but nevertheless statistically significantly (18, 19).

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References

12. World Health Organization. Cardiovascular death and disability can be reduced more than 50 percent. Press release 2002.
13. Wong ND. Cardiovascular disease epidemiology - definitions, risk assessment, incidence, and tools. University of California Heart Disease Prevention Program 2002.
14. Hurlen M, Abdelnoor M, Smith P, Erikssen J, Arnesen H. Warfarin, aspirin, or both after myocardial infarction. N Engl J Med 2002; 347:969-974.
15. Van Es RF, Jonker JJ, Verheugt FW, Deckers JW, Grobbee DE. Aspirin and coumadin after acute coronary syndromes (the ASPECT-2 study): a randomised controlled trial. Lancet 2002; 360:109-113.
16. Meta-analysis: Antithrombotic Therapy to Prevent Stroke in Patients Who Have Nonvalvular Atrial Fibrillation- Ann Intern Med. 2007;146:857-867
17. Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation as an independent risk factor for stroke: the Framingham Study. Stroke. 1991; 22(8): 983-8.
18. Van Walraven C et al. A clinical prediction rule to identify patients with atrial fibrillation and a low risk for stroke while taking aspirin. Arch Intern Med.2003; 163(8): 936-43.
19. Hart RG et al. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Ann Intern Med. 2007; 146(12): 857-67.