Heparin, myocardial infarction treatment

The CURE study involved 12,562 patients randomized to receive Plavix (300 mg loading dose followed by 75 mg daily) or placebo and were treated for up to a year. Patients also received aspirin or other standard treatment such as heparin. The results showed that Plavix had a 20% relative risk reduction compared with placebo (582 cases of cardiovascular death, myocardial infarction, or stroke) versus 719 cases for placebo. 

Krumholz HM, Hennen J, Ridker PM, Murillo JE, Wang Y, Vaccarino V et al. Use and effectiveness of intravenous heparin therapy for treatment of acute myocardial infarction in the elderly. J Am Coll Cardiol 1998 31(5) 973-9. 

Small subcutaneous closes of heparin have been found to be effective in high-nsk post-surgical patients and in patients with acute myocardial infarction. The preventive treatment is commenced a few hours before an operative procedure and continued postoperatively for 4 to 5 days. As the result of a study in 1975. low-dose heparin prophylaxis in high-nsk patients who undergo abdomina-thoracic surgery has become a widely accepted practice, However, preventive anticoagulant therapy, to date, has been unsatisfactory and controversial in the instances of hip surgery or prostatectomy. 

The FFtAXIS Study Group. Comparison of two treatment durations (6 days and 14 days) of a low molecular weight heparin with a 6-day treatment of unfractionated heparin in the initial management of unstable angina or non-Q-wave myocardial infarction FRAXIS (fraxiparine in acute ischaemic syndrome). Eur Heart J 1999 20 1553-1562. 

Pharmacokinetics Streptokinase therapy is instituted within 4 hours of a myocardial infarction and is infused for 1 hour. Its ti/2 is less than a half-hour. Thromboplastin time is monitored and maintained at two to five times control value. On discontinuation of treatment, either heparin or oral anticoagulants may be administered. 

Adverse effects. Haemorrhage occurs but is less of a problem with low doses of heparin it remains a particular risk in patients treated after failed fibrinol5 c therapy for acute myocardial infarction. Platelet transfusion after cessation of abciximab is necessary for refractory or life threatening bleeding. After transfusion, the antibody redistributes to the transfused platelets, reduces the mean level of receptor blockade and improves platelet function. Thrombocytopenia may occur from 1 hour to days after commencing treatment in up to 1% of patients. This necessitates platelet counts at 2-4 hours and then daily if severe, therapy must be stopped and, if necessary, platelets transfused. EDTA-induced pseudothrombocytopenia has been reported and a low platelet count should prompt examination of a blood film for agglutination before therapy is stopped. 

The RISC Group. Risk of myocardial infarction and death during treatment with low dose aspirin and intravenous heparin in men with unstable coronary artery disease. Lancet 1990 336(8719) 827-30. 

In a meta-analysis of individual patients data from 11 randomized comparisons of direct thrombin inhibitors (hirudin, bivalirudin, argatroban, efegatran, or inogatran) with heparin, 35 970 patients were treated for up to 7 days and followed for at least 30 days (1). Compared with heparin, the direct thrombin inhibitors were associated with a lower risk of death or myocardial infarction at the end of treatment (OR = 0.85 95% Cl = 0.77, 0.94) and at 30 days (OR = 0.91 Cl = 0.84, 0.99). There was no excess of intracranial hemorrhages with the direct thrombin inhibitors. 

The combination of thrombolytic agents with an anticoagulant and/or aspirin has been said to be life-threatening. An excess of major bleeding episodes with combined subcutaneous heparin and streptokinase or alteplase treatments (1.0% with heparin versus 0.5% without heparin) has been reported in the International Study Group Trial (103) in patients with suspected acute myocardial infarction. 

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