Fibrinolysis is the reference treatment for most
myocardial infarctions with ST-segment elevation; alternatives are angioplasty, with or without
stent. The earlier fibrinolysis is performed (preferably before hospitalization), the more effective it is. It can be optimized by adjuvant antiplatelet
therapy, such as
aspirin, and probably by
anticoagulant treatment as well. Because
fibrinolytic therapy is accompanied by intensive
thrombin generation and activation, immediate and continuous adjunctive simultaneous
heparin therapy is recommended. The efficacy of subcutaneous
low-molecular-weight heparin (
LMWH)
HBPM) is at least equivalent to that of intravenous
unfractionated heparin (UFH), but its risk of severe (but not
cerebral) hemorrhage is greater. Bolus
LMWH on the other hand is associated with an increased risk of
cerebral hemorrhage. Antithrombotic treatment thus appears optimal with bolus UFH at fibrinolysis and for at least 48 hours afterwards. An alternative after this bolus might be subcutaneous
enoxaparin until discharge. Because the major drawback of both types of
heparin is their rebound activation of
thrombosis, oral
anticoagulants are recommended thereafter. The combination of
anticoagulant treatment + (low-dose)
aspirin is not superior to
aspirin alone when the target INR is below 2. Adequate anticoagulation with INRs greater than 2.0 consistently improves angiographic and clinical outcome.
Bleeding (except intracerebral) is significantly increased whether the INR is greater than or less than 2.0. Other treatments are being investigated. Pentasaccharide (anti-Xa) combined with fibrinolysis seems to reduce reocclusion more effectively than UFH. Oral postinfarction treatment with
ximelagatran (a
thrombin inhibitor), combined with
aspirin, is associated with fewer cardiovascular events than
aspirin alone. More studies are needed.