Failure of Subcutaneous Low-Dose Heparin to Prevent Arterial Embolism After Acute Myocardial Infarction(MI)

Low-dose s.c. heparin is recommended as alternative of oral anticoagulants during the hospital phase after MI. No figures are available on pulmonary embolism (PE) and arterial embolism originating from mural thrombosis is not mentioned. During 22 months 214 patients with MI were admitted to the CCU. Heparin was given in infusion (15-30000 U/24h) for 3-4 days, followed by twice daily 5000 U s.c. 5 patients had acute arterial occlusions, all while on s.c. heparin, 4 of them underwent embolectomy of the femoral artery, one had to be amputated. An additional patient had PE documented by lung scan. One patient had a drop of the platelets to 30000/mm3 at the time of femoral artery occlusion, the count normalizing after discontinuing heparin. In the Cooperative Clinical Trial of Ebert et al.(JAMA 225-724 1973) arterial embolism into the lower extremities was found in 6 of 499 untreated patients with MI, in none of 500 on oral anticoagulants. Thus, 5 episodes of arterial occlusion in our 214 consecutive patients with MI indicate that s.c. heparin does not prevent arterial thromboembolic complications. Whether occlusions are due to embolism from mural thrombus or to local thrombosis in connection with heparin-induced thrombocytopenia as possibly in one of our cases, remains to be established.