[Myocardial infarction and thromboembolism during pregnancy]

Abstract

Acute myocardial infarction is a very rare event during pregnancy and bears the problem of misdiagnosis. However, about 150 cases have been published worldwide with a preponderance of anterior wall infarcts. With more women delaying childbearing until an older age and increasing prevalence of smoking in young women, it can be expected that all forms of coronary artery disease--including acute myocardial infarction--will be seen more often in the future. Among the causes of coronary artery occlusion in pregnancy are (1) rupture of very small coronary artery plaques triggered by different events, e.g., hypertension; (2) plain coronary artery disease; (3) dissection of coronary arteries; (4) coronary artery spasms with/without arterial thrombosis. Prompt diagnosis and immediate therapy are necessary to lower the high mortality of mother and fetus. The gold standard in the therapy of acute myocardial infarction during pregnancy is immediate coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) with or without stent implantation. Application of thrombolytics (recombinant tissue plasminogen activator [rt-PA], r-PA, streptokinase [SK], urokinase [UK]) has been reported in single patients but should be limited to cases where acute PTCA is not available and where the infarct occurs before the 14th week of pregnancy because of possible embryopathy. If the patient is in the last 10 weeks of pregnancy, anticipation of delivery should be part of the medical planning. Consultation with an obstetrician must be obtained as soon as the patient enters the hospital. Besides bleeding complications, venous thrombosis with pulmonary embolism is among the most common causes of death during pregnancy. Pregnancy-related changes in physiology - increase in the resistance to flow from the lower extremities to the heart - and congenital coagulation abnormalities are most important to be recognized. This leads to the fact that superficial and deep venous thromboses occur more often in pregnancy than in the nonpregnant state. Among the coagulation abnormalities found in pregnancy are hypercoagulability (increased levels of fibrinogen, factor VII, factor VIII, factor X), decreased fibrinolytic activity due to an increased level of plasminogen activator inhibitor, increased adhesion and aggregation of platelets, decreased level of protein C and of the APC (activated protein C) ratio. Individual risks factors justifying diagnostic screening include contraception, smoking, immobilization, infection, adiposity, placental insufficiency, and a family history of thrombosis. It is even more important to establish/rule out the diagnosis of thrombosis in pregnancy than in the nonpregnant state, because the use of anticoagulants carries certain risks during pregnancy. Doppler vein studies should be used for diagnosis. If necessary, venography may be used with shielding of the maternal abdomen. Therapy consists of subcutaneous application of heparin, compression, and early mobilization. Alternatively, especially for long-term management, treatment with low molecular weight heparins is feasible. Thrombolytic treatment is contraindicated in most cases due to the high risk of bleeding complications. However, the application of thrombolytics can be contemplated in single cases after careful consideration of the pros and cons. Most cases of pulmonary embolism should also be handled conservatively with heparin. Only in massive pulmonary embolism with severe hemodynamic compromise, thrombolytic treatment is indicated. To guide future therapy in the patients, it is necessary to establish the lifetime risk of recurrent events by determining: APC resistance, prothrombin mutation 20210 A, homocysteine, AT III, protein C and S, antiphospholipid antibodies, and anticardiolipin antibodies.