Anticoagulant therapy in Acute Coronary Syndrome

Arterial thrombosis is the most common cause of Acute Coronary syndrome(ACS). Disrupted plaque exposes thrombogenic materials in the plaque core to blood and leads to thrombotic occlusion which may be persistent or temporary. Arterial and venous thrombi have different volume of platelets and fibrins (white and red thrombi). Vascular endothelium, platelets, coagulation and fibrinolytic systems lead to normal hemostasis.Parentral anticoagulants include, Heparin, LMWH, Fundaparinux and direct thrombin inhibitors.Heparin ;Activates antithrombin and accelerates the rate at which it inhibits clotting enzymes particularly thrombin and factor Xa. Heparin has different pharmacokinetics in different persons, so it has unpredictable anticoagulant effect. Heparin administration needs to be monitored by APTT or anti-factor Xa measurement. Dosage of Heparin for ACS patients as follow,5000 units as bolous and 12 u/kg/h. Major side effects of Heparin are bleeding, heparin induced thrombocytopenia, osteoporosis and elevated transaminases.LMWH ;Activates antithrombin but the ratio of anti-factor Xa-to-anti-factor IIa is ranging from 2:1 to 4:1 and predictable dose response. LMWH monitoring is not necessary in the most of the patients. It is recommended to monitor in the renal insufficieny, pregnancy, mechanical heart valves and obese patients. LMWH dosage is 1mg/kg/SC twice daily in ACS patients. Bleeding, thrombocytopenia and osteoporosis are the side effects.Fundaparinux ;Is the synthetic analogue of the antithrombin binding pentasacharide sequence. It catalyses inhibition of factor Xa. Dosage for the ACS patients is 2.5 mg once daily through subcutaneous route.Bivaluridin ;Shortest half life which may be used in the patients with ACS especially in HIT patients.Rivaroxaban; Oral direct factor Xa inhibitor may be used in the patients with ACS.