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CARDIOLOGY - Treatment guidelines
Guidelines on anticoagulant therapy
ACUTE MYOCARDIAL INFARCTION
Acute Myocardial Infarction

It is recommended that all patients with acute myocardial infarction (AMI) should be offered anticoagulant therapy (Table 3). Unless a specific contraindication exists, it is recommended that all patients receive not less than low-dose heparin (7,500 IU SC q12h), or low molecular weight heparin (LMWH), until ambulation, to prevent venous thrombosis.
 
Table 3 : Anticoagulant therapy for AMI
 
Clinical Situation
Recommendation
Patients who have received
recombinant tissue-type plasminogen activator (rtPA),reteplase (rPA), or tenecteplase (TNK-PA)
Heparin: about 60 IU/kg IV bolus (maximum 4,000 IU) at initiation of rtPA infusion, or at first bolus of rPA or TNK-PA; initial maintenance 12 IU/kg/h (maximum 1,000 IU); activated partial thromboplastin time (APTT) 1.5 to 2 times control, maintained for 48 h
Patients who have received rtPA, rPA, TNK-PA, and are at high risk for systemic embolism or VTE*

Maintain APTT at 1.5 to 2 times control beyond 48 h; continue the IV heparin
regimen, or offer:

  • Subcutaneous (SC) heparin (initial dose about 17,500 IU q12h, APTT 1.5 to 2 times control)
  • SC LMWH
  • Conversion to warfarin therapy (goal INR 2.5; range 2.0 to 3.0), for £ 3 mo; indefinitely, in patients with AF
Patients who have received streptokinase (SK) or anisoylated plasminogen streptokinase activator complex (APSAC) and are at high risk for systemic embolism or VTE*
IV heparin; measure APTT when indication emerges, but not < 4h after beginning SK or APSAC infusion; if APTT is > 2 times control, repeat measurement as appropriate

Begin IV heparin infusion when APTT is < 2 times control, and maintain APTT at 1.5 to 2 times control while the risk for thromboembolism is considered high
After 48 h, offer :

SC heparin (initial dose approximately 17,500 IU q12h, APTT 1.5 to 2 times control)

SC LMWH

Conversion to warfarin therapy (goal INR 2.5; range 2.0 to 3.0), for £ 3 mo; indefinitely, in patients with AF
Patients who have not received thrombolytic therapy and are at increased risk for systemic embolism or pulmonary embolism (PE)*
Heparin (about 75 IU/kg IV bolus, initial maintenance 1,000 to 1,200 IU/h IV; APTT 1.5 to 2 times control)

Follow with warfarin (goal INR 2.5; range, 2.0 to 3.0) for £ 3 mo; indefinitely, in patients with AF
* Anterior Q-wave infarction, severe left ventricular (LV) dysfunction, congestive heart failure
(CHF), history of systemic embolism or PE, 2D-echo evidence of mural thrombosis, AF.