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REF:  ACP Medicine  Best Dx/Best Rx 2006

Acute Myocardial Infarction

Peter B. Berger, M.D. Duke University School of Medicine

Definition/Key Clinical Features
Differential Diagnosis
Best Tests
Best Therapy
Best Evidence

Definition/Key Clinical Features

Differential Diagnosis     

Best Tests     

Clinical Definition of MI - Myocardial Infarction  (American College of Cardiology)

Physical Exam




Predischarge Exercise Testing

Coronary Angiography

Best Therapy     

Emergent Therapy   (Remember  MONA = Morphine/analgesis, Oxygen, Nitroglycerin, Aspirin/antiplatelets/antithrombus Rx)

Reperfusion Therapy

Thrombolytic Therapy

Thrombolytic & anticoagulant Rx   (Not part of ACP Medicine  Best Dx/Best Rx 2006 )
  • IV Streptokinase (Streptase) Rx 1.5 million u IV over 1 hr.

    -Stat 1/2 tab aspirin (160 mg) to be chewed.
    -Insert 18 gauge heparin lock for blood sampling & 20 gauge heparin lock for drug administration.
    -Draw (before heparin flush) PTT, CPK, CPK MB, AST, LDH, CBC, BUN, lytes, glucose, & type & hold 2 units of whole blood for 48 hrs.
    -Prepare 1.5 million U of streptokinase in 50 cc NS, & infuse over 1 hr (at 50 cc/hr).
    -BP q10 min while streptokinase running.
    -Notify M.D. if systolic BP falls by >20 mmHg.
    -Stat EKG upon completion of streptokinase infusion.
    -Start heparin 12,500 units subc q12h for at least 24h.
    -CPK q4h for 24 hr, then daily for 2 more days.
    -*** Consider hydrocortisone 100 mg IV before & q 8 12 hr during streptokinase Rx may minimize allergic reactions.  OR
  • tPA Rx 15 mg IV bolus, then 50 mg (0.75mg/kg) over 30 min, then 35mg (0.50mg/kg) over 60 min.     
    (Total dose <100mg).
    PROTOCOL FOR  t PA (tissue plasminogen activator) IV INFUSION
    -Insert 18 gauge heparin lock for blood sampling & 20 gauge heparin lock for drug administration.
    -Draw (before heparin flush) the following blood tests: PTT, Protime, fibrinogen, CBC, type & hold 3 units of whole blood
    -or 48 hr, & CPK, CPK MB, AST, LDH.
    -Heparin 5000 u IV push.
    -t PA IV 15 mg IV bolus, then 50 mg (0.75mg/kg) over 30 min, then 35mg (0.50mg/kg) over 60 min. (Total dose <100mg).
    -Lidocaine 1 mg/kg IVP over 1 min interval, then Lidocaine 1 gm in 250 cc D5W at 1 4 mg/min.
    -Heparin 1000 u/hr IV drip.
    -EKG q30 min x4, then at 3, 6, 12 hr post, then daily.
    -CPK MB q1h x3, then q6h x4, then daily CBC q8h x2d, then daily PTT 4 hr after initiation of heparin IV, q6h x4, then daily. Have pharmacist to adjust dose to obtain PTT 2 2.5x control. Do not initiate warfarin (Coumadin).
    -Four hr after completion of t PA infusion, obtain: discard initial 5 cc blood) Protime, PTT, fibrinogen, CBC.

  • IV TNKase (Tenecteplase) single IV bolus over 5 seconds; <60 kg give 30 mg; 60-69 kg give 35 mg; 70-79 kg give 40 mg; 80-89 kg 45 mg; >90 kg give 50 mg.
  • IV Anistreplase (Eminase) Rx 30 units IV over 2- 5 min. or                
  • IV Retavase (Reteplase) 10 U and 10 U double bolus dosing give 30 min apart. (6/1999)

CONTRAINDICATION for t PA infusion Rx:

  • CVA & TIA within 12 months. CNS tumor or AV malformation. Intracranial or intrspinal surgery or trauma within 2 months.
  • General surgery, abrasive wounds or fracture < 2 wks, or hip surgery < 3 wks.
  • Recent traumatic CPR resuscitation.
  • GI bleeding < 3 months, liver failure, uremia.
  • Pregnancy.
  • Over 75 y.o. or serious advance illness, such as cancer.
  • Hypertension systolic > 180 or, diastolic > 110 mmHg.
  • SBE, acute pericarditis, high likelihood of left heart thrombus (eg. mitral stenosis with atrial fibrillation).
  • Diabetic hemorrhagic retinopathy or other hemorrhagic opthalmic conditions.
  • Septic thrombophlebitis or occluded AV cannula at seriously infected site.
  • Patients on warfarin (Coumadin).
  • Hemostatic defects as from severe liver or renal disease. OR

Immediate Angioplasty

Coronary Artery Bypass Surgery

Adjunctive Medical Therapy

Preventive Therapy

Lipid-Lowering Therapy


Holter Monitoring

Risk-Factor Modification

Best Evidence     

Berger PB, et al: Circulation 100:14, 1999 [PMID 10393675]

Braunwald E, et al: J Am Coll Cardiol 40:1366, 2002 [PMID 12383588]

Keeley EC, et al: Lancet 361:13, 2003 [PMID 12517460]

Myocardial infarction redefined: J Am Coll Cardiol 36:959, 2000 [PMID 10987628]

Rana JS, et al: Am Heart J 147:841, 2004 [PMID 15131540]

March 2006


2004 Update: ACC/AHA Guidelines for the Management of Patients With Acute Myocardial Infarction:  
Executive Summary and Recommendations