Acute MI treatment

Roger Suss MD CCFP(EM)Lecturer

Dept of Family MedicineUniversity of Manitoba

AMI Case study

• 65 year old man with crushing chest pain for 60 minutes

• DM, HTN, no allergies• BP175/105, HR 115• O2 saturation 97% RA• EKG shows anterior

STEMI

Pathophysiology of an Myocardial Infarction

Chronic plaque

Acute rupture and thrombosis

Myocardial hypoperfusion/hypoxia

Myocardial tissue necrosis

Remodeling with scar tissue

Increase pressure

Increase oxygen carrying capacity

Decrease obstruction/Increase flow

Decrease oxygen demand

Pathophysiology of an Myocardial Infarction

Increase oxygen carrying capacity

Decrease obstruction

Decrease oxygen demand

Pathophysiology of an Myocardial InfarctionExtra oxygen?Extra Hb?

Fibrinolytics,PCI (percutaneous coronary intervention)

ASA, Heparin, Clopidogrel, GIIb/IIIa inhibitors

Nitrates,BetaBlockers, Analgesics,Rest

American Heart Association

evidence based guideline 2004/2007 on STEMI and 2007 guideline on NSTEMI

Level A = “definitely”

Level B = probably

Level C = possibly

Class I = should

Class II = could

Class III = don’t

Effectiveness of “definitely should” treatments

30 day mortality from acute MI ~10%

ASA Mortality ARR ~2% NNT 50

ASA and lytics Mortality ARR~4% NNT 25

ASA and PCI Mortality ARR~6% NNT 17

Adding Clopidogrel ARR another~0.5%NNT200

Adding Heparin to ASA NNT unclear

Mortality over timeStenestrand and Wallentin. Arch Intern Med 2003

Effectiveness of Fibrinolytics

Mortality from acute MI ~10%

ARR 2% NNT 50

Decreasing effectiveness of 0.2% each hour

ie by 5 hours ARR 1%

Lytics ARR per 1000

ASA 160mg chewed

• Definitely should• Unless– Sensitivity (use clopidogrel instead)– Acute hemorrhage

Definitely should add PPI if risk of GI bleeding

Nitroglycerine sl or iv

• Possibly should for – Pain– Hypertension– Pulmonary edema

• Probably don’t if– Phosphodiesterase inhibitor recently– BP <90 sys– HR <50 or >100– Suspected RV infarct

Bed rest

• Possibly should

Oxygen

• Probably should if O2<90%• Otherwise possibly could

Morphine (2-4mg q5-15 min)

• Possibly should for– Pain uncontrolled with NTG and other Tx

• Contraindications– Sensitivity– Severe hypotension

Heparin

• Definitely should– UFH if PCI or CABG

planned, or if CRI, or after lytics in elderly

– Otherwise Enoxaparin

• Unless acute hemorrhage or high risk

In NSTEMI RRR ~33% for death or MI at 5 days. “Most of the benefits of the various anticoagulants are short term, however, and are not maintained on a long-term basis.” RR [CI] 0.44-1.02

Clopidogrel 75mg daily

• Definitely should NNT 167 (COMMIT-CCS2)

• Definitely could load with 300mg if age <75

• Unless CABG considered likely

GP IIa/IIIb inhibitors

• Probably could (as part of PCI)

Beta Blockers (Metoprolol)

• Definitely should start orally within 24 hours• Definitely don’t give acutely if – Shock– Heart failure– Heart block– Active asthma/COPD

Probably could give IV acutely if no contraindications

Probably should give verapamil or diltiazem as alternatives if active asthma or allergy

Oral ACE inhibitor within 24 hours

• Definitely should if– Pulmonary edema– LVEF < 40%

• Unless hypotension or other contraindications

ARB if ACE not tolerated

Stop all NSAIDs except ASA

• Possibly should

Reperfusion (lytics or PCI)(WRHA guidelines)

• Definitely should if– ST > or = to 0.1mV in 2 adjacent leads or new LBBB– Pain onset <12 hours– Current pain

Reperfusion by PCI (WRHA guidelines)

• Definitely should if– Can be done in contact to balloon time of <60 min– Cardiogenic shock– Pulmonary edema– Recurrent VF/VT– STEMI dx in doubt– Pain or ST elevation remains >50% at 60 minutes after

lytics– Contraindication to lytics

• Definitely don’t use lytics if – High bleeding risk (see list)

• Probably don’t use lytics if– Moderate bleeding risk (see list)– Presenting BP >180/110

Reperfusion by PCI in NSTEMI (AHA)

• Definitely should if– Cardiogenic shock– Recurrent VF/VT– Ongoing pain/symptoms despite aggressive medical

management

Treatment?

• ASA - yes• PCI? • Oxygen?• NTG sl iv?• B blocker?• Heparin?• Morphine?• Clopidogrel?• GIIa/IIIb inhibitor?

WRHA STEMI care map

AMI Case study

• 65 year old man with crushing chest pain for 60 minutes

• DM, HTN, no allergies• BP175/105, HR 115• O2 saturation 97% RA• EKG shows anterior

STEMI

• ASA - yes• PCI – if can be done in <60

minutes from presentation• Otherwise lytics• Oxygen – if low• NTG sl iv -yes• B blocker - yes• Heparin - yes• Morphine – after NTG• Clopidogrel - yes• GIIa/IIIb inhibitor - if PCI?

What can go wrong?

Hypotension from nitrates

Arrhythmias

Heart failure/cardiogenic shock

Bleeding/CVA

Questions?

Fake MI workshop - Roger Suss

What is the likelihood of ACS?

What else should be on the differential diagnosis?

Are you critical of your colleague’s record keeping?

Suggest management plan.

Are other options reasonable?