MYOCARDIAL INFARCTION

CASE 1

• Mr. A: 38 years old

• He smokes 1 pack of cigarettes per day

• He has no other past medical history

• 8 hours ago, he gets sharp central chest pain that

is worse with inspiration. It has not yet resolved.

• He feels short of breath

CASE 2

• Mr. D: 50 years old

• He also smokes 1 pack of cigarettes per day

• His past medical history includes hypertension

and diabetes

• While he was working on the farm, he develops

dull central chest pain that radiates to his neck

• With rest, the pain went away after about 5

minutes

• He also has shortness of breath

WHICH PATIENT IS HAVING AN MI?

WHY?

HISTORY

• Pain• Location• Exertional

• Other symptoms:• Shortness of breath• Nausea• Sweaty

• Risk Factors• Family history• Diabetes• Hypertension• Smoking• Hyperlipidemia• Previous MI or stroke

PHYSICAL EXAM

• Vital signs• BP

• HR

• O2 saturation

• Cardiac exam• S3 or S4 may be present

• Murmur of mitral regurgitation

• May have heart failure on cardiac and respiratory

exam

ECG: ST ELEVATION MI

ECG

ECG: NON ST ELEVATION MI

ECG

STEMI VERSUS NSTEMI

MANAGEMENT: CASE

When you examine Mr. D, he can talk to you

• BP 110/70 HR 100 O2 93% on room air

• He has normal heart sounds, no murmur, but has

S4

• Lungs are clear

• ECG shows ST depression and T wave inversion in

V2- V6.

• What do you want to do next?

MANAGEMENT

• First, ABC’s!

• If you have cardiac monitor, put him on it

• IV access

• Oxygen

• What medications do you want to give him?• For his pain?

• To prevent further thrombosis (antithrombotics)?

• To prevent arrythmia?

• To treat other cardiac risk factors?

MEDICATIONS: PAIN

• Nitrates• Vasodilation of coronary arteries

• Decrease preload (venous vasodilation)

• Decrease afterload (arterial vasodilation)

• Be careful of hypotension (aortic stenosis, right ventricular MI)

• Morphine

• Avoid NSAIDS if you can

MEDICATIONS: ANTITHROMBOTIC

• Aspirin• 162-325mg Po chewed x 1 then 75mg-100mg daily

• Patient needs to take indefinitely

• Decreases mortality

• Give as soon as you suspect an MI

• Consider clopidogrel• 300mg PO x 1 then 75mg daily for 1-12 months

• Small additional benefit

MEDICATIONS: ANTICOAGULANTS

• Heparin• Decreases risk of death and re-infarction

• If using unfractionated heparin IV, monitor PTT

• Duration is at least 48 hours

MEDICATIONS: PREVENTING ARRYTHMIA

• Beta blockers (eg. Atenolol, propranolol, metoprolol)• Decreases mortality and ventricular arrythmias

• Start within 24 hours

• Contraindications• Acute heart failure

• Heart block

• Asthma

• Hypotension

• No role for antiarrythmics such as lidocaine or digoxin

• No role for calcium channel blockers

MEDICATIONS

• ACE inhibitors (ramipril, enalopril)• Especially beneficial in those with heart failure

• Start within 24 hours

• Prevents left ventricular remodelling

REPERFUSION

• 2 options• A) Fibrinolytics

• If symptoms started less than 24 hours ago

• Contraindications: Uncontrolled hypertension, stroke in last 3

months, previous intracranial hemorrhage

• For STEMI patients only

• B) Percutaneous coronary intervention (PCI)

• If symptoms started less than 12 hours ago

• If the “door to balloon” time can be less than 90 minutes

• For STEMI patients. Can consider for NSTEMI patients

REPERFUSION

• Which NSTEMI patients should you think about

sending for reperfusion?

• Chest pain and ischemia not responding to medications

• Unstable patients

• Arrythmias

• Heart failure

COMPLICATIONS

• Heart failure

• Bradycardia from AV (conduction) block

• Arrythmia• Non sustained ventricular tachycardia (VT)

• Sustained VT and ventricular fibrillation

• New mitral regurgitation

• Ventricular wall rupture

• Cardiogenic shock