1. MANAGEMENT OF MYOCARDIAL INFARCTION
SAMEEH SAIFUDHEEN

2. INTRODUCTION
• Rapid development of myocardial necrosis due to a
critical imbalance between O2 supply & myocardial
demand.
• Also known as “Heart attack”.
• The most important form of IHD.
• One of the major cause of mortality around the
world.

3. CAUSES
• The primary cause for MI is CORONARY ARTERY
OCCLUSION.
• Factors responsible are:
– Coronary atherosclerosis
– Vasospasm
• Platelet aggregation
• Cocaine abuse.
– Emboli
• AF
• Lt. sided mural thrombus
• Vegetations of inf. endocarditis

4. – Ischemia without detectable CA & thrombosis
• Vasculitis of intramural vessels
• Sickle cell disease
• Amyloidosis
• Vascular dissection
• Low systemic BP(shock)

5. CLINICAL FEATURES
Clinical symptoms:
– May or may not present with angina pectoris.
– Dyspnoea
• due to pulmonary congestion caused by impaired
contractility .
– Diaphoresis(profuse sweating).
– Rapid, weak pulse.
– Anxiety.

6. Cardiac markers:
• Enzymes
– Creatine kinase(MB fraction)
– Aspartate transaminase(AST)
– Lactate dehydrogenase
• Non-enzyme proteins
– Troponin T & I
– Myoglobin

7. Marker Abnormal activity
detectable(hr)
Peak value of
abnormality(hr)
Duration of
abnormality(days)
CK-MB 3-8 10-24 2-3
LD 8-12 72-144 8-14
AST 6-12 24-48 4-6
MYOGLOBIN 1-3 6-9 1
TROPONIN I
TROPONIN T
3-8
3-8
24-48
72-100
3-5
5-10
CARDIAC MARKERS & TIME COURSE AFTER ONSET OF
MI

8. WHO DIAGNOSIS OF MI
Requires atleast 2 of the following criteriae:
– Prolonged ischemic-type chest discomfort.
– Serial ECG changes.
– Elevation of cardiac markers in serum.

9. TREATMENT
Initial treatment:
1.Morphine(2.5-5.0 mg i.v) - For sudden relief of pain
& anxiety.
2.Aspirin(162-325 mg orally) - For prevention of
thrombus extension, embolism, venous thrombosis.
3.O2 inhalation & assisted respiration, if needed.
4.I.V fluids - Maintain blood volume & perfusion.

10. Subsequent Management:
– Treatment of complications:
•Arrhythmias
•Pump failure
•Thromboembolism
•Acidosis – NaHCO3 i.v infusion
– Secondary prevention of further consequences
& future MI.

11. Prevention & Treatment of Arrhythmia
1. β-blocker
– Prophylactic i.v infusion
• Inj. Atenolol(50 mg)
– oral administration for few days
• Tab. Atenolol(50 mg)
– Reduce incidence of arrhythmia & mortality
Note: β-blockers used early in evolving MI can reduce the infarct
size & subsequent complications.

12. 2. Other Antiarrhythmics
– Lidocaine, Procainamide for tachyarrhythmia
Note: Bradycardia & Heart block may be managed with
Atropine or electrical pacing.

13. Pump Failure
– The objective is to C.O and/or filling pressure without
unduly increasing cardiac work or reducing B.P.
– The drugs include:
• Furosemide: Reduce preload & pulm. edema.
• Vasodilators:
–GTN, Sod. Nitroprusside
– Reduce venous return, cardiac work load.
• Inotropic agents:
–Dopamine, Dobutamine
–Augment the pumping action of heart.

14. Thrombolysis & Reperfusion
– First infarct patient
• Inj. Streptokinase – 15,00,000 units i.v infusion over 1
hour.
– Subsequent infarcts
• Recombinant tissue plasminogen activator(Alteplase).
• Regimen for coronary thrombolysis is 15 mg i.v
followed by 0.75 mg/kg over 30 min. & 0.5mg/kg over
following hour.

15. Fibrinolysis
Plasminogen
in blood
Plasmin
Fibrinolysis
Fibrinolytics
Streptokinase
Urokinase
Alteplase

16. Adverse reactions:
• Bleeding
• Nausea, vomiting
• Multiple micro emboli
• Allergic reactions – Streptokinase is
antigenic – cause anaphylaxis

17. Contraindications:
• Haemorrhagic diathesis
• Pregnancy
• Recent symptoms of peptic ulcer / GI
bleeding
• Recent stroke (Previous 3 mths)
• Recent surgery (Previous 10-14 days)
• Proliferative Diabetic retinopathy
• Severe uncontrolled hypertension
• Aortic dissection
• Acute pancreatitis

18. Long term Treatment
The objectives include:
• Prevention of remodeling & subsequent CHF.
– ACE inhibitors / ARBs are of proven efficacy & afford
long term survival benefit.
• Prevention of future attacks.
– Platelet inhibitors:
– Aspirin or Clopidogrel given on long term basis are
routinely prescribed.

19. – β blockers :
– Reduces risk of reinfarction, CHF & mortality
– Given for at least 2 years unless contraindicated.
– Control of hyperlipidemia
– Hypolipidemic drugs, especially statins.
– Dietary substitution with unsaturated fats.