Myocardial infraction (Acute coronary syndrome (ACS))

By –Savy P. Minal & Florence Chawang

Introduction Acute coronary syndrome (ACS), is a coronary artery disease in which there is an involvement of heart due to coronary artery/arteries.Ischemic heart disease is a condition of diverse antilogies, all having in common a disturbance of cardiac function due to an imbalance between O2 supply and demand.Acute coronary syndrome (ACS), are now classified on the basis of Echocardiography (ECG) into,

i. ST elevation Myocardial Infraction (STEMI), andii. Non – ST elevation Myocardial Infraction (NSTEMI)

STMI and NSTMI (In General)

• NSTEMI (Non–ST-segment elevation myocardial infarction) and STEMI (ST-segment elevation myocardial infarction) are commonly known as heart attack.

• But they are different from each other in some extent. NSTEMI account for about 30% and STEMI about 70% of all heart attack (myocardial infarction).

• In both cases, patients usually present with similar type of symptoms such as chest pain, nausea, vomiting, sweating, breathing difficulty.

Pathophysiology of NSTEMI vs STEMI :(a comparison)

NSTEMI

• NSTEMI occurs by developing a complete occlusion (blocking) of a minor coronary artery or a partial occlusion of a major coronary artery previously affected by atherosclerosis.

• This causes a partial thickness damage of heart muscle.

STEMI

• STEMI occurs by developing a complete occlusion of a major coronary artery previously affected by atherosclerosis.

• This causes a full thickness damage of heart muscle.

NSTEMI STEMI

Clinical features of NSTEMI vs STEMI :

• Complications occur both in cases.

• But some complications like cardiogenic shock, left ventricular failure, severe mitral regurgitation due to papillary muscle rupture, cardiac troponin due to ventricular wall rupture are more in STEMI (due to full thickness heart muscle damage) than NSTEMI.

Investigations / Diagnosis

Diagnosis can be done by number of tests:

1. Electrocardiography (ECG)

2. Blood tests

3. Chest X – Ray

4. Echocardiography

5. Radionucleotide scanning

Diagnosis of NSTEMI vs STEMI :

NSTEMI

• ECG - The diagnosis of a NSTEMI is based on a typical history of chest pain, no ST segment elevation in ECG ,

• Blood test - Elevation of cardiac markers in serum.

STEMI

• ECG - The diagnosis of a STEMI is based on a typical history of chest pain, ST segment elevation in ECG,

• Blood test - Elevation of cardiac markers in serum.

1. Principle of Electrocardiography (ECG)

1 . Electrocardiography (ECG)

• It is the most sensitive and specific method to diagnose myocardial infraction.

• ECG may be normal initially later on, ECG should be repeated after 12 hours of chest pain to detect the changes.

• The changes are seen in the ST segment and T wave.

• A full fledged infraction may show all the three changes ST elevation, Q wave and T wave inversion.

• These evolutionary changes may not appear in thrombolysed patients of ST elevation MI (STMI)

Electrocardiogram of STEMI and MSTEMI

A patient of acute MI showing character of pain by placing the palm of his hand over anterior chest at the site of pain and radiation of pain to left arm and forearm. The lower shows site of acute MI.

The Serial Evolution Of ECG Changes In Acute Myocardial Infraction (Diagrammatic Representation)

Clinical Evaluation Of Acute Ischaemic Chest Pain (Acute Coronary Events)

2. Blood tests

A leukocytosis may be present on the first day and Erythrocyte sedimentation rate (ESR) may be raised. Serum electrolytes, glucose, and lipid profile should be obtained.

Plasma enzymes :

• The cardiac muscles are rich in enzymes which are released within few hours of myocardial infraction and their peaks levels appear.

• Differential enzymes and different pattern of rise and peak levels.

• The change in enzyme level has diagnostic and prognostic values.

• Enzyme rise and fall pattern, studied in this are : CK (Creatinine kinase), AST (Aspartate aminotransferase) and LDH (Lactic acid dehydrogenase),

CK (Creatinine kinase), AST (Aspartate aminotransferase), and LDH (Lactic acid dehydrogenase).

3. Chest X- ray

• This may detect acute pulmonary oedema and congestion which may not be detected on clinical examination.

4. Echocardiography (ECHO)

• Echocardiogram , often referred to as a cardiac echo or simply an echo, is a sonogram of the heart.

• Echocardiography uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart

• It is a valuable technique of diagnosing STEMI.

An abnormal Echocardiogram. Image shows a mid-muscular ventricular septal defect

Treatment of NSTEMI vs STEMI :

1. Antiplatelets (Aspirin, Clopidogrel, Ticagrelor),

2. anticoagulants (Enoxaparin, Dalteparin, Fondaparinux),

3. beta-blockers (atenolol, metoprolol, bisoprolol),

4. nitrates (isosorbide dinitrate, glyceryl trinitrate),

5. Statins (atorvastatin, rosuvastatin, simvastatin, pitavastatin),

6. ACE inhibitors (ramipril, enalapril, captopril, lisinopril) or

7. ARBs (valsartan, candesartan, losartan, olmesartan), are given

both in NSTEMI and STEMI.

Therapy (Treatment)

I. In case of reperfusion therapy, primary PCI (percutaneous coronary intervention) is the treatment of choice for STEMI. Where primary PCI cannot be achieved within 120 minutes of diagnosis or PCI is not available, thrombolytic therapy such as streptokinase, tenecteplase, alteplase or reteplase should be given.

II. Early coronary angiography and revascularization, either by PCI or by CABG (coronary artery bypass grafting) is the treatment of choice for medium to high risk patients with NSTEMI.

NOTE : Drug treatment is appropriate in low risk patients with NSTEMI, and coronary angiography and revascularization reserved for those who fail to settle with drug treatment (low, medium and high risk patients are categorized in NSTEMI by GRACE score ) .

Precaution

Thrombolytic therapy is harmful in NSTEMI.The aggregate data suggest that patients with NSTEMI

may be put at risk of re-infraction (further heart attack) if thrombolytic therapy is used

Complications and their management in Myocardial Infraction

Complications corrective measures

Complications corrective measures

Complications corrective measures

Complications corrective measures

Prognosis of NSTEMI vs STEMI :

NSTEMI

• Short-term (in-hospital or one month) mortality is lower in NSTEMI (3-5%),

• Re-infarction rate (further heart attack) is higher in NSTEMI (15-25%) after hospital discharge

• Long-term mortality is similar or higher in NSTEMI.

STEMI

• Short-term (in-hospital or one month) mortality is higher in STEMI (10-15%).

• Re-infarction rate (further heart attack) is lower STEMI (5-8%) after hospital discharge .

• Long-term mortality in STEMI (two year mortality is approximately – 30% in both cases).