Acute coronary syndrome (ACS)

Acute coronary syndrome includes unstable Angina and Non ST segment Elevation MI.

Angina:

Definition:

The clinical state in which a person have chest pain mostly on the left side with radiation to left arm and relieved within 30 minutes is called Angina.

Or

The clinical syndrome characterized by chest pain occurring as a result of decreased O2/ blood supply lasting within 30 minutes is called Angina.

Etiopathogenesis of Angina:

There is narrowing of the coronary arteries either by coronary vasospasm or by atherosclerosis (deposition of fats).

Types of Angina:

1.      Classical or exertional Angina:

It occurs due to increased myocardial oxygen during exertion or emotion in a patient of narrow coronary arteries. In such angina the typical pain is felt during exertion.

2.      Decubitus Angina:

This is angina that occurs when the patient lies down. It is the pain in chest during lying position usually present in case of cardiac failure.

3.      Prinzmetal’s or variant Angina:

This is angina that occurs at rest due to coronary vasospasm. The sympathetic overdrive (hyperactivity) causes the coronary vasospasm which leads episodic reduction of myocardial blood supply.

4.      Nocturnal Angina:

This is the angina that awakes the patient from sleep. It is chest pain at night during sleep especially because of vivid dreams.

5.      Unstable Angina:

This refers to angina of recent onset (less than one month), in which there is severe pain in chest last more than 10 to 15 minutes but less than 30 minutes and there is associated nausea/vomiting.

6.      Cardiac syndrome X:

There is a typical anginal pain with normal coronary arteries but there is some abnormality in the coronary microcirculation.

Risk factors of Angina:

·         Age: old age above 50 years

·         Sex: male> female above 50 years

·         Race: initially it was considered that rich people have greater chances of angina but now excluded

·         Hypertension (HTN): damaging the vessels

·         Diabetes Mellitus (DM): fat deposition

·         Smoking: damage the endothelium of the vessels

·         Obesity: hyperlipidemia

·         Family history: any angina in the family history

Clinical features of Angina:

Symptoms:

        i.            Chest pain:

Pain may arise on the following sites.

·         Left shoulder

·         Central chest

·         Throat

·         Epigastrium (if lower part of heart is involved)

·         Middle or lower of sternum

      ii.            Radiation of pain:

Pain can radiate to any dermatome from C8 to T4 including the following sites.

·         Left arm

·         Whole of chest (right chest)

·         Back of intrascapular region

·         Throat

   iii.            Weakness

    iv.            Nausea/ vomiting

       v.            Dyspnea:

Shortness of breath or abnormal awareness of respiration

Signs:

         i.            Fist sign: clenching of chest by fist

      ii.            Sweating

   iii.            Pale face

Investigations of Angina:

A.     ECG (ElectroCardioGraphy):

During pain:

Ø  ECG shows T wave inversion.

Ø  Elevation of ST segment in Prinzmetal’s angina

B.     ETT (Exercise Tolerance Test):

ü  Recording of ECG during exercise (on jogging machine)

ü  ST segment depression and T wave inversion

C.      ECHO cardiography:

·         It reveals the regional wall motion weakness.  

·         It asses the function of heart, valves and great vessels

D.     Cardiac enzymes:

Troponin I, troponin T and CK-MB are the enzymes normally present in the myocardium called cardiac enzymes. In case of MI they are increased in the blood but normal in Angina.

E.      Coronary angiography:

In this procedure, the coronary vessels are directly visualized in order to know the location and severity of coronary artery stenosis.

Management of Angina:

Treatment of Acute attack:

·         Nitrates:

Sublingual Nitrates (Angised) are given to relief the pain.

The MOA of nitrates is coronary and peripheral vasodilatation leading to decrease afterload and preload.

·         Ca channel blockers:

Amlopdipine (Norvasc 5mg) is used which block Ca channels leading to vasodilatation mainly arterial thus decreasing workload on the heart.

·         Analgesics:

Opoid analgesics (Morphine) along with (because of ‘vomiting’ side effect of opoid analgesics) antiemetic are used for the relief of pain.

Prevention of further attacks:

·         Anti platelets:

Aspirin and clopidogril (Noclot 75mg) are platelet-inhibiting agents preventing coronary thrombosis that is responsible for unstable angina and MI. The MOA is prevention of platelets adhesion with athero-sclerotic plaque and so the further stenosis or narrowing is prevented.

·         Nitrates:

Oral nitrates like Cardnit tablets are given to the patient.

·         Beta blockers:

Atenolol, propranolol, bisoprolol or metaprolol is used to reduce the myocardial oxygen demand by reducing the heart rate, force of cardiac contraction and therefore decreasing the cardiac output.

·         Lipid lowering drugs:

Rosuvastatin (Rast) or Atorvastatin (Ator) is used to lower the lipid level in the blood and thus preventing the further narrowing of the vessel.

Revascularization:

Indication of revascularization in the form of either Angioplasty (PTCA) or Bypass (CABG) is in Refractory Angina when the patient with unacceptable symptoms despite of maximum tolerable medical therapy or patient with left main coronary artery stenosis >50% with or without symptoms.

A.      Percutaneous Transluminal Coronary Angioplasty (PTCA): by the cardiologist

PTCA is performed by passing a fine guide-wire with deflated balloon through femoral artery, moved up to the diseased coronary artery. The balloon is then positioned across the stenotic area and inflated under pressure causing the dilatation of lumen. Now metallic stent is inserted that significantly reduces the chances of restenosis.

B.      Coronary Artery Bypass Grafting (CABG): by the surgeon

It is a major surgical method in which narrowed segments of coronary artery are bypasses using either free grafts of saphenous vein or the patient’s internal mammary artery (long thoracic artery). Radial artery graft is also commonly used now. Graft is sutured between aorta and coronary arteries distal to the obstruction.