Unstable by angina is a clinical syndrome that is characterized by new-onset or rapidly worsening angina (Crescendo angina), angina on minimal exertion or angina at rest in the absence of myocardial damage.
Acute coronary syndrome is a term that encompasses both unstable angina and myocardial infarction.
Pathogenesis: Fissuring of atheromatous plaque which is associated with thrombosis or vasospasm (supply led ischemia).In contrast stable angina is related to a fixed obstruction and usually precipitated by an increase in myocardial oxygen demand.
ECG: In patient with unstable angina or partial thickness myocardial infarction the ECG shows ST/T wave changes and T wave inversion; the T wave changes are sometimes prolonged.
- More severs.
- More frequent ( 3 or more attacks per day)
- More prolonged.
- Provoked by less exertion or even at rest.
- Less relived by usual remedial measure.
- Referred to new sites.
- Unusual new symptoms.
Unstable angina: Risk stratification:
|High risk||Low risk|
|Clinical||Post infraction angina. Recurrent pain at rest. Heart failure.||No history of MI. Rapid resolution of symptoms.|
Transient ST elevation.
Persistent deep T wave inversion.
|Minor or no ECG changes.|
|Biochemistry||Troponin T >0.1 µg/L||Troponin T < 0.1µg/L|
[A] Initial treatment:
- a) Immediate hospitalization.
- b) Bed rest.
- c) Aspirin: 300 mg followed by 75-325 mg daily long term and clopidogrel 300 mg followed by 75 mg daily for 12 months.
- d) Β-blocker: Atenolol 50-100 mg daily or metoprolol 50-100 mg 12 hourly.
- e) Calcium channel blocker: Nifedipine (with β blocker).
- f) Anticoagulant therapy with heparin (i/v infusion of unfractional heparin with does adjusted thrombin time, or as subcutaneous low molecular wt. heparin)
[B] If pain persists or recurs: Intravenous nitrates- GTN 0.6-1.2 mg/hour or isosorbide dinitrate 1-2 mg/hour.
[C] If medical treatment fails: Emergency coronary angiography should be done then PTCA or CABG.
- Davidson’s Principle and Practice of Medicine, 21st edition.
- Wikipedia the free encyclopedia.