(NSTEMI) AND UNSTABLE ANGINA (UA)
Non-ST elevation MI: Chest pain that is increasing in frequency and/or severity, or occurring at rest. The chest pain is associated with elevated cardiac enzymes and ST segment depression or T wave inversion on ECG.
Unstable angina pectoris: Chest pain that is increasing in frequency and or severity, or occurring at rest. It also encompasses post-infarct angina. The chest pain may be associated with ST segment depression or T wave inversion on ECG. There is no rise in cardiac enzymes.
If clinically hypoxic:
- Aspirin, oral, 300 mg immediately as a single dose (chewed or dissolved).
- Followed with 75–150 mg daily.
- Unfractionated heparin, IV bolus, 5 000 units.
- Follow with 1 000–1 200 units hourly monitored by aPTT. o Continue infusion for 3–5 days.
Low molecular weight heparin, e.g.:
- Enoxaparin, SC, 1 mg/kg 12 hourly for two days.
Thrombolysis is not indicated except if new left bundle branch block (LBBB). See section 3.2.1: ST elevation myocardial infarction (STEMI).
To relieve spasm and pain and to reduce preload:
- Isosorbide dinitrate SL, 5 mg immediately as a single dose.
- May be repeated at 5-minute intervals for 3 or 4 doses.
For persistent pain and if oral therapy is insufficient:
- Glyceryl trinitrate, IV, 5–200 mcg/minute, titrated to response.
- Start with 5 mcg/minute and increase by 5 mcg/minute every 5 minutes until response or until the rate is 20 mcg/minute. o If no response after 20 mcg/minute increase by 20 mcg/minute every 5 minutes until pain response or drug no longer tolerated.
- Flush the PVC tube before administering to patient.
- Monitor blood pressure carefully.
|Volume of diluent||Glyceryl trinitrate
|Concentration of dilution|
|250 mL||5 mL (25 mg)||100 mcg/mL|
|10 mL (50 mg)||200 mcg/mL|
|20 mL (100 mg)||400 mcg/mL|
|500 mL||10 mL (50 mg)||100 mcg/mL|
|20 mL (100 mg)||200 mcg/mL|
|40 mL (200 mg)||400 mcg/mL|
|100 mcg/mL solution||200 mcg/mL solution||400 mcg/mL solution|
|Dose (mcg/min)||Flow rate (microdrops/min = mL/hour)|
To relieve pain:
- Morphine, IV, 1–2 mg/minute. o Dilute 10 mg up to 10 mL with sodium chloride 0.9%. o Total maximum dose: 10 mg. o Repeat after 4 hours if necessary. o Pain not responsive to this dose may suggest ongoing unresolved ischaemia.
If there is cardiac failure or LV dysfunction:
ACE inhibitor, e.g.:
- Enalapril, oral, 10 mg 12 hourly.