Non-ST Elevation Myocardial Infarction (NSTEMI) and Unstable Angina (UA)

I21.4/I21.9/I20.0

DESCRIPTION

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 biomarkers and ST segment depression or T wave inversion on ECG. Biomarker elevation in the absence of diagnostic ECG changes or symptoms compatible with myocardial ischemia should prompt consideration of alternative diagnoses (e.g. heart failure, pulmonary embolism, chronic kidney disease, sepsis, myopericarditis).

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 biomarkers.

MEDICINE TREATMENT

  • Oxygen, if saturation < 94%.

LoEI [20]

  • Clopidogrel, oral, 300 mg. Followed by 75 mg daily for 3 months.

LoEI [21]

AND

  • Aspirin, oral, 150 mg immediately as a single dose (chewed or dissolved).
    • Followed with 150 mg daily (continued indefinitely in absence of contraindications).

LoEI [22]

AND

Anticoagulation:

For NSTEMI and UA (also for STEMI not given thrombolytic therapy):

  • Enoxaparin, SC, 1 mg/kg 12 hourly for minimum of 2 days.

OR

  • Unfractionated heparin, IV bolus, 5 000 units.
    • Follow with 1 000–1 200 units hourly monitored by aPTT.
    • Continue infusion for minimum of 2 days.

LoEI [23]

To relieve possible coronary spasm and pain and to reduce preload:

  • Nitrates, e.g.:
  • 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.
    • If no response after 20 mcg/minute, increase by 20 mcg/minute every 5 minutes until pain response or medicine no longer tolerated.
    • Flush the PVC tube before administering the medicine to patient.
    • Monitor BP carefully.

For dilution of glyceryl trinitrate refer to: ST elevation myocardial infarction (STEMI).

For severe pain unresponsive to nitrates:

  • Morphine, IV, to a total maximum dose of 10 mg (See Appendix II, for individual dosing and monitoring for response and toxicity).
    • Ongoing severe pain despite all appropriate treatment above is an indication for urgent referral

When clinically stable without signs of heart failure, hypotension, bradydysrhythmias or asthma:

  • Cardio-selective β-blocker, e.g.:
    • Atenolol, oral, 50 mg daily.
  • HMGCoA reductase inhibitors (statins), e.g.:
    • Simvastatin, oral, 40 mg at night.

LoEI [24]

Patients on protease inhibitor:

  • Atorvastatin, oral, 10 mg at night.

LoEI [25]

Patients on amlodipine (and not on a protease inhibitor):

  • Simvastatin, oral, 10–20 mg at night.

LoEI [26]

If patient complains of muscle pain:

Reduce dose:

  • HMGCoA reductase inhibitors (statins), e.g.:
    • Simvastatin, oral, 10 mg at night.

OR

  • Consult specialist for further management.

LoEI [27]

If there is cardiac failure or LV dysfunction (see: Congestive Cardiac Failure (CCF).

(I50.0)

  • ACE-inhibitor, e.g.:
    • Enalapril, oral, target dose 10 mg 12 hourly.

LoEI [28]

If ACE-inhibitor intolerant, i.e. intractable cough:

  • Angiotensin receptor blocker (ARB), e.g.:
    • Losartan, oral, 50–100 mg daily. Specialist initiated.