Unstable angina is a medical emergency and if untreated can progress to Non-ST Elevation Myocardial Infarction (NSTEMI)

Diagnostic criteria

Presents as chest pain or discomfort like stable angina but with the following additional characteristics:

• Angina at rest or minimal effort, occurring for the first time, particularly at rest and prolonged > 10 minutes, not relieved by sublingual nitrates.

• The pattern of angina accelerates and gets worse

• The chest pain may be associated with ST segment depression or T wave inversion or normal ECG without rise in cardiac enzymes (biomarkers ie Total Creatine, Creatine -MB and Troponin).

Management

Unstable angina and NSTEMI are emergencies with the same progressive instability of coronary disease and the same management.

Supportive therapy

• Admit to a high dependency ward, ICU or CCU for haemodynamic monitoring; bed rest in Fowler's position and reassurance.

• Oxygen by nasal cannula or face mask if saturation is below 92% (in STEMI, 40% by face mask if below 92% or in distress).

• Peripheral IV line for fluids and medicines.

• Monitor blood pressure, heart rate and ECG rhythm; cardiopulmonary resuscitation if cardiac arrest occurs.

Control cardiac pain

• C: Glyceryl trinitrate (nitroglycerin) sublingual or spray 0.5 mg (make sure the patient has not taken a phosphodiesterase-5 inhibitor such as sildenafil).

• Persistent pain when sublingual therapy is not enough: S: glyceryl trinitrate IV 1–2 micrograms/kg/minute, titrated to chest pain over 8–24 hours, OR C: morphine IV 1–2 mg/minute (dilute 10 mg to 10 ml with 0.9% sodium chloride), total maximum 10 mg, repeat after 4 hours if necessary.

• Pain not responding to these doses suggests ongoing ischaemia: refer immediately to a facility that can manage acute coronary syndrome.

Antiplatelet therapy

• A: Acetylsalicylic acid (aspirin) 300 mg PO stat, then 75–100 mg every 24 hours.

• AND D: clopidogrel 300–600 mg PO stat, then 75 mg every 24 hours,

• OR S: ticagrelor 180 mg PO stat, then 90 mg every 12 hours for the first year after the ACS event and 60 mg every 12 hours after 1 year,

• OR S: prasugrel 60 mg PO stat, then 10 mg every 24 hours.

High-dose statin

• B: Atorvastatin 80 mg PO stat, then 40 mg every 24 hours, OR S: rosuvastatin 10–40 mg PO every 24 hours.

Anticoagulant

• C: Unfractionated heparin IV 70–100 units/kg (STG 2026 prints '24-hourly'), OR D: low molecular weight heparin (enoxaparin) 1 mg/kg SC every 12 hours.

Beta-blocker

• LV dysfunction: C: carvedilol 6.25 mg PO every 12 hours (preferred), titrated up to 25 mg every 12 hours.

• Normal LV systolic function: B: atenolol 25–50 mg PO every 24 hours, OR C: metoprolol succinate (SR) 25–200 mg PO every 24 hours, OR S: metoprolol tartrate 5 mg IV over 2 minutes (maximum 3 doses), then 50–100 mg PO every 12 hours, OR S: bisoprolol 2.5–10 mg PO every 24 hours.

ACE inhibitor (or ARB if ACE inhibitor not tolerated)

• B: Captopril 6.25–25 mg PO every 8 hours, OR C: enalapril 10 mg PO every 12 hours, OR C: lisinopril 5–10 mg PO every 24 hours.

• If ACE inhibitors are not tolerated: B: losartan 25–50 mg, OR S: candesartan 8–16 mg, OR S: telmisartan 40–80 mg, OR S: irbesartan 150–300 mg, each PO every 24 hours.

Referral: with a high suspicion of acute coronary syndrome refer immediately to a facility able to manage it. Before referral give urgently, if available:

• C: Glyceryl trinitrate 0.5 mg sublingual or spray as needed for intolerable chest pain,

• AND A: acetylsalicylic acid 300 mg PO stat (chewed),

• AND D: clopidogrel 300–600 mg PO stat,

• AND a high-dose statin: S: rosuvastatin 10–40 mg PO stat OR B: atorvastatin 80 mg PO stat.