Unstable angina is an acute coronary syndrome with chest pain at rest, new pain or a worsening pattern, but no rise in troponin. It signals an unstable plaque in a coronary artery and can progress to a heart attack, so it is treated as an emergency.
Key symptoms
- Chest pressure at rest or with minimal effort, often lasting more than 10 minutes
- Angina that is new or more frequent, longer or easier to trigger
- Pain spreading to the arm, jaw or back
- Sweating, nausea or shortness of breath
What you find on exam
- Often normal
- Vital signs: blood pressure in both arms, heart rate, oxygen saturation
- Signs of heart failure: crackles, raised jugular venous pressure
- Sweating, pallor and new murmurs
Tests
- 12-lead ECG within 10 minutes, repeated: may show ST depression or T wave inversion
- Serial high-sensitivity troponin: stays normal, unlike NSTEMI
- Risk score such as HEART or TIMI
- Coronary angiography based on risk
Treatment basics
- Chewed aspirin 162 to 325 mg
- Sublingual nitroglycerin; oxygen only if saturation is below 90 percent
- Heparin and a second antiplatelet such as clopidogrel or ticagrelor, guided by cardiology
- Beta blocker and a high-intensity statin
- Coronary angiography and revascularization depending on risk
Red flags
- Ongoing pain despite treatment
- New ST changes or arrhythmia
- Low blood pressure or signs of heart failure
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; NASEMSO National Model EMS Clinical Guidelines. Written by Making Synapses. Making Synapses is not affiliated with these organizations.