Unstable Angina
Recognition, risk stratification and management of unstable angina
Unstable angina is chest pain or discomfort that occurs at rest, or with minimal exertion, and is new in onset or worsening compared to previous stable symptoms. Unlike NSTEMI, troponin levels are not elevated. It represents myocardial ischaemia without infarction and requires urgent assessment and risk stratification. Left untreated or mismanaged, it carries a significant risk of progression to NSTEMI or STEMI. (NICE NG185, 2020)
What is unstable angina?
Unstable angina occurs when the blood supply to the heart muscle is severely reduced but not completely cut off — there is ischaemia (oxygen deprivation) without myocardial necrosis (cell death). This distinguishes it from NSTEMI, where troponin rises due to myocardial injury. The condition is triggered by plaque rupture or erosion causing partial coronary occlusion, or by significant dynamic stenosis. Symptoms include chest pain at rest, new-onset exertional angina, or angina that has recently become more frequent, more severe, or occurs with less exertion than before.
Recognition and TIMI risk score
Unstable angina must be assessed urgently. The TIMI (Thrombolysis in Myocardial Infarction) risk score for UA/NSTEMI uses 7 variables to estimate risk of death or ischaemic events: age ≥65; ≥3 CAD risk factors; known coronary stenosis ≥50%; ST deviation on ECG; ≥2 anginal events in past 24h; use of aspirin in past 7 days; raised cardiac markers. Score 0–2: low risk; 3–4: intermediate; 5–7: high risk. High-risk patients should undergo early angiography. All patients with suspected unstable angina require urgent hospital assessment, ECG and serial troponin to exclude NSTEMI.
Immediate medical management
Aspirin 300 mg immediately (loading dose), then 75 mg OD lifelong. GTN (glyceryl trinitrate) 0.4 mg sublingual spray for acute chest pain — repeat after 5 minutes if no relief; if pain persists after 2 doses, call 999. Do not give GTN if systolic BP <90 mmHg or if PDE5 inhibitor used in the last 24–48 hours. Beta-blocker (bisoprolol) for rate control and symptom relief. Fondaparinux 2.5 mg SC OD for anticoagulation. Clopidogrel or ticagrelor may be added depending on risk stratification and planned management. Oxygen only if SpO2 <94%.
Angiography and revascularisation
Patients with high-risk features (TIMI ≥3, ongoing chest pain, ECG changes, haemodynamic instability) should be referred for early coronary angiography. If angiography reveals significant coronary disease, PCI or CABG may be considered based on Heart Team assessment. Low-risk patients with negative serial troponins and a normal ECG may be managed medically and investigated electively with non-invasive imaging (CT coronary angiography or myocardial perfusion scan).
Secondary prevention and lifestyle
Long-term management of unstable angina includes aspirin 75 mg OD lifelong; high-intensity statin (atorvastatin 80 mg); ACE inhibitor if LVEF reduced or diabetes present; beta-blocker for symptom control and rate management; GTN spray for acute symptom relief. Lifestyle changes: stop smoking, Mediterranean diet, regular exercise, weight management. Cardiac rehabilitation should be offered. Patients should know when to call 999: chest pain not relieved by 2 doses of GTN, or associated with breathlessness, sweating or collapse. All information based on careful evaluation of NICE NG185 (2020).