Unstable Angina Clinical Overview
I. The "On-Call" Snapshot
Clinical Significance in Malaysia: This, along with NSTEMI, is one of the most common reasons for admission to the CCU or a medical ward from the Emergency Department. Mismanage this, and your patient can progress to a full-blown MI or worse under your care.
High-Yield Definition: Unstable Angina is an Acute Coronary Syndrome (ACS) characterized by myocardial ischemia at rest or with minimal exertion, in the absence of acute myocardial necrosis. (Source: Malaysian CPG on Management of UA/NSTEMI, 2011/2014; UpToDate).
Clinical One-Liner: Basically, it's a heart attack waiting to happen. The plaque has ruptured and a clot is forming, but it hasn't completely blocked the artery, and no significant heart muscle has died... yet.
II. Etiology & Risk Factors
Etiology: The underlying cause is almost always the rupture or erosion of an atherosclerotic plaque in a coronary artery, leading to the formation of a non-occlusive, platelet-rich thrombus.
Risk Factors: You see these every single day in our wards. Know them.
Non-Modifiable:
Age (>45 for men, >55 for women)
Male gender
Family history of premature CAD
Modifiable (Our bread and butter in Malaysia):
Diabetes Mellitus Type 2 (Critically important, often presents atypically)
Hypertension
Dyslipidemia
Cigarette Smoking
Obesity & sedentary lifestyle
III. Quick Pathophysiology
Think of it like this: an unstable, lipid-rich plaque in the coronary artery wall cracks. This exposes the blood to thrombogenic material. Platelets rush to the site and start clumping together, forming a thrombus. In UA, this thrombus is big enough to cause ischemic symptoms (chest pain) at rest but not big enough to completely block the vessel and cause infarction (cell death). This is why the troponins are negative. The situation is dynamic; the clot can grow or break off at any moment.
IV. Clinical Assessment
Red Flags & Immediate Actions: If you see any of these, you escalate to your senior immediately.
Persistent chest pain despite initial GTN: → Alert senior, repeat ECG, consider IV nitrates/morphine.
Hypotension (SBP <90 mmHg) or signs of shock: → Alert senior, secure IV access, prepare for potential inotropes, this may be a STEMI equivalent.
Acute pulmonary edema (dyspnea, desaturation, crepitations): → Alert senior, position patient upright, give high-flow oxygen, prepare IV diuretics.
New dynamic ECG changes (ST depression >1mm, transient ST elevation): → Alert senior, this patient is high-risk and needs urgent review.
History:
Common (>50%):
Retrosternal chest pain/pressure/heaviness, often described as "dull" or "squeezing".
Radiation to the left arm, neck, or jaw.
New onset angina (within the last month) that is severe and limits activity.
A crescendo pattern: previously stable angina that is now more frequent, more severe, or occurs with less exertion.
Pain at rest, typically lasting >15-20 minutes.
Pertinent Negatives to ask:
"Is the pain sharp or stabbing?" (Less likely cardiac)
"Does it change with breathing or position?" (Suggests pleuritic/pericardial cause)
"Any tearing sensation radiating to the back?" (Rule out aortic dissection)
Physical Examination: Often, the exam is completely normal. Your job is to look for signs of complications or rule out differentials.
General: Patient may be anxious, diaphoretic.
Vitals: Can have tachycardia, hypertension (due to sympathetic drive) or hypotension (if severe).
Cardiovascular: Listen for a new S3 or S4 gallop, or a new mitral regurgitation murmur (papillary muscle dysfunction), which indicate LV dysfunction and higher risk.
Respiratory: Check for bilateral basal crepitations (heart failure).
Extremities: Check for symmetrical pulses to help rule out aortic dissection.
Clinical Pearl: Cardiac pain does not point with one finger. If a patient can localise their pain to a single spot, think of other causes first. Ischemic pain is typically a diffuse pressure.
V. Diagnostic Workflow
Differential Diagnosis: In the ED, you must actively exclude these "can't miss" diagnoses.
NSTEMI/STEMI:
Points For: Identical clinical presentation.
Points Against: UA has no significant rise in cardiac enzymes.
How to Differentiate: Serial Cardiac Troponins. This is the defining difference. An ECG will differentiate from STEMI (persistent ST elevation).
Pulmonary Embolism (PE):
Points For: Acute dyspnea, tachycardia, sometimes chest pain.
Points Against: Pain is typically pleuritic. Look for risk factors (DVT, recent surgery, malignancy).
How to Differentiate: CT Pulmonary Angiogram (CTPA) is the gold standard. D-dimer can help rule out in low-risk patients.
Aortic Dissection:
Points For: Severe chest pain, history of hypertension.
Points Against: Pain is classically a "tearing" or "ripping" sensation radiating to the back.
How to Differentiate: Unequal blood pressure in both arms, widened mediastinum on CXR. CT Angiogram of the Thorax is definitive.
Investigations Plan:
Bedside / Initial (First 15 Mins):
12-lead ECG: The most important initial test. Look for ST depression, T-wave inversions, or transient changes. A normal ECG does not rule out UA. Repeat every 15-30 minutes if pain persists.
IV Access: Secure two large-bore cannulas.
First-Line Labs & Imaging:
Cardiac Troponin T/I: Send at presentation, and repeat at 3 and 6 hours (using high-sensitivity assays). By definition, these will be negative or below the threshold for MI in UA.
Full Blood Count (FBC): To exclude anemia as a precipitant of angina.
Renal Profile (RP): Crucial for creatinine levels before considering ACE inhibitors or contrast for angiogram.
Chest X-Ray (CXR): Look for cardiomegaly, signs of heart failure (pulmonary edema), or a widened mediastinum.
Confirmatory / Gold Standard:
Coronary Angiogram: This is the definitive test to visualise the coronary arteries, confirm the location and severity of stenosis, and proceed to intervention (PCI) if needed.
VI. Staging & Severity Assessment
We risk-stratify every patient to decide who needs to go to the cath lab urgently. Use a validated score. The TIMI score is simple and can be calculated at the bedside.
TIMI Risk Score for UA/NSTEMI (1 point for each):
Age ≥ 65 years
≥ 3 risk factors for CAD (HTN, DM, Dyslipidemia, Smoking, Family Hx)
Known CAD (prior stenosis ≥ 50%)
Aspirin use in the past 7 days
Severe angina (≥ 2 episodes in 24h)
ST deviation ≥ 0.5 mm
Positive cardiac marker (This would make it NSTEMI, but a slight elevation below MI threshold can be considered).
Interpretation & Impact on Management:
Low Risk (TIMI 0-1): May be suitable for a conservative strategy (medical management and outpatient follow-up).
Intermediate Risk (TIMI 2-3): Admission, medical therapy, usually proceed to early invasive strategy (<72 hours).
High Risk (TIMI ≥ 4): Urgent medical therapy and an early invasive strategy (<24 hours) is indicated.
The GRACE score is more complex but more predictive. You can use an online calculator for it. A higher score means higher mortality and dictates more aggressive, earlier intervention.
VII. Management Plan
Immediate Stabilisation (The ED Plan):
Oxygen: Only if SpO2 < 94%.
Anti-Ischemic Therapy:
Nitrates: Sublingual GTN (0.5mg), repeat up to 3 doses. If pain persists, start IV GTN infusion.
Analgesia: IV Morphine 2.5-5mg slow bolus if pain is severe and not relieved by nitrates.
Anti-Thrombotic Therapy (CRUCIAL):
Dual Antiplatelet Therapy (DAPT):
Aspirin: Loading dose of 300mg chewed and swallowed, then 150mg daily.
P2Y12 Inhibitor:
Ticagrelor: Loading dose 180mg (preferred if low bleeding risk). OR
Clopidogrel: Loading dose 300-600mg.
Anticoagulation:
Fondaparinux: 2.5mg SC once daily (often preferred, especially if a conservative strategy is likely). OR
Enoxaparin (Clexane): 1mg/kg SC twice daily.
Definitive Treatment (The Ward Round Plan):
First-Line: Based on the risk stratification:
High-Risk / Intermediate-Risk: Early Invasive Strategy. Plan for coronary angiogram within 24-72 hours with a view to Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Grafting (CABG).
Low-Risk: Conservative Strategy. Optimise medical therapy. If they have recurrent symptoms or a positive stress test, they will then be considered for an angiogram.
Continue Ward Medications:
Beta-blocker: e.g., Metoprolol or Bisoprolol. Start low, go slow. Titrate to a heart rate of 50-60 bpm.
Statin: High-intensity statin for everyone, regardless of cholesterol level. e.g., Atorvastatin 40-80mg ON.
ACE Inhibitor / ARB: Especially if patient has hypertension, diabetes, or LV dysfunction. e.g., Perindopril 2-4mg OD.
Long-Term & Discharge Plan:
Medications: Discharge with DAPT (Aspirin + Ticagrelor/Clopidogrel for up to 1 year), beta-blocker, high-intensity statin, and ACEi/ARB.
Follow-up: Cardiology clinic appointment.
Lifestyle: Document clear advice on smoking cessation, diet, exercise, and diabetes/blood pressure control. Refer to cardiac rehabilitation.
VIII. Complications
Immediate (first 24-48 hours):
Progression to NSTEMI/STEMI: Management: Escalate for urgent revascularization.
Ventricular Arrhythmias: Management: Follow ACLS protocol.
Short-Term (days to weeks):
Recurrent Angina: Management: Re-evaluate with senior, likely needs angiography.
Acute Heart Failure: Management: Diuretics, ACE inhibitors.
Long-Term (months to years):
Recurrent MI: Management: Secondary prevention is key.
Chronic Heart Failure: Management: Standard heart failure therapy.
IX. Prognosis
Prognosis depends entirely on the underlying coronary anatomy, LV function, and risk factor control. Without revascularization, patients with high-risk features have a significant 1-year risk of MI or death. The most important prognostic factors are age, extent of coronary disease, and left ventricular ejection fraction (LVEF).
X. How to Present to Your Senior
Be concise and structured.
"Dr., for review please. This is Mr. [Name] in Bed [X], a [age]-year-old man with a background of T2DM and hypertension, who presented with 1 hour of crushing central chest pain at rest. His ECG shows 2mm ST depression in the lateral leads. My main differential is Unstable Angina, high risk. I have given Aspirin 300mg, Ticagrelor 180mg, and started a GTN infusion to which his pain is settling. His TIMI score is 4. I would like to book him for an early angiogram."
XI. Summary & Further Reading
Top 3 Takeaways:
UA is ACS with ischemic symptoms, possible ECG changes, but negative serial troponins.
Immediate management is DAPT (Aspirin + Ticagrelor/Clopidogrel) and an anticoagulant (Fondaparinux/Enoxaparin).
Risk stratify every patient using TIMI/GRACE score to decide between an early invasive vs. conservative strategy.
Key Resources:
Malaysian CPG: Management of Unstable Angina/Non ST Elevation Myocardial Infarction (UA/NSTEMI) 2011 (Note: While dated, the core principles are still foundational).(
UpToDate: Search for "Acute coronary syndrome: Unstable angina and NSTEMI".
NEJM Review: [Acute Coronary Syndromes (2016
