Unstable Angina Clinical Presentation

Updated: Oct 01, 2020
  • Author: Walter Tan, MD, MS; Chief Editor: Eric H Yang, MD  more...
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Patients with unstable angina represent a heterogeneous population. Therefore, the clinician must obtain a focused history of the patient’s symptoms and coronary risk factors and immediately review the electrocardiogram (ECG) to develop an early risk stratification. (See Prognosis.)

Initially, obtain a history to determine whether any evidence of angina is present, then aim to identify whether it is stable or unstable.

Unstable angina differs from stable angina in that the discomfort is usually more intense and easily provoked, and ST-segment depression or elevation on ECG may occur. Otherwise, the manifestations of unstable angina are similar to those of other conditions of myocardial ischemia, such as chronic stable angina and myocardial infarction (MI). With unstable angina, symptoms may (1) occur at rest; (2) become more frequent, severe, or prolonged than the usual pattern of angina; (3) change from the usual pattern of angina; or (4) not respond to rest or nitroglycerin. [3]

Angina can take many forms, and inquiry should be directed at eliciting not only chest pain but also any associated discomfort and its frequency, location, radiation pattern, and precipitating and alleviating factors.

Ischemic pain can manifest as heaviness, tightness, aching, fullness, or burning of the chest, epigastrium, or arm or forearm (usually the left). These sensations less typically involve the back, lower jaw, neck, shoulders, or arms. Important associated symptoms may be dyspnea, generalized fatigue, diaphoresis, nausea and vomiting, flulike symptoms, and, less commonly, lightheadedness or abdominal pain. The intensity of pain on a 1-10 scale does not correlate with diagnosis or prognosis.

Elderly and female patients are more likely to present with atypical signs and symptoms.


Physical Examination

The physical examination is usually not as sensitive or specific for unstable angina as the history or diagnostic tests. An unremarkable physical examination is not uncommon. Perform a quick assessment of patients’ vital signs, and perform a cardiac examination. Specific diagnoses that must be explicitly considered are the following:

  • Aortic dissection

  • Leaking or ruptured thoracic aneurysm

  • Pericarditis with tamponade

  • Pulmonary embolism

  • Pneumothorax

  • Peptic ulcer disease

Increased autonomic activity may manifest as diaphoresis or tachycardia, and bradycardia may result from vagal stimulation from inferior wall myocardial ischemia.

A large area of myocardial jeopardy may manifest as signs of transient myocardial dysfunction and typically signifies a higher-risk situation. Such signs include the following:

  • Systolic blood pressure less than 100 mm Hg or overt hypotension

  • Elevated jugular venous pressure

  • Dyskinetic apex

  • Reverse splitting of the second heart sound

  • Presence of a third or fourth heart sound

  • New or worsening apical systolic murmur due to papillary muscle dysfunction

  • Rales or crackles

Findings indicative of peripheral arterial occlusive disease or prior stroke increase the likelihood of associated coronary artery disease (CAD) and are as follows:

  • Carotid bruit

  • Supraclavicular or femoral bruits

  • Diminished peripheral pulses or blood pressure

Any sign of congestive heart failure (CHF), including isolated sinus tachycardia, particularly in physiologically vulnerable populations (eg, very elderly patients), should trigger expeditious workup, treatment, or consultation with a cardiologist. Such patients can deteriorate rapidly.

The number and diversity of clinical conditions that cause the transient myocardial ischemia of unstable angina, along with its varying intensity and frequency of pain, have made classification within this disorder difficult.


Braunwald Classification

The Braunwald classification (see Table 4 below) is conceptually useful, in that it factors in the clinical presentation (new or progressive vs rest angina), context (primary, secondary, or post-MI), and intensity of antianginal therapy.

Table 4. Braunwald Classification of Unstable Angina (Open Table in a new window)






Symptoms with exertion


Subacute symptoms at rest (2-30 days prior)


Acute symptoms at rest (within prior 48 hr)

Clinical precipitating factor







Therapy during symptoms


No treatment


Usual angina therapy


Maximal therapy

Patients in Braunwald class I have new or accelerated exertional angina, whereas those in class II have subacute (>48 hours since last pain) or class III acute (< 48 hours since last pain) rest angina. The clinical circumstances associated with unstable angina are categorized as follows:

  • Secondary (anemia, fever, hypoxia)

  • Primary

  • Postinfarction (< 2 weeks after MI)

Intensity of antianginal therapy is subclassified as follows:

  • No treatment

  • Usual oral therapy

  • Intense therapy (eg, intravenous [IV] nitroglycerin)


Canadian Cardiovascular Society Grading System

Because of its simplicity and practicality, the Canadian Cardiovascular Society Grading System for effort-related angina is widely used to describe symptom severity. The grading system is as follows:

  • Grade I – Angina with strenuous, rapid, or prolonged exertion; ordinary physical activity, such as climbing stairs, does not provoke angina

  • Grade II – Slight limitation of ordinary activity; angina occurs with postprandial, uphill, or rapid walking; when walking more than two blocks of level ground or climbing more than one flight of stairs; during emotional stress; or in the early hours after awakening

  • Grade III – Marked limitation of ordinary activity; angina occurs with walking 1-2 blocks or climbing a flight of stairs at a normal pace

  • Grade IV – Inability to carry on any physical activity without discomfort; rest pain occurs


Acute Coronary Syndrome Risk Assessment

Estimation of the likelihood of acute coronary syndrome (ACS) is a complex, multivariable problem that cannot be fully specified in the list below, which is meant more to illustrate major relations than to offer rigid algorithms. A high likelihood of ACS includes any of the following features:

  • History of previous MI, sudden death, or other known history of CAD

  • Chest, neck, jaw, or left arm pain consistent with prior documented angina

  • Transient hemodynamic or ECG changes during pain

  • ST-segment elevation or depression of 1 mm or more

  • Marked symmetrical T-wave inversion in multiple precordial leads

An intermediate likelihood of ACS includes the absence of high-likelihood features but the presence of one of the following risk characteristics:

  • Age greater than 70 years

  • Male sex

  • Diabetes mellitus

  • Extracardiac vascular disease (peripheral, brachiocephalic, or renal artery atherosclerosis)

  • ST depression of 0.05-1 mm

  • T-wave inversion of 1 mm or greater in leads with dominant R waves

A low likelihood of ACS includes the absence of high- or intermediate-likelihood features and the presence of any of the following:

  • Chest pain classified as probably not angina

  • Chest discomfort reproduced by palpation

  • T-wave flattening or inversion of less than 1 mm in leads with dominant R waves

  • Normal ECG findings


Thrombolysis in Myocardial Infarction Risk Score

The Thrombolysis in Myocardial Infarction (TIMI) Risk Score for unstable angina/non-ST elevation MI (UA/NSTEMI) is currently the best-validated prognostic instrument that is simple enough to use in settings such as an emergency department. The gradient of MI, severe recurrent ischemia, or death is somewhat proportionate to the TIMI Risk Score (see the image below), though an adverse prognosis appears to be mitigated by the use of newer antithrombotic strategies.

Unstable Angina. Thrombolysis in Myocardial Infarc Unstable Angina. Thrombolysis in Myocardial Infarction (TIMI) Risk Score correlates with major adverse outcome and effect of therapy with low-molecular-weight heparin. ARD = absolute risk difference; ESSENCE = Efficacy and Safety of Subcutaneous Enoxaparin in Non–Q-wave Coronary Events; No. = number; NNT = number needed to treat.

The presence of any of the following variables constitutes 1 point, with the sum constituting the patient risk score on a scale of 0-7:

  • Age 65 years or older

  • Use of aspirin in the preceding 7 days

  • Known coronary stenosis of 50% or greater

  • Elevated serum cardiac markers

  • At least three risk factors for CAD (including diabetes mellitus, active smoking, family history of CAD, hypertension, or hypercholesterolemia)

  • Severe anginal symptoms (≥2 anginal events in the preceding 24 hours)

  • ST deviation on ECG