Unstable Angina Clinical Presentation

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 ECG to develop an early risk stratification. (See Prognosis.)

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

The physical examination is usually not as sensitive or specific for unstable angina as 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

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.

Angina can take many forms, and inquiry should be directed at eliciting not only chest pain but also any 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, and/or arm or forearm (usually the left). These sensations less typically involve the lower jaw, neck, or shoulder. Important associated symptoms may be dyspnea, generalized fatigue, diaphoresis, nausea and vomiting, flulike symptoms, and, less commonly, lightheadedness or abdominal pain.

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

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. 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

Patients with acute coronary syndrome may present with a chief symptom of pain or discomfort in the chest or left arm, particularly if it reproduces previously documented angina.

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

• Carotid bruit
• Supraclavicular or femoral bruits
• Diminished peripheral pulses or blood pressure

Any sign of congestive heart failure, including isolated 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.

The Braunwald classification is conceptually useful because it factors in the clinical presentation (new or progressive vs rest angina), context (primary, secondary, or post–myocardial infarction), and intensity of antianginal therapy.

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

Patients in class I have new or accelerated exertional angina, whereas those in class II have subacute (>48 h since last pain) or class III acute (< 48 h since last pain) rest angina. The clinical circumstances associated with unstable angina are categorized as (A) secondary (anemia, fever, hypoxia), (B) primary, or (C) postinfarction (< 2 wk after infarction). Intensity of antianginal therapy is subclassified as (1) no treatment, (2) usual oral therapy, and (3) intense therapy, such as intravenous nitroglycerin.

The Canadian Cardiovascular Society Grading System for effort-related angina is widely used since it is a simple and practical classification that is often 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 2 blocks of level ground or climbing more than 1 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.)

Estimation of the likelihood of acute coronary syndrome is a complex, multivariable problem that cannot be fully specified in the below list. The following is meant to illustrate major relationships rather than to offer rigid algorithms.

High likelihood of acute coronary syndrome includes any of the following features:

• History of prior myocardial infarction, sudden death, or other known history of coronary artery disease
• Chest or left arm pain consistent with prior documented angina
• Transient hemodynamic or electrocardiographic changes during pain
• ST-segment elevation or depression 1 mm or more
• Marked symmetrical T-wave inversion in multiple precordial leads

Intermediate likelihood of acute coronary syndrome includes the absence of high-likelihood features but the presence of 1 of these risk characteristics:

• Age older than 70 years
• Male sex
• Diabetes mellitus
• Extracardiac vascular disease (peripheral, brachiocephalic, or renal artery atherosclerosis)
• ST depression 0.05-1 mm
• T-wave inversion 1 mm or greater in leads with dominant R waves

Low likelihood of acute coronary syndrome 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 electrocardiographic findings

The TIMI Risk Score for unstable angina/NSTEMI is currently the best-validated prognostic instrument that is simple enough to use in an emergency department setting. The gradient of myocardial infarction, severe recurrent ischemia, or death is somewhat proportionate to the TIMI Risk Score (see the graphs below), although an adverse prognosis appears to be mitigated by the use of newer antithrombotic strategies.

The inflection point for myocardial infarction or death starts at a TIMI Risk Score of 3. Therefore, patients with a score of 3-7 should be considered for use of intravenous glycoprotein IIb/IIIa agents, heparin (low molecular weight or unfractionated), and early cardiac catheterization (see Treatment and Management).

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:

• Aged 65 years or older
• Use of aspirin in the last 7 days
• Known coronary stenosis of 50% or greater
• Elevated serum cardiac markers
• At least 3 risk factors for coronary artery disease (including diabetes mellitus, active smoker, family history of coronary artery disease, hypertension, hypercholesterolemia)
• Severe anginal symptoms (2 or more anginal events in the last 24 h)
• ST deviation on ECG