Angina Pectoris, Unstable

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• New (≤ 2 months) or worsening symptoms (angina, dyspnea)

• ECG changes of myocardial ischemia (ST depression, T-wave inversion)

• Absence of troponin I or T; elevation initially or ≤ 20% change on serial testing if initially mildly elevated

GENERAL CONSIDERATIONS

• Considered part of the acute coronary syndromes

• Much less common with the advent of high-sensitivity troponin assays

• Imbalance between myocardial oxygen demand and supply

• May be due to increase in coronary plaque volume or rupture with resultant platelet or thrombotic accumulation that does not completely block the artery, or coronary vasospasm

• May be triggered by extrinsic factors such as anemia, thyrotoxicosis, arrhythmia, hypertension, or hypotension in patients with stable plaques

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Chest pain typically lasts 5–30 min

• Atypical locations include neck, jaw, arms, and epigastrium

• Dyspnea, fatigue, diaphoresis, feeling of indigestion, and desire to burp or defecate may be presenting symptoms or accompany other symptoms

• Symptoms occur at rest or are provoked by minimal activity

• Chest tightness may be frequent or prolonged

• May follow an acute myocardial infarction (MI) or coronary revascularization

PHYSICAL EXAM FINDINGS

• Physical findings are nonspecific

• S₃ or S₄ may be heard

• Ischemic mitral regurgitation may be detected

• Features of left heart failure may be seen

• Arrhythmias and conduction disturbances may occur

• Hypotension or hypertension may be present

DIFFERENTIAL DIAGNOSIS

• Stable angina pectoris

• Variant angina

• MI

• Aortic dissection

• Acute myopericarditis

• Acute pulmonary embolism

• Esophageal reflux

• Cholecystitis

• Peptic ulcer disease

• Cervical radiculopathy

• Costochondritis

• Pneumothorax

DIAGNOSTIC EVALUATION

CLINICAL

• In undiagnosed patients, the likelihood of an acute coronary syndrome can be estimated by risk scores such as the HEART score (History, ECG, Age, Risk factors, Troponin)

LABORATORY TESTS

• Absence of elevated troponin I or T

• CBC, basal metabolic panel, thyroid-stimulating hormone

ELECTROCARDIOGRAPHY

• ECG may show ST depression or T-wave inversion

• If initial ECG normal, repeat every 15–30 minutes for 1 hour

• Normal ECG does not exclude cardiac ischemia

• ECG V7–9 recording can be useful in some patients

IMAGING STUDIES

• Echocardiogram if heart failure symptoms predominate

• Chest x-ray

DIAGNOSTIC PROCEDURES

• Coronary angiography in high-risk patients

• Nuclear stress test or exercise echocardiogram in low-risk patients with normal ECGs and cardiac troponins

• Additional tests depend on differential diagnosis

• CT angiogram of chest if pulmonary embolism or dissection is suspected

• Coronary CT angiogram in selected patients who cannot undergo stress testing

TREATMENT

CARDIOLOGY REFERRAL

• High-risk patients: ...