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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: continued chest pain, severe dyspnea, syncope, palpitation, ST depression on ECG, or troponin elevation

  • Known ...

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