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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • New or worsening symptoms of myocardial ischemia (angina pectoris or its equivalents)

  • New or worsening ECG changes of myocardial ischemia (ST-wave depression or T-wave inversion on ECG in 2 or more contiguous leads)

  • Positive biologic markers for myocardial injury (ie, troponin I or T)

GENERAL CONSIDERATIONS

  • Acute non–ST-segment elevation myocardial infarctions (NSTEMIs) make up about two-thirds to three-quarters of all admissions to cardiac care units

  • Usually caused by unstable plaque characterized by fissure or rupture of the fibrous cap

  • Platelet aggregation leading to thrombus formation ensues

  • Vasoconstriction occurs secondary to endothelial dysfunction

  • Most episodes occur without antecedent increase in myocardial oxygen demand

  • Worsening of stable coronary artery disease may be triggered by:

    • – Severe anemia

    • – Thyrotoxicosis

    • – Acute tachyarrhythmias

    • – Hypotension

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Angina that lasts up to 20–30 minutes or longer

  • Symptoms may occur at rest or during minimal accustomed exertion

  • Associated symptoms occur such as sweating and fatigue

  • Dyspnea with or without chest pain may be a primary manifestation

  • Recurrence of ischemic symptoms within 4 weeks after a myocardial infarction or percutaneous coronary procedure or coronary artery bypass graft surgery

PHYSICAL EXAM FINDINGS

  • No typical abnormal physical finding

  • S3 or S4

  • Transient ischemic mitral regurgitation

  • Features of left ventricular dysfunction

  • Hypotension may occur depending on the extent of myocardial involvement or secondary to an arrhythmia

DIFFERENTIAL DIAGNOSIS

  • Stable angina pectoris

  • Variant angina

  • Unstable angina

  • Aortic dissection

  • Acute myopericarditis

  • Acute pulmonary embolism

  • Esophageal reflux

  • Cholecystitis

  • Peptic ulcer disease

  • Cervical radiculopathy

  • Costochondritis

  • Pneumothorax

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC to exclude anemia

  • Basic metabolic panel (especially creatinine and potassium)

  • Cardiac troponin I or T

  • Brain natriuretic peptide

ELECTROCARDIOGRAPHY

  • 12-lead ECG (patients with resting ST-segment depression are considered high risk)

IMAGING STUDIES

  • Echocardiogram to evaluate:

    • – Regional wall motion analysis

    • – Left ventricular function

    • – Valvular heart disease

  • In patients in whom medical management is chosen, stress perfusion study may be done > 48 hours after the last episode of chest pain for further risk stratification

DIAGNOSTIC PROCEDURES

  • Coronary angiogram

TREATMENT

CARDIOLOGY REFERRAL

  • All patients with NSTEMI should be seen by a cardiologist

HOSPITALIZATION CRITERIA

  • All patients should be hospitalized

MEDICATIONS

  • General:

    • – Oxygen if hypoxemic

  • Pain relief and anti-ischemic agents:

    • – Sublingual nitroglycerin followed by IV if necessary

    • – Morphine sulfate if nitrates fail to relieve pain.

    • – Beta blockers orally can be started within 24 hours of admission in the ...

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