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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Objective evidence of myocardial ischemia is the absence of angina pectoris or its equivalent

  • Most patients have underlying coronary artery disease

  • Ambulatory ECG monitoring shows ischemic ST transients during normal activities or a positive stress test documenting ischemia

GENERAL CONSIDERATIONS

  • May occur in patients who have never developed symptoms or in patients who had prior symptomatic cardiac events

  • Ambulatory ECG monitoring has increased the recognition of this condition

  • Asymptomatic ST-segment deviation at night suggests 2- or 3-vessel disease

  • Silent ischemia is a significant predictor of mortality

  • Heart rate and blood pressure increase before silent ischemia

  • Altered peripheral pain perception and cerebral cortical dysfunction have been proposed as mechanisms for silent ischemia

  • Diabetics are more prone to silent ischemia

  • Occurs in up to one-quarter of patients with coronary microvascular dysfunction

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Sudden death

  • Patients may not experience chest pain even during acute myocardial infarction (MI)

PHYSICAL EXAM FINDINGS

  • Generally noncontributory

DIFFERENTIAL DIAGNOSIS

  • False-positive ECG or cardiac imaging studies

  • Variant or vasospastic angina with atypical symptoms

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC, metabolic panel

  • Lipid panel

  • Troponin I or T

  • Brain natriuretic peptide levels

ELECTROCARDIOGRAPHY

  • ECG may show ischemic changes

  • Ambulatory ECG monitoring showing ST transients is diagnostic

  • Exercise stress test may be positive

IMAGING STUDIES

  • Stress nuclear perfusion scan may be abnormal

DIAGNOSTIC PROCEDURES

  • Coronary angiogram indicated if:

    • – The perfusion scan shows high-risk changes (large area of ischemia or left ventricular dilatation on stress)

    • – There is asymptomatic nocturnal ST depression

TREATMENT

CARDIOLOGY REFERRAL

  • These patients require evaluation by a cardiologist

HOSPITALIZATION CRITERIA

  • After coronary angiogram if percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) is planned

MEDICATIONS

  • Beta blockers are the mainstay of therapy because most episodes are associated with increased myocardial oxygen demand

  • Nitrates and calcium channel blockers are less effective

  • Control any underlying atherosclerosis (ie, cholesterol lowering)

THERAPEUTIC PROCEDURES

  • PCI in selected patients

SURGERY

  • CABG in selected patients

MONITORING

  • ECG monitoring in hospital

DIET AND ACTIVITY

  • Cardiac low-fat diet

  • Aerobic exercise as tolerated

ONGOING MANAGEMENT

HOSPITAL DISCHARGE CRITERIA

  • After adequate treatment

FOLLOW-UP

  • Follow-up 3 months after initiation of treatment with follow-up ...

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