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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Acute myocardial infarction (MI) documented

  • Normal or near-normal coronary angiography

GENERAL CONSIDERATIONS

  • Up to 10% of all patients and 25% of patients < 35 years do not have coronary atherosclerosis on angiography after an MI

  • More common in Asian patients

  • Coronary artery spasm occurs at sites of subcritical stenosis and in completely normal arteries on angiography

  • In young patients, cocaine may induce vasospasm and MI

  • Coronary embolism with subsequent recanalization occasionally may be a cause of acute MI

  • Rarely, markedly elevated myocardial oxygen demand may precipitate an MI

  • Rarely, pseudoephedrine and ephedra cause MI with normal coronary arteries

  • Women who take estrogens and smoke can have MI with normal coronary arteries

  • Coagulopathies or hyperviscosity syndromes can lead to in situ coronary thrombosis

  • Coronary supply/demand mismatch in hypertrophic cardiomyopathies can cause MI

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Chest pain similar to that in MI that lasts > 30 minutes

  • Dyspnea

  • Palpitations

  • Diaphoresis during chest pain

PHYSICAL EXAM FINDINGS

  • S3 and S4 may occur depending on left ventricular function

  • Bilateral pulmonary rales may occur if there is heart failure

  • Elevated jugular venous distention may occur

DIFFERENTIAL DIAGNOSIS

  • Rupture of a minimal (< 50% diameter narrowing) plaque with thrombus formation and subsequent dissolution

  • Takotsubo cardiomyopathy may mimic MI

  • Myocarditis

  • Arteritis

  • Trauma

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC, brain natriuretic peptide test

  • Cardiac biomarkers such as troponin T or I

ELECTROCARDIOGRAPHY

  • Twelve-lead ECG may show ST elevation or marked ST depression

IMAGING STUDIES

  • Echocardiogram may show regional wall motion change

  • Left ventricular function may be normal or abnormal

  • Cardiac MRI usually shows normal myocardium but can show necrosis

  • Cardiac MRI useful to eliminate myocarditis and hypertrophic cardiomyopathies

DIAGNOSTIC PROCEDURES

  • Coronary angiogram

  • Angiogram will be normal without evidence of atherosclerosis or show minimal change not enough to account for complete cessation of blood supply

  • Spontaneous focal spasm of coronary artery may occur

  • Provocation tests to provoke coronary spasm no longer recommended

TREATMENT

CARDIOLOGY REFERRAL

  • All patients must be evaluated by a cardiologist

HOSPITALIZATION CRITERIA

  • All patients must be hospitalized initially

MEDICATIONS

  • Thrombolysis for suspected thrombosis or embolism

  • Nitrates or calcium channel blockers to relieve spasm

  • Specific therapy for or elimination of precipitating factors

  • Secondary prevention measures as appropriate (eg, smoking cessation)

  • Beta blockers generally avoided because of potential of unopposed alpha stimulation

  • If coronary atherosclerosis is detected, aspirin and a statin drug may be prescribed

THERAPEUTIC PROCEDURES

  • Generally none required

  • Rare patient with subcritical lesion and recurrent vasospasm of that site not adequately treated with vasodilators ...

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