Acute Coronary Syndromes: STEMI

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DESCRIPTION

Acute myocardial infarction (AMI) is the rapid development of myocardial necrosis resulting from a sustained and complete absence of blood flow to a portion of the myocardium. ST-segment elevation myocardial infarction (STEMI) occurs when coronary blood flow ceases, usually following complete atherothrombotic occlusion of an epicardial coronary artery, resulting in transmural ischemia. This is accompanied by release of serum cardiac biomarkers and ST-segment elevation on an electrocardiogram (ECG).

EPIDEMIOLOGY

Incidence

There are >800,000 cases of AMI reported annually in the United States. Early revascularization and AMI management has improved mortality, with a 30-day survival of 95%.

Prevalence

Atherosclerotic heart disease is the leading cause of morbidity and mortality in the United States. ~7.5 million people in the United States are affected by AMI. Prevalence increases with age and is higher in men (5.5%) compared to women (2.9%). Coronary artery disease (CAD) accounts for ≥12% of total U.S. health expenditures.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Atherosclerotic CAD: Atherosclerotic lesions can be fibrotic, calcified, or lipid laden. Thin-capped atheromas are more likely to rupture, causing atherothrombotic occlusion.
  • Nonatherosclerotic causes:
    • Embolism from either infective vegetations, or thrombi originating within the right atrium across the foramen ovale (“paradoxical”), from the left atrium or from within the left ventricle
    • Spontaneous coronary artery dissection: prevalent in fibromuscular dysplasia (FMD) and in young women
    • Mechanical or iatrogenic obstruction: chest trauma, dissection of the aorta and/or coronary arteries (e.g., from catheterization procedures)
    • Coronary artery spasm from increased vasomotor tone; anginal variant
    • Arteritis and other etiologies: hematologic causes (disseminated intravascular coagulation [DIC], severe anemia), aortic stenosis, cocaine, IV drug use, severe burns, prolonged hypotension

RISK FACTORS

Advancing age, hypertension, tobacco use, diabetes mellitus, dyslipidemia, family history of premature onset of CAD, sedentary lifestyle

GENERAL PREVENTION

Smoking cessation/abstinence; healthy diet; weight loss/control; regular physical activity and exercise; control of hypertension, hyperlipidemia, and diabetes mellitus

COMMONLY ASSOCIATED CONDITIONS

Abdominal aortic aneurysm, cerebrovascular disease, atherosclerotic peripheral vascular disease

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