Acute Coronary Syndromes

SOURCE

Source: Rogers KC, De Denus S, Finks SW, Spinler SA. Acute coronary syndromes. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146056870. Accessed April 8, 2017.

DEFINITION

• Acute coronary syndromes (ACS) include all clinical syndromes of acute myocardial ischemia resulting from an imbalance between myocardial oxygen demand and supply.

ETIOLOGY

• Diminished myocardial blood flow secondary to occlusive or partially occlusive coronary artery thrombus.

PATHOPHYSIOLOGY

• Partially or completely occlusive clot forms on top of ruptured atherosclerotic plaque within coronary artery.

• Release of adenosine diphosphate (ADP) and thromboxane A₂ (TXA₂) from platelets produces vasoconstriction and platelet activation.

• Activation of extrinsic coagulation cascade leads to formation of fibrin clot.

• Ventricular remodeling after myocardial infarction (MI) may lead to heart failure (HF).

EPIDEMIOLOGY

• >1.1 million Americans experience ACS each year; 116,800 die of MI.

• Approximately 660,000 Americans will have a new coronary event, while 305,000 will have a recurrent event.

• The rate of death from coronary heart disease (CHD) has declined 38% from 2003 to 2013, but the estimated annual mortality in first year after a new coronary event and MI remains high (34% and 15% respectively).

PREVENTION AND SCREENING

• Risk factor modification (smoking cessation; control of blood pressure, diabetes, dyslipidemia)

RISK FACTORS

• Increasing age.

• Hypertension.

• Male sex.

• Smoking.

• Diabetes mellitus.

• Dyslipidemia.

• Obesity.

CLINICAL PRESENTATION

SIGNS AND SYMPTOMS

• Symptoms: Chest discomfort (usually at rest), severe new-onset or increasing angina. Discomfort may radiate to shoulder, down left arm, or to back or jaw. Nausea, vomiting, diaphoresis, and shortness of breath may also occur.

• Signs: Patients with ACS may present with signs of acute HF or dysrhythmias.

DIAGNOSIS

MEANS OF CONFIRMATION AND DIAGNOSIS

• Use patient symptoms, past medical history, ECG, and troponin to stratify patients into low, medium, or high risk.

LABORATORY TESTS

• Increased troponin I or T with a typical rise and fall indicates MI.

• Serum potassium and magnesium, glucose, serum creatinine, complete blood cell count (CBC), coagulation tests, and fasting lipid panel.

DIAGNOSTIC PROCEDURES

• 12-lead ECG findings indicating myocardial ischemia or MI include ST-segment elevation, ST-segment depression, and T-wave inversion.

• Classification of ACS

  • ST-segment elevation (STE) ACS or STEMI

  • non-ST elevation acute coronary syndrome (NSTE-ACS), which includes non–ST-segment elevation myocardial infarction (NSTEMI) and unstable angina (UA).

DIFFERENTIAL DIAGNOSIS

• Aortic dissection.

• Pulmonary embolism.

• Tension pneumothorax.

• Pericarditis.

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