ACS

• Acute coronary syndrome (ACS)


  A spectrum of clinical disorders that results from a sudden and unpredictable decrease of blood flow to the myocardium
• Acute coronary syndrome (ACS)


  • Life-threatening disorder that incurs high, and in some cases immediate, mortality
  • Usually due to interaction of vulnerable atherosclerotic plaque in the coronary arteries with that of activated clotting factors and platelets in the systemic circulation
• Management of ACS


  Highly protocolized and systematic care of both procedural and medical therapies guided toward restoring blood flow to the heart
• Spectrum of ACS


  • ST-elevation myocardial infarction (STEMI)
  • Non–ST-elevation myocardial infarction (NSTEMI)
  • Unstable angina (UA)
• ST-elevation myocardial infarction (STEMI)


  The most severe type of ACS, always emergent, characterized by ST-segment elevation on ECG in the appropriate clinical setting
• Non–ST-elevation myocardial infarction (NSTEMI)


  Characterized by an abnormal ECG without the presence of ST-segment elevation in the appropriate clinical setting (i.e., chest discomfort), and additionally characterized by positive cardiac biomarkers
• Unstable angina (UA)


  Falls within the NSTEMI subtype, characterized by an abnormal ECG without the presence of ST-segment elevation in the appropriate clinical setting (i.e., chest discomfort)
• The type of ACS

  Dictates the timing of reperfusion, with STEMI being the most severe and always emergent
• In the U.S., cardiovascular disease accounts for approximately 640,000 deaths each year
• The estimated annual incidence of heart attacks in the U.S. is 600,000 new attacks and 200,000 recurrent attacks
• Approximately 70% of MIs are listed as NSTEMI, with the remainder being listed as STEMI
• Patients presenting with NSTE-ACS have worse long-term prognosis than patients presenting with STEMI
• This is due to the higher comorbidity profile of patients presenting with NSTE-ACS (i.e., significantly older population, higher burden of comorbidities, and frequent history of coronary artery disease [CAD])
• The underlying etiology, atherosclerotic CAD, remains the number one cause of mortality
• Median age at ACS presentation in the U.S.

  68 yr old (interquartile range 56 to 79)
• Male:female ratio at ACS presentation in the U.S.

  Approximately 3:2
• In a 2005 to 2011 study sponsored by National Heart, Lung, and Blood Institute, the average age-adjusted first MI or fatal coronary heart disease rates per 1000 population in patients age 35 to 84 yr of age were 3.7 for white men, 5.9 for black men, 2.1 for white women, and 4.0 for black women
• Heart disease affects African Americans disproportionately
• Heart disease is the leading cause of death in women, surpassing all forms of cancer
• Risk factors for CAD

  • Hypertension
  • Diabetes mellitus
  • Dyslipidemia
  • Tobacco use
  • Family history of premature CAD (CAD in a male first-degree relative younger than 55 yr or a female younger than 65 yr of age)
• There are also female-specific risk factors for CAD, including disorders of pregnancy and early onset of menopause
• Presence of these risk factors cause damage to the vascular endothelium and progression of atherosclerotic coronary artery plaques
• Symptoms of chest discomfort in ACS

  • Pressure that may radiate to the shoulders, neck, jaw, or back
  • Typical angina is substernal in location
  • Brought on by emotional or physical stress
  • Relieved with rest and/or nitroglycerin
  • Pain and discomfort is often diffuse rather than localized
  • Often associated with diaphoresis
• Anginal


  Dyspnea, nausea, vomiting, and fatigue
• ECG findings in NSTE-ACS

  • Transient ST-segment elevation
  • ST-segment depression
  • New T-wave inversion
• ECG findings for definition of STEMI

  • ≥1-mm ST-segment elevation at the J-point in two contiguous leads other than leads V2-V3
  • In men ≥40 yr, ≥2-mm
  • In men <40 yr, ≥2.5-mm
  • In women regardless of age, ≥1.5-mm
• Physical examination findings that may provide clues to alternative diagnoses

  • Differences in pulse and blood pressure between the arms (aortic dissection)
  • Murmur of aortic regurgitation (aortic dissection)
  • Friction rub (pericarditis)
  • Pulsus paradoxus (cardiac tamponade)
  • Absent breath sounds (pneumothorax)
• Physical examination findings in ACS

  • Assess the patient's hemodynamic stability
  • Signs of heart failure (elevated jugular venous pressure, presence of an S3 gallop, rales, peripheral edema)
• Women, diabetics, the elderly (>75 yr old), and postoperative patients often have an atypical presentation for ACS
• Composition of Vulnerable atherosclerotic plaque


  • Thin fibrous cap
  • Large lipid core
• What happens to a vulnerable plaque after it rupture?

  1. Platelet activation

  2. Platelet aggregation

  3. Systemic inflammatory cascade

  4. Thrombus formation
• Long form STEMI


  ST-Elevation Myocardial Infarction
• Long form of NSTE-ACS

  Non-ST-Elevation Acute Coronary Syndrome
• Main etiology of STEMI

  Results from complete thrombotic occlusion of a coronary artery
• Main etiology of NSTE-ACS

  Often has partial occlusion
• Initial chest pain workup

  • Focused history and physical examination
  • 12-lead ECG
  • Cardiac biomarkers
  • Chest radiograph (CXR)
• Initial biomarkers may not be positive early in the disease process
• Conventional troponin levels


  1. Drawn every 6 to 8 h

  2. For a total of three sets

  3. To rule out MI or until peak to determine the severity of an established MI
• High-sensitivity troponin


  Time to rule in MI can be done in as little as 3 h from initial presentation
• Echocardiogram


  • May reveal new regional wall motion abnormalities
  • May reveal newly depressed left ventricular (LV) function
  • May reveal aneurysm formation