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Snap Shot
  • A 67-year-old construction foreman is brought to the emergency department by ambulance after complaining to his coworkers of sudden onset chest tightness and shortness of breath. He has a 45 pack-year smoking history, takes aspirin and simvastatin, and has a BMI of 33.

 

Introduction
  • Definition
    • An imbalance between heart oxygen supply and demand resulting in ischemia
  • Cause
    • Primarily atherosclerotic occlusion of the coronary arteries 
  • Types
    • angina pectoris
    • myocardial infarction
    • sudden cardiac death
    • chronic ischemic heart disease
    • myocardial stunning
  • Major risk factors include
    • diabetes mellitus (most important and considered a CAD equivalent)
    • smoking (#1 preventable factor)
    • HTN
    • cholesterol/lipid abnormalities
      • LDL > 160
      • HDL < 35
    • family history
    • age >45 (men), age >55 (women)
  • Minor risk factors include
    • obesity
    • lack of estrogens
      • why men have earlier onset
    • elevated homocysteine levels
    • cocaine use
    • amphetamine use
Presentation
  • Symptoms
    • range from asymptomatic
      • particularly in older women and diabetics
    • to substernal tightness and/or pain
    • and shortness of breath
    • often diagnosed and characterized as
      • stable angina
        • predictable; presents with consistent amount of exertion
        • patient can achieve relief with rest or nitroglycerin
        • indicative of a stable, flow-limiting plaque
      • unstable angina
        • unpredictable; often presents at period of inactivity
        • defined as any new angina or rapidly worsening stable angina
        • limited improvement with nitroglycerin, and usually recurs soon afterward
        • indicative of a ruptured plaque with subsequent clot-formation in vessel lumen
Evaluation
  • Cardiac catheterization for definitive diagnosis 
    •  locate and assess severity of the lesion(s)    
  • CXR
    • to rule out aortic dissection
  • Elevated cardiac biomarkers
    • troponin, CK, and/or CK-MB may be present
  • EKG
    • ST elevation or depression depending on severity of ischemia
    • Q waves
  • Stress-testing
    • to evaluate simultaneously with EKG, echo, and radionuclide perfusion studies
 
Treatment
  • In acute coronary syndrome use "MONA-B"
    • morphine
    • oxygen
    • nitroglycerin
    • aspirin
    • ACE-inhibitors
    • may also use B-blockers, GPIIb/IIIa antagonists and angioplasty
  • Drugs that improve post-MI mortality rates include
    • Aspirin
    • B-blockers
    • ACE-inhibitors
    • ARBs
    • and HMG-CoA reductase inhibitors (statins)
    • NOT calcium channel blockers
 

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