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Stress Testing

Stress Testing

  • Update on Stress Testing1
  • Exercise Treadmill Test
    • Pooled data
      • Men: Sensitivity of 68% and Specificity of 77% for CAD
      • Women: Sensitivity of 61% and Specificity of 70% for CAD
    • Not interpretable for ischemia if:
      1. Old LBBB
      2. Unable to reach target HR
      3. Baseline ST elevation
      4. Digoxin use
    • Note:
      • Resting ST-segment depression <1mm increases test sensitivity but decreases specificity with no change in overall accuracy
      • Role less clear in RBBB
  • Get Stress Testing with Imaging (MPI, CMR, or Echo) aka Pharmacologic Stress Testing or "Lexiscan" if unable to do Exercise Stress Test
    • Indications:
      • Unable to exercise
      • Baseline EKG abnormalities limiting interpretation
        • LBBB, RBBB
      • Indeterminate findings on Exercise Stress Test
    • Notes
      • No adenosine in asthmatics, hypotension (stimulate A2A receptors on vascular smooth muscles, magnified from rest)
    • Positive Findings
      • 1mm of horizontal or downsloping ST-segment depression
      • 2mm of upsloping ST-segment depression
    • Findings associated with poor outcomes
      • Poor exercise capacity (<5 METs)
        • Patients achieving ≥10 METs have a 0.1%/year rate of cardiac death and 0.7%/year rate of nonfatal MI
      • Exercise-induced angina during minimal expenditure
      • Inability to achieve 85% age-predicted maximum HR with exercise
        • Calculated as (220 - Age)
      • Fall in SBP below baseline during exercise
      • ST elevation
      • ≥ 2mm ST-depression during minimal expenditure
        • Maximum ST-segment deviation is a strong predictor of both cardiac death and composite cardiac death and nonfatal MI
      • Early onset or prolonged duration of ST depression during testing
        • Rapid recovery is associated with a low rate of positive imaging or findings of CAD on angiography
      • ST depression in multiple leads
      • Ventricular couplets or tachycardia during minimal expenditure or recovery

Balanced Ischemia

  • High risk features on Exercise testing
    • Coronary blood low is equally or nearly equally impaired
    • ST depression in multiple leads during peak stress but no evidence of ischemia on radionuclide MPI

  1. https://pubmed.ncbi.nlm.nih.gov/22469057/ ↩