EKG
Stable CAD — stress testing & risk
EKG

Stable CAD — stress testing & risk

Who needs a stress test, what kind, and how to interpret findings.

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◆Stress test selection

  • •Can exercise + baseline EKG interpretable → EXERCISE EKG stress test (first-line)
  • •Can exercise + baseline EKG uninterpretable (LBBB, paced, baseline ST changes) → exercise + imaging (echo or nuclear)
  • •Cannot exercise → pharmacologic stress: dobutamine echo OR vasodilator nuclear (regadenoson, adenosine, dipyridamole)
  • •AVOID vasodilator stress in severe asthma/COPD or active bronchospasm — use dobutamine instead

◆Positive stress test findings

  • •≥1 mm horizontal or down-sloping ST depression at 80 ms after J point = ischemic
  • •Hypotension with stress = severe disease (decreased CO from extensive ischemia)
  • •Ventricular arrhythmias with stress → consider EP study
  • •Reversible perfusion defect on nuclear → flow-limiting stenosis

◆What to do with the result

  • •High-risk stress test (large area, hypotension, low workload, multivessel defects) → coronary angiography
  • •Positive moderate → maximize medical therapy (ASA, statin, β-blocker, ACE-i, nitrate)
  • •Pre-op cardiac risk: only stress test if active cardiac condition OR poor functional capacity (<4 METs) AND moderate–high risk surgery

High-yield pearls

  • ◆Treadmill stress test sensitivity 60–70% — negative test doesn't rule out CAD if pretest probability high
  • ◆Exercise tolerance of 4 METs (climb a flight of stairs) is a key threshold for pre-op clearance
  • ◆Routine cardiac stress testing is NOT recommended for asymptomatic low-risk adults (USPSTF)
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