Interpretation is qualitative and operator-dependent, leading to potential errors:
False Positives (Test says “Ischemia” but none exists)
- Tethering: A normal segment “dragged” by an adjacent scarred segment.
- LBBB/RV Pacing: Paradoxical septal motion can mimic ischemia.
- Hypertensive Response: Extreme afterload can cause global dysfunction not related to CAD.
- LVOT Obstruction: Dobutamine can induce a gradient in patients with septal hypertrophy, causing hypotension and “apparent” ischemia.
False Negatives (Test says “Normal” but CAD is present)
- Submaximal Stress: Failing to reach 85% APMHR (often due to beta-blocker use).
- Single-Vessel Disease: Particularly in the Circumflex artery, which can be “echocardiographically silent.”
- Poor Acoustic Windows: Inadequate visualization of all 17 myocardial segments.
- Delayed Imaging: If images aren’t captured within 60-90 seconds of stopping the infusion, wall motion can normalize rapidly.
4. Contraindications & Safety
While generally safe, DSE carries a small risk of serious arrhythmias (1%) or myocardial infarction (1:5000).
- Absolute Contraindications: Acute MI (within 2 days), unstable angina, severe symptomatic aortic stenosis, and uncontrolled ventricular arrhythmias.
- Key Side Effects: Palpitations (29%), chest pain (31%), and headache. Interestingly, dobutamine can cause hypotension in some patients due to β2-mediated peripheral vasodilation.