Physical, Chemical, and Clinical Characteristics of Current Pharmacologic Stress Agents
| Agent | |||
|---|---|---|---|
| Characteristic | Dipyridamole | Adenosine | Dobutamine |
| Source | Synthetic | Natural | Synthetic |
| FDA approved for stress testing | Yes | Yes | No |
| Mechanism | Tests CFR | Tests CFR | True ischemic stress |
| Action on CFR | Indirect | Direct | Indirect |
| Preparation | Simple | Simple | Complicated (requires trained nurse) |
| Dosage | mg/kg | mg/kg | mg/kg |
| Infusion | Timed pump (may be hand titrated) | Timed/isolated intravenous source | Pump titration (requires trained nurse) |
| Agent duration (half-life) | Prolonged (∼90 min) | Very short (12 s) | Short (2.4 min) |
| Intravenous line fails during infusion | Problematic | Redo | Problematic |
| Variable infusion rate | Tolerable | Intolerable | Intolerable |
| Stress-test duration | ∼10–12 min | ∼4–8 min | ∼20–30 min |
| Supervision and quality control | Modest | High | High |
| Patient tolerance | High | High | Moderate |
| Complications/side effects | Bronchospasm/heart block | Bronchospasm/heart block | Ischemia/arrhythmia hypotension |
| Symptom duration | Usually brief | Brief | May be prolonged |
| Safety | Like exercise test | Like exercise test | Less than exercise test (only apply to selected patients) |
| Safety with baseline dipyridamole | Preserved | Reduced | Preserved |
| Antidote | Aminophylline | Discontinue | β-blocker |
| Speed of reversal | Minutes | Seconds | Minutes |
| Diagnostic indicator | Perfusion | Perfusion | Perfusion/wall motion |
| Prognostic value | High | High | Modest |
| Sensitivity with caffeine | Reduced | Reduced | Unchanged |
| Sensitivity with β-blocker | Reduced? | Reduced? | Reduced |
| Prognosis with β-blocker | Enhanced? | Enhanced? | Reduced |
Adapted from (3).