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Aminophylline as Adenosine Antidote — EECC MCQ

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EasyCardiac ImagingAminophylline as Adenosine AntidoteEECC

A 62-year-old man with suspected CAD undergoes adenosine stress CMR. During the scan, the patient develops severe bronchospasm (history of mild asthma was not disclosed). What is the antidote?

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Correct answer: A — IV aminophylline 75-250 mg slowly — aminophylline is a competitive adenosine receptor antagonist that rapidly reverses all adenosine effects (bronchospasm, bradycardia, AV block); it should be immediately available during any adenosine-based stress protocol

Aminophylline (theophylline ethylenediamine) is a methylxanthine that competitively antagonises adenosine at all receptor subtypes (A1, A2A, A2B, A3). It rapidly reverses: (1) bronchospasm (A2B/A3 receptor-mediated); (2) bradycardia/AV block (A1-mediated); (3) hypotension (A2A-mediated vasodilation). Dose: 75-250 mg IV slowly (over 30-60 seconds). It must be immediately available (drawn up) whenever adenosine is used for stress testing (CMR, nuclear perfusion, stress echo). Adenosine-based stress agents are CONTRAINDICATED in: (1) severe asthma/active bronchospasm; (2) second/third-degree AV block without pacemaker; (3) SBP <90 mmHg. Patients should avoid caffeine (another adenosine antagonist) for 12-24 hours before the test as it attenuates the vasodilator response. Regadenoson has a more favourable bronchospasm profile than adenosine but aminophylline should still be available.

Reference: SCMR/ASNC Stress Testing Protocols; BNF