Vasodilator Stress Contraindications: Caffeine and Bronchospasm

A. Adenosine receptor blockade by caffeine — active bronchospasm (asthma/COPD exacerbation) or high-degree AV block

Adenosine and dipyridamole (which increases endogenous adenosine) cause coronary hyperemia by acting on A2A adenosine receptors. ABSOLUTE contraindications include: (1) active bronchospasm/severe reactive airway disease — adenosine can cause bronchoconstriction via A2B receptors; (2) second or third degree AV block without a pacemaker — adenosine slows AV conduction; (3) caffeine ingestion within 12 hours — caffeine is an adenosine receptor antagonist and blocks the vasodilatory effect, invalidating the study; (4) hypotension (SBP <90 mmHg). Dobutamine stress is used when vasodilators are contraindicated.