Intracoronary adenosine administration in the right coronary artery: a word of caution.

The study by De Luca et al. (1) elegantly demonstrates that increasing doses of intracoronary adenosine are associated with incremental reductions in fractional flow reserve. We would like to caution, however, against high-dose intracoronary adenosine administration in the right coronary artery. Although none of the 12 patients who underwent right coronary artery evaluation in the present study had a clinical event, 3 of them developed complete atrioventricular block lasting 4 s. Prolonged complete atrioventricular block can lead to ventricular fibrillation or atrial fibrillation (2), both important complications that may require emergent defibrillation. Hence, intravenous administration may be the preferred route for vasodilator administration for fractional flow reserve measurement in the right coronary artery.