Adequacy of intracoronary versus intravenous adenosine-induced maximal coronary hyperemia for fractional flow reserve measurements

Background Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperem ia. The most widely used pharmacologic stimulus for maximal coronary hypere mia is adenosine, administered either as a continuous intravenous (IV) infu sion or intracoronary (IC) bolus. IV adenosine has more side effects and is more costly than IC adenosine but has a more stable and prolonged hyperemi c effect. Methods We compared the efficacy of IC and IV adenosine administration for the measurement of FFR in a multicenter trial. Fifty-two patients with 60 l esions underwent determination of FFR with both IV and IC adenosine. IV ade nosine was administered as a continuous infusion at a rate of 140 mu g/ka. per minute until a steady state hyperemia was achieved. IC adenosine boluse s were administered at a dose of 15 to 20 mu g in the right and 18 to 24 mu g in the left coronary artery. FFR was calculated as the ratio of the dist al coronary pressure (from pressure guide wire) to the aortic pressure (gui de catheter) at maximal hyperemia. Results A total of 26 left anterior descending, 23 right, 9 left circumflex , and 3 left main coronary arteries were evaluated. Mean percent stenosis f or both groups was 55.8% +/- 23.6% (range 0% to 95%), and mean FFR was 0.78 +/- 0.15 (range 0.41 to 0.98). There was a strong and linear correlation b etween FFR measurements with IV and IC adenosine (R = 0,978, y = 0.032 + 0. 964x, P < .001). The agreement between the 2 sets of measurements was also high, with a mean difference in FFR of -0.004 +/- 0.03. However, a small ra ndom scatter in both directions of FFR measurements was noted with 5 lesion s (8.3%) where FFR with IC adenosine was higher by 0.05 or more compared wi th IV infusions, suggesting a suboptimal hyperemic response in these patien ts. Changes in heart rate and blood pressure were significantly higher with IV adenosine. Two patients with IV, but none with IC adenosine, had severe side effects (bronchospasm acid severe nausea). Conclusion These results suggest that IC adenosine is equivalent to IV infu sion for the determination of FFR in the majority of patients. However, in a small percentage of cases, coronary hyperemia was suboptimal with IC aden osine.