Intracoronary versus intravenous adenosine to assess fractional flow reserve: A systematic review and meta-analysis

Aims Intravenous infusion of adenosine is the reference method to measure fractional flow reserve (FFR). Intracoronary boluses are often used because of time and convenience, but their effectiveness has yet to be assessed. Methods We conducted a systematic review and metaanalysis of prospective studies directly comparing intravenous and intracoronary adenosine administration for FFR measurement. FFR values and prevalence of functionally critical lesions obtained with the different methods of adenosine administration were compared. Results Twelve studies evaluating 781 lesions from 731 patients were included (63.7 years, 25.5% women, median FFR 0.82). FFR values were significantly lower with intravenous adenosine than with intracoronary adenosine [mean difference 0.01, 95% confidence interval (CI) 0.00- 0.02, P=0.005], even if no significant differences were observed when only high doses of intracoronary adenosine (≥ 150μg) were considered. The prevalence of functionally critical lesions did not significantly differ between intracoronary and intravenous adenosine. Concerning the use of different doses of intracoronary adenosine, low doses (≤ 60μg) were associated with higher FFR values (mean difference 0.02, 95% CI 0.01-0.03, P<0.001) and fewer functionally critical lesions (OR 0.57, 95% CI 0.40- 0.81, P=0.002) compared with high doses. Meta-regression analysis did not show any significant interaction between the way of adenosine administration and main clinical features. Intracoronary adenosine was associated with a higher incidence of atrioventricular blocks, whereas angina and/or systemic symptoms were more frequent with intravenous adenosine. Conclusion Intracoronary adenosine might be as effective as intravenous adenosine to measure FFR, provided that adequate doses are used. Intracoronary adenosine represents a valuable alternative to intravenous adenosine whenever appropriately administered.