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BACKGROUND: The aim of the present study was to compare the quantitative flow responses of regadenoson against adenosine using cardiac ¹⁵O-water PET imaging in patients with suspected or known coronary artery disease (CAD).

METHODS: Hyperemic myocardial blood flow (MBF) after adenosine and regadenoson was compared using correlation and Bland-Altman analysis in 21 patients who underwent rest and adenosine ¹⁵O-water PET scans followed by rest and regadenoson ¹⁵O-water PET scans.

RESULTS: Global mean (± SD) MBF values at rest and stress were 0.92 ± 0.27 and 2.68 ± 0.80 mL·g·min for the adenosine study and 0.95 ± 0.29 and 2.76 ± 0.79 mL·g·min for the regadenoson study (P = 0.55 and P = 0.49). The correlations between global and regional adenosine- and regadenoson-based stress MBF were strong (r = 0.80 and r = 0.77). The biases were small for both global and regional MBF comparisons (0.08 and 0.09 mL·min·g), but the limits of agreement were wide for stress MBF.

CONCLUSION: The correlation between regadenoson- and adenosine-induced hyperemic MBF was strong but the agreement was only moderate indicating that established cut-off values for ¹⁵0-water PET should be used cautiously if using regadenoson as vasodilator.