Residual myocardial hyperemia in regadenoson stress/rest quantitative perfusion cardiac magnetic resonance

Abstract

Purpose: This study sought to investigate the presence of residual myocardial hyperemia on the recovery phase in patients undergoing stress CMR. Material and methods: Fifty patients with clinical indication for stress CMR underwent quantitative perfusion imaging in resting conditions, after regadenoson-induced hyperemia (400 mcg, 5 mL), and 10 min after recovery with euphylline. Studies showing hypoperfusion due to ischemia and/or prior myocardial infarction were excluded. Global myocardial blood flow during rest (MBFrest), stress (MBFstress) and recovery (MBFrecovery) and MPR indices (MPRstress/rest and MPRstress/recovery) were calculated using automated pixel-wise quantitative myocardial perfusion mapping. Results: A total of 30 patients (22 males, mean age of 62.7 ± 1 years) were included in the analysis. Global MBFrest and MBFstress were 0.83 ± 0.2 mL/g/min and 2.1 ± 0.6 mL/g/min, respectively. After recovery with euphylline, myocardial perfusion did not return to the resting values (MBFrecovery of 0.92 ± 0.3 mL/g/min) and statistically differed from MBFrest (p < 0.01), suggesting residual myocardial hyperemia. This resulted in an abnormally low MPRstress/recovery (2.43 ± 0.7) with respect to MPRstress/rest (2.56 ± 0.7) (p = 0.03). A linear mixed-effects model accounting for repeated measures revealed statistically significant group differences over time in global MBF (mean difference 0.1, 95% CI 0.02–0.17, p = 0.01) and global MPR (mean difference −0.13, 95% CI −0.25 to −0.02, p = 0.02). Conclusion: Despite the use of euphylline to counteract the vasodilator effect, MBF does not completely revert to resting values and MBFrecovery cannot be used as a substitute for MBFrest when regadenoson is used. Consequently, a rest/stress protocol is advised for quantitative CMR perfusion to obtain accurate MBF and MPR parameters.