Abstract 14342: Does Fixed-Dose Regadenoson Induce Comparable Myocardial Perfusion Reserve in Patients of Widely Varying Body Size? A Quantitative MRI Study
Background: A fixed dose of the A2a receptor agonist, regadenoson, is equivalent to weight-adjusted adenosine for assessment of myocardial ischemia during SPECT imaging. However, it is unknown whether regadenoson produces comparable coronary vasodilation vs. weight-based adenosine in patients with a wide range of body size. The feasibility of regadenoson for MRI myocardial perfusion imaging has not been confirmed.
Methods: 24 subjects (13 female, 11 male, mean BMI 29.8±6.2, range 19.9–46.9) were imaged on a 3T Siemens magnet. Imaging was done first at rest, then during adenosine infusion (140 ug/kg/min) and 30 minutes later with regadenoson (0.4mg/5ml bolus). A 5cc/sec injection of Gd-BOPTA (Multihance™) was used for each perfusion sequence, with doses of 0.02, 0.03 and 0.03 mmol/kg, respectively. A saturation recovery radial turboFLASH sequence with 72 rays was used (Fig A). The arterial input function was converted into gadolinium concentration. Time-intensity curves from 6 tissue regions per slice (examples Fig B) were fit to a 2-compartment model and Ktrans was used as an index of perfusion.
Results: The myocardial perfusion reserve was 2.36±0.97 for adenosine, and 2.23±0.81 for regadenoson (p=0.6). There was a good correlation between perfusion reserve measured with weight-adjusted adenosine or fixed dose regadenoson administration (slope = 0.89, r^2 = 0.86, p< 0.001, Fig C). There was no evidence of under- or overestimation of MPR with fixed dose regadenoson at the lowest (< 25) or highest (>35) BMI categories. There were no complications during administration of either agent.
Conclusion: Fixed dose regadenoson and weight adjusted adenosine provide similar/equivalent myocardial perfusion reserves across a large range of body weights. Regadenoson is a suitable agent for MRI myocardial perfusion studies and because of the bolus administration, it requires only 1 intravenous access and a magnet safe infusion pump is not required.
- © 2010 by American Heart Association, Inc.