The effect of obesity on regadenoson-induced myocardial hyperemia: a quantitative magnetic resonance imaging study

Abstract

The A2(A) receptor agonist, regadenoson, is increasingly used as a vasodilator during nuclear myocardial perfusion imaging. Regadenoson is administered as a single, fixed dose. Given the frequency of obesity in patients with symptoms of heart disease, it is important to know whether the fixed dose of regadenoson produces maximal coronary hyperemia in subjects of widely varying body size. Thirty subjects (12 female, 18 male, mean BMI 30.3 ± 6.5, range 19.6-46.6) were imaged on a 3T magnetic resonance scanner. Imaging with a saturation recovery radial turboFLASH sequence was done first at rest, then during adenosine infusion (140 μg/kg/min) and 30 min later with regadenoson (0.4 mg/5 ml bolus). A 5 cc/s injection of Gd-BOPTA was used for each perfusion sequence, with doses of 0.02, 0.03 and 0.03 mmol/kg, respectively. Analysis of the upslope of myocardial time-intensity curves and quantitative processing to obtain myocardial perfusion reserve (MPR) values were performed for each vasodilator. The tissue upslopes for adenosine and regadenoson matched closely (y = 1.1x + 0.03, r = 0.9). Mean MPR was 2.3 ± 0.6 for adenosine and 2.4 ± 0.9 for regadenoson (p = 0.14). There was good agreement between MPR measured with adenosine and regadenoson (y = 1.1x - 0.06, r = 0.7). The MPR values measured with both agents tended to be lower as BMI increased. There were no complications during administration of either agent. Regadenoson produced fewer side effects. Fixed dose regadenoson and weight adjusted adenosine produce similar measures of MPR in patients with a wide range of body sizes. Regadenoson is a potentially useful vasodilator for stress MRI studies.

Trial registration: ClinicalTrials.gov NCT00859833.

Figures

Fig. 1

Timeline of protocol. Resting perfusion was performed first with a dose of 0.02 mmol/kg, followed by adenosine perfusion (0.03 mmol/kg contrast agent injected after 3 min of infusion). Then a set of cine images were acquired, and after a waiting period regadenoson perfusion (0.03 mmol/kg injected ~90 s after the injection of regadenoson) was performed

Fig. 2

Example of 2D radial pulse sequence, acquired at 3T. Left side Every third time frame shown of part of the cardiac perfusion radial (72 ray) acquisitions at rest or under vasodilation. The two vasodilators give similar images. Right side Example tissue uptake curves during rest, adenosine and regadenoson. The regadenoson peak appears higher in this particular example, although the upslopes are similar. For the entire population, the upslopes and peak tissue values were comparable with adenosine and regadenoson stress

Fig. 3

Correlation between mean tissue curve upslopes in each patient during adenosine and regadenoson. The upslopes correlate closely

Fig. 4

Correlation between mean myocardial perfusion reserve (MPR) in each subject measured with adenosine and regadenoson. The color bar codes the subjects by BMI

Fig. 5

Bland-Altman plot showing showing a small negative bias for the difference of mean MPR with adenosine or regadenoson

Fig. 6

Correlation between MPR and BMI during a adenosine and b regadenoson. With both drugs, there is a mild inverse relationship between MPR and BMI suggesting that MPR decreases as the severity of obesity increases