Effects of Body Mass Index on the Hyperemic Response to Regadenoson
|Obesity Endothelial Dysfunction Decreased Vascular Flow||Drug: Adenosine Drug: Regadenoson|
|Study Design:||Intervention Model: Single Group Assignment
Masking: Single (Participant)
Primary Purpose: Diagnostic
|Official Title:||Effects of Body Mass Index on the Hyperemic Response to Regadenoson|
- Myocardial Perfusion Reserve Measured by Quantitative Perfusion MRI (Ratio of Myocardial Blood Flow During Stress Over Myocardial Blood Flow at Rest) [ Time Frame: 2 hours ]The ratio of myocardial blood flow during stress (with each vasodilator) divided by the myocardial flood flow at rest = myocardial perfusion reserve (MPR)
|Study Start Date:||February 2009|
|Study Completion Date:||July 2010|
|Primary Completion Date:||July 2010 (Final data collection date for primary outcome measure)|
Experimental: myocardial perfusion reserve
Myocardial perfusion reserve will be measured by quantifying myocardial blood flow using MRI at rest and then with each of 2 coronary vasodilators. Measurements are performed with first pass gadolinium perfusion (i.v. bolus injection of 0.02 or 0.03 mmol/kg of gadolinium). Each of the 2 drugs is given sequentially (30 minutes apart) in the same sequence in every patient. The shorter acting drug (adenosine) is given first so it has time to wear off before giving the second drug. It is ideal to measure MPR with each drug during the same imaging session so that there are no other clinical variables that change between the administration of the 2 agents. See below.
Myocardial perfusion reserve measured with quantitative MRI during adenosine infusion (0.14 mg/kg/min x 6 minutes).
Other Name: adenoscanDrug: Regadenoson
Myocardial perfusion reserve measured during regadenoson (0.4 mg/5 ml) bolus administration using quantitative perfusion MRI.
Other Name: Lexiscan
Introduction: Regadenoson (Lexiscan) is currently recommended for use as a targeted vasodilator in myocardial perfusion studies and is available as a single, fixed dose for all patients. Here we propose to compare the hyperemic response measured with MRI in subjects with a wide range of BMI 18-40.
MRI is an ideal test to compare the effects of regadenoson in patients with different body mass indices (BMIs). No radiation is used and multiple perfusion tests can be performed in close temporal sequence. Importantly, a number of researchers have shown the ability to obtain quantitative stress and rest myocardial blood flow values in the heart with MR imaging. This allows the calculation of myocardial perfusion reserve (MPR). Flow reserve measurements also can be done with dynamic PET, but not with SPECT. PET has the disadvantage of radiation exposure.
Regadenoson may be a more desirable agent for use with MRI than is adenosine. Adenosine requires the use of 2 intravenous lines, and the use of either a specialized, expensive, MRI-compatible infusion pump to deliver the drug, or long lengths of tubing to run to a pump outside the scanner room. Neither solution is ideal. Regadenoson does not require any such pumps or the starting of a second i.v.. The work here would accomplish 2 goals: 1) to demonstrate the feasibility of performing quantitative MRI perfusion measurements with regadenoson, and 2) to test whether a single dose of regadenoson produces maximal coronary hyperemia across a wide range of body sizes.
Study Design: This will be a prospective, open-label, study. The design is single group, one arm, 2 interventions in which we will compare MPR measured sequentially during adenosine and regadenoson using MRI. Non-invasive MRI measurements of resting flow, flow at adenosine stress, and flow at regadenoson stress will be obtained sequentially in each subject during a single two hour MRI exam. Each drug will be given in the same order to all subjects.
32 subjects will be recruited for this study. The first two subjects will be imaged only with resting perfusion, in order to determine optimal acquisition parameters for the study, and will not be used in the analysis. The main outcome measure is MPR with each agent.
Please refer to this study by its ClinicalTrials.gov identifier: NCT00859833
|United States, Utah|
|University of Utah|
|Salt Lake City, Utah, United States, 84132|
|Principal Investigator:||Sheldon E Litwin, MD||University of Utah|