CMR-Flow

1343188 - Kinetics of Regadenoson-induced Coronary Hyperemia in Patients and Healthy Controls

Wednesday, January 25, 2023

Location: E-POSTER

Presenting Author(s)

NK

Nathan M. Kattapuram

Special Volunteer
National Heart, Lung, and Blood Institute, National Institutes of Health
Bethesda, Maryland, United States

Primary Author(s)

NK

Nathan M. Kattapuram

Special Volunteer
National Heart, Lung, and Blood Institute, National Institutes of Health
Bethesda, Maryland, United States

Co-Author(s)

SS

Shahrad Shadman, MD

Clinical Fellow/ Cardiologist
National Heart, Lung, and Blood Institute, National Institutes of Health, United States
CB

Charles W. Benton, RT

MRI Technologist
National Heart, Lung, and Blood Institute, National Institutes of Health
North Bethesda, Maryland, United States
SA

Stacian Awojoodu, DNP, ACNP

Acute Care Nurse practitioner
National Heart, Lung, and Blood Institute, National Institutes of Health, United States
DK

Dong-Yun Kim, PhD

Statistician
National Heart, Lung, and Blood Institute, National Institutes of Health, United States
JR

Joao G. Ramos, MD, PhD

Research Fellow
National Heart, Lung, and Blood Institute, National Institutes of Health, United States
Ana Barac, MD, PhD

Staff Clinician/Cardiologist
National Heart, Lung, and Blood Institute, National Institutes of Health, District of Columbia, United States
Gaby Weissman, MD

Section Chief, Clinical Cardiology
Medstar Heart and Vascular Institute
Washington, District of Columbia, United States
Marcus Carlsson, MD, PhD

Professor, Head of Department
Karolinska Institute, Clinical Physiology, United States

Disclosure(s):

Gaby Weissman, MD: No relevant disclosure to display

Marcus Carlsson, MD, PhD: No financial relationships to disclose

Background: Hyperemia induced by regadenoson injection is commonly used in cardiac imaging to find regional perfusion defects and to quantify coronary flow reserve (CFR). Phase-contrast, magnetic resonance (PC-MR) imaging of the coronary sinus can quantify global LV perfusion and therefore CFR. Although the package insert for regadenoson recommends administration of radionuclide tracer 10-20 seconds after regadenoson injection in SPECT and PET¹, previous investigation has observed peak hyperemia at approximately 90 seconds after regadenoson injection in healthy controls². The time course of the hyperemic response in patients is not known. The aim of this study was to determine and compare the time courses of regadenoson-induced hyperemia in patients and healthy controls.

Methods: Fifteen healthy controls and 25 patients underwent stress perfusion CMR on a 1.5T Siemens Sola scanner with analysis of PC-MR coronary sinus imaging at rest and at serial time points after 0.4 mg regadenoson injection. Delineations of the coronary sinus and left ventricular myocardium yielded flow per minute (ml/min), and perfusion (ml/min/g). CFR was calculated as the stress to rest flow ratio associated with each stress time point for each subject. Smoothed time-resolved curves for perfusion were generated with pointwise 95% confidence intervals at key time points.

Results: Patients had significantly lower peak CFR compared to healthy controls (3.2 ± 1.1 vs 5.1 ± 1.2 , p < .0001). There were no significant differences in time to peak hyperemia between groups (Figure 2). Time to Peak CFR: (134 ± 93 s, Patients and 110 ± 74 s, Controls, p=.39). As demonstrated in higher standard deviations, there was greater variability in time to peak hyperemia among patients.

Conclusion: Patients have a similar time course of regadenoson-induced hyperemic response to controls. Imaging at roughly 90 seconds after regadenoson injection in patients is an optimal approach to capture peak hyperemia, despite being later than what is suggested in the package insert’s recommendation. Timing of imaging after regadenoson injection would affect the calculation of CFR in stress MR, SPECT, PET, and echocardiography. Stress imaging prior to peak hyperemia would result in underestimation of CFR and confound assessment of coronary vasodilatory function.