Log in to MyACC
Global Coronary Flow Reserve on Stress CMR and MACE
Study Questions:
What is the prognostic relevance of global coronary flow reserve (CFR) measured with regadenoson stress cardiac magnetic resonance (CMR) imaging?
Methods:
All patients presenting for a stress CMR study at a single tertiary care hospital were prospectively enrolled. Only patients who could not complete the study or had uninterpretable images were excluded. Patients underwent regadenoson stress CMR. Perfusion imaging was performed after injection of gadolinium contrast at rest and stress. Phase contrast imaging was performed to quantify global blood flow to the myocardium at rest and stress. CFR was taken as the ratio of stress/rest blood flow. The primary outcome was the composite of major adverse cardiac events (MACE) (death, nonfatal myocardial infarction, hospitalization for heart failure, sustained ventricular tachycardia, and late revascularization) adjudicated in blinded fashion by two cardiologists. Prognostic value of CFR was assessed by survival modeling, including adjustment for scar and semiquantitative visually assessed ischemia.
Results:
After excluding 38 (7.5%) patients for poor image quality or inability to complete the stress protocol, 469 patients were analyzed. Bland-Altman analysis of interobserver reproducibility of analysis of the same image data showed minimal bias in CFR (0.014), but relatively wide confidence intervals of approximately ± 0.3. Over a median follow-up of 2.1 years, 80 patients experienced MACE. The risk of MACE was higher in patients with CFR below the median, even after adjustment for sex, visual ischemia, and scar (hazard ratio, 1.2 per CFR unit, p = 0.018). Addition of CFR to sex, scar, and ischemia extent resulted in improved discrimination with increase in the c-index from 0.70 to 0.75 (p = 0.009) and net reclassification improvement of 0.198. A cut point of 2.2 for CFR was 55% sensitive and 70% specific for MACE.
Conclusions:
CFR measured by CMR is feasible and adds prognostic value over visual assessment of perfusion and scar.
Perspective:
This study adds to a large body of literature, which favors quantification of myocardial perfusion beyond visual estimation. CFR integrates epicardial stenosis, diffuse disease, and microvascular dysfunction and has been seen to consistently improve prognostic assessment in studies deriving this parameter from positron emission tomography (PET), CMR, and echocardiography. This paper quantifies CFR using coronary sinus blood flow, which is not yet standard practice. The relatively wide confidence intervals for interrater analysis (± 0.3) will grow wider still in clinical practice and between scans repeated over days, weeks, or months. Whether this level of precision is sufficient for clinical decision making should be evaluated further. In particular, the use of this metric for selection of optimal therapeutic strategy is an important unanswered question, regardless of measurement modality.
Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), SCD/Ventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Acute Heart Failure, Interventions and Coronary Artery Disease, Interventions and Imaging, Computed Tomography, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Nuclear Imaging
Keywords: AHA Annual Scientific Sessions, AHA18, Constriction, Pathologic, Magnetic Resonance Spectroscopy, Diagnostic Imaging, Coronary Artery Disease, Echocardiography, Gadolinium, Heart Failure, Magnetic Resonance Imaging, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Myocardium, Perfusion Imaging, Positron-Emission Tomography, Tachycardia, Ventricular
< Back to Listings
