The FLARE (Flurpiridaz vs. Rubidium Evaluation) Trial

This study seeks to evaluate if the diagnostic performance of 18F-flurpiridaz positron emission tomography (PET) myocardial perfusion imaging (MPI), given the radiotracer's properties, is non-inferior to the currently most widely utilized PET MPI radiopharmaceutical, 82Rb-chloride.

• Patients will undergo a clinically indicated rest/stress 82Rb-chloride positron emission tomography (PET) myocardial perfusion imaging (MPI) and will return to the nuclear cardiology laboratory within 1-30 days to undergo a 18F-flurpiridaz PET MPI and coronary CT angiogram. A rest 18F-flurpiridaz PET MPI will be acquired first, followed by a stress 18F-flurpiridaz PET MPI. The waiting period between the rest and stress 18F-flurpiridaz PET acquisitions will be ≥ 30 minutes. The rest dose will be 2.5-3.0 mCi, and the pharmacological stress dose will be 6.0-6.5 mCi. All PET MPI studies will be conducted using regadenoson as the pharmacologic stress agent.
• 18F-flurpiridaz and 82Rb-chloride PET MPI scans will be interpreted by three expert visual readers in a blinded manner. Both Image quality and diagnostic certainty will be classified using a five-point scale. If the study is abnormal, the perfusion defect will further be categorized as reversible or fixed. Relative perfusion and myocardial blood flow quantification will be obtained using validated software methods.
• Coronary CT angiograms will similarly be analyzed in a blinded manner by a core lab. Coronary segments with a diameter ≥1.5 mm will be included in the analysis. Each segment will be evaluated for the presence or absence of coronary atherosclerosis, defined as any tissue structure >1 mm² within the coronary artery wall differentiated from the surrounding epicardial tissue, epicardial fat, or the vessel lumen itself. Maximal stenosis ratios as well as atherosclerotic plaque characteristics and CT-derived fractional flow reserve (FFR) will be obtained in each coronary territory.
• The paired difference between 18F-flurpiridaz and 82Rb-chloride PET MPI will be evaluating by calculating the receiver operating characteristic area under the curve (ROC AUC) for the sensitivity and specificity of blinded visual reads, automated relative perfusion quantitation, and myocardial blood flow quantification, as well as for image quality and diagnostic certainty assessment.