PET with novel radiotracer able to detect CAD, superior to SPECT
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PET with a novel radiotracer met its primary endpoint for sensitivity and specificity of CAD detection, researchers reported at the Annual Scientific Session and Exhibition of the American Society of Nuclear Cardiology.
The PET system, which includes the radiotracer 18F flurpiridaz (GE Healthcare/Lantheus Medical Imaging), also had higher diagnostic efficacy and image quality than single-photon emission CT myocardial perfusion imaging, according to the results of the phase 3 AURORA study.
“Flurpiridaz has gone through many stages; phase 1 studies established its safety and appropriate dosimetry; in phase 2, we looked at a comparison of flurpiridaz and SPECT in 143 patients; and in the first phase 3 trial that was published 2 years ago, we looked at the same comparison of PET and SPECT in 755 patients,” Jamshid Maddahi, MD, FACC, FASNC, professor of cardiology and nuclear medicine at UCLA School of Medicine, said during a presentation.
For the present second phase 3 trial, Maddahi and colleagues analyzed 578 patients with suspected CAD (mean age, 64 years; 33% women) who could be evaluated by PET, SPECT and angiography.
The primary endpoint was the sensitivity and specificity of PET myocardial perfusion imaging with 18F flurpiridaz for detection of significant CAD in a major artery, defined as 50% or more on angiography. The performance goal was to exceed 60% sensitivity and specificity, meaning the lower bound of the 95% CI needed to be more than 60%. Three expert core lab readers masked to clinical and angiography data interpreted the PET and SPECT images; for the primary endpoint to be achieved, the same two readers had to exceed the sensitivity and specificity thresholds, Maddahi said during the presentation.
The secondary efficacy endpoints were a comparison of the PET system to SPECT for CAD detection in the overall cohort and in the following subgroups: women, patients with BMI of at least 30 kg/m2 and patients with diabetes.
After screening, all patients within 60 days had PET and SPECT imaging followed by angiography.
Maddahi said the primary endpoint was met due to the results from reader 1 and reader 2 (sensitivity for reader 1, 77.1%; 95% CI, 71.9-82.3; P < .0001; specificity for reader 1, 65.7%; 95% CI, 60.5-70.8; P = .0182; sensitivity for reader 2, 73.5%; 95% CI, 68-79; P < .0001; specificity for reader 2, 69.6%; 95% CI, 64.6-74.6; P = .0002).
In the overall cohort, the PET system was superior to SPECT for CAD detection (P for sensitivity for reader 1 < .0001; P for sensitivity for reader 2 = .0002; P for sensitivity for reader 3 < .0001; P for specificity for reader 1 = .0004; P for specificity for reader 2 < .0001; P for specificity for reader 3 = .0011), Maddahi said.
In women, the PET system had significantly higher sensitivity and specificity from all three readers compared with SPECT, and that was also the case in patients with BMI of at least 30 kg/m2 and in those with diabetes except for sensitivity from reader 2, he said.
All three readers rated the PET system as having higher image quality and having more diagnostic certainty (definitively normal or abnormal) than SPECT (P < .0001 for all), he said, noting that all three also rated PET better for assessing the extent and severity of CAD (P < .0001 for all).
There were 14 serious treatment-emergent adverse events in eight patients and 20 serious events overall in 14 patients, but none were deemed related to 18F flurpiridaz, Maddahi said, noting that 25 adverse events in 19 patients were judged to be potentially related to flurpiridaz, but none were serious.
“In this phase 3 clinical trial, 18F flurpiridaz was safe and well tolerated; met the primary endpoints; met the secondary endpoints of being superior to SPECT for overall diagnosis of disease and for CAD diagnosis in women, patients with BMI greater than or equal to 30 [kg/m2] and diabetic patients; and was also superior to SPECT with respect to image quality, confidence of interpretation and ischemic perfusion defect extent and severity,” Maddahi said during the presentation.
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Maddahi J, et al. Verani Lecture and Presidents’ Addresses and Late Breaking Trial. Presented at: ASNC2022: 27th Annual Scientific Session and Exhibition of the American Society of Nuclear Cardiology; Sept. 8-17, 2022; Orlando (hybrid meeting).
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