Findings from the Dan-NICAD 2 trial presented Aug. 28 during ESC Congress 2022, compared the diagnostic performance of stress myocardial perfusion imaging (MPI) via 3T cardiac magnetic resonance (CMR) and rubidium positron emission tomography (Rb-PET) in patients with suspected obstructive stenosis undergoing coronary computed tomography angiography (CTA). Invasive coronary angiography-fractional flow reserve (ICA-FFR) was used as the reference.

The trial included 1,732 consecutive patients (median age 59 years; 57% men) with symptoms suggesting obstructive coronary artery disease (CAD) who underwent coronary CTA. Based on the CTA, 445 patients (26%) had suspected stenosis (>50% diameter stenosis) and this group was randomly referred for both CMR and Rb-PET. All told, 372 patients completed both CMR and Rb-PET and were included in the analysis.

According to researchers, ICA-FFR identified obstructive CAD in 44.1% of the patients (164/372) included in the analysis. Sensitivities for CMR and Rb-PET were 59% and 64%, respectively (p=0.21), and specificities were 84% and 89%, respectively (p=0.08). The positive (PPV) and negative (NPV) predictive values were similar for the two techniques.

In other findings, overall accuracy was slightly higher for Rb-PET compared to CMR (78% vs. 73%, respectively; p=0.03) and both modalities had high sensitivity for severe stenoses with >70% diameter stenosis (CMR 83%/Rb-PET 89%). Researchers also said that Rb-PET correctly classified more patients with high-risk disease as abnormal compared to CMR.

"CMR stress and PET stress had comparably moderate sensitivities and high specificities to predict the FFR results," said Morten Bøttcher, MD, PhD, who presented the findings. "A perfusion test approach therefore seems safe as almost all patients with serious disease (high-grade stenoses, left main and three-vessel disease) were diagnosed. But the modest sensitivities to predict low FFR mean that there was often a discrepancy between these advanced perfusion results and the invasive FFR."

Based on the study findings, Bottcher said that going forward "the accuracy of coronary CTA needs to improve so that more patients without obstructive CAD avoid further investigations." He suggested this "might be achieved through better CT image quality and perhaps by more advanced image analyses like non-invasive FFR estimation and photon counting systems." He added that further studies are needed to "investigate the benefit of revascularization in patients with discordance between myocardial perfusion defect and FFR measurements."

Clinical Topics: Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Nuclear Imaging

Keywords: ESC Congress, ESC22, ACC International, Fractional Flow Reserve, Myocardial, Myocardial Perfusion Imaging, Coronary Angiography, Computed Tomography Angiography, Coronary Artery Disease, Constriction, Pathologic, Rubidium, Positron-Emission Tomography, Magnetic Resonance Spectroscopy, Perfusion

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