Reviewer: Dr. Onur Akhan

Name of the Study: More precise algorithms are needed to select patients for invasive coronary testing (Dan-NICAD 2 trial)

Published Congress: ESC 2022

Link : https://www.escardio.org/The-ESC/Press-Office/Press-releases/More-precise-algorithms-are-needed-to-select-patients-for-invasive-coronary-testing

Background:

Significant stenosis is not found in most patients referred to coronary CT angiography suspected of coronary artery disease, and myocardial perfusion imaging (MPI) techniques are recommended for revascularization in suspicious cases, according to the test result. While these imaging methods can quickly identify very severe stenosis and high-risk coronary artery disease, they are less sensitive to moderate and borderline FFR values. From this, it can be concluded that invasive methods can be avoided using a second imaging method. However, this finding also suggests that moderate stenosis may be missed.

Objective:

This study aims to compare the 3T cardiac magnetic resonance (CMR) and 82-rubidium positron emission tomography (Rb-PET) methods with the reference ICA-FFR process in patients with suspected obstructive stenosis in coronary CT angiography.

Methods:

A total of 1732 patients who underwent coronary CT angiography suspected of occlusive coronary artery disease were included in the study. The mean age is 59 years, and 57% of the patients are male. In addition, 26% of these patients were observed to have suspected stenosis (more than 50%), and these patients were randomized to both imaging modalities. A total of 372 patients who completed both imaging modalities were evaluated in the study.

Results:

Hemodynamically obstructive coronary artery disease was detected with ICA-FFR in 164 patients (44.1%). The sensitivity (64% - 59%) and specificity (89% - 84%) of Rb-PET were found to be higher than CMR (p=0.21 and p=0.08, respectively). Positive predictive and negative predictive values for both tests were found to be similar. The overall accuracy was higher in the Rb-PET method compared to CMR (78% vs. 73%; p=0.03). In addition, more high-risk patients were classified as abnormal in the Rb-PET method compared to CMR (96.8% vs. 77.4%; p=0.03). The sensitivity for severe stenosis, defined as the presence of more than 70% stenosis, was high in both methods (CMR: 83% vs. Rb-PET: 95%).

Conclusion:

CMR and Rb-PET methods have relatively moderate sensitivities and high specificities for predicting FFR results. Therefore, a perfusion test approach appears safe in almost all patients with severe disease (high-grade stenoses, left main and three-vessel disease). However, the relatively low sensitivities for estimating low FFR also means that there is often a discrepancy between these improved perfusion results and invasive FFR.

Interpretations:

The accuracy of coronary CTA needs to be improved with better CT image quality and perhaps more advanced image analysis, such as non-invasive FFR estimation and photon counting systems, thus avoiding further evaluation in more patients without a diagnosis of occlusive coronary artery disease. Finally, existing perfusion techniques can be further improved using quantitative perfusion measurements.