Methods: cQFR analysis was performed in patients selected from the hospital database who received stress MRI and coronary angiography. A relevant ischemia on stressMRI was defined as a perfusion deficit in = 2 of 16 segments. The cQFR was based on 3-dimensional quantitative coronary angiography (3D-QCA) using the QAngio XA 3D 1.1, Medis Medical Imaging System, Leiden, The Netherlands. Two blinded investigators analysed all 3 main coronary vessels of each patient measuring diameter stenosis (DS), area stenosis(AS) and cQFR. A cQFR of =0.8 was considered abnormal. The primary endpoint was sensitivity and specificity of cQFR using stress MRI as a reference standard.
Results: 125 vessels of 53 patients could be fully analysed by cQFR (78.6%). The sensitivity of cQFR in detecting significant epicardial stenoses of coronary vessels with documented ischemia in stress MRI was 75%, the specificity was 87%. The 3D-QCA-derived diameter stenoses and area stenoses in vessels with positive stress MRI were significantly higher than in vessels without ischemia (see Table 1).
Conclusion: The analysis reveals a high correlation between relevant coronary stenosis measured by cQFR and ischemic areas detected by stress MRI. Differences between the two methods are plausible because stress MRI detects ischemia due to other reasons than epicardial stenosis. Further randomized studies are mandatory to verify the prognostic significance of the cQFR measurements.