Angiography-based quantitative coronary contrast-flow ratio measurements correlate with myocardial ischemia assessed by stress MRI

Contrast-flow quantitative flow ratio (cQFR) is a new technology for quantitative evaluation of coronary stenosis using computational fluid dynamics based on angiograms. The aim of this study was to assess the sensitivity and specificity of cQFR to detect myocardial ischemia using stress magnetic resonance imaging (MRI) as a reference standard. Patients who received stress MRI and coronary angiography were selected from the hospital database. Relevant ischemia on stress MRI was defined as a perfusion deficit in >= 2 of 16 segments. cQFR was quantitated based on 3-dimensional quantitative coronary angiography using QAngio XA3D1.1 software by two blinded and independent investigators. A cQFR of <= 0.80 was considered abnormal. Among 87 patients 230 vessels met the criteria for full analysis by cQFR (88%). In vascular territories with a significant perfusion deficit, cQFR was significantly lower compared to areas with normal perfusion (0.72 (0.62-0.78) vs. 0.96 (0.89-0.99); p < 0.001). The sensitivity of cQFR in detecting significant epicardial stenoses of coronary vessels with documented ischemia in stress MRI was 81% (68-90%), the specificity was 88% (82-92%). Diameter stenoses (DS) and area stenoses (AS) in vessels with positive stress MRI were significantly higher than in vessels without ischemia (DS 59.1% (49.4-68.4%) vs. 34.8% (27.1-46.1%) p < 0.001; AS 75.6% (63.0-85.2%) vs. 45.0% (30.8-63.6%), p < 0.001). The analysis reveals a high correlation between coronary stenosis measured by cQFR and ischemic areas detected by stress MRI. The data set the stage to plan randomized studies assessing cQFR measurements with regard to clinical outcomes.