Abstract Funding Acknowledgements Type of funding sources: None. Introduction Coronary computed tomographic angiography (CTA) is an accepted noninvasive tool with high diagnostic accuracy for the evaluation of coronary artery disease (CAD). However, coronary CTA is limited in that it does not provide information on the hemodynamic relevance of coronary artery stenosis. Therefore, to determine the potential benefit of future coronary revascularization, a functional assessment is often required. A protocol combining coronary computed tomographic angiography (CTA) and CTP can provide a simultaneous assessment of both coronary artery ischemia and anatomy. Purpose This study sought to evaluate the diagnostic accuracy of stress myocardial blood flow ratio (SFR), a novel parameter derived from stress dynamic computed tomographic perfusion (CTP), for the detection of hemodynamically significant coronary stenosis. Methods A total of 98 patients (mean age 54.5 ± 10 years) with 128 vessels with either 1- or 2-vessel disease, scheduled for invasive angiography were included in this study. Stress dynamic CTP was performed followed by coronary CTA using a dual-source computed tomographic system. Fractional flow reserve was performed at subsequent invasive angiography to identify hemodynamically significant stenosis. Stress myocardial blood flow ratio (SFR) was defined as the ratio of hyperemic myocardial blood flow (MBF) in an artery with stenosis to hyperemic MBF in a non-diseased artery. The diagnostic accuracy of the SFR index was determined against the reference standard of invasive fractional flow reserve ≤0.80. Results 58 (45.3%) vessels were deemed hemodynamically significant by fractional flow reserve (FFR) measurement. Hyperemic MBF and SFR were lower for vessels with hemodynamically significant lesions (95 ± 32.2 ml/100 ml/min vs. 140.5 ± 30.4 ml/100 ml/min; p < 0.01 for both). When compared with ≥50% stenosis by CTA, the specificity for detecting ischemia by SFR increased from 44% to 92%, while the sensitivity decreased from 93% to 58%. The combination of stenosis ≥50% by CTA and SFR resulted in an area under the curve of 0.9, which was significantly higher compared with hyperemic MBF, area under the curve = 0.79 and p < 0.01. Conclusion Our study concludes that the calculation of SFR by dynamic CTP provides a pioneering and accurate method to identify flow-limiting coronary stenosis. Abstract Figure.
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