P2397Quantitative versus qualitative evaluation of static stress computed tomographic perfusion to detect hemodinamically significant coronary artery disease in intermediate to high risk patients

Abstract

Background: Static stress computed tomographic perfusion (CTP) represents a useful tool to improve the detection of hemodinamically significant coronary artery disease (CAD) of coronary computed tomographic angiography (CCTA) in the subset of patients with intermediate to high risk for CAD. Qualitative and quantitative methods were proposed to evaluate a static stress CTP showing both good diagnostic accuracy. A few data are available regarding to the comparison of diagnostic performance of these two approaches. Purpose: The aim of this study is to perform a head to head intra-patient comparison of qualitative evaluation versus quantitative evaluation of static stress CTP to detect hemodinamically significant CAD in consecutive intermediate to high risk patients scheduled for invasive coronary angiography (ICA) plus clinically indicated invasive fractional flow reserve (FFR). Methods: Consecutive symptomatic patients [mean age: 6569 years, male: 49 (64%)] with intermediate to high pre-test probability of CAD and scheduled for clinically indicated ICA+FFR, were prospectively enrolled. All patients underwent rest-CCA followed by stress-CTP protocol with adenosine (Revolution CT Scanner, GE Healthcare, Milwaukee, WI) with injection of 70 ml of Iodixanol 320 (Visipaque 320 mg/ml, GE Healthcare, Oslo, Norway). In each patient, a qualitative evaluation with visual approach (CTP was defined positive for the presence of subendocardial hypoenhancement encompassing ≥ 25% of transmural myocardial thickness within a specific coronary territory) and a quantitative evaluation with transmural perfusion ratio (TPR) (sub-endocardium mean density/sub-epicardium mean density < 0.9) were measured. At ICA, hemodynamically significant CAD was defined by the presence of >50% stenosis on left main coronary artery, severe (>80%) or occlusive stenosis or FFR<0.80. The diagnostic accuracy of qualitative and quantitative stress CTP versus ICA+FFR were compared on a per-vessel basis. Results: Obstructive CAD was found in 32% (74/228) of vessels and in 61% (46/76) of patients at ICA. According to our endpoint definition, hemodynamically significant CAD was present in 23% (52/228) of vessel and in 42% (32/76) of patients. The mean time for quantitative analysis was significantly higher as compared to qualitative analysis (3566 min vs. 562 min, p<0.01). In a vessel-based model, CTP with qualitative evaluation showed a higher specificity (86% [CI95%:81-91)] vs. 77% [CI95%:71-83)], p<0.05) and similar sensitivity (85% [CI95%:75-85)] vs. 88% [CI95%:80-97)], p:0.56) as compared to quantitative CTP. Similarly, the area under the curve (AUC) of qualitative versus quantitative static CTP was significantly higher (0.81 vs. 0.74, p<0.01). Conclusions: Static stress CTP qualitative evaluation of perfusion defect is associated with a less time consuming and higher specificity and diagnostic accuracy to detect functionally significant CAD.