Dynamic CT perfusion to identify hemodynamically significant coronary artery disease: preliminary results of an one-stop-shop approach

Introduction Coronary CT Angiography (CCTA) is effective for diagnosing coronary artery disease (CAD) but often overestimates stenosis severity and lacks hemodynamic evaluation. Dynamic stress CT perfusion (CTP) has emerged as a potential strategy to combine anatomical and functional assessment in a single scan. The aim of this study was to assess the impact on clinical pathways of performing CTP in patients with ≥50% stenosis on CCTA. Methods In this single-center study, patients with suspected CAD and ≥50% stenosis on CCTA who underwent stress dynamic CTP were compared with patients with ≥50% stenosis on CCTA who didn’t undergo CTP. To improve comparability, patients were matched in a 1:2 ratio based on age, sex, body mass index, pretest probability, coronary calcium score, and CAD-RADS. Perfusion scans were performed on a 192-slice scanner, using regadenoson as stressor agent. Hemodynamically significant CAD was defined as ≥90% stenosis on invasive coronary angiography (ICA), positive functional assessment, or decision to perform revascularization. The primary outcome was the rate of invasive angiographies without hemodynamically significant CAD. Secondary outcomes were time to diagnosis and total radiation exposure including downstream testing. All decisions on downstream testing, ICA, and revascularization were at the cardiologist's discretion. Results A total of 141 patients were studied (67±10 years, 68% male), 47 of whom underwent CCTA+CTP, and 94 CCTA only. The groups were comparable, except for a higher proportion of males and higher calcium scores in the CCTA+CTP group (Table1). Overall, 49% perfusion scans were considered positive. Downstream ischemia testing was performed in 13% of "CCTA only" patients compared to none in the other group (p=0.009). Invasive coronary angiography was performed in 50% of "CCTA only" patients and 36% of CCTA+CTP patients. The "CCTA+CTP" group had a significantly lower rate of negative invasive angiography (4% vs. 20%, p=0.001). One patient without significant ischemia on CTP underwent ICA with positive invasive functional assessment The proportion of ICA leading to revascularization was also higher in CCTA+CTP, with a positive predictive value (PPV) of 86% vs 59% on "CCTA only" group (p<0.001). Median time to diagnosis was significant lower in the "CCTA+CTP" group. Performing Perfusion CT added a median effective radiation dose of 3.6 [3-4] mSv to the scan protocol, but this difference was offset by additional downstream testing in the "CCTA only" group. Over a median follow-up of 515 days, no patient without ischemia on CCTA+CTP had an acute coronary event. Conclusion Performing stress CTP in patients with ≥50% stenosis on CCTA seems to streamline diagnosis by decreasing downstream ischemia testing, negative invasive angiographies, and time to diagnosis. After accounting for these, the overall effective radiation dose is not increased by using this strategy.