Prognostic value of a novel artificial intelligence-based coronary CTA-derived ischemia algorithm among patients with normal or abnormal myocardial perfusion

Background: Among patients with obstructive coronary artery disease (CAD) on coronary computed tomography angiography (CTA), downstream positron emission tomography (PET) perfusion imaging can be performed to assess the presence of myocardial ischemia. A novel artificial-intelligence-guided quantitative computed tomography ischemia algorithm (AI-QCT(ischemia)) aims to predict ischemia directly from coronary CTA images. We aimed to study the prognostic value of AI-QCT(ischemia )among patients with obstructive CAD on coronary CTA and normal or abnormal downstream PET perfusion. Methods: AI-QCT(ischemia) was calculated by blinded analysts among patients from the retrospective coronary CTA cohort at Turku University Hospital, Finland, with obstructive CAD on initial visual reading (diameter stenosis >50%) being referred for downstream O-15-H2O-PET adenosine stress perfusion imaging. All coronary arteries with their side branches were assessed by AI-QCT(ischemia). Absolute stress myocardial blood flow <2.3 ml/g/min in >2 adjacent segments was considered abnormal. The primary endpoint was death, myocardial infarction, or unstable angina pectoris. The median follow-up was 6.2 [IQR 4.4-8.3] years. Results: 662 of 768 (86%) patients had conclusive AI-QCT(ischemia) result. In patients with normal O-15-H2O-PET perfusion, an abnormal AI-QCT(ischemia) result (n = 147/331) vs. normal AI-QCT(ischemia) result (n = 184/331) was associated with a significantly higher crude and adjusted rates of the primary endpoint (adjusted HR 2.47, 95% CI 1.17-5.21, p = 0.018). This did not pertain to patients with abnormal O-15-H2O-PET perfusion (abnormal AIQCT(ischemia) result (n = 269/331) vs. normal AI-QCT(ischemia) result (n = 62/331); adjusted HR 1.09, 95% CI 0.58-2.02, p = 0.794) (p-interaction = 0.039). Conclusion: Among patients with obstructive CAD on coronary CTA referred for downstream O-15-H2O-PET perfusion imaging, AI-QCT(ischemia )showed incremental prognostic value among patients with preserved perfusion by O-15-H2O-PET imaging, but not among those with reduced perfusion.