Risk stratification in coronary artery disease using NH3-PET myocardial flow reserve and CAD-RADS on coronary CT angiography

Myocardial flow reserve (MFR) derived from 13N-ammonia positron emission tomography (NH3-PET) can predict the prognosis of patients with various heart diseases. Coronary computed tomography angiography (CCTA) is a non-invasive investigation for ischemic heart disease. The coronary artery disease reporting and data system (CAD-RADS) was established to standardize and facilitate the reporting of CCTA data regarding CAD. This study aimed to investigate the prognostic value of CAD-RADS and MFR. A total of 133 patients who underwent NH3-PET and CCTA within 3 months were enrolled. Patients were divided into groups with CAD-RADS 0–2 and ≥ 3 and into groups with MFR ≥ 2.0 and < 2.0. The endpoint was major adverse cardiac events (MACE) comprising all-cause death, acute coronary syndrome, hospitalization due to heart failure, and cerebrovascular disease. The ability of CAD-RADS and MFR to predict MACE was analyzed using Kaplan–Meier analysis. There was no significant difference in MFR between patients with CAD-RADS 0–2 and ≥ 3 (2.3 ± 0.9 vs. 2.2 ± 0.7, p = 0.50). The MACE rate for patients with CAD-RADS 0–2 and ≥ 3 was equivalent (log-rank test, p = 0.64). Patients with MFR < 2.0 had a significantly higher MACE rate than those with MFR ≥ 2.0 (p = 0.017). In patients with CAD-RADS ≥ 3, patients with MFR < 2.0 had a significantly higher MACE rate than those with MFR ≥ 2.0 (p = 0.034). CAD-RADS did not contribute to MACE prediction. Conversely, MFR was useful in predicting MACE, allowing for further risk stratification in addition to CAD-RADS.