Ammonia PET-derived Right Ventricular Strain: Prognostic Value in Coronary Artery Disease

Introduction: We have adapted a feature-tracking technique to electrocardiography-gated high-resolution ¹³N-ammonia positron emission tomography (NH₃-PET) imaging, and made it possible to measure right ventricular (RV) strain. We showed that RV strain identifies right coronary artery territory ischemia in patients with ischemic heart disease. Previous studies indicated that RV function be a predictor of cardiovascular events. The aim of this study was to investigate the potential of RV strain estimated by NH₃-PET as a prognostic factor in ischemic heart disease (IHD).

Methods: Between January 2017 to January 2019, 263 consecutive patients who underwent resting/ stressed myocardial NH₃-PET because of known or suspected coronary artery disease at a single center were enrolled. In this study, we included patients with coronary artery stenosis of more than 50%, diagnosed by coronary computed tomography angiography, from this cohort. Among them, congenital heart disease, a transplanted heart or adenosine ineffectiveness were excluded.RV- longitudinal strain (LS) in the free wall was measured by a feature-tracking technique on the stressed NH₃-PET images of horizontal long-axis slices.The endpoint was major adverse cardiac events (MACEs) comprising all-cause death, acute coronary syndrome, hospitalization due to heart failure, and revascularization. The ability to predict MACE was assessed using the receiver-operating characteristic (ROC) analysis. The predictability of RV-LS was analyzed using Kaplan–Meier analysis.

Results: Consecutive 93 patients were retrospectively analyzed. The ROC curve analysis demonstrated a cutoff of -26.9 for MACE with RV-LS (area under the curve, sensitivity. and specificity of 0.64, 61% and 67%). Patients with RV-LS≥-26.9 had a significantly higher MACE rate than those with RV-LS<-26.9 (log-rank, p=0.048).

Conclusions: RV-LS can prognose MACE in patients with IHD.It is possible to predict cardiovascular events from the RV strain information obtained by routine rest/stress NH₃-PET without additional imaging or additional radiation exposure.

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