In a multicentre REFINE PET registry study of 16,650 patients undergoing regadenoson 82Rb-PET MPI, elevated AI-derived splenic ratio (SR) was independently linked to higher major adverse cardiovascular event risk—even among patients with preserved myocardial flow reserve (MFR ≥2). The study suggests preserved MFR alone is no longer enough for risk reassurance on PET when stress adequacy, captured by automated SR, is abnormal.

Why It Matters To Your Practice

• Inadequate pharmacologic stress can blunt the diagnostic and prognostic value of PET MPI.

• An AI-derived SR offers an automated check on stress adequacy using routine stress and rest splenic uptake.

• Risk may be underestimated if clinicians rely on preserved MFR alone without accounting for whether vasodilator stress was truly adequate.

Clinical Implications

• Consider abnormal SR a potential warning flag when interpreting regadenoson PET studies, especially if perfusion or flow findings appear reassuring.

• Patients with preserved MFR but elevated SR may warrant closer clinical follow-up and more cautious risk assessment.

• Automated SR extraction could be integrated into PET workflows at scale because it does not depend on manual measurement.

Insights

• The analysis included 16,650 patients from six sites with clinically indicated MPI and linked outcomes.

• SR was calculated fully automatically as the ratio of splenic uptake at stress versus rest, then stratified by deciles.

• The primary endpoint was MACE, assessed with Kaplan-Meier and adjusted Cox models including clinical and imaging covariates such as MFR.

The Bottom Line

• AI-derived SR adds prognostic information beyond standard PET metrics and may identify higher-risk patients whose preserved MFR would otherwise seem reassuring.

• For clinicians interested in AI, this is a practical example of automation improving interpretation quality and risk stratification rather than replacing clinical judgment.