Beyond rhythm: can a tiny insertable cardiac monitor also tell us how patients are moving? Proud to share our LUX-Dx TRENDS exercise substudy, published in @JCardFail alongside today’s presentation at #HFSA2026. We evaluated accelerometer-based activity sensing in an investigational insertable cardiac monitor in 104 patients with heart failure across 26 U.S. sites. Patients represented the full ejection fraction spectrum, with 63% having HFpEF. Two key findings: • The activity signal tracked walking speed: accelerometer measurements increased consistently as treadmill speed increased across both study cohorts. • The algorithm accurately distinguished activity from inactivity: in the 45-patient evaluation cohort, comparing treadmill walking at ≥1.2 mph with stationary postures, agreement was near-perfect (κ = 0.971), with 97.4% sensitivity and 99.4% specificity. Why this matters: This work supports the potential to extend insertable cardiac monitors beyond rhythm surveillance to objective, continuous activity monitoring, including for patients who do not have an indication for a pacemaker or defibrillator. An important distinction: this is validation under controlled exercise conditions, not proof of improved clinical outcomes. Real-world performance, risk prediction, and the ability to guide patient management remain essential next steps. The opportunity is compelling: better understanding what happens between clinic visits, not just what we see during them. Grateful to our patients, investigators, coauthors, and Boston Scientific collaborators for advancing this work together. onlinejcf.com/article/S1071-…