Abstract Body (Do not enter title and authors here): Background: Advances in wearable technology have enabled real-time monitoring of arrhythmias and patient health metrics. However, feasibility and clinical utility of such devices for monitoring less common conditions, such as hypertrophic cardiomyopathy (HCM), remain unclear.

Objectives: To evaluate the feasibility of wearable technology to monitor health metrics and detect atrial fibrillation (AF) in patients with HCM.

Methods: Patients at the Lahey HCM center were prospectively enrolled. Each patient was provided a Withings ScanWatch^® to collect biometric data and track physical activity for ≥6 months. Patients were prompted to complete daily single-lead ECG recordings, monthly patient-reported outcome (PRO) questionnaires, including the Kansas City Cardiomyopathy Questionnaire (KCCQ), and surveys on satisfaction with the wearable technology. All ECGs were independently interpreted by blinded cardiologists at a third-party core lab (Heartbeat Health).

Results: A total of 49 patients were enrolled (age 52±12 years), with maximal wall thickness of 18±4 mm, ejection fraction of 65±4%, and LA dimension of 44±9 mm, including 16 (33%) with prior history of paroxysmal AF. At baseline, average KCCQ overall summary (OS) score was 76±15, including <80 in 49% and <50 in 8%. Compliance with daily ECG was ≥50% in 81% and ≥75% in 61%. Daytime device wear was ≥75% in 90%, while nocturnal wear was ≥50% in only 29%. Completion of monthly PRO questionnaires was ≥75% in 92%. Over 9.0±3.7 months of monitoring, 9 patients had AF episodes occurring a median of 105 days after study enrollment (IQR 29-147 days), including 7 with prior AF history and 2 with new-onset AF. Eight patients (16%) without AF episodes had worsening of KCCQ-OS score by ≥10 points. The average daily step count was 4399±2853 steps and average nightly sleep duration was 6.4±1.2 hours. At study conclusion, 40 patients (82%) expressed interest in continuing to use the wearable technology, with 21 (43%) reporting feeling more connected to their health care team. Only 4 patients (8%) reported anxiety related to study participation.

Conclusions: Use of wearable technology in patients with HCM was feasible and enabled detection of clinically important events, including AF and symptomatic deterioration, with high patient engagement, daily compliance, and satisfaction. Further study is warranted to determine whether biometric data can predict adverse events and improve clinical outcomes in this population.