Clinical and Economic Outcomes in Diagnostic-Naïve Medicare Fee-for-Service Beneficiaries Managed with Alert-Based Ambulatory Cardiac Monitors: the CAMELOT-ALERT Study.

BACKGROUND: Ambulatory cardiac monitoring (ACM) is fundamental to arrhythmia evaluation, yet robust comparative evidence among alert-based monitoring strategies is lacking. OBJECTIVE: To compare diagnostic yield and downstream clinical and economic outcomes among arrhythmia diagnosis-naïve Medicare Fee-For-Service (FFS) beneficiaries receiving mobile cardiac telemetry (MCT) or ambulatory event monitoring (AEM). METHODS: Using 100% Medicare FFS claims from 2020 to 2022, this retrospective cohort study included beneficiaries aged 65 years or older, excluding those with prior arrhythmia diagnoses, antiarrhythmic medication use, or rhythm-management procedures. Cohorts were iRhythm MCT, Other MCT, and AEM; inverse probability of treatment weighting (IPTW) balanced baseline characteristics. Outcomes included diagnostic yield at 90 days, retesting at 180 days, and clinical events and costs at one year. RESULTS: Among 441,792 eligible beneficiaries, 17,773 received iRhythm MCT (4%), 368,830 Other MCT (83%), and 55,189 AEM (13%). After IPTW, 90-day diagnostic yield was higher with iRhythm MCT (49.5%) than Other MCT (40%; HR 0.79 [95% CI, 0.77-0.81]) and AEM (39.1%; HR 0.76 [95% CI, 0.74-0.78]). Retesting at 180 days was more frequent with iRhythm MCT (8.8%) than Other MCT (6.3%; HR 0.70 [95% CI, 0.66-0.74]) and AEM (7.2%; HR 0.81 [95% CI, 0.76-0.87]). Pacemaker implantation was more common with iRhythm MCT; no differences were identified in hospitalizations, emergency visits, or heart failure. CONCLUSIONS: Diagnostic yield and retesting varied across ACM platforms, though residual confounding cannot be excluded. No differences were identified in outcomes, utilization, or costs. Randomized trials are warranted to determine true differences in platform performance.