Abstract Body (Do not enter title and authors here): Background: Cardiac rhythm monitoring is a mainstay of secondary stroke prevention. Despite this, prior studies have highlighted gaps in real-world monitoring after stroke.

Objective: To assess whether failure to complete cardiac monitoring is associated with worse clinical outcomes in patients (pts) who have had an acute ischemic stroke or TIA.

Methods: We evaluated 891 stroke pts who were prescribed ambulatory cardiac rhythm monitoring between 2019-2023. Electronic health records identified those who completed (≥ 3 days) and did not complete (< 3 days) wear. We also obtained census tract-level CDC/ATSDR Social Vulnerability Index (SVI) data for each patient. Residential addresses were geocoded in ArcGIS Pro (ESRI) and linked to overall SVI scores, which represent national percentile rankings (range 0-1). Higher values indicate greater social vulnerability. Cox proportional hazards models evaluated the associations between monitor completion and the risk for recurrent strokes, cardiovascular events, and deaths.

Results: Of 891 post-stroke pts, 229 (26%) did not complete cardiac monitoring. Compared to the monitored group, pts who did not complete monitoring were more likely to be Black and have hypertension, diabetes, and Medicaid or no insurance. Median SVI rank was significantly higher in non-monitored pts (0.83 vs. 0.58, p <0.001), indicating higher social vulnerability. After a median follow-up of 970 days [IQR 413, 1265], there were 325 events. The non-monitored group had a higher unadjusted risk of clinical events than the monitored group (Figure 1). After multivariable adjustment for age, sex, hypertension, diabetes, hyperlipidemia, smoking, prior stroke, heart failure, and coronary heart disease, non-monitored pts had a higher risk of recurrent stroke (HR 1.52, 95% CI [1.02, 2.25]), cardiovascular events (HR 1.50, 95% CI [1.00, 2.25]), and all-cause mortality (HR 2.79, 95% CI [1.81, 4.31]). In stratified analysis, failure to complete monitoring was independently associated with an increased risk of the combined endpoint in both the most socially vulnerable (SVI Quartile 4) (adjusted HR 1.54, 95% CI [1.08, 2.19]) and less vulnerable (SVI Quartiles 1-3) (HR 2.14, 95% CI [1.39, 3.27]) pts.

Conclusions: Failure to complete cardiac monitoring is associated with worse post-stroke outcomes. While more socially vulnerable pts are less likely to complete monitoring, monitoring is associated with better outcomes across highly and less vulnerable populations.