Smith, Matthew

Introduction: Four randomized clinical trials have not demonstrated the superiority of anticoagulation over antiplatelet therapy in the prevention of recurrent embolic stroke of undetermined source (ESUS). In this multicenter observational cohort study, we evaluated long-term outcomes associated with various antithrombotic strategies according to potential embolic sources. Methods: A multicenter retrospective observational cohort of consecutive adult patients with ESUS was queried (n=27 sites). Comparisons were made between patients treated with single or combination antiplatelet therapy versus anticoagulation (direct oral anticoagulant, vitamin K antagonist, low molecular weight heparin) with or without antiplatelet therapy initiated within 7 days of stroke. The primary composite outcome of recurrent stroke, major bleeding, or death was assessed using unadjusted and adjusted Cox proportional hazards regression, with clustering by site. Causal inference was assessed using inverse probability of treatment weighted regression adjustment (IPTWRA), accounting for propensity for antiplatelet treatment, with effect estimates summarized as the average treatment effect (ATE) over time (in days). Adjusted models accounted for age, stroke severity, vascular risk factors, and major categories of potential embolic sources. Results: Of the 2201 included patients (n=218 treated with anticoagulation) followed over a median of 564 days (interquartile range [IQR] 154-1124), the median age was 65y (IQR 54-74) and 49.8% were female. Patients treated with anticoagulation were older with more frequent previous stroke, concomitant left ventricular dysfunction, and more severe deficits. Over 4541 person-years of follow-up, the annualized incidence rate of the primary outcome was 14.6% (95% confidence interval [CI], 13.6%-15.8%). Compared to anticoagulation, antiplatelet(s) use was not associated with a lower risk of the primary outcome in the adjusted Cox model (HR 0.91, 95% CI, 0.64-1.29) or in the IPTWRA model (average treatment effect 0.14, 95% CI, -1376.6 to 1376.9). Major bleeding events trended toward significance in the adjusted Cox model (HR 0.51, 95% CI 0.25-1.04) but were no different with IPTWRA (ATE 58.9, 95% CI, -125.4 to 243.2). Conclusions: These results validate the observations of randomized trials indicating a lack of benefit of anticoagulation over antiplatelet therapy in ESUS. A more detailed analysis of heterogeneity of treatment effect is under way.

Background: It is known that there are discrepancies between insurance status and access to care for a variety of health conditions. In addition, differences have been shown in initial in-hospital management of stroke as well as outcomes in the acute setting. We sought to examine the relationship between insurance status and risk of recurrent stroke, major bleeding or death following an incident cryptogenic stroke. Methods: Patients with cryptogenic stroke included in a multicenter (n=27 sites) retrospective observational cohort and complete insurance status were evaluated for a primary composite outcome of recurrent stroke, major bleeding, or death. Insurance providers were categorized by Private/Veterans Administration, Medicare, Other, and Medicaid/pending/None, with the primary carrier ranked in that order when multiple insurance carriers applied. Descriptive statistics and an adjusted Cox proportional hazards regression were used to associate the primary insurance provider with the composite outcome, and with each unique secondary outcome, adjusting for age, stroke severity, pre-stroke disability, atherosclerotic risk factors, and potential embolic sources (e.g., patent foramen ovale). Results: Of the 2201 patients, 2006 (91.1%) had reported insurance information and were followed for a median of 1.50 years (interquartile range [IQR 0.41 - 2.99y]). The majority of patients were primary Medicare beneficiaries (42.3%), followed by private insurance (36.7%), Medicaid/none (18.1%) and Other (2.9%). Although there were important differences in demographic and neurodiagnostic results across insurance groups, compared to Private/VA beneficiaries, beneficiaries for Medicaid/pending/none had a higher rate of the composite outcome in adjusted regression (adjusted hazard ratio [HR] 1.35, 95% confidence interval [CI], 1.07-1.69) which was driven largely by the higher rate of recurrent stroke (adjusted HR 1.33, 95%CI, 1.02-1.73) with no significant difference in rate of major bleeding or death (p>0.05 for both). Conclusions: Independent of age, race, pre-existing disability, and atherosclerotic risk factors, insurance status was independently predictive of recurrent stroke in this diverse cohort of cryptogenic stroke.

Background: Left ventricular (LV) injury is a cardioembolic etiology of ischemic stroke. We aimed to 1) evaluate recurrent stroke risk among patients with cryptogenic stroke and LV injury, and 2) determine if there is a treatment effect with anticoagulation in this population. Methods: We analyzed the multicenter, retrospective Cardiac Abnormalities in Stroke Prevention and Recurrence cohort of patients with cryptogenic ischemic stroke. The exposure was LV injury defined by 1) LV ejection fraction (EF) 20-40% and/or 2) LV wall motion abnormality (hypokinesis or akinesis). The primary composite outcome included recurrent stroke, major bleeding, or death. Cox proportional hazard models were built and sequentially adjusted for 1) age and sex (Model 1), and 2) age, sex, race, ethnicity, anti-thrombotic use, and vascular risk factors (Model 2). We then assessed if there was heterogeneity in treatment effect by LV injury status with an interaction term of LV injury and oral anticoagulation use in Model 2. Results: Of 2,641 patients in CASPR, the analytic cohort included 2,191 patients with complete exposure and outcome data (median age 65 years, 49.8% female, median follow-up 1.55 years). There were 113 (5.2%) patients with LV injury (median LVEF 30%, interquartile range 25-34%). There were 559 incident events (321 recurrent strokes [288 ischemic], 71 major hemorrhages, 250 deaths). Among patients with LV injury, 15.9% were prescribed an anticoagulant within 7 days of index stroke (vs 9.6% without LV injury, p=0.03). The unadjusted risk of the primary outcome was non-significantly higher among patients with LV injury vs without (HR 1.40; 95% confidence interval [CI], 0.98-2.00), but became significant in Model 1 (HR 1.50; 95% CI, 1.21-1.85) and in Model 2 (HR 1.35, 95% CI, 1.11-1.64). In the LV injury subgroup, anticoagulation vs antiplatelet therapy was associated with a significant reduction in the primary outcome (HR 0.63, 95% CI, 0.43-0.94). In patients without LV injury, anticoagulation was associated with a higher risk of the composite outcome (HR 4.35, 95% CI, 1.69-11.16, p[interaction]=0.002). Conclusion: In this observational study, there was an increased risk of the primary outcome which included recurrent stroke among patients with cryptogenic stroke and LV injury. Anticoagulation use in LV injury is associated with a significant reduction in the risk of the primary outcome. These findings warrant confirmation in a dedicated randomized controlled trial.