Objective: To identify determinants and mechanisms of strokes in patients who experience ‘breakthrough ischemic strokes’ while already on therapeutic anticoagulation.

Background: Patients experiencing ischemic strokes while already on therapeutic anti-coagulation are often considered anti-coagulant failures if they are compliant with their treatment, and pose a management challenge. Stroke etiology in such patients is also often overlooked and they are routinely switched to an alternate anticoagulant or combined with an antiplatelet therapy, although evidence is lacking if doing so prevents future ischemic strokes.

Methods: We conducted a retrospective cohort analysis of patients presenting to Cleveland Clinic Akron General between January 2013 – December 2017.  Patients were included if they had an ischemic stroke diagnosis on admission and were already on therapeutic anticoagulation at the time, and were compared against a group of matched cohort from the same time period. Treatment compliance was determined using manual chart review. Stroke etiology was determined and dichotomized into embolic stroke (ES) vs Non-embolic stroke (NES) etiology based on their history, imaging and ancillary findings.

Results: A total of 2750 patients were identified to have a diagnosis of ischemic stroke during the defined period, of which 64 met the inclusion criteria for ‘cases’. Both groups were similar in age (72±13 years among cases vs 72±16 among cohorts, p=0.795) and sex (Females 69 (58%) among cases vs 30 (47%) among cohorts, p=0.150). Stroke etiology was similar among both groups, with the anticoagulated group not necessarily showing a trend towards higher incidence of ES (49 (77%) in cases vs. 83 (70%) in cohort, p=0.327).

Conclusion: Ischemic strokes among patients on therapeutic anticoagulation do not necessarily differ in stroke mechanisms compared to routine ischemic strokes, and require a thorough, individualized approach to prevent future stroke risks.