“BREAKTHROUGH” ISCHEMIC STROKE ON NOAC THERAPY IN NEWLY DIAGNOSED NONVALVULAR ATRIAL FIBRILLATION: A CASE REPORT

Abstract

Introduction: Nonvalvular atrial fibrillation (NVAF) accounts for 20–30% of cardioembolic strokes. Despite the preference for nonvitamin K antagonist oral anticoagulants (NOACs) over vitamin K antagonists, ischemic stroke still occurs in 1–2% of patients. These “breakthrough strokes” are linked to high recurrence and mortality, and optimal secondary prevention remains unclear.

Case report: A 65-year-old male with NVAF on rivaroxaban presented with left hemiparesis and central facial palsy. One month prior, he experienced transient perceptual disturbance and expressive aphasia. Workup revealed paroxysmal atrial fibrillation, mild carotid atheromatosis, and normal echocardiography. Brain CT showed leukoaraiosis and cortical atrophy; MRI demonstrated a subacute ischemic lesion in the right periventricular region. NOAC adherence and dosing were appropriate. Persistent neurological deficits and mild cognitive impairment (MoCA: 22) were noted. Management included low molecular weight heparin prophylaxis, dual antiplatelet therapy, high-dose statin, antihypertensives, and supportive measures.

Discussion: Stroke, despite anticoagulation, may result from suboptimal dosing, alternative etiologies such as small vessel disease, or non-AF-related embolism. Data from a large Hong Kong cohort study suggest that continuing the same NOAC is associated with better outcomes, while switching to another NOAC or to warfarin increases recurrence risk. Conversely, some studies report benefit from switching in select cases, highlighting the need for individualized strategies.

Conclusion: Breakthrough ischemic stroke in NVAF patients on NOAC therapy is multifactorial and carries a poor prognosis. Continuation of the same NOAC may be favorable when alternative mechanisms are excluded, but randomized trials are required to guide optimal secondary prevention.