Cardiac Testing in Search for Occult Atrial Fibrillation after Ischemic Stroke

Abstract

Determining the etiology of ischemic stroke is critical to administering targeted therapy to prevent recurrent stroke and further neurologic deterioration. Ischemic strokes of cardioembolic and cryptogenic etiologies are frequent and are often ultimately attributed to atrial fibrillation (AF). However, the paroxysmal nature of AF presents challenges for accurate and timely detection to prevent a recurrent stroke. The purpose of this review is to evaluate serologic, electrographic, echocardiographic, and radiologic markers of AF after an ischemic stroke. Innovative applications of biotechnologies such as RNA gene expression profiling are being studied to characterize stroke etiology. Extended cardiac rhythm monitoring by implantable and wearable devices allows longer periods to capture paroxysmal AF. Echocardiographic measures including left atrial volume and parameters of left atrial strain increase the probability of detecting AF. Existing radiographic modalities are being investigated in novel ways to assess left atrial abnormalities associated with paroxysmal AF. Emerging technologies and novel applications of existing methods are improving AF diagnostics in cryptogenic stroke patients with a high pre-test probability of this etiology. Future research will continue to optimize AF diagnosis after a cryptogenic ischemic stroke to inform clinical practice and prevent recurrent strokes.