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Optimal Ischemic Lesion Pattern on Brain MRI to Identify Atrial Fibrillation

MVT-AF (multiple vascular territories – atrial fibrillation)

Steven Warach, M.D., Ph.D.

Steven Warach, M.D., Ph.D.

Study Synopsis

This study is the first phase of a three-phase study design aimed at assessing the potential of MRI to identify patients that may have hidden (occult) atrial fibrillation and require stronger anticoagulants than aspirin to prevent stroke. Our hypothesis is that ischemic brain lesions in multiple vascular territories (MVT) are significantly associated with cardioembolic stroke, especially atrial fibrillation (AF). To strengthen the association of this lesion pattern to a cardioembolic source, we will examine relevant clinical data and echocardiographic findings. We will then develop a simple scale to diagnose occult AF based on the MRI and several clinical features. Subsequent phases of the project will test the prediction scale to predict previously undetected AF after stroke and to test the best therapy for stroke prevention.

Status active and enrolling

For this study, we identified a consecutive series of hospital discharges of ischemic stroke cases from the Seton Family of Hospital’s stroke database over a two-year period of October 1, 2014, to September 30, 2016.  A total of 1067 cases have been evaluated and 613 met study clinical inclusion criteria. Image analysis of these cases is underway. Additional study sites include UT Houston Hub and the UT Southwestern Medical Center Hub. Enrollment is planned for a sub-study of MVT occurrence in patients with loop recorder implants to predict AF in this population.

This project is the first in a planned series of studies to develop and validate a brain imaging biomarker of
cardioembolic stroke toward the long-term goal of identifying a high-risk group that may preferentially benefit
from long-term cardiac monitoring or anticoagulation in the absence of proven cardioembolic source.

The primary hypothesis of this study is to test whether the occurrence spatially separate acute ischemic
strokes located within multiple vascular territories (MVT) supplying the brain (right carotid, left carotid, or
posterior circulation) on DWI within 48 hours from stroke onset is associated with proven cardioembolic source.

Subsequent studies will attempt to validate the MVT biomarker in three separate samples: patients undergoing long-term cardiac monitoring with an implantable cardiac monitor, patients with new lesions on repeat MRI 3-6 months from onset, and subjects with embolic stroke of unknown source (ESUS) in ongoing prevention trials of anti-platelets vs anticoagulants.

It is anticipated that approximately 63% of ischemic stroke diagnoses from Lone Star Stroke Consortium (LSS) hubs will be eligible for this retrospective analysis. Approximately 32% of the ischemic stroke diagnoses from LSS spoke sites will be eligible.