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Fibrosis, atrial fibrillation and stroke: clinical updates and emerging mechanistic models
  1. Patrick M Boyle1,
  2. Juan Carlos del Álamo2,
  3. Nazem Akoum3
  1. 1Bioengineering, University of Washington, Seattle, Washington, USA
  2. 2Mechanical Engineering, University of Washington College of Engineering, Seattle, Washington, USA
  3. 3Cardiology, University of Washington School of Medicine, Seattle, Washington, USA
  1. Correspondence to Dr Nazem Akoum, Cardiology, University of Washington School of Medicine, Seattle, Washington, USA; nakoum{at}cardiology.washington.edu

Abstract

The current paradigm of stroke risk assessment and mitigation in patients with atrial fibrillation (AF) is centred around clinical risk factors which, in the presence of AF, lead to thrombus formation. The mechanisms by which these clinical risk factors lead to thromboembolism, including any role played by atrial fibrosis, are not understood. In patients who had embolic stroke of undetermined source (ESUS), the problem is compounded by the absence of AF in a majority of patients despite long-term monitoring. Atrial fibrosis has emerged as a unifying mechanism that independently provides a substrate for arrhythmia and thrombus formation. Fibrosis-based computational models of AF initiation and maintenance promise to identify therapeutic targets in catheter ablation. In ESUS, fibrosis is also increasingly recognised as a major risk factor, but the underlying mechanism of this correlation is unclear. Simulations have uncovered potential vulnerability to arrhythmia induction in patients who had ESUS. Likewise, computational models of fluid dynamics representing blood flow in the left atrium and left atrium appendage have improved our understanding of thrombus formation, in particular left atrium appendage shapes and blood flow changes influenced by atrial remodelling. Multiscale modelling of blood flow dynamics based on structural fibrotic and morphological changes with associated cellular and tissue electrical remodelling leading to electromechanical abnormalities holds tremendous promise in providing a mechanistic understanding of the clinical problem of thromboembolisation. We present a review of clinical knowledge alongside computational modelling frameworks and conclude with a vision of a future paradigm integrating simulations in formulating personalised treatment plans for each patient.

  • atrial fibrillation
  • stroke

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Footnotes

  • Twitter @pmjboyle

  • Contributors All three authors substantially contributed to the conception or design of the work, or the acquisition, analysis or interpretation of data; contributed to drafting the work or revising it critically for important intellectual content; provided final approval of the version published; and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding This study was funded by The John Locke Charitable Fund.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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