Pathophysiology and Risk of Atrial Fibrillation Detected After Ischemic Stroke

This study enrolls patients with acute ischemic stroke at the London Health Sciences Center in London, Ontario, Canada. The heart rhythm of the patients is monitored with a CardioSTAT® Holter device (Icentia) for 14 days after the ischemic event onset. Based on this cardiac monitoring and previous medical history, patients are stratified into three groups: (a) atrial fibrillation detected after stroke or transient ischemic attack (AFDAS), (b) atrial fibrillation diagnosed before the ischemic event or known AF (KAF), and (c) normal sinus rhythm (NSR).

Autonomic function is assessed by the levels of plasma catecholamines, a battery of validated autonomic tests [autonomic reflex screening (ARS)], heart rate variability (HRV) through data obtained by Holter monitoring by standard quantitative analysis methods according to the guidelines of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology and by the analysis of diurnal variation of heart rate. Blood samples are collected for the analysis of inflammatory markers (e.g. CRP, TNF-α, IL-1β, and IL-6), and potential AFDAS predictors such as brain natriuretic peptide (BNP- AFDAS biomarker), endothelin-1 (endothelial dysfunction marker), Lipoprotein(a) [Lp(a)] and thrombin-activatable fibrinolysis inhibitor (TAFI) plasma levels, TAFI activity, TAFI single nucleotide polymorphisms (SNPs), apo(a) isoform size and plasma catecholamines levels. Furthermore, specific neuroimaging findings (e.g., specific regions of the insula or its connections) and clinical features (e.g., impaired interoceptive processing, cognitive impairment, etc) are also analyzed. Interoception is assessed using a heartbeat detection task without feedback condition and gait, balance, frailty, and cognitive status in patients are evaluated by the administration of a battery of tests. Stroke recurrence will be assessed by a structured phone interview at 6 and 12 months after the initial stroke.

Inclusion criteria

• MCA territory-transient ischemic attack or -acute ischemic stroke patients seen in the Emergency Department or admitted to University Hospital, London, Ontario, Canada
• Age ≥ 18 years old
• Patient or Substitute Decision Maker must give written informed consent

Exclusion criteria

• Patients with autonomic dysfunction such as Parkinson's disease that can be interfering with outcome assessment based on qualified investigator's judgment.
• Patients taking tricyclic antidepressant (TCAs)
• Patients in whom the acute stroke is primarily hemorrhagic
• Patients with both TIA and atrial fibrillation
• Patients with both TIA and large vessel disease
• Patients with inflammatory diseases