Incidence of Silent Atrial Fibrillation in Patients With Clinically Silent Brain Ischemic Lesions

Arterial Fibrillation (AF) is well-recognized as a cause for cryptogenic Acute Ischemic Stroke (AIS) and searched for in clinical practice. However, although AF is associated with Silent Brain Infarction (SBI), its role in the formation of these lesions is less well established and needs clarification. A multitude of clinical, laboratory, echocardiographic and electrocardiographic parameters are associated with AF. Although no single one of these parameters has sufficient specificity to rule-in AF, their combined use may nevertheless help to identify patients with SBI at highest risk for AF. The study is expected to provide evidence that long term monitoring in subjects with SBI yields similar rates of AF as in AIS patients.

Patients aged ≥65 years with a presumably silent brain lesion in a brain magnetic resonance imaging fulfilling inclusion criteria and consenting get a subcutaneous implantation of a cardiac monitor (Reveal LINQ). Data will be directly transferred to the treating physician by the Medtronic MyCareLink Patient Monitor. In case of a relevant arrhythmia, the respective study site will be informed by the staff of Inselspital. Relevant arrhythmias are defined as follows:

• First episode of atrial fibrillation (≥30 seconds)
• Sustained ventricular tachycardia (≥30 seconds)
• Sustained supraventricular tachycardia (≥30 seconds)
• Asystoly of ≥6 seconds duration
• Atrial fibrillation with pause of ≥6 seconds duration
• Higher degree atrioventricular (AV) block (3° AV bloc; 2:1 AV conduction; 2° AV block type Mobitz)
• Sustained bradycardia <30 beats per minute (≥30 seconds) It is the responsibility of the respective study sites to take appropriate actions and inform the patients and treating physicians about relevant findings. The maximal timeframe from data transmission to data analysis is one week and from data transmission to patient notification two weeks.

The expected results of the study would be supportive in introducing long term monitoring to the care pathway in subjects with SBI. Since SBI are more prevalent than AIS and current recommendations very restrictive, this would have a relevant impact on SBI management.

Inclusion criteria

• Age

• ≥ 65 years
• ≥ 50 years AND one the following:

• NT-proBNP >400 pg/mL
• Left atrial ventricular index >42 ml/m2 or left atrial diameter >46 mm
• Covert infarctions with cortical involvement in more than one vascular territory (left carotid territory, right carotid territory, vertebrobasilar territory)
• Written informed Consent
• Any clinically silent ischemic lesions of the brain parenchyma detected on neuroimaging defined according to established criteria as either:

• Diffusion weighted imaging (DWI) positive lesions: Focus of restricted diffusion (high DWI signal and low apparent diffusion coefficient value) occurring in either white or gray matter, located in the cerebrum, cerebellum, or brain stem AND not satisfying the diagnostic criteria for multiple sclerosis OR
• Cavitatory Lesions: ≥ 3 mm in size that follow cerebro-spinal fluid on all sequences that are slit or wedge shaped with an irregular margin AND NOT longitudinally aligned with perforating vessels or with a multiple, bilateral symmetrical distribution OR
• T2 weighted (T2W) hyperintense/T1 weighted (T1W) hypointense lesions:

• Focal lesion with high T2W signal and low T1W signal that have prior evidence of restricted diffusion; OR
• Present within cortical gray matter or deep gray matter nuclei OR
• A lesion that is new, compared with an MRI performed within 3 months OR
• T2W hyper/T1W hypointense lesions in the white matter, which are discontinuous but associated with the classic confluent periventricular T2 intense change of leukoaraiosis (Fazekas ≥2) AND NOT satisfying the diagnostic criteria for multiple sclerosis or with a significant patient history of severe trauma, radiation, drug toxicity, or carbon monoxide poisoning

Exclusion criteria

• History of AF or atrial flutter
• Patients with a history of symptoms compatible with an AIS, covert neurological deficits are allowed.
• Cardiac implantable electronic devices (pacemaker, implantable cardiac defibrillator (ICD), implantable cardiac monitor (ICM))
• Indication for cardiac implantable electronic device implantation (pacemaker, ICD, ICM)
• History of or indication for major cardiac surgery or transcutaneous aortic valve implantation
• Indication for permanent oral anticoagulation
• Contraindication for permanent oral anticoagulation
• Projected life expectancy of less than 2 years
• Active intra- or extracranial high-grade malignancy
• Patient is already included in another clinical trial that will affect the objectives of this study
• Patient's lack of accountability, inability to appreciate the nature, meaning and consequences of the study and to formulate his/her own wishes correspondingly
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc.
• Known or suspected non-compliance, drug or alcohol abuse