Echocardiographic Predictors of Atrial Fibrillation

This prospective study aims to identify the diagnostic accuracy of echocardiographic predictors of atrial fibrillation in patients with ESUS (embolic stroke of undetermined source) or TIA (transient ischemic attack).

Cardiac thromboembolism attributed to atrial fibrillation (AF), the most frequent cardiac arrhythmia, is responsible for up to one-third of ischemic strokes.

Several factors have been proposed to predict AF, as findings in 12-lead ECG (electrocardiogram) or Holter ECG, epidemiological or echocardiographic parameters.

The main purpose of this research project is to test the diagnostic accuracy of the atrial electromechanical conduction time, measured as septal total atrial conduction time "sPA-TDI", an echocardiographic parameter, and the LaHAsPa-Score, which is based on patient characteristics and echocardiographic measurements for the detection of AF in patients diagnosed with ESUS or TIA, utilizing a 7-day ambulatory ECG monitor and incidental detection of AF during a two-year follow-up period, including detection via implantable cardiac monitor or pacemaker, if applicable.

Other echocardiographic measurements including left atrial volume index (area-length method), atrial electromechanical delay, left atrial myocardial strain together with laboratory, 12-channel ECG, Holter ECG findings, and established risk scores will be compared to the main parameters of interest.

The investigators expect that the results will help with better risk stratification and targeted monitoring periods for atrial fibrillation in patients with ESUS or TIA.

Eligibility Criteria:
Inclusion Criteria:

Age ≥ 18 years, written informed consent to participate in the study Clinical diagnosis of ischemic stroke or transient ischemic attack + brain imaging to rule out hemorrhagic stroke.

1. Stroke: ESUS, defined as all of the following:

   * Stroke detected by CT (computertomography) or MRI (magnetic resonance imaging) that is not lacunar. (Lacunar is defined as a subcortical (this includes pons and midbrain) infarct in the distribution of the small, penetrating cerebral arteries whose largest dimension is ≤1.5 cm on CT or ≤2.0 cm on MRI diffusion images/\<1.5 cm on T2 weighted MR images. The following are not considered lacunes: multiple simultaneous small deep infarcts, lateral medullary infarcts, and cerebellar infarcts.)
   * Absence of extracranial or intracranial atherosclerosis causing ≥50 percent luminal stenosis of the artery supplying the area of ischemia. Patients must undergo vascular imaging of the extracranial and intracranial vessels using either catheter angiography, CT angiogram (CTA), MR angiogram (MRA), or ultrasound, as considered appropriate by the treating physician and local principal investigator.
   * No major-risk cardioembolic source of embolism, including intracardiac thrombus, mechanical prosthetic cardiac valve, atrial myxoma or other cardiac tumors, mitral stenosis, myocardial infarction within the last 4 weeks, left ventricular ejection fraction \<30 percent, valvular vegetations, or infective endocarditis).
   * No other specific cause of stroke identified, such as arteritis, dissection, migraine, vasospasm, drug abuse, or hypercoagulability. Special testing, such as toxicological screens, serological testing for syphilis, and tests for hypercoagulability, will be performed at the discretion of the treating physician and local principal investigator, if needed.
2. TIA: Patients fulfilling all above criteria and diagnostic work-up, except the detection of ischemic lesions by CT or MRI is optional and clinical symptoms last \< 1 hours.

All patients must undergo electrocardiogram, transthoracic or transesophageal echocardiography (TTE or TEE) and at least 24 hours of cardiac rhythm monitoring (Holter monitor or telemetry or equivalent).

Patent foramen ovale is not an exclusion criterion. Planned or existing implantation of an implantable cardiac monitor or cardiac pacemaker is not an exclusion criterion.

Exclusion Criteria:

* History of AF, AF on 12-lead ECG, or any AF of any duration during heart-rhythm monitoring prior to inclusion into the study
* Technical problems or bad quality of the echocardiogram making it impossible to measure the main parameters for calculating the LaHAsPa-Score (sPA-TDI, LAVI)
* Wearing time \< 1 week (combined recording time \< 168 hours) due to patient withdrawing from study, patch dissolving or technical defects
* Life expectancy \< 1 month
* Patients under custody or mentally not being able to give written informed consent