High blood pressure, atrial fibrillation or deposits in the carotid arteries: A large proportion of the approximately 20,000 ischemic strokes in Austria every year can be traced back to diseases of the vessels or the cardiovascular system. However, atrial fibrillation – a cardiac arrhythmia – often remains undetected for a long time.
Researchers at Med-Uni Graz have developed a tool to better clarify the cause of the stroke. This is to prevent recurring strokes.
Often not noticed
Atrial fibrillation in the heart is often not noticed by those affected, but can lead to dangerous secondary diseases such as a stroke, in which the blood supply to areas of the brain is interrupted, explained Markus Kneihsl from the University Clinic for Neurology in an interview with the APA. In this most common form of cardiac arrhythmia, there are rapid succession of irregular impulses (fibrillation) in the auricles.
The uncoordinated rapid beating of the heart atria slows blood flow. This can cause blood clots to form, which increases the risk of a stroke, among other things. The frequency of atrial fibrillation increases with age.
Difficult to diagnose
However, if the cardiac arrhythmia only occurs in an attack, it is difficult to diagnose and is then often not recognized as the cause of an ischemic stroke: “It is insidious that many patients do not have any symptoms and atrial fibrillation often only occurs in short episodes, which then last for days can give way to a normal heartbeat for weeks,” as Kneihsl explained.
In this case, proof is often only possible with complex diagnostics such as intensive long-term ECGs, which achieve continuous monitoring of the heart rate. As a result, atrial fibrillation is often not diagnosed at all during the clinical examination of stroke patients.
Avoid strokes
“However, knowledge of the actual cause is crucial in order to avoid another stroke through the appropriate therapy,” emphasized the Graz researcher. For example, patients at high risk of atrial fibrillation might take anticoagulant (blood-thinning, NB) medication to prevent another stroke.
A team of neurologists from Graz, led by Thomas Gattringer and cardiologists from the University Clinic for Internal Medicine (study director Egbert Bisping) at Med Uni Graz, has therefore set itself the goal of improving the diagnosis of stroke so that the therapy can be designed more patient-specifically.
At the “Stroke Unit” of the Graz University Clinic for Neurology, they searched for corresponding clinical, laboratory and imaging biomarkers in patients with ischemic stroke. From this, a scoring system was finally developed that can be used to predict the individual risk of atrial fibrillation in stroke patients.
Good prediction with new calculator
The study results, which recorded a sensitivity of 92 percent and a specificity of 67 percent for the one-year prediction of atrial fibrillation for the prediction tool, were published at the beginning of the year in the “European Journal of Neurology”.
In addition to age, the predictive variables now include electrocardiographic and echocardiographic characteristics, brain imaging markers and proteins that are formed in the heart (NT-pro-BNP) and can be found in the blood.
This is the basis for the decision as to whether a patient should receive anticoagulant medication for further stroke prevention.
Patients with high risk scores have a high probability of subsequent detection of atrial fibrillation. “In this patient group, an intensified, continuous cardiac rhythm monitoring is indicated,” summarized Kneihsl.
He himself wrote a dissertation on imaging and laboratory biomarkers in unclear causes of stroke and was awarded the “Award of Excellence” by the Federal Ministry of Education, Science and Research of the Republic of Austria.
The clinical risk calculator, which has already proven to be “extremely effective” in clinical practice, has recently been used for all strokes of unclear cause that are treated at the University Clinic for Neurology. In the next few weeks, the mathematical model for predicting the risk is to be installed and used across the board in all Styrian “stroke units” and internal and cardiological departments.
