Blood biomarkers may help identify stroke risk in people with atrial fibrillation

Monitoring specific substances in the blood of people with atrial fibrillation, a type of irregular heartbeat, can help identify who is at increased risk of having a stroke, even if that person already takes blood-thinning medications and avoid the risk of a cardiovascular event, suggests research presented last month during an American Heart Association Epidemiology, Prevention, Lifestyle and Cardiometabolic Health conference in the United States.

According to the research, four biomarkers present in the blood of patients with atrial fibrillation that reflect greater cardiac overload, inflammation and clotting may be associated with an increased risk of stroke. Therefore, monitoring these markers in routine blood tests could be another tool to identify which patients are at risk and would benefit from additional preventive treatment.

Atrial fibrillation is the most common cardiac arrhythmia in clinical practice and its incidence increases with age. It is estimated that 2% of the adult population has atrial fibrillation and this number can reach 12% in people over 80 years of age. According to cardiologist Humberto Graner, from Hospital Israelita Albert Einstein in Goiânia, atrial fibrillation is characterized by the accelerated and irregular beating of the heart atria, which can lead to inefficiency in pumping blood.

The risk of stroke exists because the two upper chambers of these patients’ hearts (the atria) tremble, instead of contracting completely, which ends up interfering with the heart’s ability to pump blood adequately to the lower chambers of the organ. The problem is that blood that has not been pumped correctly can accumulate and form clots. These, in turn, can escape and migrate through the bloodstream, causing an ischemic stroke – one that happens when the vessels that irrigate the brain become blocked, interrupting blood circulation in the area.

It is precisely for this reason that most people with atrial fibrillation, especially the elderly or those with other comorbidities, need to take anticoagulants for life, with the aim of preventing these thromboembolic events”, explains the doctor.

According to the cardiologist, atrial fibrillation can be controlled, but it is often considered a chronic condition. “There are strategies for management, which include controlling the rhythm or heart rate, and in some cases, procedures such as catheter ablation can sustainably restore the heart’s normal rhythm, which some may consider a ‘cure.’ However, even after ablation, some patients may need to continue anticoagulant therapy to prevent stroke, especially if they have other risk factors,” he warns.

Using anticoagulants continuously is not always enough to prevent a person from suffering a stroke. That’s why scientists decided to investigate whether there was another way to identify the increased risk and try to prevent the event from happening, as stroke is one of the main causes of hospitalizations, death and permanent disability around the world.

“Anticoagulants reduce the risk of stroke by 60 to 70% in patients with atrial fibrillation. There is no perfect anticoagulant that can 100% prevent a stroke. That is why there is concern about this residual risk. In other words, even patients who use medication appropriately and undergo regular clinical monitoring with a cardiologist can have an ischemic stroke resulting from a thrombus that originated in the heart”, says Graner.

What the study shows

In the research, scientists evaluated 713 adults over the age of 45 (average of 76 years) who had atrial fibrillation and used oral anticoagulants at the beginning of the study, but without a history of stroke. Nine blood biomarkers were measured. The results showed that 9% (67) of participants had an ischemic stroke for the first time over 12 years of follow-up and there were positive associations of four biomarkers involved in cardiac overload, inflammation and coagulation.

According to researchers, blood clots appear to form more easily in people with higher levels of these biomarkers, so identifying them would be the first step in understanding what else may need to be done, such as using other medications and even procedures.

Graner emphasizes that, despite treatment, the risk of stroke is not completely eliminated and it can happen in patients with atrial fibrillation who correctly use prescribed medications, for example, who have drug interactions that reduce the effectiveness of the anticoagulant or even due to the presence of other vascular risk factors. “In addition, there are cases of stroke that occur despite adequate anticoagulation, which can be attributed to mechanisms that are not completely understood or to limitations in the anticoagulants themselves, which we call residual risk,” she says.

According to Graner, the biomarkers tested in the research are not linked to stroke specifically and, therefore, are not usually used in clinical practice in this sense. But he points out that some blood biomarkers have been studied more and have been associated with a higher risk of stroke, such as elevated levels of D-dimer, troponin and type B natriuretic peptide.

The objective of the study was precisely to try to find a marker that, in the context of patients with atrial fibrillation and using anticoagulants, can identify those at higher risk of stroke. The idea is to discover what could contribute to this persistent risk. The costs and complexity of the tests vary, but in general they are affordable”, says the cardiologist.

Despite this, the use of these tests in clinical practice is still limited, mainly because science still does not know what needs to be done if any of the biomarkers are at high levels. “There is still no specific strategy to deal with this information. Should we increase the anticoagulant dose? If we increase the dose, what happens to the risk of bleeding? Would there be another treatment to reduce the residual risk of having a stroke, even if treated correctly? We still don’t have answers to this information”, he concludes.

Source: Einstein Agency

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