Heart rhythm disturbance, stroke and anticoagulant therapy

This study evaluated the association between atrial fibrillation and ischemic stroke, as well as the effect of anticoagulant therapy on intracranial bleeding. 

Atrial Fibrillation (AF) is a rhythm disturbance of the heart muscle that causes turbulent blood flow within the heart. This turbulence promotes blood clotting. Such a clot is unstable and pieces of it may break off, and travel to the brain, leading to the obstruction of an artery supplying blood to the brain. Therefore, AF increases the risk for ischemic stroke (narrowing or blocking of an artery supplying blood and oxygen to the brain, causing severely reduced blood flow or ischemia). Patients with AF are sometime treated with warfarin, an anticoagulant drug (a medicine that helps prevent blood clot formation), thus may reduce the risk for stroke. However, anticoagulant therapy may increase the risk of intracranial hemorrhage or ICH (a bleeding into the cranial cavity resulting in damage of brain and the surrounding tissue). ICH may also occur secondary to high blood pressure (hypertension). This study aimed to bring an update to the association between AF and stroke and to assess the risk and benefits of anticoagulant therapy. 

The study included 2 groups of patients from hospitals in Sweden. The first group was a population of 1.56 million people, out of which 66,292 were diagnosed with AF. The prevalence (proportion of a population found to have a certain condition) of AF in the general adult population over more than 20 years was 3.2%. The second group consisted of 5426 patients with a primary diagnosis of ischemic stroke or ICH. AF prevalence in ischemic stroke was 38% compared to 23% in ICH. More than have of patients who had an ischemic stroke were more than 80 years old. Warfarin therapy reduced the risk for ischemic stroke by 50.4%, but ICH was more common in patients with AF under warfarin treatment. Hypertension was the most important risk predictor of stroke at all age groups.

In summary, AF was found to be more common than previously considered, and associated with a high risk of ischemic stroke. Warfarin therapy significantly reduced the risk of ischemic stroke in patients with AF, but increased the risk for ICH. 

There was no data about patients who were undertreated with warfarin and presented with ischemic stroke. In addition, some other disorders such as hypertension might have been under-reported. These could affect the results.

Consult your physician about the necessity of anticoagulant treatment.