Irregular Heartbeat May Raise Risk for Silent Stroke

Atrial fibrillation may more than double likelihood of silent cerebral infarction

(RxWiki News) Millions of patients may have strokes each year and not realize it. These “silent” strokes can cause memory loss but have no outward symptoms. And those with atrial fibrillation may be especially at risk.

With some strokes, a blood clot blocks blood flow to the brain — and the signs are apparent. A side of the face droops, or speaking or walking is impaired, for instance.

The silent stroke, or silent cerebral infarction (SCI), may damage part of the brain that affects memory, but symptoms aren’t always obvious. New research has found that atrial fibrillation (AF), a type of abnormal heart rhythm, may double the risk for silent stroke.

"Atrial fibrillation, a fairly common irregular heart rhythm, has long been associated with strokes," said Jeffrey Schussler, MD, an interventional cardiologist at Baylor Heart and Vascular Hospital and Baylor University Medical Center at Dallas.

"Not everyone knows when their heart is out of rhythm, and so some strokes (especially minor strokes) can happen without a person being aware. Knowing that your heart is out of rhythm can lead to treatments such as blood thinners, which can reduce a person's risk," said Dr. Schussler, who was not involved in this study.

Jeremy N. Ruskin, MD, with Massachusetts General Hospital in Boston, and colleagues, reviewed 11 studies on the link between silent strokes and AF.

They studied a total of 5,317 patients. Their ages ranged from around 50 to 83 years old.

The study authors found that AF was tied to a more than two-fold increase in risk for silent stroke — compared to patients without AF. This risk applied to patients who had no history of symptomatic stroke. "Symptomatic" means the stroke produces recognizable signs.

Silent stroke was identified in patients through computed tomography (CT) or magnetic resonance imaging (MRI). CT and MRI are common scanning methods that can allow doctors to detect lesions on the brain. Lesions typically suggest damage from a silent stroke.

Dr. Ruskin and colleagues found that 40 percent of AF patients who had MRIs and 22 percent who had CT scans had lesions on the brain.

“This [study] suggests that SCIs are very common in patients with AF,” the authors wrote.

As many as 11 million US patients have a silent stroke each year, reports the American Heart Association (AHA).

The AHA estimates that 2.7 million Americans have AF. This irregular heartbeat (arrhythmia) is the most common heartbeat abnormality in people older than 65.

There are several ways to reduce the health risks tied to AF, the AHA notes. These include getting regular exercise, eating a heart-healthy diet, managing high blood pressure, limiting alcohol and caffeine, not smoking, lowering cholesterol and keeping a healthy weight.

The research was published Nov. 3 in the Annals of Internal Medicine.

The study was funded by the Deane Institute for Integrative Research in Atrial Fibrillation and Stroke, Massachusetts General Hospital, Harvard Catalyst and the Harvard Clinical and Translational Science Center. Conflict of interest information was not available in the research provided.

Review Date: 
November 3, 2014