CHICAGO, Dec. 7, 2010 /PRNewswire-USNewswire/ -- One evening last March, Larry Ambrose left his bed in the middle of the night to check the time. Much to the 71-year-old's surprise, he was only able to see three out of the four glowing numbers on the digital clock in his kitchen. Ambrose returned to bed, but within days was hospitalized for what was later diagnosed as a stroke. After extensive testing, his physicians told him they could not determine the cause.
Cryptogenic stroke, or stroke of undetermined cause, accounts for 25 percent of all strokes. In many of these cases, physicians believe atrial fibrillation may occur without the patient's knowledge, causing the stroke. To better understand the connection between atrial fibrillation and stroke, Northwestern Medicine physician researchers from cardiology and neurology have teamed up to monitor people diagnosed with a cryptogenic strokes for intermittent atrial fibrillation as part of a study called CRYSTAL AF (Study of Continuous Cardiac Monitoring to Assess Atrial Fibrillation after Cryptogenic Stroke).
During atrial fibrillation, the most common type of arrhythmia (abnormal heart beat), the heart's upper chambers, or atria, quiver rather than beat; this allows blood to stay in the chamber and potentially cause a clot. If the clot travels from the heart and reaches the brain, a stroke is imminent. "Patients with atrial fibrillation are at a greater risk for stroke than the general population," said Rod Passman, MD, medical director for the Center for Atrial Fibrillation at the Bluhm Cardiovascular Institute of Northwestern Memorial Hospital and associate professor of cardiology at Northwestern University's Feinberg School of Medicine. "Fifteen percent of all strokes are in patients with atrial fibrillation."
The CRYSTAL AF trial will enroll approximately 450 people who have been diagnosed with a cryptogenic stroke across 55 centers. Approximately half will be