St. Jude Medical, Inc. (NYSE:STJ), a global medical device company, announced the results of the ASymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT), a St. Jude Medical sponsored trial conducted by the Population Health Research Institute of McMaster University and Hamilton Health Sciences in Hamilton, Canada. The trial demonstrated that pacemaker patients without history of atrial tachycardia (AT) or atrial fibrillation (AF) who have device-detected arrhythmias are approximately 2.5 times more likely to have a stroke than patients who don't have device-detected arrhythmias.

The results of the trial were presented today by Dr. Jeff S. Healey, principal investigator for the arrhythmias program at the Population Health Research Institute, during the "Clinical Science: Special Reports" session at the American Heart Association Scientific Sessions 2010 in Chicago.

"These results are significant because they demonstrate that even brief, asymptomatic AF episodes can cause a stroke, and that the proportion of strokes that are associated with atrial arrhythmias is much higher than previously thought," said Dr. Healey. "This trial shows that by using the information already available in implantable pacemakers and defibrillators, physicians can identify patients at risk for stroke, earlier than would otherwise be the case, even before they experience arrhythmia symptoms."

ASSERT studied 2,580 pacemaker patients over the age of 65 with hypertension and no history of AF. The trial was a cohort study designed to determine whether the detection of arrhythmias using pacemaker-based diagnostics predicts an increased risk of stroke in elderly, hypertensive patients without any history of AF. Atrial fibrillation had previously been linked to an increased risk of stroke but it was not clear that brief, often asymptomatic AF episodes are associated with an increased risk for stroke as well.

Technologies such as the AT/AF diagnostic data and alerts available in St. Jude Medical implantable devices, including the Accent(TM) pacemaker and Fortify(TM) ICD (implantable cardioverter defibrillator), via the Merlin remote monitoring system, allow physicians and patients to be notified whenever a patient experiences significant atrial arrhythmias - abnormal heartbeats in the heart's upper chambers - such as AT or AF.

"These results further demonstrate the value of the arrhythmia monitoring algorithms and alerts offered in St. Jude Medical pacemakers and implantable defibrillators," said Dr. Mark Carlson, chief medical officer and senior vice president of research and clinical affairs for the St. Jude Medical Cardiac Rhythm Management Division. "This study reaffirms our commitment to providing physicians with the clinically relevant information that allows them to deliver more timely and effective care."

Atrial fibrillation (AF) is a chaotic, uncontrolled heart rhythm. It occurs when the upper chambers of the heart (atria) contract rapidly and irregularly - from 350 to 600 times per minute compared to a normal heart rhythm of 60 to 100 times per minute. AF is known to be a common risk factor for, and cause of, stroke. Because the atria contract so rapidly and irregularly during AF, the heart cannot beat effectively and blood is not pumped completely out of the atria. Blood that pools in the atria may clot and, if the clot moves to an artery in the brain, stroke may occur. Studies show that AF increases the risk of stroke five-fold. The risk for stroke related to AF increases with age, and AF potentially leads to a range of other debilitating symptoms as well.

Source:
St. Jude Medical