Delayed Enhancement MRI Technique May Predict, Prevent Strokes

Researchers have found that delayed-enhancement magnetic resonance imaging (DE-MRI) technology has potential for predicting the risks of strokes, the third leading cause of death in the United States.

The study included 387 patients who were treated for atrial fibrillation (AF) at either the University of Utah's Comprehensive Arrhythmia and Research Management (CARMA) Center (Salt Lake City, UT, USA) or the Clinical Center Coburg (Coburg, Germany). AF is a little known heart rhythm disorder that affects more than 3.5 million Americans and causes more than 66,000 deaths a year. Individuals with AF are two to seven times more likely to suffer a stroke than the general population.

The goal of the study, published in the February 15, 2011, issue of the Journal of the American College of Cardiology, was to determine if there was an association between an AF patient's heart damage (for example, left atrial [LA] fibrosis), which was detected using DE-MRI, and typically used markers for the risk of stroke, specifically the CHADS2 index. Although additional prospective studies are needed, the preliminary findings indicate that DE-MRI-based detection of LA fibrosis is independently associated with prior history of strokes. Moreover, the results provide preliminary evidence that the physiologic features of the LA could be used, in addition to clinical features, when identifying stroke risk in patients.

"We believe this method can be a valuable tool for clinicians to use in conjunction with the CHADS2 index for risk analysis and decisions about anticoagulation medications when treating AF patients,” said Nassir Marrouche, MD, associate professor of cardiology and executive director of the CARMA Center and director, cardiac electrophysiology laboratories, for the University of Utah's division of cardiology.

"Potentially, this will lead to improvement in current risk stratification schemes and enhance our understanding of the risks of thromboembolic events in AF patients. We also hope this will lead to the development of effective strategies for stroke prevention.”

Although the anticoagulant warfarin is highly effective in preventing strokes, the agent also is associated with life-threatening hemorrhaging and requires intensive dosage monitoring. Risk stratification schemes have been developed to tailor anticoagulation therapy to the patients' risk, and the CHADS2 index is the most accepted risk stratification model. However, while this index is a valuable tool for predicting cerebrovascular events in high-risk patients, clinicians depend more heavily on clinical judgment when predicting thromboembolic risk in moderate-risk patients, a considerable portion of the AF population. The identification of novel, independent risk factors by DE-MRI may supplement existing tools to help guide clinician judgment in better allocating anticoagulation therapeutic strategies, particularly with moderate risk AF patients.

The study investigators concluded that LA fibrosis as determined through the use of DE-MRI is "associated with an increased risk of thromboembolism in AF patients. Clinician use of both a CHADS2 index and a quantified measure of atrial fibrosis has the potential to provide a more rigorous risk assessment and improve future risk stratification schemes.”

The University of Utah CARMA Center is conducting innovative research on the use of MRIs to treat atrial fibrillation. In 2009, it opened the first integrated electrophysiology (EP)-MRI research and clinical laboratory in North America. IN 2011, it has begun a worldwide patient evaluation program at 16 international medical centers to investigate the use of delayed enhancement MRI to stage the progression of the disease. The CARMA Center also has developed the Utah AF staging system, which enables early detection and personalized treatment and management for each atrial fibrillation patient.

Related Links:
University of Utah's Comprehensive Arrhythmia and Research Management Center