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| |  Novel Imaging Approach May Assist in Predicting Success of Treatment for Atrial Fibrillation SALT LAKE CITY, Utah -- October 8, 2008 -- Researchers have developed a magnetic resonance imaging (MRI)-based method for detecting and quantifying left atrium (LA) scar formation in patients who have undergone atrial fibrillation (AF). The results of the study are published in the October 7 issue of the Journal of the American College of Cardiology. "Until now, there has not been an accurate, non-invasive way to assess LA scar formation," said lead author Nassir F. Marrouche, MD, Atrial-Fibrillation Program, University of Utah School of Medicine, Salt Lake City, Utah. "We have developed a novel MRI-based method to detect and measure the extent of LA wall scarring and, potentially, predict the success of RF [radiofrequency] ablation in patients with atrial fibrillation." Dr. Marrouche and colleagues developed a technique for using delayed-enhancement cardiovascular MRI (DE-CMRI) to create 3-D images of the LA both before and after RF ablation in patients with AF. They processed and analysed these images using custom software tools and then used computer algorithms to calculate the extent of LA wall injury. The study found that all patients who underwent RF ablation showed evidence of LA wall injury on MRI 3 months after the procedure. The pattern of tissue injury correlated with the areas where the RF energy was applied during RF ablation, and thus, was presumed to reflect tissue scarring. Researchers also found patients with a higher percentage of LA wall injury were more likely to be free of arrhythmia than patients with lower percentages, suggesting the degree of scarring is linked to the likelihood of success in the RF ablation procedure. "DE-CMRI is an established method for evaluating the tissues of the heart after a heart attack," said Dr. Marrouche. "But performing DE-CMRI to detect left atrium wall injury is challenging because the wall of the left atrium is so thin." The novel visualisation technique and analysis could potentially help doctors improve planning for RF ablation procedures by making it easier to identify the heart muscle cells that need to be destroyed. Improved localisation and isolation of these heart muscle cells would likely lead to a reduction in the recurrence rate of AF. "The benefit of 3-D MRI is that it visualises the entire LA wall," said Marrouche. "And, it is safe and non-invasive, so it can be repeated without significant risk to the patient."
SOURCE: University of Utah Health Care
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