Cardiovascular MRI Predicts AF Treatment Outcome
October 8, 2008 – A new MRI-based method, delayed-enhancement cardiovascular MRI (DE-CMRI), allows doctors to detect and measure scarring on walls of heart after treated for atrial fibrillation (AF), according to a study published in the October 7, 2008, issue of the Journal of the American College of Cardiology.
In the study, Nassir F. Marrouche, M.D., assistant professor of internal medicine in the University of Utah School of Medicine and director of the Atrial-Fibrillation Program, and colleagues developed the technique DE-CMRI to create 3D images of the left atrium both before and after RF ablation in patients with AF. They processed and analyzed these images using custom software tools and then used computer algorithms to calculate the extent of LA wall injury.
Marrouche and his colleagues found that all patients who underwent RF ablation showed evidence of left atrium wall injury on MRI three months after the procedure. The pattern of tissue injury correlated with the areas where the radiofrequency energy was applied during RF ablation, and thus, was presumed to reflect tissue scarring. Marrouche and his colleagues 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 Marrouche. “But performing DE-CMRI to detect left atrium wall injury is challenging because the wall of the left atrium is so thin.”
The 3D technique used by Marrouche and his colleagues achieves a much greater imaging resolution than the two-dimensional technique typically used to evaluate the extent of tissue damage after a heart attack or in other cardiac disease processes. Marrouche and his colleagues also developed methods of processing the MRI images in order to visualize the entire volume of left atrium wall injury in 3D.
The novel visualization technique and analysis developed by Marrouche and his colleagues potentially could help doctors improve planning for RF ablation procedures by making it easier to identify the heart muscle cells that need to be destroyed. Improved localization and isolation of these heart muscle cells would likely lead to a reduction in the recurrence rate of AF.
“The benefit of 3D MRI is that it visualizes the entire LA wall,” said Marrouche. “And, it is safe and non-invasive, so it can be repeated without significant risk to the patient.”
For more information: content.onlinejacc.org