MRI may change heart care

A heart expert at the University of Utah predicts that a well-known tool commonly used in other areas of medicine — magnetic resonance imaging — is poised to change how a heart rhythm disorder is treated.

Atrial fibrillation is a common heart malfunction, affecting more than 3.5 million Americans. The unbridled and chaotic contractions of the heart's upper chambers result in more hospitalizations than any other rhythm disorder.

And because blood can pool and create clots, Afib, as it's called, is a leading cause of strokes and heart deterioration. It's most often treated with medications, which may become less effective over time, and/or a process of short-circuiting errant electrical signals around the pulmonary veins, where Afib originates, called radiofrequency (RF) ablation.

Dr. Nassir Marrouche, assistant professor at the U. School of Medicine and director of the U.'s Atrial Fibrillation Program, last week shared with the American College of Cardiology in Chicago the results of studies on MRI's value in locating precisely the tissue where errant signals originate and in assessing how much damage the heart has sustained.

But MRI also has value as a real-time imaging tool during RF ablation, he said. And it's invaluable in tracking the heart's recovery afterwards.

The U. is the first in the country to refine the imaging-based heart ablation procedure to use MRI, he told the Deseret Morning News. And that directly impacts the two historic challenges of ablation: safety and outcome.

Complications of ablation can include narrowing veins, or perforation of the atrial wall and the esophagus, which can be deadly. One approach has been to use lower RF energy to ablate the tissue. But Marrouche said that better imaging is a key to successful treatment.

He came to the U. 17 months ago from the Cleveland Clinic primarily because of the reputation of the Utah Center for Advanced Imaging and the Scientific Computing and Imaging Institute as leaders in use of interventional MRI and advanced imaging.

The technology has opened a whole new world, he said. "For the first time ever, we can see regions in left atrial muscle, which is a tiny chamber that was impossible to see." Before a procedure, MRI can show the details and extent of damage caused by arrhythmia. Through an unknown process, heart tissue subjected to the wild bounce of Afib can become fibrotic and die. Knowing the extent of that not only points out areas for treatment but also indicates whether a patient is a candidate for ablation, since cure rates are low when more than half the tissue is scarred. After the ablation, tissue changes can be tracked.