A unique scientific collaboration that could offer an innovative potential treatment for atrial fibrillation has blossomed within USF Health, thanks to a chance encounter in a hallway, a plain green chalkboard and a most surprising star: the European honeybee.

It represents a convergence of two distinctly different medical mindsets – pharmacology and immunology – and a blend of high-tech bio-engineering with an old-school writing surface. And then there’s the bee, which has pollinated the process in an exciting and novel way.

The result is a newly published paper in the Proceedings of the National Academy of Sciences that details efforts to develop a non-invasive treatment for atrial fibrillation (also referred to as AFIB or AF) by blocking a potassium channel that can go rogue within the heart, leading to a dangerous, irregular and fast rhythm in the atria, the heart’s upper chambers, increasing the risk of blood clots that can travel to the brain and cause a stroke.

The material to create this blocker  is a small peptide that has been successfully tested in mice and sheep.

“This peptide was originally isolated in the past from the European honeybee’s venom,” said Sami Noujaim, Ph.D., associate professor in Molecular Pharmacy & Physiology and senior author of the eight-person study that includes lead investigator Bojjibabu Chidipi, Ph.D., a researcher in the USF Health Morsani College of Medicine. “We have demonstrated in tests on small animals that it can block this rogue potassium channel. And by blocking this channel, it was able to eliminate atrial fibrillation.”

That research might well have never progressed to this point had it not been for a pair of fortuitously situated offices. Co-author Michael Teng, Ph.D., an associate professor in the Division of Allergy and Immunology in the College of Medicine, works in an office adjacent to the one occupied by Dr. Noujaim – in spite of their divergent fields.

Micheal Teng, PhD, (left) and Sami Noujaim, PhD, have collaborated to study whether a bioengineered peptibody could help treat atrial fibrillation.

“I work in viruses, a completely different area than Sami’s,” said Dr. Teng. “But there’s this green chalkboard hanging on the wall outside our offices – I can see it right now from my desk, in fact. You’d think, ‘Let’s take it down, nobody uses chalkboards anymore.’ But Sami loves this chalkboard. So, we’re neighbors and we talk to each other. And one day, prior to the pandemic, he was trying to figure out a problem.”

Here’s how Dr. Noujaim remembers it unfolding: “I was at the board with Bojji and other members of the lab. We drew the potassium channel on the board. And I was telling them that the drugs currently available for AF are small molecules and have side effects. What if we’re able to actually design our own blocker? And instead of that blocker being a small molecule, what if it was a protein? Because we can design and generate proteins.”

At that moment, Dr. Teng was passing by the group in the hallway en route to his office.

“I go, ‘Hey Mike, I know that in immunology there are ways people have been engineering proteins – can we do this here?’ “ Dr. Noujaim recalled. “Mike said, ‘Absolutely,’ and that’s where things took off.”

Electrical activity is generated by the heart via ion channels of sodium and potassium. They work like resistors and can conduct current. Atrial fibrillation occurs, in part, when a specific type of potassium channel in the heart goes out of whack, and starts passing potassium when it should not.

Bojjibabu Chidipi, PhD, (left) talks with Sami Noujaim, PhD, about how a bioengineered peptibody could help treat atrial fibrillation.

“This is where the problem occurs,” Dr. Chidipi said. “Instead of contracting and emptying the blood vessels into the ventricles, and the ventricles contracting and ejecting blood into the circulation, these atria cannot contract because of the atrial fibrillation caused by the rogue potassium current. They just sit there and quiver.”

“When that happens, they cannot completely empty the blood,” Dr. Noujaim added. “And blood does not like to stay stagnant. So there’s a high probability of forming a clot in the atrial chamber. At some point that clot can launch into the circulation and reach the brain, causing a stroke.”

One common form of treatment is to put a person with AFIB on blood thinners.  Pharmaceuticals are also utilized to restore normal sinus rhythm of the heart. A more invasive step is called ablation, a procedure in which the trouble spots in the atria are located and corrected via catheters inserted through the groin and advanced to the atria.

“The problem is that there is a high chance the AF will return at some point,” Dr. Noujaim said. “Another alternative is medication. But the problems with the existing medications are two-fold: One, they are not very effective, and two, they may cause other types of arrhythmia. And that is where we came in. We asked ourselves, ‘What would be the best way to restore the normal sinus rhythm with a pharmaceutical, without having other side effects on the heart?’”

Several members of Dr. Sami Noujaim’s team collaborated on the peptibody research. Pictured (l-r) are Bojjibabu Chidipi, PhD, Dr. Noujaim, Obada Abou-Assali, MS, and Mengmeng Chang, MD, PhD.

Now back to the green chalkboard. The challenge was that the very small peptide, called tertiapin, comprised of 21 amino acids from honeybee venom, doesn’t last long enough to be effective as a blocking agent. It is very short-lived when exposed to air. That led previously to the creation of a synthetic oxidation-resistant version called tertiapinQ. This is what Dr. Noujaim and his team would rely upon in their testing.

But there was still a problem with these peptides breaking down too quickly in the body, whether injected or taken as a pill. So they wondered: Could this peptide be fused with an antibody fragment and give it longer-lasting life to combat AFIB?

“We talked it through and drew on the board for about 15-20 minutes,” Dr. Teng said. “And we came up with this idea of attaching that little peptide onto the stem of an antibody.”

The stem could be hooked onto the peptide, forming a “peptibody.” That concept has been utilized before, but not for treating atrial fibrillation. With this new peptibody AFIB application, a drug could remain in the bloodstream for longer periods of time without breaking down.

“That way you will have a sustained effect of the therapeutics,” Dr. Noujaim said. “Now we have a formulation that does not need to be administered daily– it could be every week or every month. We’re excited to have received a patent for this as well as a nice grant from the National Institutes of Health.”

“So far, there are two peptibodies approved by the FDA and available in the market to treat low blood platelet counts, and for glucose control in type 2 diabetes” Dr. Chidipi added. “We are the first to demonstrate that bioengineered peptibodies could potentially treat cardiac arrhythmia.”

Meanwhile, new collaborators are on board at a cardiovascular center in Spain to work with USF Health in testing it further..

It took collaboration with a bee and a board at USF Health to make it all possible.

— Story by Dave Scheiber for USF Health News; photos by Allison Long, USF Health News.

Seeking to understand how the heart short circuits, Sami Noujaim looks for new drugs to fix atrial fibrillation

Within the last three years, USF biomedical scientist Sami Noujaim, PhD, lost his older brother to sudden cardiac death and his 80-year-old father was diagnosed with atrial fibrillation.

The experiences gave Dr. Noujaim a new appreciation for his research on understanding how normal and abnormal electrical impulses are generated in the heart. The Cardiac Electrophysiology Research Laboratory he directs focuses on finding more effective drugs to treat atrial fibrillation, the most common irregular heart rhythm and a condition for which prevalence rises markedly after age 65.

Sami Noujaim, PhD, directs the Cardiac Electrophysiology Research Laboratory in the USF Health Department of Molecular Pharmacology and Physiology.

“When life throws something like that at you, the work you do takes on a more personal tone, a sense of mission.  I realized that neither myself nor my loved ones are immune from the cardiovascular diseases I’m studying,” said Dr. Noujaim, an assistant professor in the Morsani College of Medicine’s Department of Molecular Pharmacology and Physiology. “We are all at risk.”

 Dr. Sami Noujaim describes the focus of his laboratory’s research.

Searching for noninvasive solutions to atrial fibrillation

Atrial fibrillation is a problem with the cardiac electrical circuitry that controls the rate and rhythm of the heartbeat. The condition affects about 9 percent of the U.S. population age 65 or older, according to the Centers for Disease Control and Prevention, and can lead to potentially deadly complications such as stroke and heart failure. While signs of atrial fibrillation may include heart palpitations, fatigue, lightheadedness, dizziness and shortness of breath, some people experience no noticeable symptoms.

Treatment and management options include lifestyle changes, medications to help control heart rate and rhythm and reduce the risk of blood clots, controlled electrical shock (cardioversion to reset heart rhythm), invasive procedures (catheter ablation) and surgical implantation of pacemakers.  However, a major challenge is that atrial fibrillation frequently recurs after normal heart rhythm (sinus rhythm) is restored.

“The existing treatments can be good, but there is a lot of room for improvement, so we are focusing on contributing to noninvasive treatment options,” Dr. Noujaim said. “If we could help physicians get patients with atrial fibrillation to long-term normal sinus rhythm, and perhaps increase the ability to take them off blood thinners, it would be a significant improvement.”

Dr. Noujaim’s laboratory uses specialized equipment to measure the electrical activity of heart muscle cells and image what he describes as “atrial fibrillation in a dish.”

Closing in on a pathway linking aging and Afib

Dr. Noujaim currently works with colleagues at USF and other institutions, including Tufts University, the University of Michigan, and Northeastern University, to investigate how age-related changes in specific potassium ion channels known as GIRK may trigger a cascade of molecular events leading to atrial fibrillation. His research, supported by a five-year $2.14 million RO1 grant from the National Heart, Lung and Blood Institute employs techniques including structural biology, molecular simulations, and cellular and whole organ electrophysiology.

The researchers hypothesize that in aging-associated atrial fibrillation, the condition may arise when a biochemical pathway controlling the GIRK postassium channels begins behaving abnormally, in part because of structural and metabolic cardiovascular changes that occur with aging.  High blood pressure, diabetes, and coronary artery disease– among the most common risk factors for atrial fibrillation – become more common as people grow older.

At USF, Dr. Noujaim collaborates with Javier Cuevas, PhD, in Molecular Pharmacology and Physiology, Michael Teng, PhD, in Molecular Medicine and in Allergy and Immunology, and Juan Del Valle, PhD, in Chemistry to investigate ways to target and block the GIRK potassium channels using pharmacological approaches that rely on immunology and chemistry.

Mohammed Alhadidy (left), a biomedical graduate student, and Bojjibabu Chidipi, PhD, a postdoctoral scholar in Molecular Pharmacology and Physiology, record the electrical signals from several cells using a multichannel automated patch clamp.

 The significance of investigating the relationship between aging and atrial fibrillation.

Designing a “perfect plug” using an antimalarial drug model

“Right now, we are trying to design a perfect plug using the antimalarial drug chloroquine as a model,” Dr. Noujaim said, “We have evidence that if we block that specific type of potassium channels we will be able to stop atrial fibrillation or at least reduce its occurrence.”

Earlier work by Dr. Noujaim and others, including a study reported in the journal FASEB, demonstrated that the antimalarial drug chloroquine was effective in blocking the GIRK potassium channels and suggested a new path for discovering antiarrhythmic drugs.

Dr. Noujaim continues using cellular and animal models to pinpoint how and where the chloroquine molecule interacts with the potassium channel – with the aim of discovering a “plug” that works even better than the antimalarial drug. At the same time, he has reached out to USF Health Department of Cardiovascular Sciences to begin applying the laboratory findings to the clinic.

Working with cardiologists Bengt Herweg, MD, and Dany Sayad, MD, Dr. Noujaim recently gained approval for a pilot study to enroll 40 adults without heart damage whose atrial fibrillation has persisted more than one week and less one year. The team will test the effectiveness of chloroquine in restoring and maintaining normal heart rhythm in patients with atrial fibrillation.

The laboratory uses techniques including structural biology, molecular simulations, and cellular and whole organ electrophysiology to conduct its NIH-funded research.

Collaborating with clinicians on new treatment options

Dr. Sayad, initially surprised at Dr. Noujaim’s proposal to try chloroquine, said the strength of the preclinical data convinced him of the antimalarial drug’s potential as another antiarrhythmic option. “Treating atrial fibrillation can be especially challenging in older patients, who experience a higher recurrence of atrial fibrillation (following cardioversion) and more failure on drugs used to regulate heart rhythm,” he said.

Clinicians help biomedical scientists like Dr. Noujaim frame and focus their studies to make the research more relevant to challenges faced in treating patients, such as maintaining sinus rhythm once a normal heartbeat has been restored.

“It does not mean that the fundamental, basic science questions are not important,” Dr. Noujaim said. “To the contrary, those questions are at the heart of every single experiment we do; however, we must always think about the big picture and why we are asking those questions. And that always goes back to the clinic.”

In previous electrophysiology experiments, Dr. Noujaim and colleagues helped better define the contribution of the nervous system within the heart, otherwise known as the intrinsic cardiac ganglia, to normal and abnormal heart rhythm. Using both mouse models and patients with atrial fibrillation, the study shed light on how nerves emerging from these cardiac ganglia regulate activity of the sinus node, the heart’s natural pacemaker.  The study appeared in Cardiovascular Research in 2013.

Dr. Noujaim with members of his research team, from left, Bojjibabu Chidipi, Mohammed Alhadidy and laboratory manager Michelle Reiser.

 Dr. Noujaim comments on the importance of a clinical perspective to frame biomedical research.

Impressed by USF’s biomedical research opportunities

Dr. Noujaim came to USF in 2015 from the Molecular Cardiology Research Institute at Tufts University School of Medicine. He received his PhD in pharmacology, with distinction, from SUNY Upstate Medical University in Syracuse, NY, followed by a year of postdoctoral training there.  He then completed a three-year postdoctoral fellowship, supported by the American Heart Association, and the National Institutes of Health, at the Center for Arrhythmia Research, University of Michigan, in Ann Arbor, MI.

Dr. Noujaim said he was attracted to USF by the opportunity to be part of an emerging preeminent university committed to establishing a cardiovascular institute bridging top biomedical research and clinical care.

“The opportunities that the University of South Florida is providing for scientists are equal or greater than those at any other major academic medical center,” he said.  “It was also striking to me that, in a place the size of USF, the USF Health leadership is so actively engaged in research, with their own laboratories and grants. That’s not what you would see in a lot of places, and as a biomedical scientist it makes me feel that the leadership here really values research.”

Dr. Noujaim is passionate about the cardiovascular research his laboratory conducts, which he says has taken on a greater sense of mission since his own family’s experience with sudden cardiac death and atrial fibrillation. 

 His take on the benefit of brainstorming with scientists in other disciplines.

Some things you may not know about Dr. Noujaim:

• Born in Lebanon, he moved to the United States after graduating from high school.
• He routinely swims laps in an indoor pool.
• He enjoys experimenting with cooking, specializing in inventing new dishes by combining ingredients he finds in his refrigerator. “I’ve discovered by trial and error that no matter how bad what I cook really is, adding a tablespoon of soy sauce makes it alright,” he said.
• His first scientific experiment as a college student volunteering in Boston’s Beth Israel Deaconess Medical Center laboratory was unforgettable. He fainted while his blood was being drawn so he could use it to help study blood platelet activation and aggregation. Click on video below to find out more.

//www.youtube.com/watch?v=kGRALvR46qM

-Photos and video by Eric Younghans, and audioclips by Sandra C. Roa, USF Communications and Marketing

Tampa, FL (Dec. 12, 2014) – The USF Health Morsani College of Medicine is conducting a clinical trial comparing the effectiveness of a new rapid-onset anticoagulant medication known as Apixaban with the standard anticoagulant drug warfarin in stroke patients with atrial fibrillation, the most common type of abnormal heart rhythm.

The investigator-initiated study is part of a $2.2 million research award from Bristol Myers Squibb awarded to Arthur Labovitz, MD, professor and chair of the Department of Cardiovascular Sciences for the USF Health Morsani College of Medicine and director of Non-Invasive Cardiology at Tampa General Hospital.

USF Health cardiologist Dr. Arthur Labovitz, principal investigator for the AREST study.

Dr. Labovitz is the principal investigator for the study, which is called “Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation,” or AREST. The study is the part of the USF Health Heart Institute, which is co-directed by Dr. Labovitz.

Anticoagulant therapy lowers the risk of strokes caused by embolisms (blood clots) in patients with atrial fibrillation, but its use is associated with potentially deadly bleeding. The new randomized trial will evaluate whether early treatment with Apixaban, an alternative requiring less monitoring and re-dosing than warfarin, can prevent recurrent strokes and reduce the risk of brain bleeding in patients who have suffered a first embolic stroke.

“Current guidelines suggest delaying treatment for patients with atrial fibrillation who have had a stroke, often times for two weeks or more,” Dr. Labovitz said. “This commonly results in poor outcomes in these individuals. The AREST study will more aggressively treat these patients earlier, sometimes within 24 hours of symptoms, in order to improve their outcomes. The protocol tests the hypothesis that one of the newer blood thinners, Apixaban (Eliquis), will be safe and effective in this regard.”

Early research showing that the risk of intracranial bleeding is markedly reduced (50 percent) with the new oral anticoagulant prompted him for initiate and develop the AREST study, Dr. Labovitz said.

In the USF AREST study, researchers will give either warfarin or Apixaban to 120 adult patients admitted to Tampa General Hospital with a transient ischemic attack (TIA) or small to medium ischemic stroke, who also have a history of, or current diagnosis of, atrial fibrillation. Atrial fibrillation is a common cause of stroke.

Patients will be randomly given the medications within 48 hours of stroke symptom onset and then followed for 180 days to compare the incidence of recurrent stroke, death or intracranial hemorrhage.

USF Health’s Dr. Scott Burgin directs the TGH Comprehensive Stroke Center and is a co-investigator for the AREST study.

“This study could answer a question that has long been undefined, and that is the optimal timing for giving anticoagulant medication after having an acute stroke,” said W. Scott Burgin, MD, professor of neurology and chief of the USF Cerebrovascular Division in the USF Health Morsani College of Medicine, director of the HFAP Certified Comprehensive Stroke Center at Tampa General Hospital, and a co-investigator for the AREST study.

“This new anticoagulant medication is already showing a greater effectiveness and a higher safety profile so starting the medication sooner than the standard 14 days could improve outcomes for stroke patients.”

Dr. Labovitz (left) and co-investigator Dr. David Rose stand in the heart of the Neurosciences Intensive Care Unit at TGH. The researchers will track stroke patients taking the new anticoagulant for the AREST study.

Co-Investigators for the USF AREST study, who are all USF Health faculty, are Dr. Burgin; David Rose, MD, assistant professor of Neurology and medical director, Neuro-ICU at TGH; Sanders Chae, MD, JD, assistant professor of cardiology; Michael Fradley, MD, assistant professor of cardiology; Theresa Beckie, PhD, professor in the USF Health Morsani College of Medicine and the USF College of Nursing; Waldo R. Guerrero, MD, assistant professor of vascular neurology; and Ryan Martin, MD, a fellow in the USF Department of Cardiovascular Sciences.

For more information about the AREST clinical trial at USF Health, please contact Bonnie Kirby, MSN, RN, research administrator for USF Cardiovascular Sciences, at bkirby@health.usf.edu or call (813) 259-8543.

About USF Health

USF Health’s mission is to envision and implement the future of health. It is the partnership of the USF Health Morsani College of Medicine, the College of Nursing, the College of Public Health, the College of Pharmacy, the School of Biomedical Sciences and the School of Physical Therapy and Rehabilitation Sciences; and the USF Physician’s Group. The University of South Florida is a Top 50 research university in total research expenditures among both public and private institutions nationwide, according to the National Science Foundation. For more information, visit www.health.usf.edu

]]> https://hscweb3.hsc.usf.edu/blog/2014/04/01/usf-health-cardiologists-apply-advanced-catheter-technology-to-treat-atrial-fibrillation-at-tampa-general/ Tue, 01 Apr 2014 15:46:52 +0000 https://hscweb3.hsc.usf.edu/?p=10963 Tampa General Hospital is among the first in the region to offer the new high-tech catheter device  Tampa, FL (April 1, 2014)  –Tampa General Hospital is among the […]

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Tampa General Hospital is among the first in the region to offer the new high-tech catheter device

 Tampa, FL (April 1, 2014)  –Tampa General Hospital is among the first in Tampa Bay region to offer a new high-tech catheter device that can improve the outcomes of patients treated for atrial fibrillation, or Afib, the most common sustained irregular heart rhythm. The ThermoCool® SmartTouch® catheter, recently approved by the U.S. Food and Drug Administration, enables doctors to accurately control the amount of contact force applied to the heart wall during radiofrequency catheter ablation procedures.

The FDA has also approved the device for two other types of heart rhythm disorders, ventricular tachycardia and atrial flutter.

USF Health cardiologist Dr. Bengt Herweg in the TGH Electrophysiology Lab with a 3-D color map display of an arrhythmia. The heart rhythm disorder’s site of origin, displayed on the monitor in red, guides the doctor to the target that needs to be ablated to eliminate the heart’s irregular electrical signals. The contact force of the ablation catheter also displays on the map when the device is in use.

Catheter ablation is a minimally-invasive procedure that involves inserting a therapeutic catheter through a small incision in the groin and maneuvering it up to the heart through a blood vessel. Once it reaches the heart’s left upper chamber (atrium), the doctor uses radiofrequency energy to burn away selected areas of tissue with the tip of the catheter. This produces a scar, or lesion, to block the faulty electrical signals triggering atrial fibrillation.

The new contact-force technology relays to the physician the precise angle of the catheter and how hard it is pushing against the beating heart wall. The information, displayed on a monitor as a 3-D graphic, helps doctors steer the catheter to areas where ablation is needed and apply targeted treatment.

“The new device provides critical contact force information to help confirm that we are consistently applying the intended amount of pressure with the catheter throughout the procedure, so that optimal outcomes can be achieved,” said Bengt Herweg, MD, associate professor of medicine at the USF Health Morsani College of Medicine and director of Electrophysiology at USF Health and Arrhythmia Services at Tampa General.

“Without this technology, doctors must estimate the amount of force being applied to the heart wall through other indirect measures that have been shown not to be as effective.”

Studies indicate poor tissue contact with the catheter may cause incomplete lesion formation that could require additional treatment, while too much contact force may cause tissue injury, which may lead to complications.

One-year results from a clinical trial testing the safety and effectiveness of the device in patients with Afib showed that patients experienced a 74-percent overall success rate after treatment with the ThermoCool® SmartTouch® catheter, compared to 63 percent for patients treated with a traditional catheter. Data from the trial showed higher success rates the longer physicians stayed within a targeted contact force range, with one-year results showing an 88-percent success rate when the targeted range was maintained 85 percent of the time or more.

An estimated 3 million Americans suffer from Afib, a progressive disease that increases in severity and frequency if left untreated, and can lead to chronic fatigue, congestive heart failure and stroke.

 While most Afib patients are treated with drugs, about half are unable to control their abnormal heart rhythm with drugs or cannot tolerate the side effects. When medication does not work, the American College of Cardiology and the American Heart Association suggest catheter ablation be considered as a safe and effective treatment option.

                                                                                                                                                       -Tampa General Hospital-

Tampa General is a 1018-bed academic medical center on the west coast of Florida that serves as the region’s only center for Level l trauma, comprehensive burn care, and adult solid organ transplants. It is the primary teaching hospital for the USF Health Morsani College of Medicine. TGH is a comprehensive stroke center and a state-certified spinal cord and brain injury rehabilitation center.

                                                                                                                                -USF Health-

USF Health’s mission is to envision and implement the future of health. It is the partnership of the USF Health Morsani College of Medicine, the College of Nursing, the College of Public Health, the College of Pharmacy, the School of Biomedical Sciences and the School of Physical Therapy and Rehabilitation Sciences; and the USF Physician’s Group. The University of South Florida is a Top 50 research university in total research expenditures among both public and private institutions nationwide, according to the National Science Foundation. For more information, visit www.health.usf.edu

Photo by Ellen Fiss, Tampa General Hospital

 Media contacts:
Ellen Fiss, Tampa General Hospital, (813) 844-6397, or efiss@tgh.org
Anne DeLotto Baier, USF Health Communications, (813) 974-3303, or abaier@health.usf.edu

MRI helps assess effect of atrial fibrosis on Afib ablation therapy outcome, multinational study reported in JAMA shows

A provocative study recently reported in the Journal of the American Medical Association demonstrated that delayed enhanced magnetic resonance imaging of the atrial chambers before ablation for atrial fibrillation (AF) can help predict the treatment’s success in restoring and maintaining normal heart rhythm.

The USF Health Morsani College of Medicine’s Department of Cardiovascular Sciences was a participant in the prospective one-year trial known as DECAAF, or Delayed Enhancement-MRI Catheter Ablation of Atrial Fibrillation, that followed 272 patients from 15 centers across the United States, Europe and Australia.

Bengt Herweg, MD, associate professor of medicine and director of the USF Health Electrophysiology and Arrhythmia Services, was a co-author of the promising study, which sheds new light on the mechanism of atrial fibrillation (AF) and may ultimately change the way ablation is performed.  Dr. Herweg performs ablation therapy for AF at Tampa General Hospital.

Bengt Herweg, MD, leads the Electrophysiology and Arrhythmia Services at USF Health.

The DECAAF trial evaluated the relationship between atrial fibrosis, the amount of scarring on the walls of the heart’s left atrium, and the success of ablative therapy for atrial fibrillation, a technique that uses a catheter to burn critical tissue leading to abnormal heart rhythms, or arrhythmias.

Current methods for identifying which patients are good candidates for catheter ablation are limited.

“While the procedure can be a very effective treatment for atrial fibrillation, it does not control arrhythmias for all patients,” Dr. Herweg said. “This study indicated that delayed enhancement MRI imaging before ablation may be a reliable, noninvasive way to quantify atrial fibrosis and predict which patients will benefit.”

Among the study’s findings:

–          Hypertension was the only predictor of atrial fibrosis in patients with AF.

–          Increasing degrees of fibrosis, as estimated by delayed-enhanced MRI scans 30 days before atrial fibrillation ablation, were independently associated with a greater risk of AF recurring.

–          A comparison of post-ablation MRI images with pre-ablation images indicated a surprising finding.  Procedures targeting ablation of the fibrotic (scar) tissue rather than the standard method of isolating and ablating around the pulmonary veins, long assumed to be the trigger for AF, produced better outcomes.

“The feasibility of implementing delayed enhancement MRI screening to detect left atrial fibrosis into clinical practice could potentially improve patient selection for AF ablation and could translate into cost savings by avoiding unnecessary AF ablation procedures,” the researchers concluded.