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Atrial Fibrillation - New Technology Doubles Treatment Success Rate

A new type of technology that precisely targets the causes of irregular heart rhythms in patients with atrial fibrillation has the potential to nearly double the success rate of treating the condition, according to a landmark study published online in the Journal of the American College of Cardiology this week.

The study shows the new targeting method achieved an 86% improvement on the current treatment.

Atrial fibrillation is the most common type of arrhythmia, a condition where disorders in the heart's electrical system cause disturbances in the speed or rhythm of the heartbeat. There are about 5 million Americans living with the condition.

Electrical"Hotspots" Shut Down in Minutes Now for the first time, researchers from the University of California Los Angeles (UCLA) and Indiana University in the US, report having found that the irregular heart rhythms of atrial fibrillation are caused by small electrical localized sources or "hotspots" inside the heart called focal impulses or rotors.

This shows atrial fibrillation is much simpler than the conventional view that the waves that cause the disturbance are chaotic and non-localized, thus requiring a lengthy procedure to eliminate.

The researchers liken the focal beats or rotors to mini-tornadoes or spinning tops. Rotors can be likened to an "eye of a storm", they say.

Lead author Sanjiv Narayan, a professor of medicine at UC San Diego, visiting professor at the UCLA Cardiac Arrhythmia Center, and director of electrophysiology at the San Diego Veterans Affairs Medical Center, told the press:

"We are very excited by this trial, which for the first time shows that atrial fibrillation is maintained by small electrical hotspots."

More significantly, in their study, Narayan and colleagues describe how they have found a way, using a new type of physiological mapping called FIRM (Focal Impulse and Rotor Modulation), to locate the electrical hotspots and shut them down in a matter of a few minutes. And they show that the new targeting technology produces long-lasting results.

The researchers expect their findings will help cardiologists better target and treat arrhythmias.

At present, many of the patients who receive standard treatments for atrial fibrillation see a return of the condition, because of problems pinpointing the precise source of the arrhythmia. The CONFIRM Study The study is part of a larger trial called CONFIRM, which stands for Conventional Ablation for Atrial Fibrillation With or Without Focal Impulse and Rotor Modulation.

The CONFIRM trial examined 107 cases of patients referred for non-surgical catheter ablation to treat paroxysmal or persistent (72%) atrial fibrillation.

A non-surgical catheter ablation is where an electrophysiologist inserts a wire with a metal-tipped catheter into a vein in the groin and threads it up to the heart.

When it reaches the heart, the tip of the catheter delivers radiofrequency heat waves that burn away bits of heart tissue that cause the erratic electrical signals.

36 of the patients underwent conventional ablation where the hotspots were first located using the new technology ("FIRM-guided"), while the other 71 had conventional ablation alone.

The results show that in 86% of the FIRM-guided patients, the new procedure allowed the doctors to shut down or very significantly slow atrial fibrillation in an average of just 2.5 minutes.

With FIRM, they were able to locate to administer very small, precise burns, aimed directly at the source of the electrical disturbances.

Conventional catheter procedures can take hours of treatment over large regions in the heart and often does not shut down atrial fibrillation.

The patients were then followed for at least two years after their procedures. During that time they wore implanted ECG monitors that accurately tracked their heart rhythms over time.

When they examined the ECG readings, the researchers found that the group that underwent FIRM-guided catheter ablation had 82.4% freedom from atrial fibrillation episodes compared with only 44.9% in the group that had only conventional catheter ablation.

Thus they concluded the FIRM-guided method showed an 86% improvement over the conventional method. Dawn of a New Phase of Managing Atrial Fibrillation Narayan said they were excited by the results that showed how "brief FIRM guided ablation can shut down the arrhythmia and bring the heart back to a normal rhythm after only minutes of ablation".

Co-author Kalyanam Shivkumar, director of the UCLA Cardiac Arrhythmia Center and a professor of medicine and radiological sciences at UCLA, said they were very gratified to achieve a result of 80% ablation success rate after a single procedure.

"This is the dawn of a new phase of managing this common arrhythmia that is mechanism-based," said Shivkumar.

Various grants to Narayan funded the science behind this work. These came from the National Institutes of Health, including one awarded as part of the American Recovery and Reinvestment Act, and by the Doris Duke Charitable Foundations.

The discoveries are owned by the Regents of the University of California who have licensed them to a start-up company called Topera Medical, which has secured clearance from the US Food and Drug Administration (FDA) for the physiological mapping system, which is called RhythmView.

Narayan is a co-founder of Topera, and has equity interest in the firm, as do some of his co-authors.

The following Youtube video shows Narayan giving an update on FIRM in an interview with StopAfib at the Heart Rhythm 2012 congress, which took place in Boston in May.

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