There are five million people in the U.S. alone with atrial fibrillation, a number that's expected to double in the next 20 years. When left untreated, this very complex heart rhythm disorder, also known as arrhythmia, can cause heart failure and stroke.
Treatment often starts with lifestyle changes and medication, but many patients can't tolerate the medication or continue to experience breakthrough arrhythmia. For this group, physicians have relied on surgical ablation of the areas in the heart causing the unsteady rhythm. Knowing which areas to ablate, however, hasn't been an exact science.
As a physician and software engineer, Sanjiv Narayan, MD, professor of cardiovascular medicine and director of the Atrial Fibrillation Program at Stanford, was curious about one question — Is atrial fibrillation chaos or a complex, but understandable pattern?
Narayan and his team began studying these rhythms and found that by using engineering and software modeling, together with a computational approach, they could map atrial fibrillation (AF). Rather than chaos, they discovered that AF is a complex but deterministic pattern, pinpointed with small, localized areas driving the electrical activity. These areas look like the eye of a storm or a spinning top, says Narayan, sending off disorganized activity like the corona emanating from the sun. "We developed physiological models and software that allowed us to identify 'sources' for AF and target them for ablation. If you eliminate (ablate) the sources for atrial fibrillation, your patient returns to normal rhythm."
This new form of ablation, called Focal Impulse and Rotor Modulation or FIRM, is based on understanding the rhythm better, says Narayan, and therefore has nearly doubled treatment success rates and reduced the amount of ablation a patient receives.
"We went from a 45 percent success with a single conventional procedure as shown in many recent randomized trials to a greater than 80 percent success rate from a single procedure using FIRM-based ablation," he says. "It's changed the way we think about atrial fibrillation."
In the past, physicians empirically ablated various sections of the heart to hit areas causing the arrhythmia, without actually knowing if they were important to atrial fibrillation in any one individual. But many patients experienced breakthrough arrhythmia despite the treatment, and would undergo second, third or more ablative treatments. FIRM may lead to significantly improved results, often with less ablation since it is a more targeted approach.
"My goal is to get the best result with the minimum amount of ablation," says Narayan, who joined Stanford in September, bringing ten years of experience developing and using FIRM in patients with atrial fibrillation.