Personalized Atrial Fibrillation Treatment Using New Method to “Stage” AF
June 27, 2010 8:05 AM CT
By Christine Welniak and Mellanie True Hills
At Heart Rhythm Society 2010, we saw intriguing new research into personalized afib treatment that was presented by Dr. Nassir Marrouche, Executive Director of the Comprehensive Arrhythmia Research and Management (CARMA) Center at the University of Utah Health System, and his CARMA Center team. They have developed a new methodology to personalize atrial fibrillation (AF) treatment by “staging”, which determines whether catheter ablation will likely stop the afib based on the degree of fibrosis (hardened fibrotic tissue) in the atrium. This may offer additional insight into treatment outcomes that in the past have relied on the clinical classifications of paroxysmal, persistent, and long-standing persistent atrial fibrillation.
The association between atrial fibrosis and atrial fibrillation is unclear, but generally more fibrosis means more severe afib. The CARMA Center has been using MRI (magnetic resonance imaging) to assess the level of fibrosis that results from atrial re-modeling. We first wrote about this back in 2008 in Use of MRI in Catheter Ablation for Atrial Fibrillation.
What is unique now is how this information is being used to personalize afib treatment based on the individual’s “stage”, or amount of fibrosis. The CARMA team has designated these stages as Utah 1–4 based on increasing amounts of fibrosis. Utah 1 means that there is no or minimal fibrosis in the atria, no more than 5%; Utah 2 means 5%-20% fibrosis; Utah 3 means 20%-35% fibrosis; and Utah 4 means more than 35% fibrosis in the atria.
Generally, patients with paroxysmal atrial fibrillation fall into the Utah 1 or 2 categories. However, according to Dr. Marrouche, those who are paroxysmal can still have significant atrial remodeling, and 9% of individuals so far who have been classified as Utah 4 actually had paroxysmal AF.
Thus the Utah staging system may better account for the progression of AF than the current definitions. For instance, a patient may have less than 10% atrial fibrosis at the time of diagnosis, but can progress to over 20% in just one year. The individual could continue to be considered paroxysmal despite significant atrial remodeling having occurred. Under the Utah staging system, the patient would be re-classified from Utah 2 to Utah 3.
Of the Utah staging system Dr. Marrouche says, “This concept has really helped us personalize management of atrial fibrillation. I think every patient deserves to know what happens with his or her atria. We look at the tissue. We look at the amount of diseased tissue before we start treating the disease. Is this patient a candidate for ablation?”
Atrial Fibrosis Could Predict Ablation Success and Stroke Risk
The level of fibrosis may predict treatment outcomes. Researchers at CARMA found that 86% of patients with mild remodeling (<15% atrial fibrosis) were free from arrhythmias after an ablation procedure. Individuals with extensive remodeling — Utah 4 classification — did not respond as wel as only 25% of these patients achieved normal sinus rhythm after ablation.
The extent of atrial fibrosis may also correlate with stroke. Stroke risk is typically assessed by a CHADS2 score, which is a composite of certain risk factors (congestive heart failure, hypertension, age, diabetes, and previous stroke or transient ischemic attack). However, many physicians believe CHADS2 does not take into account other key risk factors, such as gender and vascular disease. To learn more about CHADS2 and the newer risk factors, see New Stroke Risk Factors for Those with Atrial Fibrillation (AF): Female Gender, Heart Disease, and Age.
Dr. Marcos Daccarett from the CARMA Center presented his findings on left atrial remodeling and its role in predicting stroke at the recent Heart Rhythm Society (HRS) meeting. Nearly 20% of individuals who had the highest amount of fibrosis had strokes vs. less than 2% of patients who had minimal fibrosis. Dr. Daccarett received HRS’ Young Investigator award for this research.
AF staging and these findings on stroke have led to new treatment protocols at CARMA.
- Utah 1 patients (less than 5% fibrosis) undergo catheter ablation, with the goal of isolating the pulmonary veins (PVs) that carry blood from the lungs to the heart. These patients are generally able to stop taking antiarrhythmic drugs and warfarin following ablation.
- Utah 2 patients (5%–20% fibrosis) also undergo catheter ablation to isolate the pulmonary veins as well as to encircle them. These patients may also stop taking antiarrhythmic drugs and warfarin following ablation.
- Utah 3 patients (20%–35% fibrosis) generally require more extensive lesion sets so doctors at CARMA ablate around the pulmonary veins and ablate large areas of the left atrium to “debulk” it. Debulking reduces the amount of tissue that might serve as a re-entry point for afib since ablating creates scar tissue that acts as a barrier to prevent afib from circulating or perpetuating. These patients remain on anticoagulant medication following ablation as they could remain at risk for stroke.
- Utah 4 patients (more than 35% fibrosis) do not undergo a catheter ablation as evidence suggests that individuals with extensive remodeling may not benefit from it. Instead, they remain on rhythm or rate control medication as well as anticoagulant therapy.
“The bottom line is to stage your heart if you have afib to intervene early and promote the chances of cure rather than waiting too long and dealing with the consequences of the Utah 4 stage, which is the ‘point of no return’,” Dr. Marrouche advises.
The staging system has been validated now on over 400 patients. Dr. Marrouche and his colleagues are taking their single-center experience on the road. They have initiated a multi-center clinical trial to investigate the effectiveness of the Utah AF staging system in predicting outcomes of catheter ablation in a broader patient population. At least 20 centers worldwide, including Cleveland Clinic, Mayo Clinic, Loyola, the University of Pennsylvania, and CHU Bordeaux, are participating in the study. For further information on the trial, see the DECAAF Study.
- To learn more, read: Detection and Quantification of Left Atrial Structural Remodeling With Delayed-Enhancement Magnetic Resonance Imaging in Patients with Atrial Fibrillation, R. Oakes, et al, Circulation, 2009.
- See our exclusive video interview with Dr. Marrouche where he discusses this research: Interview with Dr. Nassir Marrouche on Personalized Atrial Fibrillation Treatment Through “Staging”
Disclaimer: Patients come first at StopAfib.org — we will not compromise on that. Thus donors must do something exceptional to earn coverage here. While the CARMA Center is a new donor to StopAfib.org, and Mellanie has recently visited the facility, this research is truly important information for afib patients and must be covered. When Dr. Marrouche presented this research recently at Heart Rhythm Society, we saw many EPs’ eyes light up. His earlier research into this won him the HRS’ Eric N. Prystowsky Fellow Clinical Research Award in 2008. And at HRS this year, Dr. Daccarett won the HRS’ Young Investigator Award for a part of this research. Many top centers are joining the CARMA Center in their DECAAF trial, which could potentially revolutionize atrial fibrillation treatment and stroke avoidance. Therefore, we are covering this exceptional research because of the potential significance it holds for the afib community.
Christine Welniak writes about atrial fibrillation and other heart diseases/conditions for patients, medical professionals, and investors.
Mellanie True Hills is founder and CEO of StopAfib.org and an atrial fibrillation survivor.