Highlights from the Third Annual Western Atrial Fibrillation Symposium
More than 300 cardiologists, physicians and others attended the Third Annual Western Atrial Fibrillation Symposium February 26-27 in Park City, Utah. The conference was sponsored by the University of Utah School of Medicine’s Division of Cardiology and hosted by the Comprehensive Arrhythmia Research & Management Center (CARMA). Following are five of the notable presentations from a world-class faculty that included physicians from leading medical centers in the U.S., Belgium, Canada, France, Germany and Japan.
AFIS: A New Solution to Manage AF Patients
Walid Saliba, MD
The Cleveland Clinic, Cardiovascular Medicine
The Atrial Fibrillation Information System (AFIS) is the first comprehensive software application to gather and present all associated clinical information for patient management in one place. It was developed in collaboration with the University of Utah School of Medicine and eCardio’s AFIB Advisory Board to provide electrophysiologists with a holistic view of patients being treated for atrial fibrillation (AF).
Patients with atrial fibrillation have various treatment options, including medication, device implant, cardioversion or ablation. They undergo numerous pre-procedural, intra-procedural, and post-procedural tests and must be carefully monitored during a challenging follow-up. Until now, the data for each episode of care could only be found in isolated “information silos,” which meant physicians had to search in multiple locations to assemble all the relevant information. AFIS presents all germane information in the diagnosis and treatment of the AF patient in one longitudinal application.
The three primary goals in developing AFIS were to:
• Provide a clinical tool for the management of the patient;
• Create a powerful teaching and research tool; for example, AFIS provides hospitals with unique imaging algorithms developed by the University of Utah for the analysis of scar burden;
• Facilitate the development of a centralized AF Registry, which allows participating hospitals to share depersonalized patient data for research purposes.
The AFIS software has three functions based on different types of data inputs. First, it maintains all the character-based data that comprises a patient’s medical history, medications, symptoms, physician reports, co-morbidities and risk factors. Second, it organizes all the information gleaned from pre- and post-procedural monitoring and allows the display of atrial fibrillation burden. Lastly, it handles an array of images from MRI and CT scanners to various electroanatomical mapping and echocardiographic data.
This application is the first comprehensive information system developed specifically to support the medical specialty of cardiac electrophysiology. By integrating all information in one place, AFIS is a valuable clinical tool that will help EPs treat AF patients.
Genetics in Atrial Fibrillation
Melvin Scheinman, MD
University of California, San Francisco Medical Center
Multiple genetic variations have been discussed as causes of atrial fibrillation. Initial findings revealed gene mutations, which resulted in gain of function of the K+ channel. This gain in function results in shortening of the action potential duration and atrial refractory period, which tends to promote maintenance of atrial fibrillation. More recently, other genetic mutations have been discovered that result in loss of function of K+ channels. These abnormalities serve to prolong action potential duration and promote early action potential after deplorizations, which may trigger atrial arrhythmias. In addition, mutations associated with a loss of function of sodium channel have been described and are thought to promote atrial fibrillation by decreasing atrial conduction velocity and thus enhancing reentrant circuits.
Non-channel genetic mutations (e.g., connexins and RAS) have also recently been found to be associated with atrial fibrillation. These “upstream” mutations are thought to encourage AF by promoting atrial fibrosis or by facilitating an inflammatory response. The hope is that identification of specific genetic abnormalities will allow for use of drugs targeted to the specific abnormalities.
Old and New Anticoagulation Strategies
John P. DiMarco, MD, PhD
University of Virginia, Cardiovascular Medicine
This discussion focused on new developments in stroke prevention and risk assessment in atrial fibrillation patients. Although widely used, the CHADS2 has limited predictive accuracy. Including female gender and history of vascular disease as variables may improve risk prediction, but any new scoring system will need to be validated in large populations. The duration of AF that requires anticoagulation is also controversial. Current guidelines state that detection of any paroxysmal AF in a moderate to high risk patient requires anticoagulation. However, data from studies in which AF was monitored in patients with implanted pacemakers and ICDs suggest that patients who only have short and/or infrequent episodes may not need to be treated. Larger studies on this issue are now under way.
Finally, alternatives to warfarin were discussed. Oral and injectable inhibitors of factor Xa and thrombin, as well as a warfarin analog with more predictable metabolism, are in development by pharmaceutical companies. One direct thrombin inhibitor, dabigatran, demonstrated favorable efficacy and safety results compared to warfarin in the recent RE-LY trial. This drug is now under fast track FDA review. Non-pharmacologic alternatives to warfarin are also under study. In the PROTECT-AF trial, a left atrial appendage occluder showed good long-term efficacy compared to warfarin. If early post-implant complications can be reduced, this or similar devices may come into widespread usage.
MRI for Management of AF: Staging the Disease and Beyond
Nassir F. Marrouche, MD
University of Utah, Cardiology
Delayed-enhancement MRI techniques and segmentation software developed at the University of Utah have been used to quantify the amount of pre-ablation fibrosis in the left atrium of atrial fibrillation patients. The data suggest that the amount of fibrosis has a direct correlation to the likelihood of success of an ablation procedure, where lower percentages of fibrosis obtained higher success rates after one year of follow up and higher percentages obtained lower success rates. The University of Utah has created a novel staging model for atrial fibrillation patients to determine their candidacy for the ablation procedure. The staging model includes four categories reflecting the amount of left atrial fibrosis: Utah 1 (35%). Patients that fall into the categories of Utah 1-3 are all potential candidates for an ablation procedure, but with increasing percentages of fibrosis, the more likely they are to experience a recurrence after the ablation procedure. Patients in Utah 4 have the highest likelihood of recurrence (approximately 80%) with low success rates, and are not good candidates for an ablation procedure. This staging system is revolutionizing the way AF patients are treated using non-invasive MRI technology pre-procedure to ensure that the most appropriate treatment options are used, and to avoid unnecessary stress and cost of procedures that are unlikely to be successful.
Clinical Imaging Collaboration and Development
Rob S. MacLeod, PhD
University of Utah, Scientific Imaging and Computing Institute
The Scientific Computing and Imaging (SCI) Institute at the University of Utah, in collaboration with the CARMA Center and UCAIR, has developed several software programs that are contributing greatly to the advances in diagnostic and treatment technologies for atrial fibrillation. Utilizing specialized MRI sequences developed in Utah, the SCI Institute has created software programming that allows for the synthesis of multiple imaging modalities, such as CT and MRI, into unified data outputs for physicians. The overall goal is to create imaging capabilities that provide real-time data during the ablation procedure, as well as diagnostic tools to better understand and capture all relevant data for each patient into one integrated viewing mechanism for physicians to evaluate. Specialized imaging modalities will increase our ability to non-invasively improve patient care outcomes, and through unique collaborative research endeavors between biomedical engineers, software developers, imaging experts, and clinicians, we may find the best opportunities to treat cardiac arrhythmias. As we proceed in developing new imaging software to meet the demands of improving technology, the CARMA team looks forward to continued collaborative efforts to make these improved imaging techniques available to patients and physicians throughout the globe.
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