November 22, 2010
Beating the Odds: New Treatments Combat Atrial Fibrillation
By Jennifer Mellace
For The Record
Vol. 22 No. 21 P. 24
New techniques have increased cure rates for atrial fibrillation, but providers must learn to recognize symptoms and recommend appropriate treatment.
A patient seeks treatment for dizziness, a fluttering feeling in the chest, and an overall feeling of weakness. While it could be a number of conditions, in many cases it will be diagnosed as atrial fibrillation (AFib), a condition in which the upper chambers of the heart beat in an uncoordinated and disorganized fashion, resulting in an irregular and fast rhythm.
AFib occurs when the heart’s two small upper chambers (the atria) quiver instead of beating effectively. When the blood is not completely pumped out of these chambers, it can pool and clot. If a blood clot forms in the atria, exits the heart, and blocks an artery in the brain, a stroke results. Consequently, about 15% of strokes occur in elders with AFib. In fact, according to the 1991 Framingham Study, AFib is associated with a fivefold increase in risk of stroke, worsens underlying cardiovascular disease, and doubles the risk of all-cause mortality.
The most common form of heart arrhythmia, AFib affects approximately 2.5 million Americans and, because the risk increases with age, the Mayo Clinic estimates that number may rise to 6.5 million over the next few years. And if that number is astounding, the cost of the disease is even more staggering. Currently costing the nation approximately $6.65 billion annually in treatment, a 2010 report released by Avalere Health cites research estimating that expenses associated with AFib may be as high as $15.7 billion per year.
The report, prepared and funded as an outcome of AF Stat, a collaboration of national healthcare leaders and organizations working to improve the health and well-being of people affected by the disease, describes the burden of AFib on Medicare and offers strategies to enhance quality of care, improve patient outcomes, and reduce healthcare costs associated with the disease.
“Historically, there has been a disappointing lack of urgency to change the status quo surrounding AFib,” says Eric Prystowsky, MD, the AF Stat medical chair and director of the clinical electrophysiology laboratory at St. Vincent Hospital in Indianapolis. “This call to action provides key public health directives that can motivate change and improve the understanding and management of AFib.”
There are three common goals when treating AFib: the restoration and maintenance of sinus rhythm, controlling the heart rate, and preventing stroke. There are two general approaches to treating the irregular heartbeat. The first is the rhythm-control approach, which attempts to restore and maintain sinus rhythm. The second is the rate-control approach that attempts to control the ventricular response rate to prevent the deterioration of ventricular function and minimize symptoms. The initial AFib management decision involves primarily a rate-control or rhythm-control strategy or a combination of both. If the initially selected strategy proves unsuccessful, it sometimes becomes necessary to adopt the alternate one.
While many treatments involve medications, some of which create undesirable side effects, hope comes from a study published in the January 27 issue of The Journal of the American Medical Association. The study conducted by researcher David Wilber, MD, FAHA, FACC, director of the Cardiovascular Institute at Loyola University Chicago Stritch School of Medicine, indicates that treating AFib through ablation, or the use of a new robotic catheter guidance system where heart tissue is burned, works better than drug treatments.
The study shows that one year after undergoing catheter ablation treatment, 66% of patients with AFib were free of any recurrent irregular heartbeats or symptoms compared with only 16% of patients treated with drugs. The results were so convincing that the trial was halted early. Patients receiving ablation reported immediate and major improvements in their quality of life, which were maintained over the nine months they were followed. There were no significant quality-of-life improvements among patients who received drug therapy.
“Atrial fibrillation is the most important cardiac arrhythmia that affects patients in terms of the number of patients with the condition and the healthcare expenditures to treat the condition and its main complication, which is stroke,” says Mitchell N. Faddis, MD, PhD, director of clinical cardiac electrophysiology and associate professor of medicine at Washington University School of Medicine in St. Louis.
“Catheter ablation techniques directed at curing atrial fibrillation have been evolving over the past two decades,” he says. “With the current strategies, cure rates are in the range of 80%, but two procedures are often required to achieve this cure.”
During the ablation procedure, an electrophysiologist destroys areas of heart tissue responsible for the erratic electrical signals. A catheter is guided through blood vessels to the heart, where the tip of the catheter delivers radio-frequency energy that heats and destroys tissue. The robotic system enables the physician to place the catheter in exactly the right spot and consistently apply the correct amount of pressure, burning away targeted tissue without getting so close that the catheter punctures the heart wall.
Faddis explains that current techniques utilize a three-dimensional mapping system to create barriers via ablation to wall off the zone of the left upper chamber where the AFib originates. The procedure requires about four hours to complete, and patients stay overnight in the hospital to recover. Activity restrictions are recommended for one week after the procedure, at which point normal activities such as exercise are resumed. In all, the healing process requires about three months.
“Atrial fibrillation may recur during this healing period as a result of the inflammation and repair that is triggered by the ablation,” says Faddis. “Because of the length of the procedure, the requirement for a second procedure in some patients, and a major complication rate of around 3%, patients who are candidates for this procedure are only those with severe symptoms who have had an unsuccessful attempt to treat the condition with a medication. The patients who have the best outcomes with these techniques have the most structurally normal hearts. With enlargement of the heart chambers or problems with the heart valves, the cure rate for catheter ablation declines.”
The Stereotaxis system for magnetic catheter guidance, ablation, and three-dimensional mapping was developed through a collaboration among Washington University, Barnes-Jewish Hospital, and Stereotaxis, Inc beginning in 1998. The current system, which has been FDA approved, is being used around the world at medical centers that offer catheter ablation to cure AFib.
“The system uses a computer and a magnetic control system for precise movement of the catheter within the heart,” explains Faddis. “The ablation procedure is performed at a workstation where mapping and ablation in the heart is controlled. The early results with the system, compared to a standard, manually controlled catheter, show a similar efficacy but reduced x-ray radiation exposure. The possibility that complication rates and procedure durations are reduced is being measured in a clinical trial of the technique.”
As Faddis points out, ablation is typically used on patients after drug therapy fails. Using drugs such as beta-blockers and calcium channel blockers can slow the heart rate during an AFib episode. Other drugs, such as flecainide and propafenone, can help maintain a normal rhythm. But even when medications succeed in maintaining a normal heart rhythm, the drugs’ side effects can significantly impair a patient’s quality of life.
“All antiarrhythmic drugs have side effects,” says Ralph J. Damiano, Jr, MD, the John M. Shoenberg professor of surgery and chief of cardiac surgery at Washington University School of Medicine. “Amiodarone is the most effective, but it only works about 50% of the time and has major side effects, including pulmonary fibrosis, abnormal liver enzymes, and corneal microdeposits. But most patients can tolerate it over short periods of time.”
Maze surgery is another surgical option for curing AFib. At Barnes-Jewish Hospital, where maze surgery was developed by James Cox, MD, and colleagues in the 1980s, cure rates approach 90% with a single procedure. The Cox maze IV procedure, a treatment that uses bipolar radio-frequency ablation for most of the atrial lesions that were previously placed with a cut-and-sew technique, was developed by a group headed by Damiano. This modified version of the Cox maze III procedure has simplified and shortened the surgical treatment of AFib and works best on patients who have already failed treatment via medicine, who have failed one or more catheter ablations, or prefer the surgical approach.
“Dr. Damiano and his colleagues are actively pursuing further refinements in the techniques to reduce the magnitude of the surgery that is required,” says Faddis. “A hybrid technique that utilizes a limited surgical approach with a limited catheter treatment is currently being evaluated in the hope that the most resistant cases will achieve higher cure rates.”
Damiano admits that it’s an aggressive treatment but a procedure that is extremely effective and is well tolerated. “More than 90% of patients who undergo the Cox maze IV procedure have a freedom from AFib after one year, and more than 80% are off drugs,” he says.
“Atrial fibrillation is not all that easy to diagnose and detect because it happens intermittently,” explains Phyllis Zimmer, MN, FNP, FAAN, of the American Heart Association’s Council on Cardiovascular Nursing and the Nurse Practitioner Healthcare Foundation, a faculty member at the University of Washington School of Nursing, and an active participant in the AF Stat initiative. “That’s why it’s so important to have a campaign to increase awareness, so people know the prevalence and consequences. … It’s time healthcare practitioners keep AFib at the forefront of their thinking and help raise awareness in the general public.”
Zimmer notes that over the past several years, public awareness concerning diabetes and high blood pressure has increased, with campaigns for both hammering home the fact that many people may have these diseases without even knowing it. “We need to prevent AFib by educating the general public with similar campaigns. If we can make people aware that the butterfly feeling in their chest, the fatigue they feel, and the shortness of breath they’re experiencing may be related to AFib, we’ll not only save lives, we’ll also save money,” she says.
As part of the AF Stat Working Group, Zimmer and others like her hope to raise awareness and work with policy makers on supporting initiatives such as targeted research and clinical guidelines. “There are great guidelines out there on how to manage hypertension, back pain, etc. If we can give the same federal nod to managing AFib, that would be great,” Zimmer says.
In a recent study, 97% of physicians thought AFib patients were at severe or moderate risk of cardiovascular disease. When patients were asked, only 45% believed they were at risk. This disparity shows that messages given to patients aren’t being delivered well or aren’t understood at all. And despite the far-reaching impact of AFib, many providers lack the tools to explain the disease and its potential consequences to patients. In fact, a 2009 Yankelovich survey found that 42% of physicians reported having to use their own drawings to guide patient discussions about AFib, while more than one half of nurses report using their hands to describe the disease.
“There is a need for educational materials that are easily accessible for clinicians to use with patients,” says Zimmer. “Part of the AF Stat project will address the need for good patient literature and other educational materials. We need materials that will meet the needs of diverse patient populations—things that are culturally relevant, understandable, and easy to use.” Fortunately, the team has made some strides by recently releasing the AFib Educator, a smartphone app and desktop widget that helps physicians and other healthcare workers better explain the risks and consequences of AFib to patients.
“When you explain blood flow in a coronary artery to patients, they can visualize problems such as a blockage, but it is difficult for most patients to understand the normal electrical flow of impulses through the heart,” says Prystowsky. “This is magnified many times over when trying to comprehend the complexities of AFib. Until now, healthcare professionals have lacked sophisticated tools to educate their patients about AFib. The AFib Educator offers information that can help patients better understand AFib and develop a sense of urgency about managing it.”
The AFib Educator provides a resource that demonstrates how the heart should look under normal rhythm and how it performs during AFib. Featuring detailed, animated diagrams of the human heart, fluoroscopy (x-ray) animations, and electrocardiogram demos, the AFib Educator helps physicians clarify the risks associated with AFib and shows patients how it impacts the heart’s performance.
The application also provides other resources to share with patients, including facts about the signs, symptoms, prevalence, and risks of AFib; links to resources where patients can learn more about AFib; and an “e-mail a friend” feature that enables providers to e-mail background information directly to patients.
— Jennifer Mellace is a Maryland-based freelance writer whose articles have been published in various regional and national publications.
Recurring Stroke Risk Higher for Some Hispanics
A recent study found that Mexican American stroke survivors with atrial fibrillation (AFib) are more than twice as likely to suffer a second stroke compared with white patients. It also found that even though these strokes are more likely to be severe among Mexican Americans, they don’t have a greater risk of death after a second stroke.
The study included 88 Mexican Americans and 148 white stroke survivors with AFib. Compared with the white patients, the Mexican American stroke survivors were younger, less likely to have completed 12 years of education, more likely to have diabetes, and less likely to have a primary care physician.
Over a median follow-up of 427.5 days, 19 Mexican Americans and 14 whites had at least one recurrent stroke. All but one of those cases involved an ischemic stroke, which is caused by blocked blood flow to the brain. One Mexican American patient suffered a hemorrhagic stroke, which is bleeding in the brain.
“Based on some of our prior research, we were not necessarily surprised by the higher recurrence rate in Mexican Americans with atrial fibrillation, but the greater severity of recurrent strokes in Mexican Americans was surprising,” says coauthor Darin B. Zahuranec, MD, an assistant professor of neurology at the University of Michigan Cardiovascular Center in Ann Arbor.
One reason for the difference in stroke rates could be that Mexican Americans may not have managed the blood-thinning drug warfarin, often used to prevent stroke, in the most optimal way, Zahuranec says. He and his colleagues did not evaluate outpatient use of warfarin, which might have contributed to the increased risk of stroke in Mexican Americans.
— Source: American Heart Association