Atrial Fibrillation

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Atrial fibrillation involves the rapid ineffective beating of the atria and often rapid or irregular conduction to the ventricles.
Atrial fibrillation is the rapid and uncontrolled beating of the atria, the upper chambers of the heart, and is the most common cardiac arrhythmia. It can result from congestive heart failure, myocardial infarction, valvular disease, hypertension, infection, or, in 20 to 35% of cases, without any evidence of other cause. Patients with AFib experience palpitations, chest discomfort, weakness, fainting and breathlessness. Their quality of life can be so severely reduced that in one study the average quality of life was equivalent to that of patients crippled from rheumatoid arthritis and below that for patients with congestive heart failure or recent myocardial infarction.[1]

Patients with AFib have a severely elevated risk of stroke (5% risk of stroke per year or 5 to 6 times the risk of the general population). In the U.S. approximately 100,000 strokes per year are due to AFib.[2] Because of the risk of stroke, patients require lifelong treatment with anticoagulants. This involves two office visits per year and monthly blood tests to measure clotting rates. Even so, such therapy only reduces the stroke risk by two-thirds, (to double the risk of those without AFib), and carries a 2.4% yearly risk of major hemorrhage.[3]

Atrial Fibrillation affects nearly 2.3 million people in the United States and 4.5 million people in the developed world. From 200,000 to 400,000 new cases are diagnosed each year and the size of the AFib population is expected to more than double by mid century.[4] It was the primary cause of 399,000 hospitalizations in the U.S. in 2000 increasing 1.7- fold in only 15 years.

Researchers at the Mayo Clinic conducted a study of AF incidence and uncovered dramatic increases in the AF incidence rate. The authors concluded that whether or not this rate of incidence continues to increase, the projected number of persons with AF in the United States will exceed 10 million by 2050 “…underscoring the urgent need for primary prevention strategies against AF development.[5]

Atrial fibrillation is also an expensive disease. In the Framingham study, adjusted total Medicare spending for those with AFib was 8.6 to 22.6 times higher for men and 9.8 to 11.2 times higher for women.[6] Just the cost of maintaining a patient on anti-coagulation therapy is $3,000 per year; including treatment of resultant hemorrhage, this increases to $7,000 per year.[7] Researchers at Beth Israel Hospital in Boston followed 973 patients for up to three years aiming to characterize resource utilization and costs of treating new onset AFib for patients during the first few years following initial diagnosis with emphasis on the incremental costs associated with arrhythmia recurrence. Following initial diagnosis, patients with AF treated with traditional therapies incur $4-5000 in annual direct healthcare costs

Atrial fibrillation is believed to be a progressive disease. Initially it is “paroxysmal” – consisting of isolated, self-terminating episodes. Over time these episodes tend to become more frequent and longer in duration. Eventually, the continued presence of AFib provokes changes or “remodeling” in the atrial tissue that make the tissue more susceptible and better able to maintain the arrhythmia. At this point it will become “persistent,” requiring electrical or chemical cardioversion to restore normal sinus rhythm. Finally it becomes “permanent” (also called “chronic”) when it can no longer be terminated by cardioversion. It is estimated that 30% of patients have permanent AFib.[8]

1 Crijns HJGM, et al. Why is atrial fibrillation bad for you? From Nonpharmacological Management of Atrial Fibrillation. 1997; Futura Publishing Co.
2 Heart Facts. American Heart Association. 2002.
3 SPAF Investigators. Adjusted dose Warfarin versus low fixed-dose Warfarin plus aspirin for high-risk patients with atrial fibrillation. Lancet 1996; 348:633-638.
4 Go AS, et al. Prevalence of diagnosed atrial fibrillation in adults. JAMA 2001; 285: 2370-2375.
5 Miyasaka Y, et al Secular Trends in Incidence of Atrial Fibrillation in Olmsted County, Minnesota, 1980 to 2000, and Implications in the Projections for Future Prevalence, Circulation, 2006; 114:119-125
6 Wolf PA, et al. Impact of atrial fibrillation on mortality, stroke and medical costs. Arch Intern Med 1998;158:229-234.
7 Jensen S, et al. Long-term follow-up of patients treated by radiofrequency ablation of the atrioventricular junction. PACE. 1995;18:1609-1614.
8 U.S. Opportunities in the Management of Atrial Fibrillation. Health Resource International, October 2002.