Mom’s Eyes and Dad’s
Atrial Fibrillation?
Study reveals a genetic connection
By Susanne J. Pavlovich-Danis, RN, MSN, ARNP-C, CDE
February 14, 2005
In the future, assessing family history to determine individual patient risk may well include inquiring about atrial fibrillation (AF), the most common arrhythmia that causes an irregular heartbeat, palpitations, unexplained rapid heart beat, and a sensation of extra or “missed” beats. Atrial fibrillation typically affects more than 2 million adults. This figure is a conservative estimate, because AF is often undiagnosed until it is associated with significant symptoms or found on routine screening.1 Statistics reveal gender, ethnic, and age differences – with men, whites, and the elderly more likely to develop AF.1 The new data reveals the discovery of a genetic predisposition for the arrhythmia in a community setting.2
According to the study 85 it’s relative
The study evaluated 2,243 individuals whose parents were in the original National Heart, Lung, and Blood Institute (NHLBI) Framingham Heart Study. The study participants were at least 30 years old and had no history of atrial fibrillation on their first examination for the study.2
During the four-year follow-up period, 70 Framingham offspring developed atrial fibrillation. Individuals with at least one parent diagnosed with AF were twice as likely to develop the arrhythmia as individuals who did not have a parent with AF. If both parents had AF before age 75, the risk for offspring developing the disorder tripled, as it did for offspring with no clinically apparent signs of heart disease.2
“Until now, AF has not been thought of as a genetic or familial condition,” says the study’s lead investigator, Caroline Fox, MD, MPH. Nurses, however, may not see clinical application of the research findings anytime soon. Teri Manolio, MD, PhD, director of the epidemiology and biometry program in the Division of Epidemiology and Clinical Applications of the National Heart, Lung, and Blood Institute, points out the difficulty in changing clinical practice. She adds that at the present time, there is no evidence that screening for AF is necessary in asymptomatic relatives.
Atrial fibrillation — what we know
The uncoordinated electrical conduction in AF causes the atria to quiver instead of contract in a coordinated fashion. This quivering causes an irregular ejection of blood from the atria, the upper chambers of the heart, to the ventricles, the lower chambers. The irregular ejection can also cause blood to pool in the atria and form clots. When these clots travel beyond the atria, a stroke, pulmonary embolism, or loss of distal circulation may occur.
The prevalence of AF increases with age. Less than 1% of people age 60 have the condition, while 1 of every 10 individuals age 80 or older has AF.1
Presently, there are factors that contribute to the development of atrial fibrillation, including cardiomyopathy, hypertension, congestive heart failure, previous myocardial infarction, and diabetes.3 Atrial fibrillation is also found with rheumatic heart disease and mitral valve disorders including prolapse, stenosis, or annular calcification.
Treatment with medications, cardioversion, surgery, or implanted devices is aimed at slowing the heart rate and ideally restoring a normal rhythm. Surgical ablation of common AF trigger sites has proven to be effective, but may not represent a “cure,” as new sites that provoke fibrillation may develop4.
Treatment may require a step-wise approach with more conservative medication therapy being attempted before surgical interventions. The effectiveness of each treatment approach varies among patients and what is effective for one patient may not be appropriate for another.
Medications aimed at reducing the frequency or duration of AF episodes include amiodarone (Cordarone, Pacerone); sotalol (Betapace, Sotacar); procainamide (Pronestyl); and quinidine (Quinidex, Quinaglute).
Digoxin (Lanoxin), one of the most commonly prescribed medications for the treatment of atrial fibrillation, decreases conduction of impulses through the SA and AV nodes and promotes stronger cardiac contraction. While long proven to be an effective medication in the treatment of AF, there is a narrow therapeutic serum level window (0.5-2.0 ng/mL) that nurses must cautiously monitor and evaluate patients for signs of toxicity.
Long-term anticoagulants, such as warfarin (Coumadin), are often prescribed to prevent strokes and other embolic events among patients with atrial fibrillation. Yet treating patients with long-term anticoagulants requires extensive education and monitoring and is not without risks. On the near horizon, an oral direct thrombin inhibitor drug, ximelagatran (Exanta), that will not require laboratory coagulation monitoring is expected to receive approval from the Food and Drug Administration for use in the United States.5
Atrial fibrillation and nursing
The onset of AF varies from a dramatic and discomforting presentation to an asymptomatic one. Sometimes the first indication an individual has AF may be the onset of congestive heart failure or stroke.
Major emphasis should be placed on making the public aware that AF is a common problem caused by many factors in addition to a genetic predisposition, says Barbara Alving, MD, MACP, acting director of the National Heart, Lung, and Blood Institute. Manolio emphasizes that patients with a family history of AF who are symptomatic warrant a more diligent search for AF.
Early detection and treatment is the key, and while nurses should encourage routine health care screening, the new research findings should not be cause for anxiety. “The clinical implications of this work are less immediate than the research implications,” Fox says, and adds that patients with a parental history of AF should not be alarmed. Further research is necessary to reveal which genes are involved and what steps to take to enhance early diagnosis and treatment options for individuals with AF.
Regardless of genetic predisposition, Fox, Alving, and Manolio all agree that with AF so prevalent, it is important to educate the public about signs and symptoms suggestive of AF. Caffeine or alcohol intake and smoking are other triggers that may produce the same symptoms, something that medical professionals should consider when assessing a patient’s symptoms, Manolio adds.
Much can be done to prevent the adverse consequences of cardiac arrhythmias, Alving says. Nurses, as caregivers and promoters of preventive care, can play a key role in improving cardiac outcomes.
S usanne J. Pavlovich-Danis, RN, MSN, ARNP-C, CDE, maintains a private adult health practice in Plantation, Fla. She is also professor and area chair for nursing at the University of Phoenix, Fort Lauderdale, Fla.
References
1. Go AS, Hylek EM, Phillips KA, et al. Prevalence of diagnosed atrial fibrillation in adults. National implications for rhythm management and stroke prevention: the anticoagulation and risk factors in atrial fibrillation study. JAMA. 2002;285(18):2370-2375.
2. Fox CS, Parise H, D’Agostino RB, et al. Parental atrial fibrillation as a risk factor for atrial fibrillation in offspring. JAMA. 2004;291(23):2852-2856.
3. Centers for Disease Control and Prevention — Cardiovascular Health Program. Atrial fibrillation fact sheet. 2004. Available at: www.cdc.gov/ cvh/library/fs_atrial_fibrillation.htm. Accessed August 22, 2004.
4. Haissaguerre M, Saunders P, Hocini M, et al. Changes in atrial fibrillation cycle length and inducibility during catheter ablation and their relation to outcome. Circulation. 2004;109 (24):3007-3013.
5. Petersen P. New approaches to anticoagulation in atrial fibrillation. Current Cardiology Reports. 2004;6(5):354-364.