Elsevier

Cardiology Clinics

Volume 27, Issue 1, February 2009, Pages 13-24
Cardiology Clinics

Current Perceptions of the Epidemiology of Atrial Fibrillation

https://doi.org/10.1016/j.ccl.2008.09.015Get rights and content

Atrial fibrillation (AF), an escalating dysrhythmia, is accountable for extensive population morbidity and mortality. In the United States, approximately 2.3 million people are presently diagnosed with AF and it is estimated that this prevalence may increase to 5.6 million by 2050. Foremost predisposing risk factors for this dysrhythmia include advanced age and cardiovascular disease and its risk factors. The chief hazard of AF is embolic stroke, which is increased four- to fivefold, and in advanced age, it becomes a dominant stroke risk factor. AF also carries a doubled mortality rate.

Section snippets

Incidence, prevalence, and secular trends

Atrial fibrillation (AF) is a common, growing, and serious cardiac rhythm disturbance that is responsible for considerable morbidity and mortality in the population. The currently diagnosed estimate of 2.3 million people in the United States with it is expected to increase to 5.6 million by 2050. Its prevalence doubles with each decade of age, reaching almost 9% at the age of 80 to 89 years. Its population prevalence has reached epidemic proportions. This doubling with each decade of age occurs

Cardiovascular risk factors

Based on Framingham Study data, men have a 1.5-fold age- and risk factor–adjusted greater risk for AF than women. Of the standard cardiovascular risk factors, hypertension, diabetes, and obesity are the significant independent AF predictors. Because of its greater prevalence, hypertension is responsible for more AF in the population (14%) than any other risk factor (Table 2).2 Cigarette smoking was a significant risk factor in women adjusting only for age (odds ratio [OR] = 1.4) but was just

Cardiovascular conditions

Persons who develop AF usually are elderly and more likely than persons of the same age to have predisposing cardiac abnormalities.2, 5 Adjusting for cardiovascular risk factors, valvular heart disease, myocardial infarction, and heart failure substantially increases AF occurrence. Echocardiographic predictors of AF include left atrial enlargement, LV fractional shortening, LV wall thickness, and mitral annular calcification, offering prognostic information for AF beyond traditional clinical

Echocardiographic abnormalities

Echocardiographic enlargement of the left atrial dimension and abnormal mitral or aortic valve function were each associated independently with increased prevalence and incidence of AF in the Cardiovascular Health Study.1, 11 In the Framingham Study, echocardiographic predictors of AF include left atrial enlargement (39% increase in risk per 5-mm increment), LV fractional shortening (34% per 5% decrement), and LV wall thickness (28% per 4-mm increment) (Table 4). These echocardiographic

Clinical manifestations

AF can cause palpitations, fatigue, lightheadedness, and exertional dyspnea by precipitating myocardial decompensation. When there is underlying coronary disease, it can bring on or aggravate angina because of an often associated rapid heart rate. AF is often undetected, however, because of lack of symptoms it often is first detected by routine ECG examination in the course of a myocardial infarction or stroke, on implanted pacemakers, or on ambulatory ECG monitoring.

AF was diagnosed

Prognosis

AF is associated with an increased long-term risk for stroke, heart failure, and all-cause mortality, particularly in women.28 The doubled mortality rate of patients who have AF is linked to the severity of the underlying heart disease.29, 30, 31 Approximately two thirds of the 3.7% mortality over 8.6 months in the Activité Liberale la Fibrillation Auriculaire study was attributed to cardiovascular causes.32 AF also independently predicts excess mortality and an increased incidence of embolic

Public health burden and cost

AF, first described in 1909, has acquired increasing clinical and public health importance because of the expanding elderly population containing vulnerable candidates.47 Data from a National Hospital Discharge Survey indicate that hospital admissions resulting from AF increased two- to threefold from 1985 to 1999. During this period, hospitalizations listing AF increased from fewer than 800,000 to more than 2 million, predominantly in the elderly and men. Coyne and colleagues,49 assessing

Thyroid disease

For decades, hyperthyroidism has been an undisputed condition predisposing to AF. The prevalence of AF reported in patients at the time of diagnosis of overt hyperthyroidism varies from 2% to 30%.51, 52, 53 Approximately 10% to 15% of persons who have overt hyperthyroid disease with AF are reported to have an arterial embolic event.54, 55, 56 Studies also suggest that subclinical abnormalities of thyroid-stimulating hormone have detrimental effects on the cardiovascular system.57 Although AF is

Novel risk factors

Many novel modifiable and nonmodifiable risk factors for AF have been identified. These include reduced vascular compliance, atherosclerosis, insulin resistance, environmental factors, inflammatory markers, the obesity-induced metabolic syndrome, thrombogenic tendencies, sleep apnea, decreased arterial compliance, left atrial volume, diastolic dysfunction, and natriuretic peptides. There is emerging evidence that genetic variation also contributes to the risk for AF.

An inflammatory contribution

Genetic influences

Alleged genetically determined risk factors, such as blood pressure, obesity, and greater stature, predispose to AF. It is uncertain how these constitutional factors promote AF, but metabolic disorders and genetic factors may be implicated. A familial occurrence of AF has been recognized but is considered uncommon. The Framingham Study confirmed that observed parental AF increases its risk for offspring two- to threefold after excluding persons with predisposing conditions. This observation

Multivariable risk assessment

Multivariable risk assessment for stroke in patients who have AF is desirable for selecting those who most and least need aggressive anticoagulant therapy. The number needed to treat to prevent one event is inversely related to the level of risk; thus, estimating the risk for stroke for individual patients with AF is crucial for the decision to prescribe anticoagulation therapy. The threshold risk warranting anticoagulation remains controversial, however. Patients who have a stroke risk of 2%

Summary

We are faced with a burgeoning epidemic of AF, which urgently demands improved prevention and treatment of this condition and its cardiovascular substrate. AF and the left atrial enlargement associated with it are likely direct causes of embolic stroke, requiring early detection and treatment. Targeted multivariable profile screening to detect persons who are likely candidates for AF is needed.

Disappointing results of therapy to suppress or eliminate the rhythm disturbance have justifiably

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      Our study confirms that age is independently associated with a higher risk of AF and CHF in hyperthyroid patients [8,18–22]. Actually, the risks of AF and CHF increase with age regardless of the presence of hyperthyroidism or not [23,24]. These risks are however higher in case of hyperthyroidism [20,22].

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    A version of this article originally appeared in Medical Clinics of North America, volume 92, issue 1.

    Funding for this study was provided by grants N01-HC 25195, RO1 HL076784, 1R01 AG028321, and 6R01-NS 17950.

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