Elsevier

Progress in Cardiovascular Diseases

Volume 48, Issue 2, September–October 2005, Pages 79-87
Progress in Cardiovascular Diseases

Asymptomatic Atrial Fibrillation

https://doi.org/10.1016/j.pcad.2005.06.005Get rights and content

Atrial fibrillation (AF) is a significant cause of morbidity and health care expenditures. Patients with AF suffer a variety of symptoms including chest pain, palpitations, shortness of breath, and fatigue. Some patients have no symptoms, a condition referred to as asymptomatic or “silent” AF. Asymptomatic AF has significant clinical implications. Patients with unrecognized AF may present with devastating thromboembolic consequences or a tachycardia-mediated cardiomyopathy. The incidence of asymptomatic AF is greater than previously perceived. This manuscript provides an overview of the clinical entity of asymptomatic AF including the epidemiology, clinical significance, and the implications it has on the daily management of patients suffering from AF.

Section snippets

Symptoms

Patients with AF commonly experience palpitations, dyspnea, chest pain, light-headedness, and fatigue. The precise mechanism by which AF causes symptoms is poorly understood. The hemodynamic consequences of (1) loss of atrial contraction and, thus, loss of atrioventricular (AV) synchrony; (2) heart rate (HR) irregularity; and (3) rapid ventricular response in AF may each contribute in varying degrees to the manifestation of symptoms. Loss of atrial contractility and its contribution to

Epidemiology of Asymptomatic AF

The reported incidence of asymptomatic AF depends on the frequency of monitoring, duration of follow-up, and the burden of AF in the population studied. In a study by Camm et al, among 106 asymptomatic elderly patients (≥75 years old), the incidence of AF detected by a “scout” 24-hour ambulatory monitor was 10.5%.11 Psaty et al reported 304 new cases of AF in 4844 patients aged 65 years or older screened with annual ECGs, history and physical examination, or hospital discharge diagnoses.

Asymptomatic AF in Patients With Implantable Monitoring Devices and Indications for a Permanent Pacemaker

Another high-risk population for AF is patients with sinus node dysfunction or AV conduction abnormalities. The reported incidence of AF in this population of patients may be as high as 4% to 6% per year.16 Many of these patients require a permanent pacemaker or, rarely, an atrial defibrillator, which then provides the opportunity to continuously monitor for atrial arrhythmias. In a study of patients with a clinical history of symptomatic AF by Defaye et al, a diagnostic algorithm for

Reliability of Symptoms

The study by Israel et al illustrates the poor correlation between symptoms and AF. During the study, 40% of patients reported symptoms suggestive of AF, but device interrogation proved absence of AF during the respective episodes.17 Symptoms cannot be relied upon, even in patients who initially present with symptomatic AF. In one study, it was shown that asymptomatic AF occurred 12 times more frequently than symptomatic AF.9 The poor correlation between symptoms and AF demonstrated in these

The Role of Drugs in Asymptomatic Bouts of AF

The presence of asymptomatic AF in patients treated with antiarrhythmic drugs is well recognized; however, the interaction of pharmacological interventions on the manifestation of symptoms has not been systematically studied. Antiarrhythmic agents could potentially alleviate symptoms by shortening the duration of arrhythmia, smoothing the ventricular rhythm (making it less irregular), or by slowing the ventricular response. Certain AV nodal drugs, including digoxin, β-adrenergic receptors

Clinical Consequences of Silent AF

The prevalence of asymptomatic AF has significant clinical implications:

  • 1.

    The magnitude of the problem reported in epidemiological studies of AF significantly underestimates the burden of arrhythmia on society because asymptomatic arrhythmias are not included.

  • 2.

    Given the well-documented presence of asymptomatic AF in patients treated with antiarrhythmic agents, the efficacy of pharmacological interventions on clinical AF burden may be overestimated. Many trials focus on symptomatic recurrence as a

Epidemiology of AF When Asymptomatic AF is Considered

Atrial fibrillation is associated with significant morbidity and is responsible for significant health care expenditures, so it is important to accurately represent its clinical and economic impact. Epidemiological studies of AF are limited by the unreliable methods used to determine cases of arrhythmia, such as extraction of hospitalization data, patient self-reporting, or on screening ECG databases.2, 14 In the ATRIA study, Go et al searched an automated clinical database of patients within a

Thromboembolic Consequences of Asymptomatic AF

Stroke is a devastating consequence of AF. Patients with AF have a 5- to 6-fold increase in stroke risk in comparison to patients in sinus rhythm.20 Evidence from randomized controlled studies supports warfarin use in all patients with one or more risk factors for stroke.21 Warfarin significantly reduces the risk of stroke and has been demonstrated to reduce clinical severity of strokes and mortality in patients who have strokes.22 In assessing stroke risk in individuals with AF, it is

Tachycardia-Induced Cardiomyopathy and Asymptomatic AF

Asymptomatic patients with inadequate rate control may develop significant CHF. Chronic exposure to rapid ventricular rates may result in a partially or completely reversible impairment of LV function. Grogan et al reported significant improvement in LV function in 10 patients who presented to the Mayo Clinic with severe LV dysfunction and AF who were then treated with adequate rate control.33 The mean LV ejection fraction before treatment was 25% (range, 12%-30%) and 52% (range, 40%-64%) after

Conclusion

Asymptomatic AF is common and has significant clinical implications. Asymptomatic AF should be considered in estimating the prevalence of the disease and its impact on health care resources, when interpreting the results of studies reporting the efficacy of various rhythm control strategies (eg, antiarrhythmic agents, AF ablation), and in the day-to-day management of patients suffering from AF. Failure to acknowledge the frequency of asymptomatic AF could lead to devastating consequences,

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