Clinical relevance of silent atrial fibrillation: Prevalence, prognosis, quality of life, and management

Although first described about 100 yr ago, atrial fibrillation (AF) is now recognized as the most common of all arrhythmias. It has a substantial morb idity and presents a considerable health care burden. Improved diagnosis an d an ageing population with an increased likelihood of underlying cardiac d isease results in AF in more than 1% of population. AF is associated with a n approximately two-fold increase in mortality, largely due to stroke which occurs at an annual rate of 5-7%. Another risk to survival is heart failur e, which is aggravated by poor control of the ventricular rate during AF. U sually AF is associated with a variety of symptoms: palpitations, dyspnea, chest discomfort, fatigue, dizziness, and syncope. Paroxysmal AF is likely to be symptomatic and frequently presents with specific symptoms, while per manent AF is usually associated with less specific symptoms. However, in at least one third of patients, no obvious symptoms or noticeable degradation of quality of life are observed. This asymptomatic, or silent, AF is diagn osed incidentally during routine physical examinations, pre-operative asses sments or population surveys. Recently, a very large incidence of generally short paroxysms of AF has been seen in patients with implantable pacemaker s or defibrillators and these arrhythmias are often silent. Pharmacological suppression of arrhythmia may be associated with a conversion from a sympt omatic to an asymptomatic form of AF. Holter monitoring and transtelephonic monitoring studies have demonstrated that asymptomatic episodes of AF exce ed symptomatic paroxysms by twelve-fold or more. Although symptoms may not stem directly from AF, the risk of complications is probably the same for symptomatic and asymptomatic patients. AF is found incidentally in about 25% of admissions for a stroke. Studies in patients with little or no awareness of their arrhythmia condition indicate that unr ecognized and untreated AF may cause congestive heart failure. In patients with coronary bypass, AF may not only represent risk for immediate postoper ative morbidity and increase hospital resource utilization, but being unrec ognized, may produce a significant impact on long-term survival and quality of life. Although silent AF merits consideration for anticoagulation and r ate control therapy according to standard criteria, whether antiarrhythmic therapy is relevant in this condition remains unclear.