Seek and Ye Shall Find Subclinical Atrial Fibrillation in High-Risk Elderly Patients
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Article, see p 1276
Atrial fibrillation (AF) is a rapidly growing public health and economic burden.1 The global number of individuals with clinically diagnosed AF was estimated to be 33 million in 2010 and is expected to double by 2050 as a result of demographic changes and the rising prevalence of risk factors for AF such as obesity, diabetes mellitus, and hypertension. AF is associated with substantial morbidity and mortality (mostly secondary to an increased risk of stroke), reduced quality of life, and considerable costs.1 However, these figures are likely to underestimate the true prevalence of AF; prolonged electrocardiographic monitoring detects clinically silent subclinical AF (SCAF) in a variable proportion of subjects presenting in sinus rhythm, depending on the type and duration of monitoring, the characteristics of the study population (in particular, age and medical history), and the definition of AF.2
SCAF could have a significant impact on health and disability in that it may be linked to a significant proportion of strokes of undetermined origin.3,4 In this regard, patients with an implanted cardiac device (eg, pacemaker or defibrillator) that includes an atrial lead have provided novel data on the prevalence and potential clinical significance of atrial high-rate episodes (AHREs), which largely represent SCAF (but may also include artifacts, atrial flutter, or reentrant supraventricular tachycardia). In particular, in the ASSERT study (Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial), continuous electrocardiographic recording for 3 months by an implanted pacemaker (n=2451) or defibrillator (n=129) identified episodes of AHRE (defined as rapid atrial rate >190 bpm lasting >6 minutes) in 10% of patients (mean age, ≈76 years) who were in sinus rhythm and had no history of AF.5 Compared with sinus rhythm, the presence of AHRE was associated …