title: Subclinical atrial fibrillation and stroke: insights from continuous monitoring by implanted cardiac electronic devices.
abstract: Nearly one out of five strokes is associated with atrial fibrillation (AF). Atrial fibrillation is often intermittent and asymptomatic. Detection of AF after cryptogenic stroke will likely change therapy from antiplatelet to oral anticoagulation agents for secondary stroke prevention. A critical step is to convert 'covert' AF into electrocardiogram documented AF. External rhythm recording devices have registered a high incidence of AF to occur after a cryptogenic stroke, but are limited by short duration of continuous recordings. Invasive cardiac monitoring using insertable leadless cardiac monitors are sensitive means to identify subclinical AF (SCAF) after cryptogenic stroke, and AF has been reported to occur in 8.9% of these patients by 6 months in one study. It will be more attractive to identify SCAF before a stroke occurs. Recent series in pacemaker and implantable cardioverter-defibrillator (ICD) recipients showed that short episodes of SCAF increased stroke risk, with odds ratio ∼2.2-3.1 compared with those without SCAF recorded. However, temporal sequence of recorded SCAF and stroke occurrence was uncertain, and the overall stroke risk was lower compared with patients with clinical AF at similar risk scores. This article reviews the incidence and clinical role of using implanted devices to detect SCAF and discusses the implication of SCAF so detected in primary and secondary stroke prevention.
authors: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China Research Center of Heart, Brain, Hormone and Healthy Ageing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China Cardiac Health Heart Centre, Suite 1303, Central Building, 1 Pedder Street, Central, Hong Kong cplau@hkucc.hku.hk.
authors: Chu-Pak
authors: CP
authors: Lau
authors: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China Research Center of Heart, Brain, Hormone and Healthy Ageing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors: Chung-Wah
authors: CW
authors: Siu
authors: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China Research Center of Heart, Brain, Hormone and Healthy Ageing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors: Kai-Hang
authors: KH
authors: Yiu
authors: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China.
authors: Kathy Lai-Fun
authors: KL
authors: Lee
authors: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China.
authors: Yap-Hang
authors: YH
authors: Chan
authors: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China Research Center of Heart, Brain, Hormone and Healthy Ageing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors: Hung-Fat
authors: HF
authors: Tse
mesh_terms: D058070:Asymptomatic Diseases / Q000453:epidemiology*; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D015984:Causality; D015897:Comorbidity; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data; D015716:Electrocardiography, Ambulatory / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D010138:Pacemaker, Artificial / Q000706:statistics & numerical data; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control
keywords: Atrial fibrillation; Atrial high rate; Cryptogenic; Implantable cardioverter-defibrillater; Implanted pacemaker; Insertable cardiac monitor; Stroke