Burden of asymptomatic episodes of atrial fibrillation in a heart failure cohort.

Heart failure is associated with an increased risk of developing atrialfibrillation (AF). The prevalence of AF in heart failure patients is 20-50%compared to a prevalence of ???1% in the general population. Prevalencestudies rely on detecting AF by standard ECG which fails to detectasymptomatic episodes of AF that often occur during AF development.In patients with heart failure AF is associated with increased risk ofstroke, all cause mortality and hospitalisation, hence the importance ofidentifying these at risk patients.We examined the occurrence of AF in 162 heart failure patients with cardiacresynchronization therapy (CRT) devices. AF episodes were definedas a period of mode-switching on the CRT devices with atrial rate >200for over 30s. Patient records were reviewed to establish which patientswere known to have chronic or paroxysmal AF.Of the 162 patients, 43 had chronic AF (26.5%), 18 paroxysmal AF(11.1%), and 101 (62.3%) had no previous history of AF and were insinus rhythm at their last clinic appointment. Of the 101 patients notknown to have AF, 27 had significant episodes of AF (26.7%, Fig. 1A)with mean AF burden of 1.6??0.9% and longest duration of 5.6??2.3hours (Fig 1B). The mean AF burden (30.6??8.8%, p