Echocardiographic changes and predictors of arrhythmia recurrence after long-term use of the atrial defibrillator

Background: The patient-activated atrial defibrillator allows patients to cardiovert themselves from atrial fibrillation soon after the onset of symptoms. The long-term effects of early cardioversion from persistent atrial fibrillation on left ventricular performance and left atrial size are unknown. Methods: Eighteen patients, mean age 63.4, 83% male, had the Jewel® AF atrial defibrillator implanted for persistent atrial fibrillation only. Transthoracic echocardiography was performed 3-monthly following implant. Parasternal long axis measurements were taken using conventional M-mode techniques. Results: Over follow-up of 28.0±9 months, 377 episodes of persistent atrial fibrillation were terminated by patient-activated cardioversion (median 15 per patient). Echocardiographic measurements at implant were; left atrium 44±6 mm, left ventricular end-diastolic diameter 49±7 mm, left ventricular end-systolic diameter 34±7 mm, fractional shortening 33±10% and ejection fraction 65±17%. After 1 year there had been a significant decrease in mean left atrial size to 41±6 mm (P=0.02) and an increase in mean ejection fraction to 73±8% (P=0.04). At long-term follow-up however, all parameters reverted to pre-implant levels. Baseline echocardiographic variables did not predict which patients would demonstrate serial increases in sinus rhythm duration between shocks during long-term follow-up. Patients on antiarrhythmic drug therapy however were more likely to demonstrate ‘sinus rhythm begetting sinus rhythm’. Conclusions: Use of the atrial defibrillator for spontaneous persistent atrial fibrillation is associated with a medium-term (1 year) reduction in left atrial size and an increase in ejection fraction. These changes were not maintained in the long-term. Synergistic therapy with antiarrhythmic drugs may prolong periods of sinus rhythm between arrhythmia recurrences.