Temporal changes in atrial refractoriness following DC cardioversion of persistent atrial fibrillation in man.

AIMS: Studies have demonstrated shortening of the atrial effective refractory period (ERP) after episodes of atrial fibrillation (AF). This is termed atrial remodelling. It is unclear whether restoration of SR after persistent AF in patients with a clinical substrate results in reversal of this shortening and whether this is maintained long term. METHODS AND RESULTS: The ERP was determined at mid-lateral right atrial wall (MLRA) and right atrial appendage (RAA) at 600 ms and 400 ms drive cycle lengths and at basic sinus cycle length in 81 patients with persistent AF immediately, 24 h and 2 weeks following external DC cardioversion. All atrially active drugs were stopped for at least 5 half lives. (1) Prolongation of the ERP was observed at both atrial sites and all cycle lengths up to 24 h post cardioversion (p < 0.0001). (2) However, between 24 h and 2 weeks a subsequent shortening occurred in the ERP returning it to near post cardioversion levels. (3) The ERP was significantly longer at 24 h post cardioversion in patients who remained in SR for 2 weeks or longer compared with those who reverted to AF. CONCLUSION: Prolongation of the atrial ERP occurred following restoration of SR in persistent AF patients but was not maintained and displayed a biphasic pattern such that by 2 weeks the ERP had returned to baseline values. Despite this finding, a longer ERP at 24 h post cardioversion was associated with maintenance of SR in the medium-term.

Does sinus rhythm beget sinus rhythm? Long-term follow-up of the patient activated atrial defibrillator.

The aim of this study was to determine the effect of early patient activated cardioversion of atrial fibrillation (AF) using the atrial defibrillator on recurrence of AF. Fifteen patients, mean age 63 +/- 14 years, 80% men, with drug-resistant persistent AF were implanted with the Jewel AF atrial defibrillator. All patients performed self-administered cardioversion for AF recurrences. Over a 2 year follow-up, 238 patient-activated cardioversions were performed in 14 patients. Sinus rhythm was restored on every occasion with 96% of episodes terminating with a single shock. The median time from AF onset to patient awareness of symptoms was 2.5 hours. The median time from onset of symptoms to cardioversion was 3.5 hours. Comparison of the first and second six month period following implant showed a nonsignificant increase in mean total AF duration (75.7 +/- 107.8 hours vs 146.6 +/- 194.1 hours, P = 0.28). Two patients (13%) had a decreasing frequency of AF recurrences. The majority continued to have regular recurrences of AF. The atrial defibrillator is an extremely effective method of restoring sinus rhythm in patients with persistent AF. Regular early use of the atrial defibrillator, increased the duration of sinus rhythm in a minority of patients during long-term follow-up. Most patients had regular recurrences of AF requiring patient-activated cardioversion.

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((R)) 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.