Persistent atrial fibrillation: a population based study of patients with their first cardioversion

Abstract

Background: Electrical cardioversion is effective in terminating even long standing atrial fibrillation (AF), but the relapse risk of AF is high. Data on long-term success of cardioversion in real life clinical practice are scant. Methods: Restoration and maintenance of sinus rhythm as well as acceptance of permanent AF was studied in a population based cohort (catchment area with a population of 440 000) of patients with persistent AF after first elective cardioversion. Results: Of the 183 patients having their first electrical cardioversion during the 1-year study period, sinus rhythm was restored in 153 patients (84%). Only 39 of these (25%) maintained sinus rhythm for 1 year, even though 108 (71%) patients had anti-arrhythmic medication. Age, hypertension, coronary artery disease, heart failure and valvular disease, or absence of these known risk factors for AF were not associated with the outcome. The outcome was better if the cardioversion was performed earlier than the median delay (78 days) from the diagnosis of AF to cardioversion compared to longer delay (P=0.022 in multivariate modelling). The decision of acceptance of permanent AF was made in 74 cases (40%) during 1 year of follow-up. Conclusions: Patients with persistent AF had a high tendency to remain in or relapse into AF, even though most patients had anti-arrhythmic medication after first cardioversion. Short history of arrhythmia was associated with better outcome. Acceptance of permanent AF was made in almost half of the cases during 1 year of follow-up.

Introduction

Since 1962 when Lown et. al. established the effectiveness and safety of synchronised direct current countershock for terminating atrial arrhythmias, electrical cardioversion has been the routine therapy for atrial fibrillation (AF) [1]. However, it was soon discovered that although cardioversion was successful in a high percentage of patients [1], [2], [3], [4], [5], most patients had a relapse of AF [2], [3], [4], [5]. At 1 year after single cardioversion only 18–29% of patients remained in sinus rhythm, even though a majority had been treated with quinidine or procainamide [3], [4], [5]. In these earlier reports well over half of the patients had rheumatic heart disease (54–80%), the selection of anti-arrhythmic drugs used was scarce, and duration of arrhythmia had been lengthy, even extending over periods of years [2], [3], [4], [5].

Since 1960s and 1970s there has been a large number of publications considering restoration and maintenance of sinus rhythm. However, the knowledge of long-term success rates of cardioversion in real life clinical practice is sparse [6], and we have found no reports describing the outcome after first cardioversion in a population based cohort of patients with persistent AF.

In our institution all patients who have elective cardioversion are registered. This register provided an opportunity to describe and study the restoration and maintenance of sinus rhythm of patients with persistent AF in everyday practice. The relations of the outcome to clinical characteristics, duration of AF, and medication with anti-arrhythmic properties were studied, as well as progression to permanent AF was also recorded.