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TURIN, ITALY. Electrical cardioversion (ECV) is considered first-line treatment for persistent atrial
fibrillation (AF) defined as paroxysmal (intermittent) AF which does not self-terminate, or is
sustained beyond 7 days. Although the acute (immediate) success rate of cardioversion is acceptable,
only about 50% or less of patients undergoing ECV remain in normal sinus rhythm (NSR) a year
following their cardioversion.
A group of researchers from the University of Turin recently released the results of a study
aimed at determining the main factors influencing cardioversion outcome. Between January 2005
and December 2009 a total of 521 persistent afibbers were enrolled in the study. About half
the participants had structural heart disease, 67% had hypertension, and 11% had suffered a
previous stroke or TIA. Only 5% were classified as having idiopathic (lone) AF.
The study participants were divided into 4 groups according to the length of time they had
spent in AF prior to undergoing ECV. Group A consisted of 141 patients who had been in AF
for 2 months or less, group B comprised 176 patients who had been in AF for more than 2
months but no more than 4 months, group C comprised 89 patients who had been in AF for
more than 4 months but no more than 6 months, while group D consisted of 115 patients who
had been in AF for more than 6 months. Eighty-five percent of participants were on
antiarrhythmic drugs (53% on amiodarone and 28% on flecainide or propafenone) prior to
ECV and continued on these drugs after their cardioversion. They were also anticoagulated
for 4 weeks before and 12 weeks after ECV.
All participants underwent direct-current biphasic shock with an initial energy of 200 Joule.
Acute and long-term success rates for the 4 groups are shown below.
The researchers conclude that waiting more than 6 months for cardioversion is associated with a significantly reduced chance of remaining in sinus rhythm over the long term. They also observed that having an enlarged left atrium, as well as having had a prevision cardioversion, markedly reduced the chance of a successful long-term outcome. Thus, the combination of AF duration more than 6 months, an enlarged left atrium, and a previous ECV reduced 5-year success rate to 13%. During the first 30 days after the ECV, one 79-year-old woman (CHA2DS2-VASc score of 8) suffered a stroke and one 78-year-old man (CHA2DS2-VASc score of 7) suffered a TIA (transient ischemic attack). Both were on warfarin within therapeutic range (INR of 2.41 and 2.63 respectively) at the time of their event. A total of 13 symptomatic ischemic events (mainly strokes and TIAs) occurred during the entire follow-up � all in patients having a CHA2DS2-VASc score greater than 2.
The researchers conclude that properly conducted ECV is associated with a high acute success
rate and low complication rates. However, long-term success declines dramatically in patients
having been in persistent AF for more than 6 months prior to their cardioversion.
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