The purpose of this study is to investigate the complications of cardioversion of acute (<48 hours duration) atrial fibrillation (AF).

Primary Outcome Measures:

- Incidence and predictors of thromboembolic complications, especially stroke, and death <31 days after cardioversion of acute AF

Secondary Outcome Measures:

• Number of therapy non-responder and early recurrence of AF
• Bleeding complications during the 31 days follow-up
• Hemodynamic complications of cardioversion

Estimated Enrollment: 3000 cases

Study Start Date: Jun 2011

Estimated Study Completion Date: December 2011

It has been a common practice to perform cardioversion of acute (<48 hour) AF without any anticoagulation. The new European guidelines recommend that anticoagulation should be started already before cardioversion in all patients with CHADS2VASC score indicating need for long-term oral anticoagulation. The evidence behind these guidelines is, however, scarce. In this retrospective study we collect data on the safety of acute AF cardioversion from emergency rooms of two university hospitals and one secondary referral center from the years 2003-2010.

Inclusion criteria:

All patients admitted to emergency room because of acute AF in whom electrical or pharmacological cardioversion was attempted <48 from the beginning of the symptoms.

Inclusion Criteria:

• patients admitted to emergency room because of acute AF in whom electrical or pharmacological cardioversion was attempted <48 from the beginning of the symptoms

Exclusion Criteria:

• duration of the AF is unknown or >48 hours

All patients admitted to emergency room because of acute AF in whom electrical or pharmacological cardioversion was attempted <48 from the beginning of the symptoms.