Thomboembolic events after cardioversion in afib

Clinical Scenario:
55 year old with past medical history of hypertension presents with sudden onset palpitations and chest pain that awoke him from sleep at midnight.  Patient presents 3 hours later with complaint of palpitations, chest pain, shortness of breath with stable vitals.  EKG demonstrates atrial fibrillation (a.fib).  Patient undergoes successful synchronized cardioversion.

Clinical Question:
In a patient who is electrically cardioverted within 48 hours of symptom onset of new atrial fibrillation, what is the incidence of thromboembolic complications?  Do you still have to anticoagulate?

Literature review:
Based on the Finnish CardioVersion Study, which included 2,481 patients who had a.fib for less than 48 hours and underwent cardioversion and were NOT started on oral anticoagulation nor peri-procedural heparin, there are certain groups who have higher risks for thromboembolic events.  Of the group as a whole, 0.7% (95% CI 0.5-1.0) had thromboembolic events within 30 days with a median of 2 days and mean of 4.6 days.  The three highest risk factors were female gender (OR 2.1 95% CI 1.1 to 4.0), heart failure (OR 2.9 95% CI 1.1 to 7.2), and diabetes (OR 2.3 with 95% CI 1.1 to 4.9).  Those with no heart failure who were younger than 60 years old had the lowest risk of thromboembolism (0.2%). 

Example of Afib

Additionally, when deciding between low molecular weight heparin or unfractionated heparin in cardioversion, based on the ACE trial (Anticoagulation in Cardioversion using Enoxaparin), there is no significant difference between the two with regard to embolic events, death, and bleeding complications.  This study included 428 people, and it was a randomized prospective multicenter trial.  Of the enoxaparin patients 7/216 vs. 12/212 heparin patients had primary end point incidents (p=0.016).

Take home points:
-Consider anticoagulation in patients who have heart failure/diabetes who must undergo electric cardioversion
-Low risk patients do not need anticoagulation when cardioverted within 48 hours of onset of a.fib
-No difference between enoxaparin or heparin

References:
1. Airaksinen KE, Grönberg T, Nuotio I, Nikkinen M, Ylitalo A, Biancari F, Hartikainen JE. Thromboembolic complications after cardioversion of acute atrial fibrillation: the FinCV (Finnish CardioVersion) study. J Am Coll Cardiol. 2013 Sep 24;62(13):1187-92.

2. Stellbrink C, Nixdorff U, Hofmann T, Lehmacher W, Daniel WG, Hanrath P, Geller C, Mügge A, Sehnert W, Schmidt-Lucke C, Schmidt-Lucke JA; ACE (Anticoagulation in Cardioversion using Enoxaparin) Study Group. Circulation. 2004 Mar 2;109(8):997-1003.

Submitted by Lydia Luangruangrong, PGY-3.

Edited by  Steven Hung (@DocHungER), PGY-2

Faculty reviewed by Doug Char