Virtual Journal Club October 2014: Time to Cardiovert or NOT to Cardiovert?

Time to Cardioversion for Acute Atrial Fibrillation and Thromboembolic Complications

Ilpo Nuotio, MD, PhD; Juha E. K. Hartikainen, MD, PhD; Toni Grönberg, BM; Fausto Biancari, MD, PhD; K. E. Juhani Airaksinen, MD, PhD


In 1995, practice guidelines recommended a limit of 48 hours after the onset of atrial fibrillation (AF) for cardioversion without anticoagulation. Whether the risk of thromboembolic complications is increased when cardioversion without anticoagulation is performed in less than 48 hours is unknown.

Methods
In the retrospective Finnish CardioVersion study, all patients with a primary diagnosis of AF, aged 18 years or older, with successful cardioversion in the emergency department within the first 48 hours of AF, and residence in the catchment areas of Turku and Kuopio university hospitals from 2003 to 2010 and Pori central hospital during 2010 were included. Clinical details and the occurrence of thromboembolic complications within 30 days after cardioversion were retrospectively collected from medical reports.

The primary outcome, a thromboembolic event, was defined as a clinical stroke or systemic embolism confirmed by computerized tomography or magnetic resonance imaging, surgery, or autopsy. Time to cardioversion was determined as the difference between the beginning of arrhythmic symptoms to the exact time of cardioversion. If the duration of arrhythmia was uncertain, the cardioversion was excluded. Procedures were divided into groups according to the time to cardioversion: less than 12 hours (group 1), 12 hours to less than 24 hours (group 2), and 24 hours to less than 48 hours (group 3).

The protocol was approved by the ethics committees of the Hospital District of Southwest Finland and the National Institute for Health and Welfare, with a waiver of informed consent. Bivariable comparisons between groups were performed with the χ2 test, the Fisher exact test, or the Wilcoxon nonparametric test. Multivariable logistic regression analysis with a repeated-measures model was conducted to evaluate risk factors for thromboembolic complications, including comparisons between groups 2 and 1 and between groups 3 and 1.

Clinical features (age, female sex, heart failure, and diabetes) with independent predictive value for thromboembolic complications were used as covariates in the multivariate analysis based on our previous work. Statistical analyses were performed using SAS version 9.3 (SAS Institute Inc). Twosided differences at P < .05 were considered significant.

Results
Of 2481 patients with acute AF, 5116 successful cardioversions were performed without anticoagulation. The mean age was 61.0 (SD, 12.4) years, 1638 were female (32.0%), and 2434 had more than 1 risk factor for stroke (47.6%). Thirty eight thromboembolic events occurred in 38 patients (0.7%; 95% CI, 0.5%-1.0%); 31 were strokes. The incidence of thromboembolic complications increased from 0.3% in group 1 to 1.1% in group 3 (P = .004, Table 1).

The incidence of thromboembolic complications according to the time to cardioversion in subgroups is presented in Table 1. In multivariable logistic regression analysis (Table 2), time to cardioversion longer than 12 hours was an independent predictor for thromboembolic complications (odds ratio of 4.0 [95% CI, 1.7-9.1] between groups 2 and 1 [P = .001]; odds ratio of 3.3 [95% CI, 1.3-8.9] between groups 3 and 1 [P = .02]).

Discussion
Stroke is the most serious complication of AF. After the recommended 3 weeks of therapeutic anticoagulation, the stroke risk in elective cardioversion of AF ranges from 0.3% to 0.8%. In our study, the risk of thromboembolic complications was 0.7% when cardioversion was performed without anticoagulation within 48 hours of AF onset.

However, we found that a delay to cardioversion of 12 hours or longer from symptom onset was associated with a greater risk of thromboembolic complications (1.1%). When the duration of AF was less than 12 hours, the risk of thromboembolism was low (0.3%) without anticoagulation. The main limitation of this retrospective study lies on the verification of AF duration based on real-life evaluation in the emergency department.

Source: JAMA August 13, 2014 Volume 312, Number 6


Original Study Link: http://content.onlinejacc.org/article.aspx?articleid=1711119




CME Questions (available in SABA):



1) The most serious complication of AF is?

 a) MI

 b) CVA

 c) PE

 d) CHF

2) Based on the most recent literature it is safe to cardiovert  AF without anti-coagulation up until ?

    a) 72 hrs

     b) 48 hrs

     c) 36 hrs

     d) 12 hrs

3) If a patient has been in AF for greater than 48 hrs they should be anti-coagulated for how many weeks prior to having the procedure?

   a) 4

   b) 6

   c) 3

   d) 2

4) If you are sending a patient home with po rate control medication your should also have them on anti-coagulation?

  a) true

  b) false

5) Current research supports that we should trust when a patient reports the time they went into AF?

a)True

b) False