Pro vs. Con: Cardioversion of AFib With or Without Anticoagulation?

A 67 year old woman presents to the emergency room with atrial fibrillation (AFib) that began 24 hours ago. She has no past medical history. Can she be cardioverted without anticoagulation on board?

Pro: Bulent Gorenek, MD

To evaluate whether or not the patient can be cardioverted without anticoagulation on board, we have to know the patient's risk of stroke, as both European and American AFib guidelines recommend that anticoagulation begins 48 hours prior for high-risk patients. According to the guidelines, it looks as though her CHA2DS2-VASc score is 2 (Sex, female: 1; Age, 67: 1) However, I think there are some points missing in the guidelines that we need to discuss:

  1. If the patient was just two or three years younger, her score would be a '1' and she would be in the low risk group. We really don't know if an age of 67 is a real and important risk factor for stroke. Since the reasoning behind the age cut-off in the guidelines is unclear – why not 67 instead of 65? – I really want to know the "biological age" of the patient.
  2. Do we always need anticoagulation in females to reduce the risk of stroke in AFib? Surely not. According to the European guidelines for a female younger than 65 with AFib alone, anticoagulation is not recommended. So, although the CHA2DS2-VASc score of this patient is theoretically '2', in reality it probably is not.
  3. The guidelines recommend that anticoagulation for AFib should begin 48 hours prior in high-risk patients. However, in this case, AFib began 24 hours ago. It has been shown that delaying cardioversion increases the risk of thromboembolic complications. This risk decreases if cardioversion is done within 24 hours.

For the reasons discussed above, the patient is not in a high-risk group for cardioversion without anticoagulation on board. For further assurance, we could perform a risk assessment prior to cardioversion, such as a transesophageal echocardiography to exclude thrombus in left atrium or in left atrial appendage.

Con: Mina K. Chung, MD

The patient is a 67 year old woman with onset of AFib 24 hours ago, presumably by symptoms. She has no known past medical history. Her CHA2DS2-VASc score is 2 for female sex and age. Her HAS-BLED score is 1.

The 2014 AFib Guidelines state a class I recommendation for anticoagulation as soon as possible before or immediately after cardioversion for AFib or flutter of less than 48 hours duration and high risk of stroke, to be followed by long-term anticoagulation therapy. Even for low thromboembolic risk, a class IIb recommendation is made for anticoagulation to be considered for cardioversion. Unfortunately, no randomized controlled trials have been done to compare event rates with no anticoagulation versus anticoagulation in patients with AFib onset less than 48 hours. However, there are some data that can inform these recommendations that will be reviewed during today's debate, including the large Finnish Cardioversion study and a study we performed at the Cleveland Clinic.

Key questions to be addressed include: How reliable are we at determining AFib onset? What is the incidence of left atrial thrombus in acute AFib? What are the thromboembolic outcomes after cardioversion within 48 hours by anticoagulation status? And can we risk stratify the need for anticoagulation in this situation?

Clinical Topics: Arrhythmias and Clinical EP, Noninvasive Imaging, EP Basic Science, Atrial Fibrillation/Supraventricular Arrhythmias, Echocardiography/Ultrasound

Keywords: Atrial Appendage, Atrial Fibrillation, Echocardiography, Transesophageal, Electric Countershock, Emergency Service, Hospital, Heart Atria, Incidence, Risk Assessment, Risk Factors, Stroke, Thrombosis, ACC Annual Scientific Session

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