Atrial fibrillation (afib) is the most commonly diagnosed arrhythmia, affecting 2.7 million in the United States. Afib prevalence increases with age. By age 60, 4% have afib; by 80, up to 8% suffer from the condition.
In the emergency department, primary concerns with afib are whether acute symptoms are directly related to the condition, and to manage and treat underlying causes. As examples: In a late-70s female with generalized weakness, are her symptoms caused by afib? Or in a mid-40s male, heavy coffee drinker with intermittent palpitations and chest tightness, maybe afib is the cause?
Acute detection of afib is an “emergency” diagnosis, but the reality is that having poorly managed afib can dramatically increase the risk of many serious downstream conditions. Patients with afib are at five times the risk for debilitating stroke. This risk can potentially be reduced using several anticoagulants, including aspirin, warfarin, and many of the “new” oral anticoagulant agents such as dabigitran. Data on apixiban and rivaroxaban are still emerging.
The problem is that stroke risk in many patients with afib is not optimally managed. In a 2002 stroke study, approximately 1% of asymptomatic emergency department patients had EKG-proven afib. In those with known afib, 27% were on no antithrombotic therapy whatsoever. In the patients on warfarin with a measured INR, more than 60% were outside of the American Heart Association recommended range of 2-3.
Certainly, no emergency physician would argue that emergency department patients are often undermanaged for primary care treatable diseases. So, one might ask, what is the emergency department’s role in assessing and helping managed stroke risk in patients with afib?
Here is an answer: While emergency department providers don’t typically prescribe medications to reduce long-term stroke risk, particularly medications with potentially serious side effects, a better approach is: Detect, Risk-stratify, Notify, and Refer.
In general, detection is simple. Patients get EKGs in the emergency department for many reasons. When afib is detected, especially the “incidental” kind (i.e., unrelated to today’s symptoms), the next step is to assess stroke risk with the CHADS2 score.
CHADS2 can be easily calculated:
- Congestive heart failure (1 point)
- Hypertension history (1 point)
- Age greater than or equal to 75 years (1 point)
- Diabetes history (1 point)
- Stroke symptoms or TIA or thromboembolism (2 points)
Higher CHADS2 scores are associated with higher stroke risk. For CHADS2 of 0, yearly stroke risk is 1.9%, for CHADS2 of 3, yearly risk is 5.9%, and for CHADS2 of 6, the yearly risk is 18.2%.