By Dr. Alexander Jay PGY2
Basics
Atrial fibrillation is defined as an irregularly irregular rhythm, in which there are many irritable atrial foci firing all at once. Although many atrial foci are firing at once, the AV node is still at peak function and only allows a set number of beats to pass through (the ultimate “bouncer”). This leads to an undulating baseline on ECG and an irregular ventricular rhythm.
Definitions:
Paroxysmal: self-terminating (usually <48 hours)
Persistent: lasts >7 days or requires termination by cardioversion
Long Standing persistent: Lasts >1 year
Permanent: the decision has been made between the patient and provider to no longer pursure a rate control strategy
**atrial fibrillation usually starts paroxysmal and becomes more and more frequent, and ultimately leads to permanent afib in most cases **
Causes:
- Ischemic or valvular heart disease
- Congestive cardiomyopathy
- Alcohol use (“Holiday Heart”)
- Thyrotoxicosis
- Blunt chest trauma
- Pulmonary embolism
- Drugs (cocaine, TCA’s, etc)
- Infection (pneumonia, sepsis)
Diagnosis
Primarily made by ECG, showing an irregularly irregular rhythm
**note the wavy, undulating baseline cause by the firestorm of angry atrial foci firing at all once, competing for a chance to go down the slide that is the AV node (who, like every summer waterpark slide employee makes you wait waaaay longer than you need to before letting you go through). Also note the absence of P waves, because there is no coordinated contraction because each atrial foci is being a little diva and vying for the spotlight, no team work here.
Workup:
- ECG (obviously)
- Baseline labs (chem panel, magnesium)
- TSH/T4 (should be checked on all new onset atrial fibrillation patients)
- Echo (not really emergently needed, but looks for structural causes of afib)
Management
First things first…are they stable? No? Stop reading this and go grab your closest defibrillator and prepare for a SYNCHRONIZED cardioversion (no R on T phenomenon happening here). Consider starting with 150-200J. And please be nice and give a little pain medication/light sedation.
Some reasons to cardiovert:
- Hypotension
- Myocardial ischemia
- Pulmonary edema
If your patient is stable, this buys you some time to think about RATE vs RHYTHM control
Rate control:
- Target HR <110 in AF patients
- Typically start with IV medications first for immediate rate control followed by oral dosing (“PO chaser”) for sustained control
- BB vs CCB often first line
- Metoprolol vs Diltiazem
- Other meds to consider
- Digoxin – if patient can’t get AV nodal blocking drugs or advanced HF
- Amiodarone – typically second line after digoxin, can convert patients back to sinus rhythm so consider starting anticoagulation, and typically in consultation with EP or cardiology
Rhythm control
- Consider cardioversion if:
- First episode of AF even if minimally symptomatic
- Provoked episode of AF
- Symptomatic AF (exertional intolerance, fatigue, etc)
- Consider duration of AF
- If >48 hours, increased risk of embolic stroke so need TEE or 3 week of anticoagulation prior to cardioversion
Management is primarily about SYMPTOM control and STROKE PREVENTION
- Symptom control primarily achieved with rate control
STROKE PREVENTION
- Use CHADS-VASc score to guide need for anticoagulation
- If women and score >=3 then start AC
- If man and score >=2 then start AC
- Counter with HAS-BLED score to weight risk fo bleeding if started on AC
- If high risk of bleeding, they need to follow up with cardiology to consider non-pharmacologic management
- i.e. Left atrial appendage occlusion (Watchman closure device)
- NOAC preferred over Warfarin
- Except in moderate to severe mitral stenosis or prosthetic heart valve
Disposition
Ok to DC home IF
- Stable hemodynamics
- Rate well controlled
- Symptoms relieved
- Anticoagulated where appropriate
- Plugged in for EP or cardiology follow up and outpatient cardioversion if needed
Citations:
Cline, D., Ma, O., Meckler, G., Stapczynski, J., Tintinalli, J., & Yealy, D. (2016). Tintinalli’s emergency medicine: a comprehensive study guide (8th ed.). McGraw-Hill Education LLC.