Atrial fibrillation with RVR

Unstable (Cardioversion)

• Indications:

1. Ischemic CP
2. SBP < 90
3. Acute pulmonary edema
4. Altered mental status

Above must be 2/2 RVR (i.e. if HR is <130 look for other cause of above signs)

• Sedate: Etomidate 5-7mg
• 100-200j biphasic synchronized cardioversion

If shock doesn't work:

1. Verify not preexcitation
2. Incr diastolic BP to perfuse the heart
   1. Push-dose phenyleprhine
      1. Will maintain BP when give rate-control meds
      2. 50-200mcg q2-5min w/ goal dia BP >60
3. Amiodarone 150mg over 10min OR
4. Diltiazem 2.5mg/min until HR<100 or max 50mg

Stable but Symptomatic (Rate Control)

• Goal < 110bpm
• Make sure you are not slowing down a normal physiologic response
  • RVR in AF may be appropriate response to fever, hypovolemia, hypoxemia, withdrawal

Calcium-Channel Blockers

1. Preferred in pts with chronic lung disease or low EF
2. Contraindications
   1. Decompensated heart failure
   2. Preexcitation
   3. Significant hypotension

Diltiazem

1. Bolus 0.25 mg/kg (average adult dose 20mg) over 2 min
   1. If, after 15 minutes the first dose is tolerated but inadequate, re-bolus 0.35 mg/kg (average adult dose 25 mg)
   2. If pt responds to 1st or 2nd bolus start infusion at 5-15mg/hr
2. Takes 2-5 minutes to work, last 1-4 hours
3. 94% responive
4. If effective, can start PO dilt at 30mg QID

Beta-Blockers

1. Particularly useful with a fib associated with exercise, after an acute MI, or with thyrotoxicosis
2. Contraindicated in COPD, low EF CHF

Metoprolol

1. 2.5-5mg IVP over 2min q5 min up to 3 doses
   1. PO load with MTP 25-50mg following successful rate control with IV

Esmolol

1. Use if unsure whether pt will tolerate a BB (duration of action is only 10-20min)
2. Bolus 0.5 mg/kg over one minute, followed by 50 µg/kg/min
   1. If, after 4 minutes response is inadequate, re-bolus followed by infusion of 100 µg/kg/min
   2. If, after 4 minutes response is still inadequate, try final bolus followed by infusion of 150 µg/kg/min
   3. If necessary, infusion can be increased to maximum of 200 µg/kg/min after another four minutes

Digoxin

1. Consider as initial therapy for pts with LV dysfunction who:
   1. Do not achieve rate control targets on beta blockers alone
   2. Cannot tolerate addition of or increased doses of a beta blocker due to acute decompensated HF
   3. Would have digoxin added anyway to improve CHF symptoms independent of AF
2. Consider as initial therapy in pts with severe hypotension
3. Consider as 2nd agent in pts in whom IV BB or IV CCB has failed to control their rate
4. May take up to 6-8 hours to work
5. Dosing
   1. 0.25 mg IV q2hr up to 1.5 mg, then 0.125-0.25 mg PO or IV QD
   2. Adjust dose in presence of renal failure, amiodarone, etc

Amiodarone

1. Consider for use in pts with decompensated heart failure or those with accessory pathways
2. 2nd-line agent for chronic rate control when BBs and CCBs, alone, combined, or when used with digoxin, are ineffective
3. Load 5-7 mg/kg IV over 30 min; then 1200 mg over 24 h via continuous infusion or in divided oral doses

Stable and Asymptomatic

If mild or no symptoms and pulse only mildly elevated (<120bpm), ok to manage with PO meds

Evidence of preexcitation

1. Initial therapy is aimed at reversion to sinus rhythm
2. Avoid AV nodal agents
   1. Unstable -> urgent cardioversion
      1. DC cardioversion
      2. Pharmacologic cardioversion
         1. Procainamide
            1. 20-50 mg/min until arrhythmia is controlled, hypotension occurs, QRS complex widens by 50% of original width, or total of 17 mg/kg is given; followed by continuous infusion of 1-4 mg/min
   2. Stable -> try to avoid cardioversion without adequate anticoagulation

See Also

Atrial Fibrillation (General)

Source

UpToDate

EMcrit Podcast 20