Atrial fibrillation with RVR

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Background

Categories[1]

Atrial Fibrillation Category Definition
Paroxysmal
  • Terminates spontaneously or with intervention within 7 days of onset.
  • Episodes may recur with variable frequency.
Persistent
  • Continuous sustained >7 days
Long-standing persistent
  • Continuous >12 mo in duration.
Permanent
  • Used when the patient and clinician make a joint decision to stop further attempts to restore and/or maintain sinus rhythm.
  • Acceptance represents a therapeutic attitude on the part of the patient and clinician rather than an inherent pathophysiological attribute.
  • May change as symptoms, efficacy of therapeutic interventions, and patient and clinician preferences evolve.
Nonvalvular
  • In the absence of rheumatic mitral stenosis, a mechanical or bioprosthetic heart valve, or mitral valve repair.

Causes

Clinical Features

Differential Diagnosis

Palpitations

Evaluation

Management

Unstable

  • Synchronized cardioversion (100-200J)
    • Atrial fibrillation - start at 200 J
    • Atrial flutter - start at 50 J
  • Indications: ischemic chest pain, SBP < 90, acute pulmonary edema, altered mental status
  • Consider cardiostable sedation such as 5mg etomidate
    • +/- subdissociative pain dosage ketamine at 15mg
  • If shock does not work:
    • Verify not preexcitation
    • Increase diastolic BP to perfuse the heart
      • Push-dose phenylephrine
        • Will maintain BP when give rate-control meds
        • 50-200mcg q2-5min with goal DBP >60
    • Amiodarone 150mg over 10min (preferably through central venous access) OR diltiazem 2.5mg/min until HR <100 or max 50mg
    • Magnesium 2 g over 1-5 min, repeat if no response after 15 min, then consider 1-2 g/h for 4 hrs if response[2]
      • Significantly less effective than amio or calcium-channel blockers
      • Ensure baseline magnesium level
      • Check magnesium q2hrs if infusing

Stable and Asymptomatic

If mild or no symptoms and pulse only mildly elevated (<110bpm) ok to manage with PO meds

Stable and Symptomatic

  • Goal <110bpm
    • Make sure you are not slowing down a normal physiologic response (e.g. fever, hypoxia, etc)
    • RACE-II trial demonstrated that lenient control (goal HR < 110bpm) was noninferior to strict control (HR < 80 bpm) in preventing the primary outcome[3]

Cardioversion

  • Consider for:[4]
    • Symptoms <48hr
    • New diagnosis
    • No history of similar episodes
    • No LV dysfunction
    • No mitral valve disease
    • No prior thromboembolic event
    • Already Anticoagulated
  • If cardioversion is considered, pretreatment with rate or rhythm control medications can reduce effectiveness[5]
    • 90% effective, 60% effective with pretreatment

Anticoagulation Prior to Cardioversion

  • Anticoagulation with Heparin or LMWH should be considered before cardioversion if time permits, otherwise immediately after cardioversion. (unless you are sure it has been <48 hours since onset of afib) [6][7] [8]
  • Generally cardioversion while anti-coagulated is believed to be safe with a 1.3% risk of thromboembolism if on aspirin or other anticoagulant[9] However the risk may be as great as 2% risk after 48 hours and preference should be given to anticoagulation prior to cardioversion in longer cases[10]

Medication Choices

Medication Dose Comments Contraindications
Calcium-Channel Blockers
Diltiazem
  • Bolus 0.25mg/kg (average adult dose 20mg) over 2 min
  • If, after 15min 1st dose is tolerated but inadequate re-bolus 0.35mg/kg
  • If patient responds start infusion at 5-15mg/hr or give PO diltiazem 60mg QID
  • Decompensated heart failure
  • Preexcitation (especially in pediatrics)
  • Significant hypotension
Beta-Blockers
Metoprolol
  • Bolus 2.5-5mg IVP over 2min q5min up to 3 doses
  • If patient responds orally load with 25-50mg
  • Particularly useful when A-fib associated with exercise, after acute MI, or with thyrotoxicosis
  • Long-term beta blocker improves patient survival (CCB may worsen outcomes), thus starting a beta blocker upon discharge, strongly consider using the agent for rate control also.[12]
Esmolol
  • Bolus 0.5mg/kg over one minute, followed by 50 µg/kg/min
  • If, after 4min response is inadequate, re-bolus followed by infusion of 100 µg/kg/min
  • If, after 4min response is still inadequate, try final bolus followed by infusion of 150 µg/kg/min
  • If necessary, infusion can be increased to maximum of 200 µg/kg/min after another four minutes
  • Use if unsure whether patient will tolerate a beta blocker since the duration of action is only 10 minutes
Other
Digoxin
  • 0.25mg IV q2hr up to 1.5mg, then 0.125-0.25mg PO or IV QD
  • Adjust dose in presence of renal failure, amiodarone, etc
  • Consider as initial therapy for patients with LV dysfunction who:
    • Do not achieve rate control targets on beta blockers alone
    • Cannot tolerate addition of or increased doses of beta blocker due to decompensated CHF
    • Would have digoxin added anyway to improve CHF symptoms independent of A-fib
  • Consider as initial therapy in patients with severe hypotension
  • Consider as 2nd agent in patients in whom IV BB or IV CCB has failed to control their rate
  • May take up to 6-8 hours to work
Amiodarone
  • Load 3-7mg/kg IV over 30 min
  • then, 1200mg over 24hr via continuous infusion or in divided oral doses[13]
  • Consider for patients with decompensated heart failure or those with accessory pathways
  • 2nd-line agent for chronic rate control when beta-blockers and calcium-channel blockers, alone, combined, or when used with digoxin, are ineffective

Evidence of preexcitation

  • Avoid AV nodal agents
  • Unstable:
    • Unsynchronized cardioversion (200J)
    • Procainamide (if cardioversion unsuccessful)
      • 20-50mg/min until arrhythmia is controlled, hypotension occurs, QRS complex widens by 50% of original width, or total of 17mg/kg is given; followed by continuous infusion of 1-4mg/min
  • Stable:

See Also

External Links

References

  1. 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary. J Am Coll Cardiol. 2014;64(21):2246-2280. doi:10.1016/j.jacc.2014.03.021
  2. Kwok MH et al. Use of intravenous magnesium to treat acute onset atrial fibrillation: a meta‐analysis. Heart. 2007 Nov; 93(11): 1433–1440.
  3. Van Gelder IC et al. Lenient versus strict rate control in patients with atrial fibrillation. N Engl J Med. 2010 Apr 15;362(15):1363-73. full text
  4. Ottowa Aggressive Protocol
  5. Blecher GE, et al. Use of rate control medication before cardioversion of recent-onset atrial fibrillation or flutter in the emergency department is associated with reduced success rates. CJEM. 2012;14(3):169-177.
  6. You JJ, Singer DE, Howard PA, Lane DA, Eckman MH, Fang MC, Hylek EM, Schulman S, Go AS, Hughes M, Spencer FA, Manning WJ, Halperin JL, Lip GY. Antithrombotic therapy for atrial fibrillation: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012 Feb;141(2 Suppl):e531S-75S
  7. FusterV et al;American Collegeof Cardiology/ American Heart Association Task Force on Practice Guidelines; European Society of Cardiology Committee for Practice Guidelines; European Heart Rhythm Association; Heart Rhythm Society. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation. 2006;114(7):e257-e354.
  8. Camm AJ, Kirchhof P, Lip GY, et al; European Heart Rhythm Association; European Association for Cardio-Thoracic Surgery. Guidelines for the management of atrial fibrillation: the task force for the management of atrial fibrillation of the European Society of Cardiology (ESC). Eur Heart J. 2010;31(19):2369-2429.
  9. 48hr Cardioversion for A.fib.
  10. Nuotio I. et al. Time to cardioversion for acute atrial fibrillation and thromboembolic complications. JAMA. 2014 Aug 13;312(6):647-9
  11. Short PM, Lipworth SI, Elder DH, Schembri S, Lipworth BJ. Effect of beta blockers in treatment of chronic obstructive pulmonary disease: a retrospective cohort study. BMJ. 2011 May 10;342:d2549
  12. Effect of metoprolol CR/XL in chronic heart failure: Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF). Lancet. 1999 Jun 12;353(9169):2001-7Effect of verapamil on mortality and major events after acute myocardial infarction (the Danish Verapamil Infarction Trial II–DAVIT II). Am J Cardiol. 1990 Oct 1;66(10):779-85
  13. Khan IA et al. Amiodarone for pharmacological cardioversion of recent-onset atrial fibrillation. Int J Cardiol. 2003 Jun;89(2-3):239-48.
  14. http://ehced.org/wp-content/site/Drips/dilt-load.pdf