Atrial Fibrillation

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A 64-year-old male with a history of hypertension and hyperlipidemia presents with palpitations. He reports intermittent symptoms over the past 3 days, associated with dyspnea on exertion, but no chest pain, dizziness or syncope. His vital signs are notable for tachycardia (HR 129bpm) without hypotension or hypoxia. An ECG shows atrial fibrillation with rapid ventricular response.

Evaluation and Management

While the patient’s tachyarrhythmia is not yet associated with hypotension or evidence of malperfusion, preparation is key and includes continuous telemetry and vital sign monitoring, establishment of intravenous access, and application of cardioversion pads 1.

The presence of atrial fibrillation is new and the rapid ventricular response (RVR) may be symptomatic of more serious and potentially reversible pathology. A thorough history and physical examination may elucidate a precipitant and should precede attempts at rate- or rhythm-control. RVR may be provoked by any of the processes that would otherwise induce a sinus tachycardia, including bleeding, infection, toxic/metabolic etiologies and endocrinopathies 2, 3

Candidacy for Cardioversion

In hemodynamically stable patients with new-onset atrial fibrillation, candidacy for cardioversion includes:4-6

  • Stable without ischemia, hypotension or acute CHF
  • Clear onset of <48 hours
  • Non-severe symptoms
  • Few prior episodes/treatments
  • Existing anti-coagulation with warfarin and therapeutic INR (at least 3 weeks)
  • Absence of high-risk features: rheumatic/valvular disease, severe left-ventricular dysfunction, prosthetic valves, or history of thromboembolism

Cardioversion may be pharmacologic (with procainamide, or amiodarone), or electrical (synchronized at 100-200J). Electrical cardioversion for acute atrial fibrillation is both more effective and results in shorter lengths-of-stay in the emergency department – though stable patients should participate in shared decision-making7. Another important consideration when cardioversion is pursued is the prevention of systemic embolization. While atrial fibrillation of duration less than 48-hours is rarely associated with systemic embolization, certain populations are at higher risk8. One retrospective study of 3143 patients with atrial fibrillation for less than 48-hours demonstrated an overall risk of 0.7% for thromboembolic events – though the rate was significantly higher in patients older than 60 years or with other comorbidities (heart failure, diabetes)9. The risk of embolic events should be weighed against the risk of bleeding.

CHA2DS2VASc10-12

C Congestive Heart Failure 1
H Hypertension 1
A2 Age >75 2
D Diabetes Mellitus 1
S2 Stroke, TIA, Thromboembolism 2
V Vascular disease 1
A Age >65 1
Sc Sex Category Female 1

 

  • 0: low risk (may not require anti-coagulation)
  • 1: low-moderate risk (consider anti-platelet or anti-coagulation)
  • ≥ 2: moderate-high risk (anti-coagulation recommended)

HAS-BLED13,14

H Uncontrolled hypertension 1
A Abnormal renal/liver function
Renal (renal replacement therapy, creatinine >2.3mg/dL) 1
Liver (cirrhosis, bilirubin >2x, AST/ALT >3x) 1
S Stroke 1
B Bleeding history/anemia 1
L Labile INR 1
E Elderly (>65) 1
D Drugs
Anti-platelet agent, NSAID 1
Alcohol (>8 drinks/week) 1

 

  • 0: low risk (0.6-1.13% annual risk of major bleeding)
  • 1-2: intermediate risk (1.02-3.2% annual risk of major bleeding)
  • ≥ 3: high risk (4.9-19.6% annual risk of major bleeding)

Pharmacologic Management

For patients who are not candidates for cardioversion, rate-control should be pursued. Options include AV nodal blocking agents such as calcium channel blockers and beta-blockers15. The most frequently studied agents of each category are metoprolol and diltiazem. Both classes show comparable efficacy and safety profiles with trends favoring diltiazem16, 17.

Algorithm for the management of atrial fibrillation with rapid ventricular response:

Algorithm for the management of atrial fibrillation with rapid ventricular response

References

  1. Atzema, C.L. and T.W. Barrett, Managing atrial fibrillation. Ann Emerg Med, 2015. 65(5): p. 532-9.
  2. January, C.T., et al., 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary. A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society, 2014. 64(21): p. 2246-2280.
  3. Scheuermeyer, F.X., et al., Emergency Department Patients With Atrial Fibrillation or Flutter and an Acute Underlying Medical Illness May Not Benefit From Attempts to Control Rate or Rhythm. Ann Emerg Med, 2015. 65(5): p. 511-522 e2.
  4. Stiell, I.G., et al., Association of the Ottawa Aggressive Protocol with rapid discharge of emergency department patients with recent-onset atrial fibrillation or flutter. CJEM, 2010. 12(3): p. 181-91.
  5. von Besser, K. and A.M. Mills, Is discharge to home after emergency department cardioversion safe for the treatment of recent-onset atrial fibrillation? Ann Emerg Med, 2011. 58(6): p. 517-20.
  6. Cohn, B.G., S.M. Keim, and D.M. Yealy, Is emergency department cardioversion of recent-onset atrial fibrillation safe and effective? J Emerg Med, 2013. 45(1): p. 117-27.
  7. Bellone, A., et al., Cardioversion of acute atrial fibrillation in the emergency department: a prospective randomised trial. Emerg Med J, 2012. 29(3): p. 188-91.
  8. Weigner, M.J., et al., Risk for clinical thromboembolism associated with conversion to sinus rhythm in patients with atrial fibrillation lasting less than 48 hours. Ann Intern Med, 1997. 126(8): p. 615-20.
  9. Airaksinen, K.E., et al., Thromboembolic complications after cardioversion of acute atrial fibrillation: the FinCV (Finnish CardioVersion) study. J Am Coll Cardiol, 2013. 62(13): p. 1187-92.
  10. Friberg, L., M. Rosenqvist, and G.Y. Lip, Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. Eur Heart J, 2012. 33(12): p. 1500-10.
  11. Lip, G.Y., et al., Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest, 2010. 137(2): p. 263-72.
  12. Ntaios, G., et al., CHADS(2), CHA(2)S(2)DS(2)-VASc, and long-term stroke outcome in patients without atrial fibrillation. Neurology, 2013. 80(11): p. 1009-17.
  13. Lip, G.Y., et al., Comparative validation of a novel risk score for predicting bleeding risk in anticoagulated patients with atrial fibrillation: the HAS-BLED (Hypertension, Abnormal Renal/Liver Function, Stroke, Bleeding History or Predisposition, Labile INR, Elderly, Drugs/Alcohol Concomitantly) score. J Am Coll Cardiol, 2011. 57(2): p. 173-80.
  14. Pisters, R., et al., A novel user-friendly score (HAS-BLED) to assess 1-year risk of major bleeding in patients with atrial fibrillation: the Euro Heart Survey. Chest, 2010. 138(5): p. 1093-100.
  15. Goralnick, E. and L.J. Bontempo, Atrial Fibrillation. Emerg Med Clin North Am, 2015. 33(3): p. 597-612.
  16. Demircan, C., et al., Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation. Emerg Med J, 2005. 22(6): p. 411-4.
  17. Fromm, C., et al., Diltiazem vs. Metoprolol in the Management of Atrial Fibrillation or Flutter with Rapid Ventricular Rate in the Emergency Department. J Emerg Med, 2015. 49(2): p. 175-82.
  18. DiMarco, J.P., Atrial fibrillation and acute decompensated heart failure. Circ Heart Fail, 2009. 2(1): p. 72-3.