Atrial fibrillation

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Diagnosis

Routine office evaluation

A study of routine pulse checks or electrocardiograms during routine office visits, found that the annual rate of detection of atrial fibrillation in elderly patients improved from 1.04% to 1.63%.[1] This implies that the sensitivity of the routine examination is 64% (1.04/1.63).

Electrocardiogram

Regarding the accuracy of the electrocardiogram[2]:

Prognosis

Risk of stroke

The risk of stroke in a patient with atrial fibrillation can be predicted with the CHADS2 score.

Treatment

Clinical practice guidelines by the American College of Physicians and the American Academy of Family Physicians address treatment.[3][4]

Rate control versus rhythm control

Medications

"Rate control with chronic anticoagulation is the recommended strategy for the majority of patients with atrial fibrillation. ... Rhythm control is appropriate when based on other special considerations, such as patient symptoms, exercise tolerance, and patient preference."[3]

The goal rate is "80 beats per minute during resting ... and of less than 110 beats per minute during a 6-minute walk test."[5]

As compared to rate control, rhythm control was associated with slight, although statistically insignificant, increase in adverse outcomes in randomized controlled trials.[6][5][7] In addition, "the incidence of the components of the primary end point did not differ significantly according to whether the patient had sinus rhythm or atrial fibrillation at the end of follow-up."[6] Whether the index episode was the initial or a recurrent episode did not effect results.[7]

Randomized controlled trial of rhythm versus rate control
Study Patients Intervention in rhythm control group Results
Rhythm control group Rate control group
Van Gelder[6]
2002
  • All had prior episode of atrial dysrythmia requiring electrical cardioversion.
  • All had current atrial dysrythmia for median of 32 days.
  • 50% has previous heart failure.
  • Cardioversion followed by sotalol
  • 86% to 99% received anticoagulation.
  • 2.3 years.
  • Sinus rhythm: 39%
  • Cardiovascular death: 6.8%
  • Thromboembolism: 5.5%
  • Sinus rhythm: 10%
  • Cardiovascular death: 7%
  • Thromboembolism: 7.9%
AFFIRM[7]
2002
  • 65% had prior episode of atrial dysrythmia.
  • All had current atrial dysrythmia with 69% lasting 2 or more days.
  • 23% has previous heart failure.
  • "antiarrhythmic drug used was chosen by the treating physician"
  • 70% received anticoagulation.
  • 5 years.
  • Sinus rhythm: 63%
  • Any death: 23.8%
  • Ischemic stroke: 5.5%
  • Sinus rhythm: 35%
  • Any death: 21.3%
  • Ischemic stroke: 7.1%
Roy[5]
2008
  • All had prior episode of atrial dysrythmia.
  • 55% to 60% with current atrial dysrythmia.
  • All with a history of heart failure and systolic dysfunction.
  • Sinus rhythm: 73%
  • Cardiovascular death: 27%
  • Any stroke: 3%
  • Sinus rhythm: 30%
  • Cardiovascular death: 25%
  • Any stroke: 4%
Episodic therapy

Episodic medical therapy has conflicting results with a positive uncontrolled before and after trial of flecainide and propafenone[8] and a negative randomized controlled trial of episodic amiodarone versus continuous amiodarone.[9]

Artificial pacemakers

Regarding artificial pacemakers, "dual-chamber minimal ventricular pacing, as compared with conventional dual-chamber pacing, ...reduces the risk of persistent atrial fibrillation in patients with sinus-node disease" according to a randomized controlled trial.[10]

Dual site, overdrive pacing be effective.[11]

Ablation

Pulmonary-vein isolation

Randomized controlled trial have found that using ablation to cause pulmonary-vein isolation was superior to medical therapy[12][13] and to atrioventricular-node ablation[14].

Anticoagulation

"Patients with atrial fibrillation should receive chronic anticoagulation with adjusted-dose warfarin, unless they are at low risk of stroke or have a specific contraindication to the use of warfarin (thrombocytopenia, recent trauma or surgery, alcoholism). "[3]
Dabigatran versus warfarin for atrial fibrillation[15]
Intervention Outcomes
Stroke or systemic embolism Major bleeding Mortality
Dabigatran 110 mg twice daily 1.53% 2.71%† 3.75%
Dabigatran 150 mg twice daily 1.11%† 3.11% 3.64%
Warfarin 1.69% 3.36% 4.13%
† p < 0.05 as compared to warfarin group

Anticoagulation can prevent recurrent stroke. Among patients with nonvalvular atrial fibrillation, anticoagulation can reduce stroke by 60% while antiplatelet agents can reduce stroke by 20%. [16]. However, a recent meta-analysis suggests harm from anti-coagulation started early after an embolic stroke.[17]

In 2009, dabigatran, a direct thrombin inhibitors, was compared to warfarin in the RE-LY randomized controlled trial.[15]

Antiplatelet therapy

Randomized controlled trials of antiplatelet therapy for atrial fibrillation[18][19][20]
Trial Patients Intervention Comparison Outcome Results
Intervention Control
Copenhagen AFASAK study[18]
1989		 1007 patients aspirin 75 mg daily Warfarin stroke, transient ischemic attack, or systemic embolism 6.0% 1.4%
SPAF[19]
1991		 1,330 patients aspirin 325 mg daily Warfarin ischemic stroke and systemic embolism 3.6% 2.3%†
ACTIVE study[20]
2009		 7554 patients:
• All were taking aspirin, usually at 75 to 100 mg per day
•None were taking warfarin		 clopidogrel 75 mg daily Placebo stroke, myocardial infarction, systemic embolism, or death from vascular causes 6.8%‡ 7.6%
† This was not a direct comparison as warfarin patients were younger and had to be eligible for warfarin.
‡ However, combination therapy increased major bleeding from 1.3% to 2.0%.

If warfarin is contraindicated, the combination of clopidogrel and aspirin can help, especially be reducing stroke, but increases the risk of major hemorrhage.[20]

References

  1. ↑ Fitzmaurice DA, Hobbs FD, Jowett S, et al (2007). "Screening versus routine practice in detection of atrial fibrillation in patients aged 65 or over: cluster randomised controlled trial". DOI:10.1136/bmj.39280.660567.55. PMID 17673732. Research Blogging.
  2. ↑ Mant J, Fitzmaurice DA, Hobbs FD, et al (2007). "Accuracy of diagnosing atrial fibrillation on electrocardiogram by primary care practitioners and interpretative diagnostic software: analysis of data from screening for atrial fibrillation in the elderly (SAFE) trial". DOI:10.1136/bmj.39227.551713.AE. PMID 17604299. Research Blogging.
  3. ↑ 3.0 3.1 3.2 Snow V, Weiss KB, LeFevre M, et al (December 2003). "Management of newly detected atrial fibrillation: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians". Ann. Intern. Med. 139 (12): 1009–17. PMID 14678921. [e]
  4. ↑ McNamara RL, Tamariz LJ, Segal JB, Bass EB (December 2003). "Management of atrial fibrillation: review of the evidence for the role of pharmacologic therapy, electrical cardioversion, and echocardiography". Ann. Intern. Med. 139 (12): 1018–33. PMID 14678922. [e]
  5. ↑ 5.0 5.1 5.2 Roy D, Talajic M, Nattel S, et al (June 2008). "Rhythm control versus rate control for atrial fibrillation and heart failure". N. Engl. J. Med. 358 (25): 2667–77. DOI:10.1056/NEJMoa0708789. PMID 18565859. Research Blogging.
  6. ↑ 6.0 6.1 6.2 Van Gelder IC, Hagens VE, Bosker HA, et al (December 2002). "A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation". N. Engl. J. Med. 347 (23): 1834–40. DOI:10.1056/NEJMoa021375. PMID 12466507. Research Blogging.
  7. ↑ 7.0 7.1 7.2 Wyse DG, Waldo AL, DiMarco JP, et al (December 2002). "A comparison of rate control and rhythm control in patients with atrial fibrillation". N. Engl. J. Med. 347 (23): 1825–33. DOI:10.1056/NEJMoa021328. PMID 12466506. Research Blogging.
  8. ↑ Alboni P, Botto GL, Baldi N, et al (December 2004). "Outpatient treatment of recent-onset atrial fibrillation with the "pill-in-the-pocket" approach". The New England journal of medicine 351 (23): 2384–91. DOI:10.1056/NEJMoa041233. PMID 15575054. Research Blogging.
  9. ↑ Ahmed, Sheba; Michiel Rienstra, Harry J. G. M. Crijns, Thera P. Links, Ans C. P. Wiesfeld, Hans L. Hillege, Hans A. Bosker, Dirk J. A. Lok, Dirk J. Van Veldhuisen, Isabelle C. Van Gelder, for the CONVERT Investigators (2008-10-15). "Continuous vs Episodic Prophylactic Treatment With Amiodarone for the Prevention of Atrial Fibrillation: A Randomized Trial". JAMA 300 (15): 1784-1792. DOI:10.1001/jama.300.15.1784. Retrieved on 2008-10-15. Research Blogging.
  10. ↑ Sweeney MO, Bank AJ, Nsah E, et al (September 2007). "Minimizing ventricular pacing to reduce atrial fibrillation in sinus-node disease". N. Engl. J. Med. 357 (10): 1000–8. DOI:10.1056/NEJMoa071880. PMID 17804844. Research Blogging.
  11. ↑ Saksena S, Prakash A, Ziegler P, et al (September 2002). "Improved suppression of recurrent atrial fibrillation with dual-site right atrial pacing and antiarrhythmic drug therapy". J. Am. Coll. Cardiol. 40 (6): 1140–50; discussion 1151–2. PMID 12354441. [e]
  12. ↑ Wazni OM, Marrouche NF, Martin DO, et al (June 2005). "Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of symptomatic atrial fibrillation: a randomized trial". JAMA 293 (21): 2634–40. DOI:10.1001/jama.293.21.2634. PMID 15928285. Research Blogging.
  13. ↑ Oral H, Pappone C, Chugh A, et al (March 2006). "Circumferential pulmonary-vein ablation for chronic atrial fibrillation". N. Engl. J. Med. 354 (9): 934–41. DOI:10.1056/NEJMoa050955. PMID 16510747. Research Blogging.
  14. ↑ Khan MN, Jaïs P, Cummings J, et al (October 2008). "Pulmonary-vein isolation for atrial fibrillation in patients with heart failure". N. Engl. J. Med. 359 (17): 1778–85. DOI:10.1056/NEJMoa0708234. PMID 18946063. Research Blogging.
  15. ↑ 15.0 15.1 Connolly SJ, Ezekowitz MD, Yusuf S, Eikelboom J, Oldgren J, Parekh A et al. (2009). "Dabigatran versus Warfarin in Patients with Atrial Fibrillation.". N Engl J Med 361 (12): 1139-1151. DOI:10.1056/NEJMoa0905561. PMID 19717844. Research Blogging.
  16. ↑ Hart RG, Pearce LA, Aguilar MI (2007). "Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation". Ann. Intern. Med. 146 (12): 857-67. PMID 17577005. [e]
  17. ↑ Paciaroni M, Agnelli G, Micheli S, Caso V (2007). "Efficacy and safety of anticoagulant treatment in acute cardioembolic stroke: a meta-analysis of randomized controlled trials". Stroke 38 (2): 423-30. DOI:10.1161/01.STR.0000254600.92975.1f. PMID 17204681. Research Blogging. ACP JC synopsis
  18. ↑ 18.0 18.1 Petersen P, Boysen G, Godtfredsen J, Andersen ED, Andersen B (1989). "Placebo-controlled, randomised trial of warfarin and aspirin for prevention of thromboembolic complications in chronic atrial fibrillation. The Copenhagen AFASAK study.". Lancet 1 (8631): 175-9. PMID 2563096.
  19. ↑ 19.0 19.1 (1991) "Stroke Prevention in Atrial Fibrillation Study. Final results.". Circulation 84 (2): 527-39. PMID 1860198.
  20. ↑ 20.0 20.1 20.2 Connolly SJ, Pogue J, Hart RG, et al. (May 2009). "Effect of clopidogrel added to aspirin in patients with atrial fibrillation". N. Engl. J. Med. 360 (20): 2066–78. DOI:10.1056/NEJMoa0901301. PMID 19336502. Research Blogging.
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