Atrial fibrillation

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Diagnosis

Prevalence

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).

Routine cardiac monitoring for seven days after ischemic stroke detected atrial fibrillation in 40% of patients.[2]

Electrocardiogram

Regarding the accuracy of the electrocardiogram[3]:

Prognosis

Risk of stroke

The risk of stroke in a patient with atrial fibrillation can be predicted with the CHADS2 score and perhaps better with the CHA2DS2-VASc score.[4][5] CHA2DS2-VASc is:

Interpretation is:

Treatment

Clinical practice guidelines by the American College of Physicians and the American Academy of Family Physicians address treatment.[6][7]

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."[6]

Regarding target heart rate, a recent randomized controlled trial found that resting heart rate <110 beats per minute had similar outcomes to stricter control.[8] Previously, the goal rate is "80 beats per minute during resting ... and of less than 110 beats per minute during a 6-minute walk test."[9]

As compared to rate control, rhythm control was associated with slight, although statistically insignificant, increase in adverse outcomes in randomized controlled trials.[10][9][11] 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."[10] Whether the index episode was the initial or a recurrent episode did not effect results.[11]

Randomized controlled trials of rhythm versus rate control.[10][11][9]
Study Patients Intervention in rhythm control group Results
Rhythm control group Rate control group
Van Gelder[10]
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[11]
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[9]
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%

Regarding the choice of medication:
Shown effective in some randomized controlled trials

Shown not effective in some randomized controlled trials

Episodic therapy

Episodic medical therapy has conflicting results with a positive uncontrolled before and after trial of flecainide and propafenone[15] and a negative randomized controlled trial of episodic amiodarone versus continuous amiodarone.[16]

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.[17]

Dual site, overdrive pacing be effective.[18]

Ablation

Pulmonary-vein isolation

Randomized controlled trial have found that using ablation to cause pulmonary-vein isolation was superior to medical therapy[19][20][21] and to atrioventricular-node ablation[22]. About two thirds of patients remain in sinus rhythm after 9 months.[19]

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). "[6]
Randomized controlled trials of new anticoagulants compared to warfarin for atrial fibrillation.[23] [24] [25]
Trial Patients Intervention Comparison Outcome Results Comments
Intervention Control
ARISTOTLE[23]
2011		 18,201 patients Apixaban 5 mg twice daily warfarin (target INR 2.0 to 3.0; time in therapeutic range 62%) stroke or systemic embolism at 1.3 years 1.3% per year 1.6% per year • hazard ratio for primary outcome 0.79
• relative risk for death 0.89 (95% CI: 0.80 to 0.99; P=0.047)
ROCKET AF[24]
2011		 14,264 patients Rivaroxaban 20 mg daily
(15 mg daily if creatinine clearance 30 to 49 ml per minute)		 warfarin (target INR 2.0 to 3.0; time in therapeutic range 55%) stroke or systemic embolism at 1.6 years 2.1% per year 2.4% per year • hazard ratio for primary outcome 0.79
• relative risk for death 0.92 (95% CI: 0.82 to 1.03; P=0.15)
RE-LY[25]
2009		 18,113 patients Dabigatran 150 mg twice daily warfarin (target INR 2.0 to 3.0; time in therapeutic range 64%) stroke or systemic embolism at 1.3 years 1.1% per year 1.5% per year • relative risk for primary outcome 0.66
• relative risk for death 0.88 (95% CI: 0.77 to 1.00; P=0.051)
• Not blinded
Dabigatran versus warfarin for atrial fibrillation[25]
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%. [26]. However, a recent meta-analysis suggests harm from anti-coagulation started early after an embolic stroke.[27]

Anticoagulants is underused for atrial fibrillation.[28] Both doctors[29] and patients[30] are reluctant to use anticoagulants. Patients may avoid warfarin even when they prefer the outcomes of warfarin.[31]

In 2009, dabigatran, a direct thrombin inhibitors, was compared to warfarin in the RE-LY randomized controlled trial.[25]

Antiplatelet therapy

Randomized controlled trials of antiplatelet therapy for atrial fibrillation[32][33][34]
Trial Patients Intervention Comparison Outcome Results
Intervention Control
Copenhagen AFASAK study[32]
1989		 1007 patients aspirin 75 mg daily Warfarin stroke, transient ischemic attack, or systemic embolism 6.0% 1.4%
SPAF[33]
1991		 1,330 patients aspirin 325 mg daily Warfarin ischemic stroke and systemic embolism 3.6% 2.3%†
ACTIVE study[34]
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.[34]

Screening

Screening may increase detection according to a systematic review by the Cochrane Collaboration.[35]

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. ↑ Higgins P, MacFarlane PW, Dawson J, McInnes GT, Langhorne P, Lees KR (2013). "Noninvasive cardiac event monitoring to detect atrial fibrillation after ischemic stroke: a randomized, controlled trial.". Stroke 44 (9): 2525-31. DOI:10.1161/STROKEAHA.113.001927. PMID 23899913. Research Blogging.
  3. ↑ 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.
  4. ↑ Lopes RD, Crowley MJ, Shah BR, et al . Stroke Prevention in Atrial Fibrillation. Comparative Effectiveness Review No. 123. AHRQ Publication No. 13-EHC113-EF. Rockville, MD: Agency for Healthcare Research and Quality; August 2013. www.effectivehealthcare.ahrq.gov/ reports/final.cfm.
  5. ↑ Olesen JB, Lip GY, Hansen ML, Hansen PR, Tolstrup JS, Lindhardsen J et al. (2011). "Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study.". BMJ 342: d124. DOI:10.1136/bmj.d124. PMID 21282258. PMC PMC3031123. Research Blogging.
  6. ↑ 6.0 6.1 6.2 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]
  7. ↑ 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]
  8. ↑ Van Gelder IC, Groenveld HF, Crijns HJ, Tuininga YS, Tijssen JG, Alings AM et al. (2010). "Lenient versus strict rate control in patients with atrial fibrillation.". N Engl J Med 362 (15): 1363-73. DOI:10.1056/NEJMoa1001337. PMID 20231232. Research Blogging.
  9. ↑ 9.0 9.1 9.2 9.3 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.
  10. ↑ 10.0 10.1 10.2 10.3 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.
  11. ↑ 11.0 11.1 11.2 11.3 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.
  12. ↑ 12.0 12.1 Manios EG, Mavrakis HE, Kanoupakis EM, Kallergis EM, Dermitzaki DN, Kambouraki DC et al. (2003). "Effects of amiodarone and diltiazem on persistent atrial fibrillation conversion and recurrence rates: a randomized controlled study.". Cardiovasc Drugs Ther 17 (1): 31-9. PMID 12843685.
  13. ↑ Kühlkamp V, Schirdewan A, Stangl K, Homberg M, Ploch M, Beck OA (2000). "Use of metoprolol CR/XL to maintain sinus rhythm after conversion from persistent atrial fibrillation: a randomized, double-blind, placebo-controlled study.". J Am Coll Cardiol 36 (1): 139-46. PMID 10898425.
  14. ↑ Nergårdh AK, Rosenqvist M, Nordlander R, Frick M (2007). "Maintenance of sinus rhythm with metoprolol CR initiated before cardioversion and repeated cardioversion of atrial fibrillation: a randomized double-blind placebo-controlled study.". Eur Heart J 28 (11): 1351-7. DOI:10.1093/eurheartj/ehl544. PMID 17329409. Research Blogging.
  15. ↑ 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.
  16. ↑ 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.
  17. ↑ 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.
  18. ↑ 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]
  19. ↑ 19.0 19.1 Wilber DJ, Pappone C, Neuzil P, De Paola A, Marchlinski F, Natale A et al. (2010). "Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial.". JAMA 303 (4): 333-40. DOI:10.1001/jama.2009.2029. PMID 20103757. Research Blogging.
  20. ↑ 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.
  21. ↑ 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.
  22. ↑ 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.
  23. ↑ 23.0 23.1 Granger CB, Alexander JH, McMurray JJ, Lopes RD, Hylek EM, Hanna M et al. (2011). "Apixaban versus warfarin in patients with atrial fibrillation.". N Engl J Med 365 (11): 981-92. DOI:10.1056/NEJMoa1107039. PMID 21870978. Research Blogging. Review in: Ann Intern Med. 2012 Jan 17;156(2):JC1-2, JC1-3
  24. ↑ 24.0 24.1 Patel MR, Mahaffey KW, Garg J, Pan G, Singer DE, Hacke W et al. (2011). "Rivaroxaban versus Warfarin in Nonvalvular Atrial Fibrillation.". N Engl J Med. DOI:10.1056/NEJMoa1009638. PMID 21830957. Research Blogging.
  25. ↑ 25.0 25.1 25.2 25.3 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. Cite error: Invalid <ref> tag; name "pmid19717844" defined multiple times with different content Cite error: Invalid <ref> tag; name "pmid19717844" defined multiple times with different content
  26. ↑ 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]
  27. ↑ 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
  28. ↑ Wess ML, Schauer DP, Johnston JA, Moomaw CJ, Brewer DE, Cook EF et al. (2008). "Application of a decision support tool for anticoagulation in patients with non-valvular atrial fibrillation.". J Gen Intern Med 23 (4): 411-7. DOI:10.1007/s11606-007-0477-9. PMID 18373138. PMC PMC2359511. Research Blogging.
  29. ↑ Go AS, Hylek EM, Borowsky LH, Phillips KA, Selby JV, Singer DE (1999). "Warfarin use among ambulatory patients with nonvalvular atrial fibrillation: the anticoagulation and risk factors in atrial fibrillation (ATRIA) study.". Ann Intern Med 131 (12): 927-34. PMID 10610643.
  30. ↑ Protheroe J, Fahey T, Montgomery AA, Peters TJ (2000). "The impact of patients' preferences on the treatment of atrial fibrillation: observational study of patient based decision analysis.". BMJ 320 (7246): 1380-4. PMID 10818030. PMC PMC27382.
  31. ↑ Holbrook A, Labiris R, Goldsmith CH, Ota K, Harb S, Sebaldt RJ (2007). "Influence of decision aids on patient preferences for anticoagulant therapy: a randomized trial.". CMAJ 176 (11): 1583-7. DOI:10.1503/cmaj.060837. PMID 17515584. PMC PMC1867833. Research Blogging.
  32. ↑ 32.0 32.1 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.
  33. ↑ 33.0 33.1 (1991) "Stroke Prevention in Atrial Fibrillation Study. Final results.". Circulation 84 (2): 527-39. PMID 1860198.
  34. ↑ 34.0 34.1 34.2 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.
  35. ↑ Moran PS, Flattery MJ, Teljeur C, Ryan M, Smith SM (2013). "Effectiveness of systematic screening for the detection of atrial fibrillation.". Cochrane Database Syst Rev 4: CD009586. DOI:10.1002/14651858.CD009586.pub2. PMID 23633374. Research Blogging.
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