Atrial fibrillation natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anahita Deylamsalehi, M.D.[2]
Overview
Atrial fibrillation can be complicated by embolic events including stroke and systemic embolization. The atrial kick (active filling of the left ventricle by atrial contraction) often contributes importantly to the filling of the left ventricle, and the loss of the atrial kick can be associated with the development of congestive heart failure.
Natural History
- Atrial fibrillation may be continuous (persistent or permanent AF) or alternating between periods of a normal heart rhythm (paroxysmal AF).[1]
- The natural tendency of atrial fibrillation is to become a chronic condition. Chronic AF leads to a small increase in the risk of death.[1][2]
- Based on epidemiological studies atrial fibrillation starts as the paroxysmal form and then evolves to the permanent form eventually in some cases.[3][4]
Complications
The following are complications of atrial fibrillation:[5][6] However, many patients do have additional risk factors and AF is a leading cause of stroke.[7][1][8][3]
- Reduced mechanical pumping action of the atrium:
- Due to the lack of coordination of atrial activation, there is a decline in the mechanical pumping action of the atrium. The decline in mechanical function of the atrium may or may not lead to inadequate filling of the ventricles depending upon the importance of the atrial kick or atrial contribution to ventricular filling in a given patient.
- In patients with a stiff left ventricle (such as patients with hypertension), the atrial kick may be critical to achieve adequate ventricular filling.
- Heart failure:
- Worsening the signs and symptoms of congestive heart failure usually occurs in patients with previous history of congestive heart failure.
- Particularly among patients with valvular heart disease
- Due to the reduced atrial kick needed to fill the left ventricle.
- Increased stroke risk
- Patients with atrial fibrillation usually have a significantly increased risk of stroke (up to 7 times that of the general population).
- Stroke risk increases during AF because blood may pool and form clots in the poorly contracting atrium and especially in the left atrial appendage (LAA).
- One in every 6 strokes occurs in atrial fibrillation patients.
- The level of increased risk of stroke depends on the number of additional risk factors. If the AF patient has none, the risk of stroke is similar to that of the general population.
- Consequences such as vascular dementia and cognitive disturbances are also related to stroke due to AF.[9][10]
- The following table is a summary of stroke risk in different population: [11][12]
| Region | Year | Risk of Stroke |
|---|---|---|
| The United States | 1992 | 48 per 1,000 person |
| The United States | 2007 | 17 per 1,000 person |
| Sweden | 2012 | 25 per 1,000 person |
| France | 2013 | 10 per 1,000 person |
- Death
- Cardiomyopathy
- If left untreated, the chronic tachycardia associated with atrial fibrillation may result in a tachycardia mediated cardiomyopathy.
Prognosis
- After introduction of anticoagulant treatment rate of stroke and consequently risk of death have been decreased.[11]
- Based on numerous studies the improved prognosis of atrial fibrillation has been demonstrated after anticoagulant treatment.
- In a study done on Swedish patients with atrial fibrillation risk of stroke is 25 per 1,000 person/year in patients treated with anticoagulants, compared to 45 per 1,000 person/year risk of stroke in AF patients who didn't received anticoagulant therapy.[11]
- The rate of ischemic stroke among nonrheumatic atrial fibrillation patients averages over 5% per year, a rate that is between 2 and 7 times that of non-AF patients.
- The CHADS Score can estimate this rate with greater certainty:
- The rate of brain ischemia in conjunction with nonvalvular atrial fibrillation exceeds 7% per year.
- Patients with both rheumatic heart disease and atrial fibrillation have an 17-fold risk increase when compared to age-matched controls and an attributable risk of 5 times greater than those with nonrheumatic atrial fibrillation.
Atrial Fibrillation in the Setting of STEMI
- The occurrence of atrial fibrillation in the setting of ST elevation MI is associated with a poor prognosis including a 40% rise in the risk of mortality in meta-analyses. [13]
- The basis for this increase risk of mortality is not clear. Most likely it reflects the fact that atrial fibrillation is a marker of impaired LV function, but it may also reflect the loss of the atrial kick or the hazard associated with triple therapy with aspirin, clopidogrel, and coumadin.
Observational Studies
- The Framingham Heart Study also found that the annual risk of stroke attributable to atrial fibrillation increased from 1.5% in those aged 50-59 years to 23.5% for those aged 80-89 years
- In the Manitoba follow up study, atrial fibrillation doubled the risk of stroke independently of other risk factors.
- The relative risk for stroke in the Whitehall study was 6.99%.
- Relative risk in the Regional Heart study was 2.3%.
- In the ALFA study follow up, patients with atrial fibrillation were found to have a 2.4% incidence of thromboembolism with the mean being 8.6 months of follow-up time.[14]
Mortality
- Atrial fibrillation is associated with a 1.5 to 1.9 fold increase in the risk of death.[14]
- The mortality rate of patients with atrial fibrillation is nearly double that of patients with normal sinus rhythm. This increase is due not only to atrial fibrillation but this also associated with the severity of the underlying disease, and is often due to thromboembolic events.[14]
- The administration of drugs aimed at rate control alone offers no survival advantage over the use of rate control along with anticoagulation as demonstrated in the AFFIRM trial.[15]
References
- ↑ 1.0 1.1 1.2 Benjamin EJ, Wolf PA, D'Agostino RB, Silbershatz H, Kannel WB, Levy D (1998). "Impact of atrial fibrillation on the risk of death: the Framingham Heart Study". Circulation. 98 (10): 946–52. PMID 9737513.
- ↑ Wattigney WA, Mensah GA, Croft JB (2002). "Increased atrial fibrillation mortality: United States, 1980-1998". Am. J. Epidemiol. 155 (9): 819–26. doi:10.1093/aje/155.9.819. PMID 11978585.
- ↑ 3.0 3.1 Nieuwlaat R, Prins MH, Le Heuzey JY, Vardas PE, Aliot E, Santini M; et al. (2008). "Prognosis, disease progression, and treatment of atrial fibrillation patients during 1 year: follow-up of the Euro Heart Survey on atrial fibrillation". Eur Heart J. 29 (9): 1181–9. doi:10.1093/eurheartj/ehn139. PMID 18397874.
- ↑ de Vos CB, Pisters R, Nieuwlaat R, Prins MH, Tieleman RG, Coelen RJ; et al. (2010). "Progression from paroxysmal to persistent atrial fibrillation clinical correlates and prognosis". J Am Coll Cardiol. 55 (8): 725–31. doi:10.1016/j.jacc.2009.11.040. PMID 20170808.
- ↑ Fuster V, Rydén LE, Asinger RW; et al. (2001). "ACC/AHA/ESC 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 and Policy Conferences (Committee to develop guidelines for the management of patients with atrial fibrillation) developed in collaboration with the North American Society of Pacing and Electrophysiology". Eur. Heart J. 22 (20): 1852–923. doi:10.1053/euhj.2001.2983. PMID 11601835. Unknown parameter
|month=ignored (help) - ↑ Jahangir A, Lee V, Friedman PA, Trusty JM, Hodge DO, Kopecky SL, Packer DL, Hammill SC, Shen WK, Gersh BJ (2007). "Long-term progression and outcomes with aging in patients with lone atrial fibrillation: a 30-year follow-up study". Circulation. 115 (24): 3050–6. doi:10.1161/CIRCULATIONAHA.106.644484. PMID 17548732.
- ↑ Wolf PA, Dawber TR, Thomas HE, Kannel WB (1978). "Epidemiologic assessment of chronic atrial fibrillation and risk of stroke: the Framingham study". Neurology. 28 (10): 973–7. PMID 570666.
- ↑ Wattigney WA, Mensah GA, Croft JB (2002). "Increased atrial fibrillation mortality: United States, 1980-1998". Am. J. Epidemiol. 155 (9): 819–26. doi:10.1093/aje/155.9.819. PMID 11978585.
- ↑ Ott A, Breteler MM, de Bruyne MC, van Harskamp F, Grobbee DE, Hofman A (1997). "Atrial fibrillation and dementia in a population-based study. The Rotterdam Study". Stroke. 28 (2): 316–21. doi:10.1161/01.str.28.2.316. PMID 9040682.
- ↑ Cha MJ, Park HE, Lee MH, Cho Y, Choi EK, Oh S (2014). "Prevalence of and risk factors for silent ischemic stroke in patients with atrial fibrillation as determined by brain magnetic resonance imaging". Am J Cardiol. 113 (4): 655–61. doi:10.1016/j.amjcard.2013.11.011. PMID 24360776.
- ↑ 11.0 11.1 11.2 Zoni-Berisso M, Lercari F, Carazza T, Domenicucci S (2014). "Epidemiology of atrial fibrillation: European perspective". Clin Epidemiol. 6: 213–20. doi:10.2147/CLEP.S47385. PMC 4064952. PMID 24966695.
- ↑ Friberg L, Rosenqvist M, Lip GY (2012). "Net clinical benefit of warfarin in patients with atrial fibrillation: a report from the Swedish atrial fibrillation cohort study". Circulation. 125 (19): 2298–307. doi:10.1161/CIRCULATIONAHA.111.055079. PMID 22514252.
- ↑ Jabre P, Roger VL, Murad MH, et al. Mortality associated with atrial fibrillation in patients with myocardial infarction: a systematic review and meta-analysis. Circulation. Apr 19 2011;123(15):1587-93.
- ↑ 14.0 14.1 14.2 Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA et al. (2006) 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 114 (7):e257-354. DOI:10.1161/CIRCULATIONAHA.106.177292 PMID: 16908781
- ↑ Wyse DG, Waldo AL, DiMarco JP, Domanski MJ, Rosenberg Y, Schron EB, et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med. Dec 5 2002;347(23):1825-33.