Background and Purpose: There are few data on the occurrence of microembolic signals (MES) in patients with lone atrial fibrillation (LAF). The aim of this work was to systematically study the frequency of MES in patients with symptomatic and asymptomatic LAF and to compare it with that of nonvalvular atrial fibrillation (NVAF). Methods: 37 consecutive acute stroke patients with LAF, 10 asymptomatic patients with LAF and 100 age-matched healthy controls were studied. Another 92 stroke patients with known NVAF were included in the study to compare patients with LAF regarding the presence of MES. Both middle cerebral arteries were monitored by transcranial Doppler ultrasound for at least 30 min at admission and after 1 week in symptomatic and asymptomatic patients with LAF. All patients with LAF were followed up for a mean duration of 18 months, and recurrent strokes were registered. Results: MES was detected in 11 (29%) symptomatic patients with LAF but only in 1 asymptomatic patient with LAF (χ2 = 11.3; p = 0.0008) and in no control subjects (χ2 = 106; p = 0.00001). There was no difference in the frequency of MES-positive patients and the number of MES between subjects with symptomatic LAF and known NVAF (29% in both groups; mean count, 16 ± 4 vs. 17 ± 6; p = 0.73). In patients with symptomatic LAF and NVAF who underwent anticoagulant therapy, there was no difference in the frequency of MES after 1 week of hospitalization (χ2 = 1.53; p = 0.2). During a mean follow-up period of 18 months, 1 patient with symptomatic LAF and MES had a recurrent ischemic event 1 year after the first stroke and none of those with asymptomatic LAF had any events. Conclusion: Our study suggests that asymptomatic and paroxysmal LAF with a lower frequency of MES is a benign disorder compared to chronic and symptomatic LAF with a higher frequency of MES. Further studies need to justify whether MES has a predictive value in patients with chronic LAF who are prone to ischemic stroke.

Keywords:
Microembolic signals, Lone atrial fibrillation, Transcranial Doppler ultrasonography
1.
Phillips E, Levine SA: Auricular fibrillation without other evidence of heart disease: A cause of reversible heart failure. Am J Med 1949;7:478–489.
2.
Brand FN, Abott RD, Kannel WB, Wolf PA: Characteristics and prognosis of lone atrial fibrillation: The Framingham study. JAMA 1985;254:3449–3453.
3.
Scardi S, Mazzone C, Pandullo C, Goldstein D, Poletti A, Humar F: Lone atrial fibrillation: Prognostic differences between paroxysmal and chronic forms after 10 years of follow-up. Am Heart J 1999;137:686–691.
4.
Nabavi DG, Allroggen A, Reinecke H, Schulte-Altedorneburg G, Droste DW, Breithardt G, Ringelstein EB: Absence of circulating microemboli in patients with lone atrial fibrillation. Neurol Res 1999;21:566–568.
5.
Ringelstein EB, Droste DW, Babikian VL, Evans DH, Grosset DG, Kaps M, Markus HS, Russell D, Siebler M: Consensus on microembolus detection by TCD. Stroke 1998;29:725–729.
6.
Kopecky SL, Gersh BJ, McGoon MD: The natural history of lone atrial fibrillation: A population-based study over three decades. N Engl J Med 1987;317:669–674.
7.
Markus HS, Thomson ND, Brown MM: Asymptomatic cerebral embolic signals in symptomatic and asymptomatic carotid artery disease. Brain 1995;118:1005–1011.
8.
Siebler M, Sitzer M, Rose G, Bendfeldt D, Steinmetz H: Silent cerebral embolism caused by neurologically symptomatic high-grade carotid stenosis. Brain 1993;116:1005–1015.
9.
Infeld B, Bowser DN, Gerraty RP, Voukelatos J, Grigg L, Mitchell PJ, Hopper JL, Davies SM: Cerebral microemboli in atrial fibrillation detected by transcranial Doppler ultrasonography. Cerebrovasc Dis 1996;6:339–345.
10.
Cullinane M, Wainwright R, Brown A, Monaghan M, Markus HS: Asymptomatic embolization in subjects with atrial fibrillation not taking anticoagulants: A prospective study. Stroke 1998;29:1810–1815.
11.
Report of the Quality Standards Subcommittee of the American Academy of Neurology: Stroke prevention in patients with nonvalvular atrial fibrillation. Neurology 1998;51:671–673.
12.
European Atrial Fibrillation Trial Study Group: Secondary prevention of vascular events in patients with nonrheumatic atrial fibrillation and recent transient ischemic attack or minor ischemic stroke. Lancet 1993;342:1255–1262.
13.
Conti CR: Stroke and atrial fibrillation: To anticoagulate or not. Clin Cardiol 1993;16:529–530.
14.
Aronow WS: Atrial fibrillation and thromboembolic stroke. Compr Ther 1994;20:186–191.
15.
Bogousslavsky J, Adnet-Bonte C, Regli F, Van Melle G, Kappenberger L: Lone atrial fibrillation and stroke. Acta Neurol Scand 1990;82:143–146.
16.
Droste DW, Ritter M, Kemeny V, Schulte-Altedorneburg G, Ringelstein EB: Microembolus detections at follow-up in 19 patients with acute stroke. Cerebrovasc Dis 2000;10:272–277.
© 2001 S. Karger AG, Basel
2001
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