Microembolic Signal Detection in Patients with Symptomatic and Asymptomatic Lone Atrial Fibrillation

Abstract

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.

Microembolic Signals within 24 Hours of Stroke Onset and Diffusion-Weighted MRI Abnormalities

“…Microembolic signals (MES) have been detected by transcranial Doppler (TCD) in patients with carotid diseases, atrial fibrillation, prosthetic cardiac valves and carotid angiography, as well as intraoperatively in patients undergoing cardiac or carotid surgery [1,2,3,4,5,6,7,8,9,10]. MES is detected in 4–56% of acute stroke patients [11,12,13,14,15,16,17].…”

Aspirin Attenuates the Incidence of Silent Brain Lesions in Patients With Nonvalvular Atrial Fibrillation

“…14,15 If circulating microthrombi cause silent BI, particularly small lesions, in patients with NVAF, oral anticoagulation therapy and antiplatelet therapy may be effective for prevention. 16 Indeed, many clinical trials have shown that these treatments are useful for reducing the risk of stroke and systemic embolism in patients with NVAF. [17][18][19][20][21] However, a large, well-designed study carried out by the SPINAF group did not show a significant effect of aspirin on the annual event rate of silent BI.…”

Microemboli Monitoring in Ischemic Stroke

“…The highest prevalence of microemboli is seen in patients with prosthetic heart valves, about 60% with mechanical prosthetic heart valves and about 10% with biological prosthetic heart valves (Eicke, Barth et al 1996). In patients with atrial fibrillation, the prevalence of microemboli seems to be higher in symptomatic atrial fibrillation (29%) as opposed to asymptomatic atrial fibrillation (10%) (Kumral, Balkir et al 2001). Similarly, there is a higher prevalence of microemboli in valvular atrial fibrillation as opposed to non-valvular atrial fibrillation corresponding to a higher risk for thromboembolic events (Kumral, Balkir et al 2001).…”

“…In patients with atrial fibrillation, the prevalence of microemboli seems to be higher in symptomatic atrial fibrillation (29%) as opposed to asymptomatic atrial fibrillation (10%) (Kumral, Balkir et al 2001). Similarly, there is a higher prevalence of microemboli in valvular atrial fibrillation as opposed to non-valvular atrial fibrillation corresponding to a higher risk for thromboembolic events (Kumral, Balkir et al 2001). Except for mechanical prosthetic heart valves, the overall prevalence of microemboli in various heart conditions seems to be lesser than in carotid artery disease.…”