Atrial fibrillation and silent stroke: links, risks, and challenges

Abstract

Atrial fibrillation (AF) is the most common cardiac arrhythmia, with a projected number of 1 million affected subjects in Germany. Changes in age structure of the Western population allow for the assumption that the number of concerned people is going to be doubled, maybe tripled, by the year 2050. Large epidemiological investigations showed that AF leads to a significant increase in mortality and morbidity. Approximately one-third of all strokes are caused by AF and, due to thromboembolic cause, these strokes are often more severe than those caused by other etiologies. Silent brain infarction is defined as the presence of cerebral infarction in the absence of corresponding clinical symptomatology. Progress in imaging technology simplifies diagnostic procedures of these lesions and leads to a large amount of diagnosed lesions, but there is still no final conclusion about frequency, risk factors, and clinical relevance of these infarctions. The prevalence of silent strokes in patients with AF is higher compared to patients without AF, and several studies reported high incidence rates of silent strokes after AF ablation procedures. While treatment strategies to prevent clinically apparent strokes in patients with AF are well investigated, the role of anticoagulatory treatment for prevention of silent infarctions is unclear. This paper summarizes developments in diagnosis of silent brain infarction and its context to AF.

Keywords: atrial fibrillation; cardiac embolic events; silent strokes; stroke risk.

Figure 1

MRI (FLAIR-weighted sequence) of a 76-year-old patient with chronic atrial fibrillation. Notes: Approximately 3 years ago, cortical stroke on the right side (white arrow). Silent brain infarction on the left side without clinical symptoms (gray arrow). With kind permission from Springer Science + Business Media: Nervenarzt, Silent brain infarctions, Volume 82(8), 2011, pages 1043–1052, Ritter MA, Dittrich R, Ringelstein EB. © Springer-Verlag 2011. Abbreviations: FLAIR, fluid-attenuated inversion recovery; MRI, magnetic resonance imaging.

Figure 2

MRI of a 61-year-old patient with embolic silent brain infarction in cerebellum (arrow). Note: With kind permission from Springer Science +Business Media: Nervenarzt, Silent brain infarctions, Volume 82(8), 2011, pages 1043–1052, Ritter MA, Dittrich R, Ringelstein EB. © Springer-Verlag 2011. Abbreviation: MRI, magnetic resonance imaging.