It has long been known that patients with atrial fibrillation (AF) have increased risks for clinical brain infarcts and cognitive decline, but underlying mechanisms were incompletely understood. The research team of Philipp Krisai and Michael Kühne could previously observe in a cross-sectional study that one in five AF patients had clinically silent brain infarcts – despite a high rate of anticoagulation – and that these silent infarcts are associated with cognitive dysfunction similar to clinical infarcts. These results offered a potential explanation for the association between AF and cognitive decline in patients without a previous stroke, but prospective data were lacking.

To further investigate this association, the scientists followed 1227 AF patients prospectively in a multi-center study across Switzerland. The participants underwent brain magnetic resonance imaging (MRI) at the beginning of the study and after two years to investigate the occurrence of new ischemic brain infarcts, white matter lesions and microbleeds. Clinically silent infarcts were assessed in patients without a clinical stroke or ischemic attack during follow-up. Additionally, cognitive performance was analyzed with different neurocognitive tests.

The results after two years were as following: After two years, new ischemic brain infarcts were found in 5.5%, new white matter lesions in 18.7%, and new microbleeds in 11.4% of the patients. Nearly 9 out of 10 ischemic brain infarcts occurred in anticoagulated patients. Although most of the brain infarcts were clinically silent, they had similar associations with cognitive decline as clinically overt brain infarcts. By contrast, white matter lesions and microbleeds were not associated with cognitive decline.

The data of Philipp Krisai and his team are relevant for a growing population of AF patients at risk for cognitive decline. They suggest that anticoagulation alone may not be sufficient to prevent progressive brain damage in all AF patients and other preventive measures are needed. In summary, this study prospectively assessed the occurrence of clinically silent and overt brain lesions and their association with cognitive decline in patients with atrial fibrillation.

Silent brain infarcts impact on cognitive function in atrial fibrillation. Michael Kühne*, Philipp Krisai*, Michael Coslovsky, Nicolas Rodondi, Andreas Müller, Jürg H Beer, Peter Ammann, Angelo Auricchio, Giorgio Moschovitis, Daniel Hayoz, Richard Kobza, Dipen Shah, Frank Peter Stephan, Jürg Schläpfer, Marcello Di Valentino, Stefanie Aeschbacher, Georg Ehret, Ceylan Eken, Andreas Monsch, Laurent Roten, Matthias Schwenkglenks, Anne Springer, Christian Sticherling, Tobias Reichlin, Christine S Zuern, Pascal B Meyre, Steffen Blum, Tim Sinnecker, Jens Würfel, Leo H Bonati, David Conen, Stefan Osswald, Swiss-AF Investigators. European Heart Journal (2022) 43, 2127–2135.
* Contributed equally