Reyes de Torres Chacon, MD
The concept of ESUS is still a broad field of study that includes multiple etiologies, including hidden atrial fibrillation (AF), among many others. The latest published studies of secondary prevention in patients with ESUS (NAVIGATE-ESUS, RESPECT-ESUS) have not demonstrated superiority of anticoagulation versus aspirin, probably due, among other reasons, to the etiological heterogeneity of the ESUS concept. The latest studies, still in development, such as ARCADIA or ATTICUS, seek to refine and reformulate the concept of ESUS using biomarkers of atrial pathology such as morphological (left atrial enlargement) or electrical changes (atrial high rate episodes, increased P-wave terminal force in V1 on ECG) as indicators of hidden atrial fibrillation in patients with ESUS.
Jordan et al. show that left atrial enlargement measured as left atrial volume indexed (LAVI) is a good biomarker of the presence of atrial fibrillation in stroke patients. The LAVI of 1020 patients admitted to their hospital after an ischemic stroke are prospectively analyzed and correlated with the etiological subtype, divided into three categories: cardioembolic stroke (CES), non-cardioembolic stroke (NCE), and ESUS. In addition, in the ESUS subtype, prolonged cardiac monitoring was performed in 24% of them, with a hidden AF detection rate of 18.2%.
The CES patients have a higher LAVI compared to the NCE patients (41.4 mL/m2±18.0 versus 28.6 mL/m2±12.2; P<0.001); however, no significant differences are found between the ESUS and the NCE patients (28.9 mL/m2±12.6 versus 28.6 mL/ m2±12.2; P=0.61), which probably reflects the aetiological heterogeneity of the ESUS concept. It should be noted that within the ESUS group, patients in whom hidden AF was detected during prolonged cardiac monitoring do have a higher LAVI compared to those who did not (33.0±10.1 mL/m2 versus 25.5±8.4 mL/m2; P=0.001), which refers to the fact that LAVI is a direct biomarker of atrial pathology and, therefore, of atrial fibrillation. On multivariable analysis adjusting for age, LAVI was independently associated with AF detection in ESUS (adjusted OR per mL/m2 increase, 1.09; 95% CI, 1.02–1.15; P=0.007).
The concept of left atrial enlargement and its relationship with the detection of hidden AF in patients with ESUS has been widely studied in recent years, with special emphasis on which type of measurement is the most accurate, finally prevailing LAVI in front of the diameter or the atrial area. This study demonstrates, once again, that there are biomarkers related to atrial pathology that can help indicate which patients with ESUS really have a higher probability of presenting with hidden AF and are, therefore, candidates for a more extensive cardiac assessment that includes prolonged cardiac monitoring to detect the arrhythmia and being able to initiate the most appropriate treatment in secondary stroke prevention.
