Prevalence and Characteristics of Known versus Newly Detected Atrial Fibrillation in Ischemic Stroke: A Population-Based Study.

Background: Atrial fibrillation (AF) is frequently diagnosed during the acute stage of ischemic stroke (IS), and it may reflect undiagnosed AF before stroke, thus representing a missed opportunity for stroke prevention. This population-based study aimed to assess the prevalence of known AF (KAF) and AF diagnosed early after IS (AFDAS) and to compare clinical and brain/arterial imaging characteristics between patients.

Methods: Among patients with acute IS recorded in the population-based Dijon Stroke Registry, France (2013-2020), we identified those with KAF or AFDAS. AFDAS was considered when AF was diagnosed during the initial work-up based on electrocardiograms, in-hospital continuous electrocardiographic and/or Holter monitoring. Clinical and imaging characteristics on brain CT scan or angio-CT scan when available including old parenchymal lesions, arterial territory of the index IS, and aortic arch, cervical and intracranial arteries atheroma were compared between groups (KAF vs. AFDAS). Regression logistic models were used to assess factors associated with AFDAS (compared to KAF).

Results: Among 1,756 IS patients, 550 (31.3%) had AF (mean age: 83.6 ± 10.3 years old, 60.5% women), of whom 367 (66.7%) presented with KAF and 183 (33.3%) had AFDAS. In multivariable model, hypertension (OR = 0.37; 95% CI: 0.21-0.64, p < 0.001), chronic heart failure (OR = 0.34; 95% CI: 0.18-0.67, p = 0.002), previous stroke (OR = 0.42; 95% CI: 0.26-0.67, p < 0.001), and preexisting dementia (OR = 0.36; 95% CI: 0.21-0.63, p < 0.001) were inversely associated with AFDAS, whereas NIHSS score was associated with AFDAS (OR = 1.02; 95% CI: 1.00-1.05, p = 0.012).

Conclusions: Our findings indicate a more advanced stage of the atrial cardiomyopathy in KAF as compared with AFDAS patients and may thus contribute to the fact that in these latter patients AF had not been diagnosed prior to stroke. This group of patients undeniably represents a missed opportunity for stroke prevention.