Atrial fibrillation detection using an implantable loop recorder after cryptogenic stroke

Implantable loop recorders (ILRs) assist in detecting occult atrial fibrillation (AF) in patients with cryptogenic stroke (CS), yet many patients do not manifest subsequent AF.

To identify factors associated with ILR-detected AF, thereby improving device specificity.

All 744 patients implanted with ILRs at our Stroke Center from 2014 to 2025 after ischemic CS were followed for AF episodes of ≥6 minutes and recurrent stroke.

During 657 ± 450 (median 591) days, 138 (18.5%) patients manifested AF lasting ≥6 minutes, with the highest risk within the first 6 months. Older age (hazard ratio [HR], 1.05 per year; 95% confidence interval [CI], 1.03-1.07; P < .001), tricuspid regurgitation (HR, 1.61; 95% CI, 1.10-2.35; P = .015), and middle cerebral artery stroke (HR, 1.79; 95% CI, 1.18-2.71; P = .006) were independently associated with shorter time to initial AF. Multivessel strokes were not associated with AF detection. In the oldest age quartile (≥76), 28% manifested AF. Mitral regurgitation, tricuspid regurgitation, and β-blocker use were associated with shorter time to initial AF. In the middle 2 age quartiles (57-75), 18% had detected AF. Middle cerebral artery stroke was independently associated with AF risk. Only 6% in the youngest age quartile (≤56) manifested AF. Of 44 patients with recurrent stroke, 6 had detected AF. Stroke was temporally related to AF in 2 patients.

Older age is highly associated with subsequent AF detection in CS. Mitral and tricuspid regurgitation and middle cerebral artery strokes are associated with AF in older and middle-aged patients, respectively. Recurrent stroke was rarely associated with temporally related AF.