Detection of atrial fibrillation by implantable loop recorders following cryptogenic stroke: A retrospective study of predictive factors and outcomes

Cryptogenic strokes account for 40% of ischemic strokes. Atrial fibrillation (AF) is a known cause of stroke. Current data shows that occult AF is detected by implantable devices at higher rates than conventional monitoring. The objective of this study was to investigate risk factors and outcomes associated with AF detection by implantable loop recorders (ILRs) in patients with cryptogenic stroke. We conducted a retrospective study of 172 patients admitted with cryptogenic stroke at Ascension St John and Macomb-Oakland Hospitals who had ILRs placed from 1/1/2016 to 1/31/2020. AF detection was defined as sustained AF for 30 s. The incidence of AF detection by ILR was 14% (24/172) over a mean follow-up of 12.75 ± 10.71 months. The mean duration of monitoring prior to AF detection was 4.5 months. The median duration of AF was 6 min. With univariable analysis, older age (p = 0.03), male sex (p = 0.09), embolic stroke pattern on imaging (p = 0.06), and presence of symptoms (p = 0.001) were associated with AF detection. Using multivariable analysis, patients with AF were more likely to be older (OR = 1.04, p = 0.04), male (OR = 3.6, p = 0.03), symptomatic (OR = 6.3, p = 0.01), and had embolic stroke pattern (OR = 3.3, p = 0.04). 95.8% of patients with AF were started on anticoagulation for secondary stroke prevention. In patients with cryptogenic stroke, age, sex, stroke pattern, and presence of AF symptoms are independent predictors of AF detection by ILR. Most patients with AF were started on anticoagulation for secondary stroke prevention.