Efficacy of atrial fibrillation detection in cryptogenic stroke according to data of implantable loop recorders: pilot study

Aim. To estimate the efficacy of invasive and non-invasive long-term ECG monitoring in comparison with conventional follow-up for the detection of silent atrial fibrillation (AF)/atrial flutter (AFL)/atrial tachycardia (AT) in patients with a cryptogenic stroke.Methods. The randomized, prospective, two-center study enrolled 36 patients who suffered cryptogenic stroke (CS) or transient ischemic attack (TIA) without past history of AF/AFL/AT. Patients were randomized in a 1:1:1 ratio to one of the three ECG monitoring strategies: standard arrhythmia monitoring (group I, n=12), ECG-monitoring with implantable loop recorder (group II, n=12), and ambulatory noninvasive ECG monitoring (group III, n=12). The primary endpoint was the time to the first detection of AF/AFL/AT. Patients, assigned to the group I, underwent an assessment at scheduled and unscheduled visits and received ambulatory ECG monitoring 28 days and 1 year after randomization. Patients in the group II underwent implantation of Reveal XT (Medtronic, USA) with the daily remote data transmission to CareLink Network. In the group III, for long-term external monitoring, Spyder system (WEB Biotechnology, Singapore) was used for up to 28 days.Results. During the first 28 days of observation, there were no significant differences in AF detection rates between groups I, II, and III: 0 (0%), 1 (8%), and 2 (17%) cases, respectively, р=0.537. During the year of observation, AF/AFL/AT episodes were detected in 1 case (8%) in the group I, 6 cases (50%) in the group II, and 2 cases (17%) in the group III, p=0.0486. The mean time from enrollment into the study to detection of the first AF/AFL/AT episode was 67 days (15; 97) in all groups. In the groups II and III, the first arrhythmia episodes were detected by monitoring devices on days 24 and 6, respectively. In most cases, arrhythmia episodes detected by long-term monitoring were asymptomatic. Recurrent stroke or TIA events occurred in group I and III (1 case in each group), but not in the group with implantable cardiac monitors. Subgroup analysis showed that significantly higher AF/AFL/AT detection rate was associated with stroke, CHA2DS2VASc score ≥2, and the presence of hypertension. For the 12 months of follow-up, the mean AF burden in the group II was 0.4 (0.2; 0.5) hours per day (1.6%). In the patients with recurrent stroke, AF burden was 3.2% compared to 0.9% in the rest of patients.Conclusion. Detection of silent AF with implantable cardiac monitors is superior to standard and long-term external monitoring in cryptogenic stroke patients.