375 ATRIAL FIBRILLATION BURDEN IN PATIENTS WITH IMPLANTABLE LOOP RECORDER AFTER A CRYPTOGENIC STROKE


 
 
 After a cryptogenic stroke, long-term monitoring is recommended to start an anticoagulation therapy in patients with at least a documented paroxysm of subclinical atrial fibrillation (AF). Literature is sparse about the recurrence of AF (AF burden) after a cryptogenic stroke, but this might have significant implications in terms of therapeutic strategy.
 
 
 
 This is a retrospective single-center study of 129 patients who received implantable loop recorders (ILRs), after a cryptogenic stroke, between March 2015 and March 2022. All patients were followed through remote monitoring for at least 6 months. The primary endpoint was AF detection; the secondary endpoints were the AF burden, the earliness (within or after 90 days from the ILR implant) of the first AF episode and if there was an association between these two variables.
 
 
 
 Mean age was 70.3 ± 10.4 years old (67 males, 51.9%); the mean value of left ventricular ejection fraction was 61% ± 5.8. Atrial fibrillation has been detected by ILR in 40.3% of patients (AF= 52 patients, NO AF= 77 patients) and each intracardiac electrogram was visually reviewed by two physicians. Median CHAD2S2-Vasc Score was 5 [4-6]; the median AF burden (assessed in 39 of the 52 patients) was 1.2% [0.1%-14.6%]; among these, 23 patients (59%) had the first episode within 90 days from the ILR implant versus 16 patients (41%) which experienced the first episode later than 90 days. AF burden was significantly higher in the first group (median 3.9% [1.2%-30.9%] vs 0.1% [0.03%-0.75%]; p=0.001). Of note the univariate analysis showed that both detection of the first AF episode within 90 days and echocardiographic findings of atrial disease (atrial dilation or diastolic dysfunction) were significantly associated with AF burden > 1% (about 7 hours for month) (respectively OR 16.5; 95% IC=3.34-81.21, p=0.001 and OR 4.5; 95% IC=1.2-17.5, p=0.03); at the multivariate analysis the significance was confirmed for the earliness of the first AF episode (OR 14.6; 95% IC=2.8-76.75, p=0.002).
 
 
 
 In this small, retrospective study, AF was detected by ILR, after a cryptogenic stroke, in more than one third of patients. AF onset during the first 90 days might be a marker of a high AF burden and might highlight patients who could benefit from a rhythm control strategy of AF. Larger studies and clinical outcomes evaluation of these patients are required to confirm our results.
