INTRODUCTION
Cryptogenic stroke accounts for 20 to 40% of all ischemic strokes. Atrial fibrillation (AF) has been found in up to 30% of cryptogenic stroke patients during long-term monitoring1.  AF may be paroxysmal, occur rarely and be asymptomatic, making detection with routine methods difficult.  The presence of AF discovered within days, weeks or months following cryptogenic stroke does not establish the etiology of cardiogenic embolism, but does impact on medical stroke prevention in the vast majority of patients, prompting change in treatment from antiplatelets to anticoagulation.  Optimal monitoring duration to detect AF is currently undetermined.  We present our real world experience of surveillance for AF in patients with cryptogenic stroke using an implantable loop recorder in the community hospital setting.

METHODS
We reviewed electronic medical records of a prospective cohort of cryptogenic stroke patients who underwent implantable loop recorder insertion from March 2014 to December 2018.  All patients met ESUS criteria for cryptogenic stroke and had remote follow-up in the cardiology device clinic.

RESULTS
A total of 432 patient underwent ILR implantation from March 2014 to December 2018.  116 (27%) developed AF and were not followed further.  In patients without AF, median device follow-up time was 1013 days (range 81-1736), median times from index event to insertion was 4.5 days, and AF detection was 141.5 days (range 0-1074).  All patients had AF duration greater than 6 minutes.  111 patients were started on anticoagulation (95%) and 5 patients refused.  Median time from AF detection to start of anticoagulation was 1 day.  Average CHA2DS2-VASC2 score was 5.  There were no significant differences in age, sex or race amongst patients with and without AF detected.

CONCLUSIONS
During long-term follow-up, AF was identified in 27% of our patients with implantable loop recorders, similar to the CRSTYAL AF trial results. Our median time to AF detection of 141 days suggests the need for long-term continuous monitoring for AF in this patient population. Detection of AF led to change in secondary stroke prevention to anticoagulation for the majority of our patients. Early initiation of anticoagulation after AF detection will likely lead to reduction of future recurrent strokes and reduce morbidity and mortality.

5 - LONG TERM SURVEILLANCE RESULTS FOR ATRIAL FIBRILLATION DETECTION IN A COHORT OF CRYPTOGENIC STROKE PATIENTS IN A COMMUNITY HOSPITAL SETTING