Diagnostic yield of implantable loop recorders in patients with unexplained syncope: single-center experience

BACKGROUND: A significant proportion of patients have syncope of uncertain etiology. While implantable loop recorder (ILR) has become an important diagnostic tool in diagnosing syncope, its contemporary role in accordance with the recently updated syncope guidelines is not well established. The purpose of this single-center retrospective study was to determine the diagnostic yield of ILR in patients with unexplained syncope following initial diagnostic work-up as recommended by the guidelines. METHODS: Medical records of 100 consecutive patients with syncope or presyncope who received ILR following the recently updated recommended diagnostic work-up were retrospectively evaluated. RESULTS: Seven patients were lost to follow-up (7%). During a median follow-up of 12 months (IQR 6.5-27.5), syncope or presyncope recurred in 61 patients (65.6%). In 37 (37/61, 60.7%), correlation between abnormal heart rhythm and symptoms was confirmed by ILR. Syncope was predominantly caused by bradyarrhythmia (33/37, 89.2%). Of the remaining four patients, three (8.1%) had ventricular tachycardia and one had atrial fibrillation with rapid ventricular response. Arrhythmogenic cause of syncope or presyncope was excluded in 24 patients (24/61, 39.3%) as no arrhythmia was recorded at the time of reported symptoms. Median time to establishing diagnosis was 354 days (171-783). CONCLUSIONS: The diagnostic yield of ILR after initial inconclusive recommended diagnostic work-up in accordance with the relevant guidelines was high. The findings affirm ILR as an important diagnostic tool in contemporary management of syncope.