The diagnostic value of the syncope-to-ILR interval on syncope etiology.

Objective: Implantable loop recorders (ILRs) are useful in determining syncope etiology. We observed a higher diagnostic rate in patients receiving early implantation. We hypothesized that shorter implantation times were associated with higher diagnostic rates and investigated how the syncope-to-ILR interval affected diagnosis.

Methods: Medical data of patients at our hospital with syncope of unknown etiology who received ILRs between January 2017 and July 2023 were analyzed in relation to the date of syncope, first visit, and ILR use. Patients were classified into event and non-event groups according to whether ILRs revealed the syncope etiology.

Results: We examined the medical records of 113 patients (median age, 72.6 ± 13.1 years). Syncope etiologies were identified in 34 (30%) patients. We identified 37 (16-58) syncope-to-ILR days. The event group had significantly shorter syncope-to-ILR days (event group, 28 days; non-event group, 44 days, p = 0.001) and syncope-to-first visit days (1.5 vs. 13 days, respectively; p = 0.00). To improve diagnostic rates, a receiver operating characteristic curve indicated cut-off values for syncope-to-ILR days and syncope-to-first visit days of 17 and 12 days (area under the curve, 0.69 and 0.74), respectively. Patients accompanied by family or friends underwent ILR placement significantly earlier than unaccompanied patients.

Conclusion: The number of syncope-to-ILR days significantly affected syncope diagnosis, indicating that early hospital attendance following syncope is critical. Public awareness campaigns and the presence of family or friends may be useful.