Discrepancy between clinical practice and standardized indications for an implantable loop recorder in patients with unexplained syncope.

Aim: An implantable loop recorder (ILR) is indicated in patients with unexplained syncope after complete conventional work-up. Data from the literature imply that, in clinical practice, the ILR is underused. The aim of the study was to verify if there is any discrepancy between the use of ILRs in clinical practice and the potential indications based on the most potentially appropriate guideline indications.

Method And Results: We compared the prevalence of ILRs actually implanted in patients with unexplained syncope in the Syncope Unit Project (SUP) study and the potential one using the standard given by the guidelines. In the SUP study, 28 (18%) out of 159 patients with unexplained syncope received an ILR. Appropriate criteria for implantation of ILRs according to guidelines were present in 110 (69%) patients. Moreover, 7 (25%) of ILRs actually implanted did not satisfy the guideline standards. During the follow-up, 32% of patients who had received an ILR had a diagnosis compared with 5% of those who did not (P= 0.001).

Conclusions: The estimated indications were four times higher than those observed. Moreover, in about one quarter of the cases, the use of ILRs proved to be potentially inappropriate according to guideline indications. Two-thirds of patients with unexplained syncope had indications potentially appropriate for ILRs.