Loop recorders for syncope evaluation: what is the evidence?

Implantable loop recorders (ILRs) have become an important pillar in the diagnostic work-up of patients with unexplained syncope. Areas covered: The modern ILR is minimally-invasive and provides an extended-duration of monitoring with high diagnostic yield. These insertable cardiac monitors (ICMs) enable prolonged monitoring that extends the opportunity for symptom-rhythm correlation from days-weeks to years, with associated incremental diagnostic yield. Over the years, observational studies and randomized trials have supported a unique role for ILRs in the assessment of recurrent or high-risk unexplained syncope. Furthermore, ILRs have been used in the elderly, in children, patients with overt heart disease, and patients with conduction block with varying success. The current guidelines recommend ILRs in the early phase of evaluation in recurrent syncope, and as part of the comprehensive evaluation of high-risk patients with syncope. Expert commentary: In this review, we discuss the evidence surrounding ILRs, including comparison studies with 'conventional' management and the external loop recorder.