• Vol. 41 No. 3, 115–124
  • 15 March 2012

The Implantable Loop Recorder—An Important Addition to the Armentarium in the Management of Unexplained Syncope



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Introduction: Unexplained syncope is a common condition with a significant impact both on the patient and on healthcare expenditure. Often, the diagnosis is hampered due to the temporary sporadic nature of the symptoms. Conventional monitoring methods have a low yield for identifying an abnormality during a spontaneous event. The implantable loop recorder (ILR), often underutilised, is an important diagnostic device that may fill this void in the early assessment of patients presenting with syncope.

Materials and Methods: This article begins with 2 case vignettes which highlight the clinical utility of ILRs in making a definitive diagnosis and guiding subsequent management. This is followed by a review of the existing evidence for ILRs, including the recent international guidelines, underpinning the role of ILRs in the present management algorithm of patients presenting with unexplained syncope. The technical aspects and cost implications will also be reviewed.

Results: Present evidence-based international guidelines have recommended the early use of ILRs in the management of patients with unexplained syncope. Furthermore, there may also be an important role for ILR use in patients with presumed epilepsy refractory to treatment and in the neurally mediated syncope cohort with recurrent symptoms. Cost benefit analysis also demonstrates advantages with early ILR use.

Conclusion: The early use of ILR in selected patients remains an accurate, cost-effective, high yield tool for diagnosis and management of patients with unexplained syncope. However, its use should not detract from the importance of taking a detailed medical history and physical examination in the initial assessment to facilitate identification of the aetiology and risk stratification of patients.

Syncope is a clinical syndrome characterised by transient loss of consciousness and postural tone that is most often due to temporary and self terminating global cerebral hypoperfusion. It is a commonly encountered condition with up to 40% of selected populations having experienced an episode of syncope in their lifetime, moreover 6% of all acute medical admissions can be attributed to a recurrent syncopal event. Although a benign prognosis in the majority, syncope secondary to a cardiac cause can carry 18% to 33% of 1-year mortality.

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