The implantable loop recorder in older patients with syncope: is sooner better?

摘要

Syncope is common in older people, with a three- to fourfoldnrise in syncope incidence with advancing age [1, 2].nOlder patients with syncope disproportionately bear thenburdens of morbidity, mortality and hospitalisations [1-3],nwhile comorbidity, polypharmacy, cognitive impairmentnand age-related physiological change can make assigning ancause of syncope challenging. Older patients are muchnmore likely to have a cardiac (and in particular arrhythmic)ncause of syncope than younger patients, with up to 30% ofnolder patients with syncope having such underlying diagnosesn[1]. Current guidelines [1] advocate an initial evaluationnstrategy of detailed history, clinical examination, orthostaticnblood pressure measurement and 12-lead ECG with subsequentninvestigations dictated by the likely aetiology basednon this initial workup. The implantable loop recordern(ILR) has a role to play when the suspected aetiology isnarrhythmic, either primary cardiac rhythm disturbance ornas part of neurally mediated syncope, and is currently considerednat the end of a series of investigations, which mayninclude ambulatory or external loop recorder monitoring,ntilt testing, carotid sinus massage, echocardiography andnexercise testing. Where the cause of syncope remains unknown,nthe ILR has become the diagnostic test of choicenwhen arrhythmic syncope is suspected but more invasiventests including electrophysiology studies are contraindicated,nunlikely to be helpful or simply not available. ILRsnare implanted in a pre-pectoral pocket in the left hemithoraxn(similar to a permanent pacemaker) under local anaesthetic,nwith a low procedure complication rate (1%, largely infection-nrelated [4]). The models currently available in thenUK have the approximate dimensions of a USB memorynstick (Reveal®DX, Medtronic Inc., Minneapolis, MN andnSJM Confirm™, St Jude Medical, St. Paul, MN) and recordna high-fidelity bipolar ECG signal stored as a loop,nwhich can be frozen at the time of symptoms using anhandheld activator by the patient, or auto-activated basednon preset bradycardic or tachycardic parameters. ILRs’ keynstrengths lie in ECG monitoring of infrequent episodesnand the ability to retrospectively assess heart rate andnrhythm during a syncopal episode, both of which allownsymptom–rhythm correlation, the gold standard of syncopendiagnosis.