Evaluation of Syncope: Who Needs an Implantable Loop Recorder?

Syncope is a frequently encountered condition and accounts for up to 3% of emergency department consultations and 6% of hospital admissions. Although clinical history and examination combined with laboratory testing are adequate in obtaining a diagnosis in many patients, there are some who experience infrequent episodes that are elusive in nature and the cause difficult to detect. This is because correlation between syncopal events and any alteration of physiological signals (ECG, blood pressure) is the “gold standard” for the diagnostic work-up. In these individuals, prolonged ambulatory monitoring with implantable electrocardiographic recorders can be of great benefit. Implantable loop recorder (ILR) is a relatively recent investigational tool in undiagnosed syncope that permits prolonged monitoring without external electrodes. It is ideally suited to patients with infrequent recurrent syncope thought to be due to an arrhythmic cause. The newly available REVEAL LINQTM is a miniature ILR device which could be literally injected under the skin without a surgical incision. The mean diagnostic yield of ILR reported in the literature is about 50–60%.