Indications for the use of diagnostic implantable and external ECG loop recorders

Abstract

ECG loop recorders have a retrospective (loop) memory which continuously records and deletes the patient's ECG. They include a patient-activation function that allows the patient to activate ECG storage as a result of symptoms and an auto-activation feature that allows the capture of arrhythmic events without relying on patient compliance or perception of symptoms. Loop recorder devices can be both implantable (ILR) and external (ELR). Table 1 summarizes the characteristics of the most common diagnostic loop recorders. The retrospective memory differentiates loop recorders from prospective-only event recorders. While event recorders have some usefulness in patients with intermittent palpitations, they have no indication to detect syncope. View this table: Table 1 Most common implantable and external loop recorders Knowledge of what occurs during a spontaneous event is the ideal gold standard for evaluation. Patients with infrequent short-duration transient symptoms, recurring over weeks or months, are unlikely to be diagnosed by conventional Holter monitoring, since the likelihood of symptom-ECG correlation is very low. Consideration should be given to patient-activated event recording in such patients, but this technique has important limitations that might prevent a successful ECG recording of the event, especially for those with syncope, as it implies the activation of recording by the patients once the patient has already recovered consciousness. In such circumstances, consideration should be given to implantable and external ECG loop recorders. It is likely that loop recorders will become increasingly important, and their use will increasingly be appropriate instead of, or before, many current conventional investigations. This early loop recorder approach implies, on the one hand, the need for careful initial risk stratification in order to exclude from such a strategy patients with potential life-threatening conditions that require immediate hospitalization or intensive evaluation and treatment. On the other hand, as a general rule ECG loop recorders are indicated only when there is …