Arrhythmia Detection by Patient and Auto-Activation in Implantable Loop Recorders

Aims:The Reveal® Plus implantable loop recorder offers additional automatic detection of arrhythmias that may not be symptomatic. We evaluated the clinical utility of this function compared with standard patient activation. Methods:Over an 18 month period, 50 consecutive patients (age 54 ± 20 years; 24 male) with unexplained dizziness, palpitations and/or syncope had ILR activations which were downloaded for analysis. Patient and auto-activation were analysed with respect to arrhythmia detection and the impact on management of patients was examined. Results:Patient symptoms were syncope in 72% and non-syncope (dizziness and/or palpitations) in 28%. There were 181 patient activation events with 16% showing symptomatic arrhythmia leading to a positive diagnosis in 8 patients. Of 682 auto-activations, detection was appropriate in 17% and inappropriate in 83% (undersensing in 76% and oversensing in 24%). In 8 patients clinically relevant arrhythmia was detected by patient activation alone. In 4 of these patients, further arrhythmia was detected by auto-activation. No patient had important arrhythmia detected only by auto-activation. Conclusion:Automatic detection of asymptomatic arrhythmia did not appear to improve the diagnostic utility of the ILR in our series. The large number of stored inappropriate auto-activation events limits the ability of this function to detect clinically relevant arrhythmia. Symptom-rhythm correlation using the patient activation function remains clinically useful in patients with unexplained syncope or palpitation.