Arrhythmia detection by patient and auto-activation in implantable loop recorders

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. 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. 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. 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.