P- and R-wave Amplitude Sensed by Reveal LINQ™ Loop Recorder in Pediatric Patients

Implantable loop recorders are commonly used to sense arrhythmias. The purpose of this study is to assess the P- and R-wave amplitudes at implantation (I) and follow-up (F) following insertion of the Reveal LINQ™ Insertable Cardiac Monitor (Medtronic, Minneapolis, MN) in an institutional review board-approved, multicenter study performed on pediatric patients younger than 18 years old. Collected data included demographics, presence of congenital heart disease (CHD), P- and R-wave-sensed amplitude at I and F, and the method of implant (i.e. mapping or standard.) P waves were manually measured and R-wave sensing was recorded by the device. A total of 87 patients had a Reveal LINQ™ (Medtronic, Minneapolis, MN) device implanted; the mean patient age was 11.8 years (0.5 years to 18 years) with 48% of patients being female and 19% of patients having CHD; mapping was used in 43% of patients. The Reveal LINQ™ (Medtronic, Minneapolis, MN) experienced no change in average sensed R-wave amplitude at either I or F (1.28 mV vs 1.26 mV, p = NS). There was no difference in sensed R-wave amplitude noted with or without mapping used at I (1.29 mV vs 1.26 mV, p = NS) or F (1.48 mV vs 1.18 mV, p = NS). Additionally, no difference could be found in R-wave sensing of patients with CHD or without CHD at I (1.26 mV vs 1.4 mV, p = NS) or F (1.32 mV vs 1.32 mV, p = NS). R-wave sensing trended towards being inversely proportional to patient body surface area (BSA) (p = NS). P waves were detected on 48% of tracings in all patients at I and/or F, irrespective of whether the Reveal LINQ™ (Medtronic, Minneapolis, MN) device was placed with mapping. The R wave was (0.37–3.5 mV) at I and (0.3–3 mV) (p = NS) at F when P waves were detected. From these results, it can be said that the Reveal LINQ™ Insertable Cardiac Monitor (Medtronic, Minneapolis, MN) has an excellent ability to sense R-wave amplitude in pediatric patients. No significant difference in the sensing ability of the device could be identified with respect to the presence of CHD, use of mapping or BSA. P waves tended to be identified when there was a higher baseline R-wave amplitude.