LAUSR

A 61-year-old woman with severe sleep apnea, enrolled in the Reveal XT-SA study (implantable loop recorders in patients with severe sleep apnea and NO history of atrial fibrillation—AF) came to clinic for routine follow-up. An ILR (Reveal XT; Medtronic, Minneapolis, MN, USA) was implanted to monitor for atrial arrhythmias. A download was performed and interpreted as AF in two snapshots (Figure 1A). In closer interrogation, patient recalled using transcutaneous electrical nerve stimulation (TENS), which is a commonly used treatment for the relief of acute and chronic musculoskeletal pain. TENS has proved to interact with cardiac implantable devices. Careful review of 2 separate EGM episodes (Figure 1B) revealed high-frequency spikes (TENS pulses) and native QRS complexes “marching through.” These native QRS signals can be distorted during an episode of electromagnetic interference oversensing and be easily confused with fibrillatory waves. Variations in positioning of the ILR within the chest, and oscillations produced during respiration, can also account for other reasons of ILR oversensing. In this case, the rapid oscillatory waves produced by TENS were oversensed by the ILR and, along with the detection of the native QRS complexes, produced an irregular detected rhythm, leading to the wrong diagnosis of true AF. Healthcare providers in charge of reading these more frequently used devices need to be aware of possible oversensing (and its sources) to avoid taking wrong medical decisions. There was no contraindication to continue with TENS in this case, and the personnel was made aware of this interaction.