13 December 2025
: Case report 
Coexistence of R-Wave Oversensing and Undersensing in an Implantable Loop Recorder: The Issue of Multiple Sensing in Implantable Loop Recorders
Unknown etiology, Unusual or unexpected effect of treatment
Peter Cwalina
ABDEF 1*, Nicolas Rutig ABDE 2, Natalia Turkiewicz ABE 3, Adam S. Budzikowski AE 4
DOI: 10.12659/AJCR.949624
Am J Case Rep 2025; 26:e949624
Figure 2 (A) P- and T-wave oversensing resulting in erroneous atrial fibrillation detection. Note, R wave is undersensed in this tracing. (B) Double oversensing of P and T waves and undersensing of some R waves, resulting in erroneous atrial fibrillation detection. (C) Over-detection of some P waves (third and fourth) and under-detection of some R waves (third and fourth) resulting in erroneous atrial fibrillation detection. (D) Over-detection of some P waves with correctly sensed R waves, resulting in erroneous atrial fibrillation detection. Note, Vn annotation is noise picked up on the loop recorder. (E) Adequate sensing with correct recognition of normal sinus rhythm following reprogramming of the implantable loop recorder’s settings.