Background: Overly sensitive nominal arrhythmia detection programming in implantable loop recorders (ILRs) can cause a high false positive (FP) episode rate.
Objective: To report the clinical implications and resource utilization for ILRs using nominal programming.
Methods: Study comprises all 1811 ILRs (LINQ^TM: 1671; Biomonitor: 93; ConfirmRx: 47) implanted at the Ohio State University from Jan 2017 to November 2019. Indications for implantation included atrial fibrillation (n=769), cryptogenic stroke (n=569), syncope (n=278), palpitation (n=164) and miscellaneous (n=31). Detection parameters were similar in all 3 commercially available ILRs as recommended by the manufacturers for specific indications. Consecutive transmissions during 4 weeks were reviewed and all episodes were adjudicated for the incidence of FP. Heart rate (HR) characteristics and duration of FP and true positive (TP) episodes were compared. Consecutive 200 transmissions were used to quantify the device nurse time required for adjudication of each transmission.
Results: During 4 week study period, a total of 1457 individual transmissions comprising 10636 arrhythmia episodes with interpretable electrograms were adjudicated. Overall incidence of FP episodes was 50 % and was similar among various ILR manufacturers (p value =0.4). Median duration for FP episodes [4 min (interquartile range: IQR, 8)] was significantly smaller than TP episodes [14 min (IQR: 38); p value, 0.01]. The average maximum HR (beats per minute) for TP episodes (135±54)was significantly higher than FP episodes (111±43; p value < 0.01). Average time for adjudication of one transmission was 9.6±7.5 minutes equating to an approximately 116 hours spent every 4 weeks with FP transmissions.
Conclusion: Incidence of FP episodes during ILR monitoring is significant and imposes significant workload. Duration and HR characteristics of FP episodes can be incorporated into existing algorithms to improve the specificity.