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Managing Alert Burden: A Case Study Illustrating the Need for Tailored Implantable Loop Recorder Programming
Background
Implantable loop recorders (ILRs), also known as insertable loop recorders or insertable cardiac monitors (ICMs) are widely used in the diagnosis and treatment of many cardiac conditions. Specifically, ILRs are implanted in patients with an increased risk of cardiac arrhythmia or who experience symptoms of dizziness, syncope, palpitations, and chest pain suggestive of arrhythmia.
An ILR’s ability to detect, record, and report episodes and alert conditions provides valuable data to patients and their care teams. In fact, ILRs often generate and transmit significant and disproportionate amounts of data via remote monitoring as compared with pacemakers and implantable cardioverter-defibrillators.
Consequently, the struggle to manage exponential volumes of ILR data poses serious challenges to device clinics. Sifting through false-positive episodes and nonactionable alerts, triaging patient-initiated symptomatic episodes, generating appropriate billing claims, and identifying truly actionable arrhythmias can be overwhelming for cardiac device clinic staff. Often, determining appropriate detection parameters and setting alert criteria will require multiple office visits, coordination with physicians, and in-depth knowledge of each manufacturer’s monitoring platform capabilities. It is not unusual that patients may be discharged post-implant with little follow-up as struggling device clinics attempt to keep up with the rapidly increasing volume of ILR implants and subsequent abundance of data.
When detection parameters and alerts are not tailored over time, it can result in negative outcomes for the patient as well as the device clinic. More episodes equal more recordings and transmissions, which result in shortened battery performance. Patients may require multiple ILR procedures to capture meaningful data due to wasted battery longevity impacted by frequent, unnecessary, and nonactionable recordings.
The following case study presents a little-known effect of undermanaged detection parameters in an ICM patient.
Case Presentation
An 82-year-old male with a history of paroxysmal atrial fibrillation (AF), not currently anticoagulated, presented with isolated premature ventricular contractions and stable nocturnal sinus bradycardia with beats per minute (bpm) rates in the upper 30s to 40s. An ICM was implanted on December 31, 2019, for the indication of AF management.
Programming Parameters
- Tachy detection at >171 bpm for ≥16 beats
- Pause detection at >3 seconds
- Brady detection at <40 bpm for ≥4 beats
- Atrial tachycardia (AT) detection off
- Alert settings disabled for Brady, AT, AT/AF burden, and average rate during AT/AF
The ICM monthly summary report was received onto the PaceMate™LIVE platform on June 12, 2022, for the monitoring period from May 13, 2022, to June 12, 2022. The transmission counter reported zero for all event types. Lifetime counter for Pause events = 2; Brady events = 65535; AF events = 439. Despite Brady counters reported at zero, the transmission contained 5 Brady recordings, revealing nocturnal sinus bradycardia throughout the monitoring period.
The PaceMate cardiac device specialist consulted with the device manufacturer’s technical support to inquire about the mismatch between the data and counters and seek advice for resolution.
Discussion
The ILR highlighted in this case presentation has a lifetime counter maximum for each episode type. Once the lifetime counter maximum is reached, the device will continue to record electrocardiograms (ECGs) for events. However, the counter will permanently display zero once the lifetime counter maximum is reached.
The lifetime maximum for Brady, Tachy, and Pause events is 65,535. The AT and AF events maximum counter is 16,777,215. This is expected device behavior. Symptom events do not have a maximum limit. The counters cannot be reset by manual transmission or by reprogramming. Manual transmissions will transmit additional stored ECGs, but the counters for episode types reaching lifetime maximum limits will continue to display zero for that episode type.
Conclusion
Detection Programming
Appropriate programming of detection parameters is essential for all ILRs and ICMs to collect meaningful, actionable data targeted toward the implant indication for each patient. Neglecting to adjust alerts and detection parameters results in increased battery drain, increased transmission volume, and an increased risk for missing meaningful episodes due to data dilution. Lifetime maximum counts represent an additional risk for missing actionable data. Without accurate counts, clinicians cannot rely on this information to determine if a patient’s condition is worsening or improving.
For this case study, less aggressive programming on the Brady detection may have been warranted to prevent the lifetime maximum from being reached. This patient’s clinical care team has been burdened with reading and interpreting Brady events on every patient-initiated and monthly summary report since the device was implanted, despite this being a nonactionable condition for his care. Additionally, remote device clinicians’ in-depth knowledge of each device type and reporting is essential to identify abnormal or unexpected device behavior.
Professional Transmission Review
Critical review of all transmissions is needed to discern actionable vs nonactionable findings. Through keen review of device data, the PaceMate cardiac device specialist was able to identify the discrepancy on the vendor-generated device report. Many of today’s device clinics lack staffing resources for the frequency and volume of this level of timely device data oversight.
PaceMate’s consistent, exacting standards for recruiting, training, and retaining highly skilled and experienced device clinicians provides a competitive edge, and our clients and their patients reap the benefits. Each PaceMate technician has demonstrated cardiac implantable electronic device management expertise and validation of knowledge via the International Board of Heart Rhythm Examiners’ Cardiac Device Specialist Certification or Cardiac Device Remote Monitoring Specialist Certification.
Battery Longevity and Algorithms
Overutilization of ILRs or ICMs due to suboptimal programming or poor patient education, and the subsequent impact on longevity, are not unique to any one device type. ILR battery longevity is shortened by more frequent transmissions than those projected by the manufacturer in their specifications for estimated longevity.
For all 4 major manufacturers, more frequent transmissions shorten battery life. Enabled Bluetooth functionality in ILRs with this capability can also reduce longevity. However, the focus for practitioners should remain on longevity promotion and alert burden reduction through (1) appropriate programming of alerts specific to the patient’s implant indication, (2) effective patient education, and (3) ongoing device assessment and optimization.
Each ILR manufacturer has unique algorithms for arrhythmia- and patient-triggered data storage. These algorithms specify the number of events, event types, and/or the number of minutes over a specific time period that the episode will be retained in the device’s memory for full disclosure. Rules-based storage algorithms denote which episodes are retained in the device, how many of those episodes are retained, and which episodes will display associated ECGs.
Prioritizing Patient Education
Because many cardiac diagnoses are treated based on symptomatology, it is important to correlate auto-recorded episodes with patient symptoms. Symptoms without auto-detected episodes may be due to patient education issues or noncardiac health concerns. To avoid additional battery drain, staff burden, and patient frustration, patients should be educated to use the symptom marker for symptoms related to the implant indication.
Once education has been validated, device clinicians should work with patients to discuss new and worsening symptoms leading them to use the symptom activator. ILR patients should be brought into the office at a regular cadence so that device clinic staff can discuss results, provide and reinforce education, and adjust detection parameters to ensure optimal device function and focused episode reporting.
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This article is published with support from PaceMate™.
