Loop Recorder Remote / In-Office Check

For ILR checks we use the abbreviated PBOP framework: Presenting rhythm, Battery status, Observations, Programming. The ILR is a monitor, not a therapeutic device — there are no leads, no pacing, and no therapy to test, so the L/S/T letters of the device-side PBL-STOP framework do not apply. Sensing checks (R-wave amplitude, artifact screen) live at the top of O because they’re part of what we’re observing, not a separate calibration step.

Device overview

An implantable loop recorder is a small subcutaneous monitor placed in the left parasternal area. It records a single-channel ECG continuously and stores episodes triggered automatically by algorithm or by the patient with a handheld activator or smartphone app. Most ILR follow-up is remote, with in-office visits reserved for specific issues — sensing problems, episode review for borderline findings, or end-of-indication decisions. Indications are narrow but important: unexplained syncope, palpitations without documented arrhythmia, cryptogenic stroke (AF surveillance), and post-ablation AF monitoring.

PBOP walkthrough

P — Presenting Rhythm

• Live strip at the start of the session — sinus vs AF vs other
• Snapshot heart rate and any obvious ectopy
• Symptoms in the room — palpitations, lightheadedness, recent syncope
• The clinical question driving the visit: are we still hunting for the same arrhythmia, or has the picture changed?

A 30-second chart pass before opening the episode list keeps the review focused.

B — Battery Status

• Voltage and estimated remaining longevity
• Expected total service typically 3–4.5 years depending on platform and episode volume
• Plan ahead:
  • >12 months remaining: continue monitoring per indication
  • 6–12 months: confirm whether the clinical indication still exists
  • <6 months: plan explant vs replacement based on whether the diagnostic question is unresolved

Battery alone rarely drives a replace-vs-explant decision; the clinical question does.

O — Observations

The main event of an ILR check. Everything else exists to support this section.

Signal-quality snapshot first — before opening the episode list, confirm the device is recording cleanly. A 30-second baseline strip is enough.

• R-wave amplitude: should be >0.3 mV; trend it across visits — declining sensing is the leading cause of new false positives
• Sustained R-wave <0.2 mV degrades every downstream algorithm — AF, pause, brady, tachy
• Far-field and T-wave oversensing — double-counting that fakes tachycardia
• Myopotentials during arm/torso movement — common source of noise-driven false positives
• Body-position effects (supine vs upright) on platforms that expose them
• If sensing has dropped meaningfully, consider device migration, scar maturation, body habitus change, or a sensing-gain reprogramming

Triage order

• Patient-activated symptomatic episodes first — tied to symptoms, highest diagnostic value
• Then auto-detected episodes by clinical severity:
  • Asystole / long pause
  • AF
  • Sustained tachycardia
  • Bradycardia
  • Non-sustained tachycardia
  • HR-trigger episodes (rate-based, not rhythm-based)

EGM review for every flagged episode

• AF claims: irregular RR with no organised P-waves vs noise vs SVT vs frequent PACs
• Pause/asystole claims: true asystole vs R-wave undersensing vs lead artifact vs T-wave dropout
• Tachycardia claims: sinus vs SVT vs VT — width matters, onset matters
• Bradycardia claims: true sinus brady vs sensed pause from undersensing
• False-positive sources to know on sight: noise, myopotentials, PAC runs that mimic AF, sensing dropout that mimics pauses, T-wave oversensing that mimics tachycardia

Symptom correlation

• Cross-reference each device episode with the patient diary
• Symptomatic episode + documented arrhythmia = diagnostic
• Symptomatic episode + sinus rhythm = also diagnostic (rules out arrhythmic cause)
• Asymptomatic AF in a cryptogenic stroke patient = anticoagulation discussion

Memory management

• Clear reviewed episodes to free storage
• High event volume between transmissions can overflow memory and lose data
• If overflow is happening, tighten triggers or shorten the transmission interval

P — Programming

• Detection trigger adjustments: tighten if false positives are overwhelming the workflow; loosen if the clinical question demands maximum sensitivity (active cryptogenic stroke workup)
• Save EGM strips of any clinically relevant episode to the EMR
• Clear reviewed episodes per institutional policy
• Patient education refresh: activator use, what to do if symptomatic, when to call
• Save and print the summary report for the chart
• Set next remote transmission and next in-office visit
• Escalate to the EP attending for:
  • Asystole >6 seconds, regardless of symptoms
  • AF with stroke risk and no anticoagulation
  • Any wide-complex tachycardia
  • Syncope with a corresponding device-recorded arrhythmia
  • Worsening symptoms with no device correlation — may need a different monitoring strategy
  • End-of-indication explant decisions

A note on volume

The biggest workflow challenge with ILRs is volume. A single patient with a borderline AF algorithm can generate dozens of false positives per week. Triage policies — who reviews what, what gets escalated, and how often we revisit detection triggers — keep the device clinic functional. A trained ILR reader who knows the difference between noise, pseudo-AF from PACs, and true AF saves the practice an enormous number of hours.

Reference

Framework reference: “Keeping the Pace using PBL-STOP” — Chart Healthcare Academy