How to know if a patient with an LP is pacing‑dependent?

Question & answer for quick clinical reference.

The question

How to know if a patient with a leadless pacemaker (LP) is a pacing‑dependent patient?

The answer

Practical definition

A patient is considered pacemaker‑dependent if, when ventricular pacing is temporarily minimized or stopped in a monitored setting, there is no adequate intrinsic rhythm to maintain perfusion. Operationally, if the device is programmed to VVI 30 for about 10 seconds (or pacing is briefly turned off) and there is no stable escape rhythm ≥ 30 bpm without symptoms or hypotension, the patient is treated as dependent.

Step‑by‑step testing (safe setting only)

Interrogate the LP and ensure continuous ECG and perfusion monitoring with immediate backup pacing/defibrillation available.
Temporarily lower the base rate to VVI 30 (or briefly turn pacing off, if appropriate) while observing for intrinsic ventricular activity and blood pressure/pulse.
No intrinsic rhythm, or rhythm that is clearly inadequate/unstable ⇒ classify as pacemaker‑dependent.
A present, stable intrinsic rhythm ≥ 30 bpm ⇒ not strictly dependent (even if day‑to‑day pacing percentage is high).

Do not use % ventricular pacing to define dependence. High pacing burden can coexist with a safe escape rhythm; the dependency test requires observing the heart without (or with minimal) pacing.

Leadless‑specific notes (magnet & programming)

Device family	Magnet behavior	Implication
Medtronic Micra (VR/AV/AV2)	No magnet response (does not switch to asynchronous with a magnet).	Use the programmer to change modes (e.g., VOO for EMI) and to perform dependency testing.
Abbott Aveir (VR/DR)	Has a magnet response to asynchronous pacing at a “magnet rate” (feature can be programmed off).	Magnet is useful for EMI scenarios; for dependency, still confirm by observing intrinsic rhythm at a low programmed rate.

Peri‑procedural rule of thumb (when status is unknown)

If a dependency test cannot be performed (e.g., urgent surgery with expected EMI), manage the patient as potentially dependent: ensure a safe asynchronous pacing strategy (via programmer for Micra; magnet or programmer for Aveir), continuous monitoring, and immediate backup pacing availability.

Safety checklist

Perform testing only with continuous ECG and perfusion/BP monitoring.
Have external pacing/defibrillation immediately available.
Keep the low‑rate or pacing‑off interval as short as necessary; stop immediately if instability occurs.
Document the intrinsic rhythm (rate, morphology, stability) and the patient’s symptoms/BP response.

Bottom line

A patient with an LP is pacing‑dependent if there is no adequate intrinsic rhythm when the LP is set to a very low rate (e.g., VVI 30) for ~10 seconds under monitoring, or when pacing is briefly off. Micra requires programmer‑based testing; Aveir has a magnet response but dependence is still confirmed by directly observing intrinsic rhythm at a low programmed rate.