Key result
Aveir AR implantation triggers early bradycardia-dependent capture loss with ~4-fold higher thresholds at lower rates.
Why the study?
Bradycardia-dependent pacing threshold elevation is a rarely reported cause of early postimplant loss of atrial capture in leadless atrial pacemakers.
Case Report (n=1)
When early intermittent capture loss occurs after atrial leadless pacemaker implantation despite stable device parameters, clinicians should perform threshold testing across different pacing rates to assess for bradycardia-dependent threshold elevation.
Clinicians should assess rate dependence in postimplant atrial capture loss; extends the single prior report of this mechanism in leadless pacemakers.
BACKGROUND: Bradycardia-dependent pacing threshold elevation is a rarely reported cause of early postimplant loss of capture, with only 1 prior case reported in an atrial leadless pacemaker. CASE SUMMARY: 88-year-old woman with sinus pauses underwent Aveir AR implantation. On postoperative day 1, intermittent loss of atrial capture occurred at the programmed lower rate limit. Interrogation revealed stable impedance, current of injury, and sensing. Threshold testing revealed marked rate-dependence: 2.75 V/0.4 milliseconds at 60 beats/min vs 0.75 V/0.4 milliseconds at 90 beats/min. Fluoroscopy confirmed device stability, and output was increased conservatively. DISCUSSION: Proposed mechanisms of this phenomenon include rate-dependent variation in the electrode-tissue interface and phase 4 block from diastolic depolarization in injured myocardium. When early intermittent capture loss occurs with stable device parameters, threshold testing across pacing rates should be performed to assess for bradycardia-dependent threshold elevation. TAKE-HOME MESSAGE: Bradycardia-dependent capture threshold elevation is a possible etiology of early postimplant loss of atrial capture after Aveir AR implantation.
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Soderstrom et al. (2026) conducted a case report in Sinus pauses and postimplant loss of atrial capture (n=1). Aveir AR implantation was evaluated on Pacing threshold and loss of capture. Aveir AR implantation in an 88-year-old woman was complicated by early bradycardia-dependent capture loss, with thresholds of 2.75 V at 60 beats/min versus 0.75 V at 90 beats/min.
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