Progressive Lead Threshold Rise — EECC MCQ

Correct answer: C — Progressive lead threshold rise suggests lead maturation fibrosis or lead insulation degradation — if threshold reaches a point where battery drain is excessive (reducing device longevity), options include: lead revision, adding a new lead, or early generator replacement; echocardiography and lead impedance trends help differentiate the cause

Pacing threshold changes over time are normal to a degree: (1) acute phase (first 2-4 weeks): threshold rises due to local tissue inflammation/oedema around the lead tip; (2) chronic phase: threshold typically decreases and stabilises at ~1.0-2.0V by 3 months (steroid-eluting leads minimise inflammation). PROGRESSIVE late threshold rise (beyond the acute phase) suggests: (1) lead tip fibrosis (chronic tissue encapsulation); (2) lead insulation degradation (electrical leak); (3) lead conductor fracture (intermittent or progressive); (4) lead dislodgement (micro-perforation). Diagnosis: impedance trends (rising = lead fracture; falling = insulation breach), CXR (lead position), threshold testing. Management per ESC 2021 Pacing Guidelines: (1) increase output (if battery allows); (2) if battery drain becomes excessive: early generator replacement with higher output capability, or lead revision/addition; (3) lead extraction and replacement if clearly failed. Systematic device interrogation every 6-12 months is essential for early detection.

Reference: ESC (2021): Pacing Guidelines