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Pacing‑Induced Cardiomyopathy (PICM)

Last updated: October 9, 2025 • Category: Cardiac Electrophysiology

At a glance

What is it?	A decline in left‑ventricular function caused by chronic right‑ventricular (RV) pacing–related dyssynchrony.
Typical definition	Drop in LVEF by ≥10% to <50% with an RV pacing burden typically ≥20–40%, with no other clear cause.
Mechanism	Unnatural activation sequence (LBBB‑like) → electrical/mechanical dyssynchrony → adverse LV remodeling.
Key risks	High RV pacing %, apical lead position, wide paced QRS, pre‑existing borderline LVEF, long pacing duration.
Prevention	Minimize unnecessary RV pacing; consider physiologic pacing (His‑bundle or LBBAP) or CRT in appropriate patients.
Treatment	Upgrade to physiologic pacing (HBP/LBBAP) or CRT; guideline‑directed HF therapy; address alternative causes.

Why it happens

Standard RV apical pacing produces a left bundle branch block–like activation. The ventricles contract out of sync, reducing pump efficiency and, over time, remodeling the left ventricle. This can manifest as a progressive fall in left ventricular ejection fraction (LVEF) and heart‑failure symptoms.

How clinicians define PICM

LVEF decline: ≥10% absolute reduction to <50% from pre‑implant baseline.
Pacing burden: usually ≥20–40% ventricular pacing over time.
Exclusion: no alternative explanation (ischemia, myocarditis, tachy‑mediated, valvular, etc.).

Note: Exact cutoffs vary by study and guideline; use clinical judgment and serial imaging.

Who is at higher risk

High cumulative RV pacing (especially >40%).
Right‑ventricular apical pacing vs septal/outflow pacing.
Wide paced QRS duration.
Pre‑existing borderline LV function, older age, longer pacing duration.

Symptoms to watch

Exertional dyspnea, fatigue, reduced exercise tolerance.
Peripheral edema, weight gain, orthopnea/PND.
Decline in 6‑minute walk distance or functional class.

Diagnosis & Monitoring

Baseline & follow‑up

Pre‑implant echo to document baseline LVEF.
Repeat echo at 6–12 months and with symptoms.
Device checks for pacing % and paced QRS width.

Look for alternatives

Ischemia evaluation when appropriate.
Rate/rhythm issues (AF with RVR, PVC burden).
Valvular disease, myocarditis, infiltrative causes.

Prevention and Treatment

Minimize RV pacing with device algorithms when atrioventricular conduction is intermittently intact.
Physiologic pacing to restore near‑normal activation:
- His‑bundle pacing (HBP)
- Left bundle branch area pacing (LBBAP)
Cardiac resynchronization therapy (CRT) for appropriate candidates (e.g., LVEF ≤35% with dyssynchrony).
Guideline‑directed medical therapy for heart failure.
Reassess with echocardiography 3–6 months after a pacing strategy change to document reverse remodeling.

Leadless pacemakers: special notes

Single‑chamber leadless devices (e.g., VR systems) typically pace the RV 100% of the time. Most patients do well; however, a subset may develop PICM over years. If LV function declines with high RV pacing burden and no other cause, consider an upgrade path (e.g., LBBAP or CRT) to restore synchrony.

When to consider an upgrade

LVEF drop ≥10% to <50% from baseline with high RV pacing.
Worsening HF symptoms attributable to dyssynchrony.
Wide paced QRS despite optimization.

Patient FAQ

Is PICM common?

It occurs in a minority of chronically paced patients, but the risk rises with higher RV pacing percentages and longer duration.

Can it be reversed?

Often yes—by switching to physiologic pacing (HBP/LBBAP) or CRT and optimizing HF therapy, many patients show meaningful recovery in LVEF.

Does a leadless pacemaker change my risk?

Leadless single‑chamber systems pace the RV continuously. Your electrophysiologist will monitor LV function and may recommend an upgrade if remodeling appears.