#pacing-induced-cardiomyopathy #right-ventricular-pacing #heart-failure #cardiac-pacing #biventricular-pacing

Pacing-Induced Cardiomyopathy

Definition

Pacing-induced cardiomyopathy (PICM) is left ventricular systolic dysfunction caused by frequent right ventricular (RV) pacing, after alternative causes have been excluded. The most commonly used definition is a ≥10% decrease in LVEF with a resultant LVEF <50%, with active exclusion of myocardial infarction, ischaemia, severe valvular disease, uncontrolled tachyarrhythmia, frequent ventricular premature depolarisations and uncontrolled hypertension. It is a dyssynchrony-mediated cardiomyopathy and is potentially reversible if pacing is upgraded to a biventricular or conduction-system strategy. (sources/pacing-induced-cmp-hrs-2014, rating: medium)

Key Concepts

Diagnostic Definition

PICM = ≥10% fall in LVEF with resultant LVEF <50%, diagnosed only after excluding alternative causes (MI, inducible ischaemia, severe valve disease, uncontrolled atrial/ventricular arrhythmia, >20% VPDs, uncontrolled hypertension). (sources/pacing-induced-cmp-hrs-2014, rating: medium)
There is no single universally agreed definition. The CRT appropriateness criteria use a different formulation — "LVEF decline ≥10% or LVEF <50% attributable to RV pacing" — and treat it as sufficient grounds for CRT upgrade. (sources/icd-crt-auc-2025, rating: high)
The diagnosis is therefore retrospective and exclusionary: it requires a baseline LVEF before pacing, a follow-up measurement, and a judgement that no other cause explains the decline. (sources/pacing-induced-cmp-hrs-2014, rating: medium)

Incidence

In a single-centre cohort of 257 eligible patients (from 1,750 consecutive implants), 50 (19.5%) developed PICM over a mean 3.3 years. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Of the 277 patients meeting inclusion criteria, 70 (25.3%) developed any cardiomyopathy, but 20 had an alternative explanation and were excluded — so the incidence depends heavily on how aggressively alternatives are excluded. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Prior estimates span a wide range: 9% at 1 year (Yu et al.) and 26% at 7.8 years (Zhang et al., without exclusion of alternative causes or echocardiographic confirmation). (sources/pacing-induced-cmp-hrs-2014, rating: medium)

Risk Factors

Male sex — HR 2.15 (95% CI 1.14–4.02) — independently associated with PICM. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Wider native QRS — HR 1.03 per 1 ms (95% CI 1.01–1.05) — independently associated, in patients without bundle branch block. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Native QRS ≥115 ms was 90% specific for PICM; ≥100 ms gave the best balance (sensitivity 63%, specificity 78%). (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Lower baseline LVEF was associated on univariate testing but lost significance in the multivariate model (HR 0.97; P = .09). (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Not associated: age, body mass index, coronary disease, atrial fibrillation, hypertension, diabetes, post-surgical heart block, β-blocker or ACE-inhibitor/ARB use, LV dimensions, heart rate, LBBB or RBBB, single-chamber device, apical versus septal lead position, paced QRS duration, or pacing percentage. (sources/pacing-induced-cmp-hrs-2014, rating: medium)

Pacing Burden

Risk begins below the conventional 40% threshold: PICM occurred in 13.0% of patients pacing 20–39%, 16.7% at 40–59%, 26.1% at 60–79% and 19.8% at 80–100% (P = .7 across groups). (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Pacing percentage did not predict PICM in this cohort (HR 1.00, 95% CI 0.99–1.02; P = .7). The authors offer two explanations: both groups averaged >80% pacing, so low burdens were under-represented; or a threshold model, in which once the ≥20% insult occurs, predisposition determines the outcome — the model they previously found for VPD burden. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
This challenges the 40% cut-off derived from MOST, where pacing >40% tripled heart-failure hospitalisation and AF versus <40%; the authors note that MOST's risk also began at 20%. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
The guidelines nonetheless use >40% expected pacing as the trigger for choosing CRT or His bundle pacing over RV pacing when LVEF is 36–50%. (sources/bradycardia-acc-aha-hrs-2018, rating: very high)

Time Course and Reversibility

Onset ranged from 1 month to 8.4 years after implantation, so risk persists with continued exposure. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Mean LVEF fell from 62.1% to 36.2%; 36% developed new or worsened mitral regurgitation. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
28.0% (14/50) underwent biventricular upgrade, with LVEF improving in all but 2 — from 32.1% before to 44.4% after upgrade. (sources/pacing-induced-cmp-hrs-2014, rating: medium)

Prevention and Management

Pre-implant risk stratification: the authors propose that men with native QRS >115 ms warrant closer clinical and echocardiographic follow-up, and may be considered for upfront biventricular pacing — while cautioning that most patients do not develop PICM, so universal biventricular pacing would overtreat the majority and the strategy's effectiveness and cost need prospective study. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Established upgrade criteria: RV pacing-induced cardiomyopathy (LVEF decline ≥10% or LVEF <50% attributable to RVP) is rated A(7) for upgrade to CRT; RV pacing burden >40% with LVEF ≤50% is also A(7) for pre-emptive upgrade. (sources/icd-crt-auc-2025, rating: high)
Conduction-system pacing is an alternative to biventricular upgrade in patients who need continued ventricular pacing; CSP-CRT is rated M(5–6) pending randomised data, and LBBP has been used successfully in established PICM after long-term RV pacing. (sources/icd-crt-auc-2025, rating: high) (sources/denker-pes-lbbap-jce-2020, rating: low)
Surveillance: the diagnosis requires a follow-up echocardiogram, so high-risk patients need scheduled imaging rather than symptom-driven assessment — the very inclusion bias that inflates incidence estimates when imaging is symptom-driven. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
LBBP-optimized upgrade can reverse a related cardiomyopathy. In LBBB-associated non-ischaemic cardiomyopathy (a progressive conduction disease rather than a purely pacing-induced one), LBBP produced LVEF normalisation in 82.2% at 2 years when scar burden was <10%, and 6.9% vs 26.1% composite adverse events compared with a high-scar group. The distinction between PICM and LBBB-associated cardiomyopathy matters, but both are reversible conduction-mediated substrates. (sources/mri-lbbap-hrs-2025, rating: high)
LOT-CRT has been used for upgrade in established PICM (78-year-old woman, paced QRS 185 ms, LVEF 35%, NT-proBNP 19,032 pg/mL): QRS narrowed to 132 ms, but the first post-implant day was complicated by PVC-triggered VF without a reversible cause, and QT prolongation/T-wave inversion were noted. The case highlights the need for early monitoring after upgrade in severely remodelled ventricles. (sources/lot-crt-vt-ane-2026, rating: low)

Contradictions / Open Questions

There is no agreed definition, and the published ones are not interchangeable. The Khurshid definition (≥10% fall to <50%) and the AUC wording (LVEF decline ≥10% or LVEF <50% attributable to RV pacing) can classify different patients; incidence figures inherit the definition. (sources/pacing-induced-cmp-hrs-2014, rating: medium) (sources/icd-crt-auc-2025, rating: high)
The incidence range is wide and probably biased upward. 19.5% here versus 9% at 1 year and 26% at 7.8 years elsewhere; the cohort required a follow-up echocardiogram, which was clinically driven, so symptomatic patients were preferentially included. The authors concede this could overestimate the true incidence. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
The 40% pacing threshold is not supported by a dose–response in this cohort. Incidence was non-monotonic across burden quartiles and pacing percentage was not a predictor; the authors' threshold model is plausible but untested. The clinical consequence — whether to pace less, or to upgrade earlier — is unresolved. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
The QRS predictor is specific but not sensitive. ≥115 ms was 90% specific, but the best overall cut-off (≥100 ms) had only 63% sensitivity, and the model has no external validation and no risk score. Most patients who develop PICM would not be identified by this rule alone. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Why male sex confers risk is unexplained, and the finding has not been mechanistically validated; it parallels other non-ischaemic cardiomyopathies but no mechanism is offered. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Reversibility after upgrade is uncontrolled. LVEF improved in 12/14, but there was no randomised comparison, no core laboratory, and regression to the mean cannot be excluded. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Whether upfront biventricular pacing is better than RV pacing plus surveillance is untested. It would overtreat the majority who never develop PICM, and the authors explicitly call for a prospective study of effectiveness and cost. (sources/pacing-induced-cmp-hrs-2014, rating: medium)
Whether conduction-system pacing prevents PICM is unproven. CSP avoids RV apical dyssynchrony physiologically, but no randomised trial has tested PICM incidence as an endpoint; the evidence is observational and extrapolated from electrical surrogates. (sources/icd-crt-auc-2025, rating: high)

Connections

Related to entities/CRT — biventricular upgrade is the established treatment and an A(7) indication
Related to entities/Heart-Failure — PICM is a reversible cause of HFrEF
Related to concepts/Permanent-Pacing-Indications — pacing-mode selection when ventricular pacing is anticipated
Related to concepts/PVC-Induced-Cardiomyopathy — a parallel dyssynchrony-mediated cardiomyopathy; both use QRS width as a risk marker and both have contested burden thresholds
Related to concepts/Conduction-System-Pacing — an alternative strategy that avoids RV apical pacing
Related to concepts/Left-Bundle-Branch-Area-Pacing — used for upgrade in established PICM
Related to concepts/His-Bundle-Pacing — guideline-endorsed alternative when >40% pacing is expected