Cardiac physiologic pacing (CPP) — conduction system pacing (CSP: HBP or LBBAP), or CRT — preserves ventricular synchrony and can mitigate pacing-induced cardiomyopathy (PICM).
CRT evidence is robust with multiple RCTs showing benefit in LVEF ≤35%, LBBB, QRS ≥120 ms, and NYHA II–IV symptoms.
Periodic LVEF assessment is recommended in patients with substantial RV pacing (≥20–40%) or chronic LBBB to detect PICM early.
For substantial RVP with LVEF 36–50%, CPP (CRT, HBP, or LBBAP) is reasonable 2a to reduce PICM risk.
For normal LVEF, CPP may be reasonable 2b to prevent future cardiomyopathy in high RVP burden patients.
CRT with BiV recommended (Class 1) for LVEF ≤35%, LBBB, QRS ≥150 ms, NYHA II–IV on GDMT.
CSP (HBP/LBBAP) efficacy is emerging with high procedural success, QRS narrowing, and stable thresholds as CRT alternatives.
Lead optimization — quadripolar LV lead, narrow QRS, late LV site targeting, and minimal RV pacing percentage improve CRT response.
Post-implant echo at 3–12 months assesses reverse remodeling; remote monitoring and multidisciplinary HF clinic optimize outcomes.
Shared decision-making is foundational — discuss evidence, device risks, patient values, and alternatives with every CPP candidate.
Core Definitions
Cardiac Physiologic Pacing (CPP): Any form of pacing intended to restore or preserve ventricular synchrony via CSP, HBP, LBBAP, or CRT.
Conduction System Pacing (CSP): Recruitment of the intrinsic conduction system by HBP or LBBAP.
His Bundle Pacing (HBP): Direct stimulation of the His bundle; may be selective or nonselective.
Left Bundle Branch Area Pacing (LBBAP): Ventricular pacing engaging the LBB or nearby tissue; selective (LBB fibers only) or nonselective (LBB + local myocardium).
Pacing-Induced Cardiomyopathy (PICM): LVEF decline attributable to RV pacing burden ≥20–40%. Risk factors: degree of RVP, mitral regurgitation, baseline LBBB.
Epidemiology & PICM Detection
RV and LBBB pacing cause dyssynchrony and impaired LV function. Pooled prevalence of PICM: 5.9%–39% (12% mean across 26 studies). Time to development: 0.7–16 years.
COR
LOE
Recommendations
1
B-NR
In patients with substantial RVP, periodic LVEF assessment is recommended to detect PICM.
2a
B-NR
In patients with chronic LBBB, periodic LVEF assessment is reasonable to detect cardiomyopathy.
CPP for Substantial RV Pacing (≥20–40%)
COR
LOE
Recommendations
2a
B-R/B-NR
In patients with pacing indication, LVEF 36–50%, and anticipated substantial RVP, CPP is reasonable to reduce PICM risk.
2b
B-NR
In patients with normal LVEF anticipated for substantial RVP, CPP may be reasonable to reduce PICM risk.
CPP for Less Than Substantial RV Pacing (<20–40%)
COR
LOE
Recommendations
2a
B-R
In patients with LVEF <35%, it is reasonable to minimize RVP with traditional lead placement.
2b
C-LD
In patients with LVEF 36–50% and LBBB, CPP may be considered to improve symptoms and LVEF.
3
B-R
CRT with BiV pacing is not indicated in normal LVEF patients with <20–40% anticipated RVP.
CRT in Heart Failure Patients
LBBB, QRS ≥150 ms, NYHA II–IV
COR
LOE
Recommendations
1
A
In patients with LVEF ≤35%, sinus rhythm, LBBB, QRS ≥150 ms, NYHA II–IV on GDMT, CRT with BiV pacing is indicated to improve symptoms and reduce mortality and HFH.
LBBB, QRS 120–149 ms, NYHA II–IV
COR
LOE
Recommendations
1
A
In select patients (eg, female sex) with LVEF ≤35%, LBBB, QRS 120–149 ms, NYHA II–IV on GDMT, CRT with BiV pacing is recommended.
2a
B-R
CSP with HBP or LBBAP is reasonable if effective CRT cannot be achieved with BiV pacing based on anatomical or functional criteria.
Non-LBBB Pattern, QRS ≥150 ms
COR
LOE
Recommendations
2a
A
In patients with LVEF ≤35%, non-LBBB, QRS ≥150 ms, NYHA II–IV on GDMT, CRT can be useful to improve functional class and LVEF.
In AF patients undergoing AV node ablation with LVEF ≤50%, CRT with BiV pacing is reasonable to improve HF outcomes and LVEF.
2a
B-NR
In AF patients meeting CRT eligibility criteria, CRT with BiV pacing can be beneficial to improve quality of life and LVEF.
Preprocedure Evaluation
Essential Testing
COR
LOE
Recommendations
1
A
12-lead ECG is recommended to evaluate rhythm, rate, AV conduction, QRS duration to determine CPP type.
1
A/C-E0
Preoperational echo screening for LVEF is recommended in all CPP candidates.
2b
B-R
Imaging modality (echo, CMR, CT) may be considered to target LV lead placement in CRT.
Shared Decision-Making
COR
LOE
Recommendations
1
C-E0
Clinicians and patients should engage in shared decision-making discussion of evidence base, risks, benefits, goals of care, and patient preferences.
Implant Procedure — Techniques
CRT with Biventricular Pacing
COR
LOE
Recommendations
1
B-R
Quadripolar LV lead is recommended to optimize lead stability, thresholds, and avoid phrenic nerve pacing.
2a
B-NR
Lead positioning and programming to achieve narrowest QRS is beneficial for improving LV structure and function.
2a
C-LD
Nonepical LV lead placement is reasonable to improve CRT response.
CSP Lead Placement (HBP or LBBAP)
COR
LOE
Recommendations
1
C-E0
12-lead ECG during implantation is useful to assess conduction system capture accurately.
1
C-E0
Accurate demonstration of conduction system and myocardial capture thresholds is useful for programming at implant and follow-up.
His Bundle Pacing & LBBAP Techniques
His Bundle Pacing (HBP)
Direct stimulation of His bundle achieves narrow QRS and preserved ventricular synchrony. Capture can be selective (isolated His) or nonselective (His + local myocardium).
Diagnostic Criteria (HBP)
HBP Type
Baseline
Normal QRS Criteria
Selective HBP
S-QRS = H-QRS; Discrete local VEG with S-V = H-V
Paced QRS = native QRS; Single capture threshold
Nonselective HBP
S-QRS > H-QRS; Pseudodelta wave or broad H-QRS
Paced QRS slightly wider; Two distinct thresholds
Left Bundle Branch Area Pacing (LBBAP)
Targets LBB via LV septum. High procedural success, QRS narrowing, and stable long-term thresholds. Capture can be selective (LBB fibers) or nonselective.
Diagnostic Criteria (LBBAP)
Criterion
Definition
LV septal location
Deep septal placement (fulcrum sign, contrast, echo, CT)
LBB capture
Abrupt RWPT shortening; V_R RWPT <75 ms (nonselective); V_R RWPT >12 ms with LBB-specific pattern
QRS narrowing
Correction of RBBB or preservation in nonselective HBP
LBB potential
Stimulation to retrograde His <35 ms or antegrade LBB potential
Pearl: HBP thresholds may increase acutely (24–48 hrs) then stabilize. LBBAP thresholds are more stable long-term with lower revision rates.
Follow-up Evaluation & Management
Post-Implant Echocardiography
COR
LOE
Recommendations
1
B-NR/C-E0
Follow-up echo within 3–12 months post-CPP in HFrEF determines reverse remodeling and improved survival likelihood.
1
B-NR
Remote monitoring in CPP patients is beneficial for device and arrhythmia management.
2a
B-NR/C-E0
Multidisciplinary HF and device clinic for medication and programming adjustment can improve outcomes.
Device Programming & Optimization
COR
LOE
Recommendations
1
C-E0
12-lead ECG confirms LV lead capture and optimizes pacing configurations in CRT.
1
B-NR
Multileaf/12-lead ECG during CSP follow-up assesses conduction system capture including BBB correction.
Generator Replacement
COR
LOE
Recommendations
1
C-LD
In HFimpEF, continue CRT with BiV pacing at elective generator replacement.
1
C-E0
In patients benefiting from CRT, continuation is recommended based on patient-individualized risks/benefits and shared decision-making.
In HFrEF unfavorable CRT response, continued optimization of medical and device therapies is recommended.
1
C-LD
Posteroanterior and lateral chest X-ray is recommended to assess LV lead position in nonresponders.
2a
C-LD
In unfavorable response with suboptimal LV pacing %, ablation/suppression of frequent PVCs or AF rate control is reasonable to improve function.
Crossover & Alternative Strategies
When to Consider HBP or LBBAP After Failed CRT
COR
LOE
Recommendations
2a
C-LD
In CRT with BiV implantation, crossover to CSP with HBP or LBBAP is reasonable when CS LV lead placement is unsuccessful or suboptimal.
2a
C-LD
In unfavorable CRT response, CSP (HBP/LBBAP) or surgical epicardial CRT can be useful when other approaches have failed.
Pearl: Success rates for HBP/LBBAP as rescue after failed LV lead placement: 85–91%. These techniques offer viable alternatives in difficult anatomies.
Special Populations — CHD & Pediatrics
Congenital Heart Disease
COR
LOE
Recommendations
2a
C-LD
In CHD patients with systemic LV, LVEF <45%, and dyssynchrony (QRS >120 ms), CRT with BiV pacing is reasonable to reduce transplant risk.
2a
C-LD
In CHD with single ventricle, apical pacing is reasonable over nonapical sites.
Pediatric Patients
COR
LOE
Recommendations
2a
C-LD
In pediatric patients with complete AV block, preexisting RV pacing, and symptomatic HF on GDMT, CRT with BiV pacing is reasonable.
2a
C-LD
In pediatric AV block, target RV mid-septal or LV epicardial pacing in preference to RV apical sites.
Related Calculators & Decision-Support Tools
Use these tools alongside clinical judgment for CPP patient selection, risk stratification, and response prediction.