What are the indications for Biventricular (BiV) pacing?

Indications for Biventricular (BiV) Pacing

Biventricular pacing is indicated for patients with heart failure (NYHA class III-IV), severely reduced left ventricular ejection fraction (LVEF ≤35%), and prolonged QRS duration (≥120 ms), particularly those with left bundle branch block, as this combination demonstrates the strongest evidence for improved cardiac function and symptom reduction. 1

Primary Indications

Heart Failure with Reduced Ejection Fraction and Wide QRS

• NYHA class III/IV symptoms with LVEF ≤35% and QRS ≥120 ms represent the strongest Class I indication for BiV pacing 1
• The evidence demonstrates significant improvements in left ventricular ejection fraction (mean difference 5.33%, 95% CI 2.86-7.80) compared to right ventricular pacing alone 2
• BiV pacing reduces LV end-systolic volume (mean difference -7.09 mL, 95% CI -11.27 to -2.91) and LV end-diastolic volume (mean difference -2.74 mL, 95% CI -4.37 to -1.10) 2
• Left bundle branch block with QRS ≥150 ms shows the most robust response to cardiac resynchronization therapy 3

NYHA Class II-III with Broader Criteria

• Consider BiV pacing for NYHA class III/IV symptoms with LVEF ≤35% even when QRS <120 ms if mechanical dyssynchrony is documented (Class IIa recommendation) 1
• NYHA class II symptoms with LVEF ≤35% and QRS <120 ms may warrant consideration (Class IIb recommendation) 1

Special Clinical Scenarios

Patients with Existing Pacemakers and High RV Pacing Burden

• Upgrade to BiV pacing is strongly recommended when RV pacing burden exceeds 40% in patients with LVEF ≤35% 1
• Chronic right ventricular pacing induces left ventricular dyssynchrony with deleterious effects on LV function, particularly in patients with pre-existing LV dysfunction 2, 1
• Patients with right ventricular paced QRS, NYHA class III, and LVEF ≤35% on optimized heart failure therapy should undergo device upgrade 2

Atrial Fibrillation Patients

• BiV pacing should be considered for permanent atrial fibrillation patients with NYHA class III/IV symptoms and LVEF ≤35% 1
• AV nodal ablation is often necessary to ensure near 100% biventricular pacing capture in AF patients 1
• Pacemaker dependency (≥95% ventricular pacing) is crucial for optimal cardiac resynchronization therapy benefit 1

Patients Undergoing Cardiac Surgery

• Heart surgery provides an opportunity for positioning an epicardial LV lead intraoperatively on the lateral epicardial surface when transvenous approach may be challenging 2
• This approach can overcome potential failures of transvenous lead placement 2

Physiologic Benefits Demonstrated

Cardiac Function Improvements

• BiV pacing significantly improves the extent of contracting myocardium in synchrony by 15.4% and duration of contraction synchrony by 17% 4
• Ejection fraction increases by 22.8 ± 9% with acute BiV pacing 4
• End-diastolic and end-systolic volumes decrease by 7 ± 4.5% and 13 ± 6% respectively 4

Functional Capacity

• Peak oxygen uptake significantly increases during BiV pacing (14.89 ± 2.1 ml/min/kg) compared to intrinsic rhythm or RV pacing (12.65 ± 2.3 ml/min/kg) 5
• Approximately 70-80% of appropriately selected patients demonstrate clinical response (defined as ≥1 NYHA class improvement or >5% LVEF increase) 6, 7
• Hospitalization rates for heart failure decrease significantly following BiV pacing implementation 5

Decision-Making Algorithm

Step 1: Assess Heart Failure Status

• Confirm NYHA class III/IV symptoms despite optimal medical therapy 1
• Document medication optimization including guideline-directed medical therapy 1

Step 2: Evaluate Cardiac Function

• Verify LVEF ≤35% by echocardiography 1
• Assess for mechanical dyssynchrony if QRS <120 ms 1

Step 3: Determine QRS Characteristics

• QRS ≥120 ms (especially ≥150 ms) represents the strongest indication 1
• Left bundle branch block morphology predicts better response than other conduction patterns 3
• QRS <120 ms requires additional evidence of mechanical dyssynchrony 1

Step 4: Check Pacing Dependency (if applicable)

• Determine RV pacing burden in patients with existing pacemakers 1
• RV pacing >40% warrants consideration for upgrade 1

Step 5: Evaluate Life Expectancy

• Patients must have reasonable expectation of survival with good functional status for >1 year 1
• This ensures adequate time to derive benefit from the intervention 1

Step 6: Assess Rhythm Status

• For atrial fibrillation patients, plan for potential AV nodal ablation to ensure adequate biventricular capture 1
• Sinus rhythm patients generally have more straightforward programming requirements 2

Common Pitfalls to Avoid

• Do not rely solely on QRS duration: The extent of myocardium with asynchronous contraction measured by tissue velocity imaging is the strongest predictor of pacing efficacy in multivariate analysis 4
• Avoid BiV pacing in patients with narrow QRS (<120 ms) without documented mechanical dyssynchrony, as these patients show minimal benefit 1
• Do not proceed without ensuring adequate life expectancy: Patients with <1 year expected survival derive insufficient benefit to justify the procedural risks 1
• Ensure adequate ventricular pacing percentage: Suboptimal biventricular capture (<95%) significantly reduces therapeutic benefit 1