What are the recommended programming or medication changes for a patient with a biventricular (BiV) pacemaker, underlying atrial fibrillation (AF) with a ventricular response in the 70s-100s, and a recent drop in BiV pacing percentage, currently experiencing ventricular sensing episodes with rates of 118-125 beats per minute (bpm) and a heart rate (HR) mostly below 110bpm?

Recommended Management for Reduced BiV Pacing in AF Patient

Optimize medical rate control first with beta-blockers or nondihydropyridine calcium channel blockers to suppress the 118-125 bpm ventricular sensing episodes, and if this fails to restore BiV pacing >95%, proceed with AV nodal ablation to ensure complete biventricular capture and prevent tachycardia-induced cardiomyopathy. 1

Understanding the Problem

Your patient's BiV pacing has dropped to 79.6% due to intrinsic ventricular conduction during AF episodes with rates of 118-125 bpm. The 20.3% ventricular sensing (VS) time represents periods when the patient's intrinsic AF-conducted beats are faster than the pacemaker's programmed rate, preventing BiV capture. 1 This loss of resynchronization therapy significantly compromises the therapeutic benefit of CRT and can lead to progressive heart failure deterioration. 1

Step 1: Medication Optimization (First-Line Approach)

Intensify rate control medications to suppress the rapid ventricular response episodes:

• Beta-blockers are the preferred first-line agent for rate control in AF patients with BiV pacemakers, as they provide superior control during both rest and activity compared to other agents. 1, 2 Target a resting heart rate <80 bpm and <100 bpm during activity. 3, 4

• Nondihydropyridine calcium channel blockers (diltiazem or verapamil) can be added or used as monotherapy if beta-blockers are contraindicated, though avoid in decompensated heart failure. 1, 2

• Digoxin may be added as adjunctive therapy to beta-blockers or calcium channel blockers to optimize rate control, particularly in heart failure patients, though it should not be used as monotherapy in active patients. 1, 4

• Avoid dronedarone for rate control in permanent AF as it increases cardiovascular mortality risk. 1

Step 2: Device Programming Adjustments

While optimizing medications, implement these programming changes:

• Increase the lower pacing rate to 60-70 bpm in patients with permanent AF to promote more consistent BiV pacing and reduce rate variability. 1, 5 The 2020 ESC HFA/EHRA position statement specifically recommends programming a slightly higher base rate of 60 bpm with rate-adaptive pacing in AF patients with adequate rate control to improve biventricular capture percentage. 1

• Program the device in VVIR or DDIR mode (inhibited mode) since the patient has permanent AF. 1

• Ensure the upper tracking rate is programmed sufficiently high (approximately 80% of maximal age-predicted heart rate) to maintain BiV pacing during faster intrinsic rates. 1

• Verify AV delay optimization with a sensed AV interval of 100-120 ms if using DDIR mode. 1

Step 3: AV Nodal Ablation (Definitive Solution)

If medical optimization fails to achieve >95% BiV pacing within 4-8 weeks, refer for AV nodal ablation:

• AV nodal ablation with permanent pacing is the definitive solution for patients with AF and inadequate rate control preventing effective CRT. 1 This approach ensures 100% BiV pacing and has been shown to reduce all-cause mortality by 58% (risk ratio 0.42) and cardiovascular mortality by 56% (risk ratio 0.44) compared to CRT without ablation in AF patients. 1

• The APAF trial demonstrated that CRT with AV nodal ablation decreased the composite endpoint of HF death, HF hospitalization, or HF worsening by 63% compared to RV pacing alone in AF patients. 1

• Quality of life, NYHA functional class, and left ventricular ejection fraction all significantly improve after AV nodal ablation in patients with impaired LV function. 1

Critical Monitoring Points

• Assess rate control during physical activity, not just at rest, as adequacy must be verified during exercise to prevent loss of BiV pacing with exertion. 1, 2

• Review device diagnostics at 2-4 week intervals after medication changes to assess BiV pacing percentage and ventricular sensing episode frequency. 1

• Target >95% BiV pacing to maximize CRT benefit and prevent progressive heart failure. 1

Common Pitfalls to Avoid

• Do not rely on digoxin alone for rate control, as it has delayed onset (60 minutes) and reduced efficacy during high sympathetic states. 2

• Do not accept suboptimal BiV pacing percentages (<95%) as adequate, since even modest reductions in BiV pacing compromise CRT efficacy and clinical outcomes. 1

• Do not delay AV nodal ablation indefinitely in patients with refractory rate control, as prolonged periods of inadequate BiV pacing lead to progressive ventricular remodeling and worsening heart failure. 1