Optimization of pacing for patients receiving ineffective cardiac resynchronization therapy

Area of Science:

• Cardiology
• Electrophysiology
• Medical Device Technology

Background:

• Effective pacing is crucial for cardiac resynchronization therapy (CRT) success.
• High rates of ineffective CRT (i-CRT) are associated with adverse patient prognoses.
• Characteristics and optimal management of high %i-CRT remain poorly understood.

Purpose of the Study:

• To investigate the specific patient characteristics associated with high ineffective CRT (%i-CRT).
• To evaluate the efficacy of pacing optimization strategies in patients with high %i-CRT.
• To identify common causes of high %i-CRT and their impact on CRT response.

Main Methods:

• Assessed 225 patients using the EffectivCRT system to measure %i-CRT.
• Defined CRT response as improved LVEF (≥10%) and/or reduced LVESV (≥15%).
• Identified high %i-CRT as >2.0% and analyzed causes like pseudo-fusion or latency.

Main Results:

• 16% of patients (36/225) exhibited high %i-CRT, showing significantly lower CRT response rates (48% vs. 76%).
• Pseudo-fusion or latency were primary causes of high %i-CRT, occurring earlier and at higher levels.
• Pacing optimization in 10 patients reduced %i-CRT from 64.6% to 6.4% and QRS duration from 165 ms to 138 ms, converting 3 non-responders to responders.

Conclusions:

• High i-CRT, particularly with latency or pseudo-fusion, emerges early in CRT therapy.
• Optimization of atrioventricular or interventricular delays effectively reduces i-CRT.
• Pacing optimization improves CRT effectiveness and shortens QRS duration, potentially converting non-responders.