Optimization of Pacing for Patients Receiving Ineffective Cardiac Resynchronization Therapy.

Abstract

Background: Effective pacing is essential for maximizing response to cardiac resynchronization therapy (CRT). High ineffective CRT pacing (%i-CRT) has been linked to poor prognosis, but characteristics of high %i-CRT and optimal follow-up settings remain unclear.

Objectives: To investigate the characteristics and efficacy of pacing optimization for patients with high-percentage ineffective cardiac resynchronization therapy (%i-CRT).

Methods: We assessed 225 consecutive patients (2018 - 2024) using EffectivCRT (Medtronic Inc., Minneapolis, MN, USA). The %i-CRT was measured throughout the follow-up period. CRT response was defined as an improved left ventricular (LV) ejection fraction ≥10% and/or reduced LV end-systolic volume ≥15%. High %i-CRT was defined as >2.0%.

Results: Thirty-six patients (16%) had high %i-CRT. They exhibited significantly lower CRT response rates than others (14 patients [48%] vs. 129 patients [76%]; p=0.003). The predominant causes were pseudo-fusion or latency (13 patients [36%]). Among patients with high %i-CRT, the time from CRT initiation to the maximum i-CRT was shorter (p=0.012) and the maximum i-CRT was higher (p<0.001) among those patients with pseudo-fusion or latency. Atrioventricular (AV) or interventricular (VV) delay optimization was performed for 10 patients, resulting in %i-CRT improvement from 64.6% (interquartile range [IQR], 39.3%-87.5%) to 6.4% (IQR, 1.8%-32.0%) (p=0.005) and shortening of the QRS duration from 165±31 ms to 138±21 ms (p=0.003). Three of seven initial non-responders converted to CRT responders after optimization.

Conclusions: I-CRT occurred early, and the maximum i-CRT was high among patients with latency or pseudo-fusion. Optimization of AV or VV delay improved i-CRT and shortened the QRS duration.