During cardiac resynchronization, ultra-high-frequency electrocardiographic parameters focused on left ventricular dyssynchrony provide a comprehensive reflection of hemodynamic improvement

Background

Synchronous electrical activation of the left ventricle (LV) is crucial for improving hemodynamic status in patients undergoing cardiac resynchronization therapy (CRT). Previously, we demonstrated a strong correlation between ultra-high-frequency ECG (UHF-ECG) derived dyssynchrony and ventricular activation patterns during different cardiac pacing modalities. However, the relationship between UHF-ECG parameters and hemodynamics remains unclear.

Purpose

To evaluate how QRS duration and UHF-ECG parameters correspond to hemodynamic conditions.

Methods

We studied 23 CRT patients (LBBB: 83%, IVCD: 17%, LVEF: 28.7±6.6%, QRSd: 168±26 ms). A 14-lead UHF-ECG (VDI Technologies) was recorded, and we measured QRS duration (QRSd), UHF-ECG interventricular dyssynchrony (DYS) as maximum activation time difference between V1-V6 leads, UHF-ECG LV free wall dyssynchrony (LVFWDYS) as maximum activation time difference between V3-V8 leads [1,2], and broadband ECG LV intraventricular dyssynchrony (LVDYS) a novel parameter that integrates two frequency bands, UHF (150-1000 Hz) for localization of near-source activation in the LV free wall and MF (60-300 Hz) for far-source activation localization in the septum (Figure 1). While DYS reflects interventricular dyssynchrony, LVFWDYS and LVDYS reflect intraventricular LV synchrony. Changes in invasively measured systolic arterial blood pressure (SBP) were assessed with an arterial line during right ventricular (RV) apical pacing (baseline) and biventricular pacing (BivP) or Left bundle branch area pacing (LBBAP). Concordance between change of SBP and dyssynchrony parameters was defined as 1 if a decrease in dyssynchrony parameter coincided with an SBP increase.

Results

SBP changes were for BivP (8.0 ± 3.4 mmHg) and for LBBAP (10.7 ± 5.8 mmHg). A total of 46 paired comparisons were available for each parameter. QRSd (0.826) and DYS (0.913) change demonstrated high concordance with SBP change. Full concordance (1.000) was observed for LVFWDYS and LVDYS (Figure 2).

Conclusion

In CRT patients, UHF-ECG parameters reflecting intraventricular dyssynchrony reflect acute hemodynamic improvement the best, outperforming interventricular dyssynchrony measures and QRS duration.

Figure 1. UHF-ECG and broadband ECG parameters – DYS, LVFWDYS, and LVDYS.

Figure 2. Comparison of 46 pairwise changes for QRSd and UHF-ECG parameters (vertical axis) and SBP (horizontal axis). In all patients, SBP was always lower in A (RV apex pacing) than in B (BivP) or C (LBBAP).Figure 1.Figure 2.