Background: QRS area (QRSarea), derived from vectorcardiography (VCG) is a marker of delayed left ventricular (LV) activation.
Objective: To determine whether changes in QRS area (ΔQRSarea) in LV lead vectors of a quadripolar lead (QUAD) relates to the acute haemodynamic response (AHR) to CRT.
Methods: In this acute study, we performed 12-lead ECGs and measured LV pressure (LV dP/dtmax) in 25 CRT recipients (age: 69 ± [9.1] years, mean ± [SD], QRS: 150.8 ± 22.0 ms, LBBB in 19 [79.2%]) in whom a QUAD was deployed in a posterolateral position. VCGs were synthesized from digital ECGs using the Kors matrix. An AHR was defined as a ≥10% ΔLV dP/dtmax.
Results: Intraindividually, the change in LV dP/dtmax across different LV pacing configurations of a QUAD (in relation to AAI pacing) ranged from a minimum of 0.95% to a maximum of 20.5% (7.3 ± 5.8%, mean ± SD). Intraindividually, the ΔQRSarea ranged from 2.8 to 75.7 μVs (27.5 ± 21.2 μVs, mean range ± SD). In regression analyses, ΔQRSarea (area under the curve [AUC] 0.87, 95% confidence intervals [CI]: 0.78–0.97, p<0.0001) was a better predictor of AHR than ΔQRS duration (AUC 0.79, 95% CI: 0.7–0.91, p<0.0001). Using a reduction in QRSarea of 47 μVs, ΔQRSarea predicted AHR with a sensitivity of 87.5% and a specificity of 79.3%. In 19/24 (79%) patients, the LV pacing configuration providing the greatest ΔQRSarea also provided the best AHR (p=0.009).
Conclusion: Changing the LV pacing vector on an ideally deployed QUAD lead is associated with varying AHR to CRT. ΔQRSarea may be useful for LV pacing vector optimization in CRT recipients with a QUAD lead.