A novel measure of AV-conduction predicts clinical outcomes and benefit from CRT-D in non-LBBB patients with wide QRS and a low left ventricular ejection fraction.

Abstract

Background: PR-interval reflects atrioventricular timing but does not well characterize adverse hemodynamics. Novel ECG parameters of conduction may identify benefit from non-dyssynchronous ventricular pacing to correct long atrioventricular conduction delays.

Objective: Evaluating novel ECG parameters to identify risk of heart failure (HF)/death and benefit vs harm by CRT-D in MADIT-CRT non-LBBB patients.

Methods: We analyzed intervals from ECGs in 535 non-LBBB patients enrolled in MADIT-CRT, using ImageJ. Onset of atrial activation, P wave zero crossing in V1, latest P offset, earliest QRS onset, and time to the first R peak in V1 and V6 were determined. Endpoints included HF or death. Associations between novel conduction measures and clinical outcomes in ICD patients (n = 209), and CRT-D (n = 326) vs. ICD benefit, were assessed using Kaplan-Meier and multivariable Cox regression analyses.

Results: We identified the delay from P zero crossing to the first R peak in V1 (P0PV1) at quintile 5 as the strongest risk predictor in ICD patients (n = 159, 30%), over PR-interval, for all endpoints (p < 0.001), with a more than threefold risk increase. In this group, CRT-D was associated with a 66% lower risk of HF/Death (95% CI: 0.22-0.68, p = 0.001) vs. an ICD. However, in patients with a P0PV1 < 201 ms, CRT-D vs. an ICD was associated with a 64% increased risk of HF/death (95% CI: 1.12-2.55, p = 0.012), with significant bidirectional interaction (p-value < 0.001).

Conclusions: We propose a novel variable, P0PV1, to identify risk and benefit vs. harm from CRT-D in HF patients with non-LBBB. Prospective studies are warranted to confirm our findings.