The relationship between ECG predictors of cardiac resynchronization therapy benefit

Abstract

Introduction Cardiac resynchronization therapy (CRT) is an effective treatment that reduces mortality and improves cardiac function in patients with left bundle branch block (LBBB). However, about 30% of patients passing the current criteria do not benefit or benefit only a little from CRT. Three predictors of benefit based on different ECG properties were compared: 1) “strict” left bundle branch block classification (SLBBB); 2) QRS area; 3) ventricular electrical delay (VED) which defines the septal-lateral conduction delay. These predictors have never been analyzed concurrently. We analyzed the relationship between them on a subset of 602 records from the MADIT-CRT trial. Methods & results SLBBB classification was performed by two experts; QRS area and VED were computed fully automatically. High-frequency QRS (HFQRS) maps were used to inspect conduction abnormalities. The correlation between SLBBB and other predictors was R = 0.613, 0.523 and 0.390 for VED, QRS area in Z lead, and QRS duration, respectively. Scatter plots were used to pick up disagreement between the predictors. The majority of SLBBB subjects– 295 of 330 (89%)–are supposed to respond positively to CRT according to the VED and QRS area, though 93 of 272 (34%) non-SLBBB should also benefit from CRT according to the VED and QRS area. Conclusion SLBBB classification is limited by the proper setting of cut-off values. In addition, it is too “strict” and excludes patients that may benefit from CRT therapy. QRS area and VED are clearly defined parameters. They may be used to optimize biventricular stimulation. Detailed analysis of conduction irregularities with CRT optimization should be based on HFQRS maps.

3-Dimensional ventricular electrical activation pattern assessed from a novel high-frequency electrocardiographic imaging technique: principles and clinical importance

“…This study explains the HF ECG mechanism to determine dyssynchronous activation and its validation with the ex-vivo approach. The HF ECG theory will help better understand the activation maps obtained by HF and UHF 14-lead ECG technology recently introduced 12 , 14 , 27 , 28 .…”

Contemporary management of heart failure patients with reduced ejection fraction: the role of implantable devices and catheter ablation

“…Causes of non-response include mechanical dyssynchrony, presence and extent of myocardial scar, and suboptimal LV lead position [77][78][79]. Other factors that have been shown to influence response to CRT include QRS width and morphology pattern, device optimization, and post-implant programming [80,81]. With respect to future directions, alternative modes of LV pacing with the capacity to overcome the limitations of non-response include isolated LV pacing (potential as a tiered therapy) [82], endocardial pacing (LV end-systolic volume reduction in patients enrolled after CRT non-response) [83], septal pacing (short-term haemodynamic improvements and electrical resynchronization on par with BiV pacing) [84], and multipoint LV pacing (reductions in hospitalization for HF, improved LVEF on follow-up, and an increase in CRT response) [85].…”

Cardiac Resynchronization Guided by Ultra-High-Frequency ECG Maps

“…The UHF-ECG method was first introduced in [3], and clinical benefit was tested on a large MADIT-CRT 1 kHz Holter database [4] in the high-frequency range up to 350 Hz. Recently the study [5] has compared ventricular dyssynchrony with other ECG parameters. Ventricular dyssynchrony estimated from high-frequency ECG has been confirmed as a parameter that best predicts positive CRT outcome in left bundle branch block patients.…”