Time Course of Electrical Remodeling of Native Conduction After Cardiac Resynchronization Therapy and Its Impact on Clinical Outcome

J Card Fail. 2017 Mar;23(3):257-261. doi: 10.1016/j.cardfail.2016.10.014. Epub 2016 Oct 29.

Abstract

Background: Cardiac resynchronization therapy (CRT) induces structural and electrical remodeling (ER) in heart failure (HF) patients. Our aim was to assess time course of ER of native conduction and mechanical remodeling after CRT and impact of CRT-induced ER on clinical outcome.

Methods and results: We prospectively included 62 patients (aged 66 ± 10 years). Echocardiographic and ECG parameters were measured at baseline and 1, 3, 6, 9, and 12 months after implantation. Biventricular pacing was temporary inhibited during each follow-up to record intrinsic ECG. ER was defined as a decrease in native pre-implantation QRS duration ≥10 ms. During follow-up HF hospitalizations, cardiovascular death and transplantation (combined end point) were recorded. There were significant changes in intrinsic ECG parameters during follow-up; the narrowing of QRS duration was already observed after 1 month (median 185 ms [interquartile range (IQR) 175-194] vs 180 ms [170-194]; P < .001). Left ventricular (LV) volumes decreased only after 3 months of CRT (median end-systolic volume 167 mL [137-206] vs 140 mL [112-196]; P < .001). Only patients with ER (n = 24) exhibited significant mechanical remodeling and showed superior survival free from the combined end point compared with patients without ER (log-rank P = .028).

Conclusions: Electrical remodeling of native conduction precedes detectable left ventricular structural changes after CRT. ER of native conduction is associated with better clinical outcome following CRT.

Keywords: Cardiac resynchronization therapy; electrical remodeling; native conduction.

MeSH terms

  • Aged
  • Atrial Remodeling*
  • Cardiac Resynchronization Therapy / methods*
  • Echocardiography
  • Electrocardiography / methods
  • Female
  • Follow-Up Studies
  • Heart Conduction System / physiopathology*
  • Heart Failure / physiopathology
  • Heart Failure / therapy*
  • Heart Rate / physiology
  • Heart Ventricles / diagnostic imaging
  • Heart Ventricles / physiopathology*
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Treatment Outcome
  • Ventricular Remodeling*