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Prolonged QRS duration (QRS >/=170 ms) and left axis deviation in the presence of left bundle branch block: A marker

M K Das1, K Cheriparambil, A Bedi

  • 1New York Presbyterian Hospital-Cornell University Medical College, New York, NY 10021, USA. mithileshdas@hotmail.com

American Heart Journal
|October 31, 2001
PubMed

Insights

Prolonged QRS duration in patients with left bundle branch block (LBBB) indicates significant left ventricular systolic dysfunction. Left axis deviation does not further decrease ejection fraction in LBBB patients.

Area of Science:

  • Cardiology
  • Electrophysiology

Background:

  • Left bundle branch block (LBBB) is often linked to structural heart disease and impaired left ventricular function.
  • The study investigates if QRS duration and left axis deviation (LAD) can predict left ventricular systolic dysfunction in LBBB patients.

Purpose of the Study:

  • To determine the relationship between QRS duration, LAD, and ejection fraction (EF) in patients with LBBB.
  • To assess the predictive value of QRS duration and LAD for significant left ventricular systolic dysfunction.

Main Methods:

  • Prospective evaluation of 300 consecutive patients with LBBB using echocardiography to assess EF.
  • Analysis of the correlation between QRS duration, LAD (axis between -30° and -90°), and EF.

Main Results:

  • A QRS duration of ≥170 milliseconds was significantly associated with lower mean EF (24% ± 10%) compared to shorter durations (<170 milliseconds, 36% ± 16%).
  • QRS duration showed a significant inverse correlation with EF (P <.001).
  • Left axis deviation (LAD) did not show a significant correlation with EF and did not add predictive value.

Conclusions:

  • Prolonged QRS duration (≥170 milliseconds) in LBBB is a marker of significant left ventricular systolic dysfunction.
  • LAD in the context of LBBB does not indicate a further reduction in EF.
Abstract

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