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Usefulness of QRS axis change to predict mortality in patients with left bundle branch block

Parin J Patel1, Ralph J Verdino

  • 1Hospital of the University of Pennsylvania, Philadelphia, PA, USA. parin.patel1@uphs.upenn.edu

The American Journal of Cardiology
|May 7, 2013
PubMed

Insights

Left bundle branch block (LBBB) with left-axis deviation (LAD) does not increase mortality risk. However, developing LAD after a normal axis in LBBB patients indicates significantly higher mortality, suggesting a potential prognostic indicator.

Area of Science:

  • Cardiology
  • Electrocardiography
  • Prognostic Biomarkers

Background:

  • Left bundle branch block (LBBB) is associated with poor prognosis, but the prognostic value of left-axis deviation (LAD) in LBBB patients remains unclear.
  • Existing research highlights QRS duration's correlation with outcomes in LBBB, necessitating further investigation into other electrocardiographic markers like LAD.

Purpose of the Study:

  • To investigate whether left-axis deviation (LAD) confers an independent mortality risk in patients diagnosed with left bundle branch block (LBBB).
  • To identify significant risk factors for all-cause mortality in a cohort of patients with LBBB.

Main Methods:

  • A retrospective, population-based cohort study including 2,794 patients with LBBB over a 17-year follow-up period.
  • Analysis of all-cause mortality rates and time-to-event data, assessing the association of LAD with mortality.
  • Bivariate analysis to identify factors associated with LAD, including atrial fibrillation, ventricular tachycardia, age, and congestive heart failure.

Main Results:

  • Left-axis deviation (LAD) was present in 50% of patients with left bundle branch block (LBBB) and was not independently associated with increased all-cause mortality.
  • Significant mortality risk factors identified included elevated creatinine, low hemoglobin, history of atrial fibrillation, prior myocardial infarction, and ventricular tachycardia.
  • Patients with LBBB who developed LAD from a normal axis during follow-up exhibited significantly higher mortality (p = 0.02).

Conclusions:

  • Left-axis deviation (LAD) does not appear to be an independent predictor of mortality in patients with left bundle branch block (LBBB).
  • The development of LAD in patients with a pre-existing normal axis and LBBB may indicate a worse prognosis, warranting further investigation into the underlying mechanisms.
  • While concurrent LBBB and LAD may not increase risk, a change to LAD may signal a poorer outcome in LBBB patients.

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