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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
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Relationships between electrical and mechanical dyssynchrony in patients with left bundle branch block and healthy

Saara Sillanmäki1,2, Jukka A Lipponen3, Mika P Tarvainen4,3

  • 1Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Puijonlaaksontie 2, 70210, Kuopio, Finland. saara.sillanmaki@kuh.fi.

Journal of Nuclear Cardiology : Official Publication of the American Society of Nuclear Cardiology
|February 10, 2018
PubMed

Insights

Left bundle branch block (LBBB) can cause dyssynchronous left ventricular (LV) contraction. QRS duration and end-diastolic volume predict mechanical dyssynchrony in LBBB patients, explaining 55% of its variation.

Area of Science:

  • Cardiology
  • Cardiac Electrophysiology
  • Medical Imaging

Background:

  • Abnormal electrical activation can lead to dyssynchronous left ventricular (LV) contraction.
  • Left bundle branch block (LBBB) is a common conduction abnormality affecting LV electrical activation.
  • Understanding the relationship between electrical and mechanical dyssynchrony in LBBB is crucial for patient management.

Purpose of the Study:

  • To characterize and analyze electrical and mechanical dyssynchrony in patients with LBBB.
  • To identify predictors of mechanical dyssynchrony in LBBB.
  • To compare electrical and mechanical synchrony between LBBB patients and healthy controls.

Main Methods:

  • Analysis of myocardial perfusion imaging (MPI) data from 994 patients, including 43 with LBBB and 24 controls.
  • Characterization of electrical activation using vector electrocardiography (VECG).
  • Assessment of LV function and mechanical dyssynchrony using ECG-gated MPI phase analysis.

Main Results:

  • QRS duration (QRSd) and end-diastolic volume (EDV) significantly correlated with mechanical dyssynchrony (phase bandwidth).
  • QRSd and EDV independently explained 55% of the variation in mechanical dyssynchrony.
  • Patients with LBBB and mechanical dyssynchrony had significantly wider QRSd and larger EDV compared to those without.

Conclusions:

  • Left bundle branch block (LBBB) does not always result in mechanical dyssynchrony.
  • QRS duration and end-diastolic volume are key predictors of mechanical dyssynchrony in LBBB.
  • Specific cut-off values for QRSd (≥165 ms) and EDV (≥109 mL) may indicate mechanical dyssynchrony in LBBB.
Abstract

Keywords:
Gated SPECTLeft bundle branch blockMyocardial perfusion imagingPhase analysisSPECTVector electrocardiography

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