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Mechanical Dyssynchrony and Perfusion Heterogeneity Predict Adverse LV Remodeling in Patients with and without LBBB

Simone Cristina Soares Brandão1, Lee Joseph1, Jenifer M Brown1

  • 1Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.

Medrxiv : the Preprint Server for Health Sciences
|February 6, 2026
PubMed

Insights

Mechanical dyssynchrony and perfusion heterogeneity predict adverse left ventricular remodeling, regardless of left bundle branch block (LBBB). Integrated imaging improves cardiomyopathy risk stratification.

Area of Science:

  • Cardiology
  • Cardiovascular Imaging
  • Nuclear Cardiology

Background:

  • Left bundle branch block (LBBB) is linked to mechanical dyssynchrony, heterogeneous perfusion, and adverse left ventricular (LV) remodeling.
  • However, not all LBBB patients develop cardiomyopathy, and dyssynchrony can exist without conduction defects.
  • The role of microvascular dysfunction in LBBB-associated remodeling is not fully understood.

Purpose of the Study:

  • To assess the relationship between mechanical dyssynchrony and perfusion heterogeneity with LV remodeling and function.
  • To compare these relationships in patients with and without LBBB.
  • To evaluate the prognostic value of integrated imaging parameters in LBBB and non-LBBB populations.

Main Methods:

  • Retrospective analysis of 233 patients with isolated LBBB and 932 matched controls.
  • PET myocardial perfusion imaging was used to assess mechanical dyssynchrony (phase entropy), myocardial blood flow (MBF), coronary vascular resistance (CVR), myocardial flow reserve (MFR), and septal-to-lateral MBF ratio (SLR) for perfusion heterogeneity.
  • LV volumes and ejection fraction (EF) were measured; multivariable regression and Cox proportional hazards analyses were performed.

Main Results:

  • Patients with LBBB exhibited greater dyssynchrony, larger LV volumes, and lower EF compared to controls.
  • LBBB patients also showed signs of impaired microvascular function, including higher stress CVR, lower stress MBF, reduced MFR, and lower SLR.
  • Phase entropy and SLR independently predicted LV volumes and EF, with SLR reduction effects amplified in LBBB. Phase entropy, MFR, and LVEF were associated with mortality and heart failure hospitalization.

Conclusions:

  • Mechanical dyssynchrony and perfusion heterogeneity are independent predictors of adverse LV remodeling, irrespective of LBBB.
  • Integrated imaging, assessing both mechanical and perfusion parameters, enhances the stratification of cardiomyopathy risk.
  • These findings suggest that targeting dyssynchrony and perfusion abnormalities may be crucial for managing LV remodeling in diverse patient groups.
Abstract

Keywords:
Left bundle branch blockMechanical dyssynchronyMicrovascular dysfunctionPETPhase entropy

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