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July 23, 2026Journal of Personalized MedicineOpen Access

Strauss LBBB links to improved CRT outcomes, while conduction system pacing shows operator-dependent mixed results.

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Why the study?

About one-third of patients receiving CRT do not show clinical improvement, possibly because standard LBBB criteria do not clearly isolate true conduction block from other causes of wide QRS.

Does patient selection using Strauss criteria for LBBB or conduction system pacing improve CRT outcomes compared to conventional criteria or biventricular pacing?

Population

17 comparative studies (n ≈ 4200) and six randomized controlled trials

Comparison

Strauss-positive vs Strauss-negative LBBB patients, and randomized CSP trials using Strauss-type vs typical LBBB

Design

Systematic evidence synthesis conducted in accordance with PRISMA 2020 guidelines

Key result

Strauss-defined LBBB is associated with improved CRT outcomes in observational studies, but randomized trials of conduction system pacing show mixed results dependent on operator experience.

Authors

ASAthanasios SaplaourasPMPanagiotis MililisSKStavroula Koskina

Discussion

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Overview

Strauss-defined LBBB is associated with improved CRT outcomes in observational studies, but randomized trials are needed to confirm superiority over conventional criteria, and CSP outcomes heavily depend on operator experience.

Key Points

  • The research aims to assess the link between true left bundle branch block as defined by Strauss criteria and outcomes in cardiac resynchronization therapy, alongside trial design considerations.
  • Conducted a systematic search of PubMed, EMBASE, and Cochrane Library following PRISMA 2020 guidelines.
  • Included 17 comparative studies evaluating CRT outcomes in Strauss-positive versus Strauss-negative groups, and six randomized CSP trials focusing on patient selection based on morphology.
  • 14/17 observational studies favored Strauss-defined LBBB, especially in non-ischemic cardiomyopathy, but two large registry analyses showed no added benefit of strict criteria.
  • HeartSync-LBBP trial revealed lower mortality/hospitalization (8% vs. 28%; HR 0.26; 95% CI 0.12–0.57) for LBBP compared to BiVP.
  • LEFT-BUNDLE-CRT trial indicated that LBBAP did not meet non-inferiority criteria compared to BiVP (RR 0.95; 95% CI 0.88–1.02).

Study Design

Type

Systematic Review

Structured PICO

Does patient selection using Strauss criteria for LBBB or conduction system pacing improve CRT outcomes compared to conventional criteria or biventricular pacing?

P
Population
Systematic review of 17 observational studies (n ≈ 4200) and 6 randomized trials evaluating Strauss criteria for LBBB and conduction system pacing in CRT candidates.
I
Intervention
Patient selection using Strauss criteria for left bundle branch block (LBBB) and/or conduction system pacing (CSP/LBBP/LBBAP)
C
Comparator
Conventional LBBB criteria and/or biventricular pacing (BiVP)
O
Outcome
CRT outcomes including composite of mortality or heart failure hospitalizationcomposite

Strauss-defined LBBB is associated with improved CRT outcomes in observational studies, but randomized trials are needed to confirm superiority over conventional criteria, and CSP outcomes heavily depend on operator experience.

Limitations

  • Observational evidence consists mostly of small retrospective studies with heterogeneous outcome definitions
  • No randomized trial has yet compared Strauss-guided against guideline-based patient selection
  • Mostly small retrospective studies with heterogeneous outcome definitions
  • Operator experience heavily confounded CSP trial results

Cite This Study

Saplaouras et al. (2026) conducted a systematic review in Left bundle branch block (LBBB) in patients receiving cardiac resynchronization therapy (CRT). Strauss criteria for LBBB and conduction system pacing (CSP) vs. Conventional LBBB criteria and biventricular pacing (BiVP) was evaluated. Strauss-defined LBBB is associated with improved CRT outcomes in observational studies, but randomized trials of conduction system pacing show mixed results dependent on operator experience.

synapsesocial.com/papers/6a61b0f6faa9903c5116b445https://doi.org/10.3390/jpm16070389
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