Reduced Left Ventricular Global Longitudinal Strain in Coronary Slow Flow Phenomenon: A Systematic Review and Meta-Analysis

Abstract

Objective: Coronary Slow Flow Phenomenon (CSFP) involves delayed coronary artery filling without obstruction and is associated with angina and myocardial ischemia. This meta-analysis assessed the link between CSFP and impaired Left Ventricular Global Longitudinal Strain (LVGLS), a marker of subclinical myocardial dysfunction.

Methods: A systematic search (PubMed, Embase, Scopus up to January 2025) identified 18 observational studies comparing LVGLS and layer-specific strain in CSFP patients versus controls with normal coronary flow.

Results: CSFP patients showed significantly reduced LVGLS vs. controls (SMD: 1.22, 95% CI: 0.69 to 1.75). Layer-specific analysis revealed impairment across all myocardial layers, most pronounced in the endocardium (SMD: 0.79, 95% CI: 0.21 to 1.38). While LVEF was preserved, LVGLS demonstrated moderate-to-high diagnostic accuracy for CSFP (AUC: 0.80, 95% CI: 0.66 to 0.95). Reduced LVGLS independently predicted CSFP (adjusted OR: 1.43, 95% CI: 1.19 to 1.46). Exercise stress effects on LVGLS were inconsistent.

Conclusions: CSFP is associated with impaired LVGLS, particularly in the endocardial layer, despite preserved LVEF. LVGLS may serve as a noninvasive marker for subclinical dysfunction in CSFP.