reduced left ventricular global longitudinal strain in the coronary slow flow phenomenon: a systematic review and meta-analysis

Background: the 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 patients with csfp vs controls with normal coronary flow.results: patients with csfp 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 left ventricular ejection fraction (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.conclusion: 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.