Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 20 4 2025 12 06 310 322 Mahin Seifi Alan Alborz University of Medical Sciences Kobra Hosseini Alborz University of Medical Sciences Sanaz Seifi Alan Alborz University of Medical Sciences Zahra Mirzaei Alborz University of Medical Sciences Peyman Saeedi Alborz University of Medical Sciences Soroush Bahrami Alborz University of Medical Sciences Vahid Shahnavaz Alborz University of Medical Sciences Haniyeh Rashidi Alborz University of Medical Sciences Mahnaz Seifi Alan Alborz University of Medical Sciences Hadith Rastad Alborz University of Medical Sciences 2025 10 03 2025 11 04 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. https://jthc.tums.ac.ir/index.php/jthc/article/view/2366 https://jthc.tums.ac.ir/index.php/jthc/article/download/2366/1234