Prognostic significance of carotid intima-media thickness in patients with coronary slow flow: A systematic review and meta-analysis.

Abstract

<h4>Background</h4>Carotid intima-media thickness (CIMT), a marker of systemic atherosclerosis, has been proposed as a prognostic marker of coronary slow flow (SCF). This systematic review and meta-analysis was performed to evaluate the predictive outcomes of CIMT in SCF patients compared to patients with normal coronary flow (NCF).<h4>Methods</h4>This systematic review, conducted according to PRISMA and a pre-specified PECOS protocol, systematically searched PubMed/MEDLINE, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar for observational studies (cohort, case-control, cross-sectional) comparing CIMT and TIMI frame count (TFC) in SCF versus NCF patients. Two reviewers independently extracted data and assessed methodological quality using ROBINS-I and AXIS. A random-effects model estimated mean differences (MD) in CIMT and TFC, with heterogeneity evaluated by the I² statistic.<h4>Results</h4>Eight studies involving 451 SCF patients and 344 NCF controls were included. CIMT was significantly higher in SCF patients (pooled MD -0.14 mm; 95% CI -0.21 to -0.07; I² = 91%; p < 0.0001). Seven studies showed higher CIMT in SCF patients (MD -0.40 to -0.11 mm; p < 0.05), while one study found no difference (MD 0.01 mm; p = 0.73). Maximal CIMT was consistently greater in SCF patients (MD -0.17 to -0.15 mm; p < 0.01). In all studies, TFC demonstrated markedly reduced coronary flow in SCF patients (pooled MD -16.58 frames; 95% CI -18.08 to -15.08; I² = 80%; p < 0.00001). Qualitative synthesis correlated increased CIMT with endothelial dysfunction, systemic inflammation, reduced coronary and systemic vascular flow velocities, and early atherosclerotic changes, underscoring its prognostic significance.<h4>Conclusion</h4>The association of slow coronary flow with increased carotid intima-media thickness supports its role as a marker of systemic subclinical atherosclerosis and highlights CIMT as a potential non-invasive tool for early risk stratification.