Relationship of retinal arteriolar and venular diameters with coronary slow flow phenomenon

Coronary slow flow (CSF) is claimed to be a systemic microvascular pathology rather than an isolated cardiac vascular pathology. We aimed to investigate the relation of CSF with retinal vascular calibers. This cross-sectional study enrolled 122 consecutive patients with CSF and 109 age- and sex-matched controls. Central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and artery-vein ratio were measured using Interactive Vessel Analyzer, a semi-automated retinal vascular analyzer. There were significant differences in CRAE, CRVE, and artery-vein ratio between the CSF and control groups (P < .001, .009, and <.001, respectively). Correlation analysis revealed statistically significant negative correlations between CRAE and left anterior descending artery-corrected TIMI frame count, circumflex-TIMI frame count, mean TIMI frame count, systolic blood pressure, diastolic blood pressure, and high-density lipoprotein cholesterol levels (r = -0.373, -0.390, -0.459, -0.416, -0.471, and -0.350, respectively, P < .001 for all), significant positive correlations of CRVE with left anterior descending artery-corrected TIMI frame count, mean TIMI frame count, smoking, and triglyceride levels (r = 0.341, 0.315, 0.404, and 0.447, respectively, P < .001 for all), and significant negative correlations of CRVE with systolic blood pressure and high-density lipoprotein cholesterol levels (r = -0.254 and -0.359, respectively, P < .001 for all). The CSF is closely associated with retinal vascular caliber, suggesting that, it is a systemic generalized microvascular phenomenon. The utility of retinal imaging for CSF screening is worth further investigation.