Association of abnormal coronary sinus reflux with coronary slow flow and importance of the Thebesian valve.

Background: The relationship between coronary slow flow (CSF) and coronary sinus (CS) reflux has not been previously studied. This study aimed to investigate the relationship between CSF and CS reflux and Thebesian valve presence as well as the relationship between CS reflux and serum annexin-V and ICAM-1 levels.

Methods: In this case-control study, patients were divided into two groups: CSF (n = 13) and control (n = 7) groups. CS flow parameters and Thebesian valve presence were evaluated by cardiac magnetic resonance (CMR). Moreover, serum ICAM-1 and annexin-V levels were measured.

Results: Regurgitation volume and regurgitation fraction, indicators of reflux flow in CS, were higher in the CSF group than in the control group (p = 0.039 and p = 0.019). Fewer Thebesian valves were observed in the CSF group than in the control group (p = 0.022). Furthermore, a positive correlation was found between regurgitation volume and regurgitation fraction and serum annexin-V and ICAM-1 levels (r = 0.813, p < 0.001 and r = 0.996, p < 0.001; r = 0.817, p < 0.001 and r = 0.993, p < 0.001, respectively).

Conclusions: This study revealed the significant relationship between CSF and reflux flow in CS. The fact that the patients in the CSF group have fewer Thebesian valves suggests the importance of the valve in preventing backward flow from the coronary vein. A positive correlation between serum ICAM-1 and annexin-V levels with regurgitation volume and regurgitation fraction indicates that after a certain threshold, CS reflux should be considered an abnormal condition.