Association of Coronary Sinus Flow with Long-Term Risk of Acute Coronary Syndrome and Composite Cardiovascular Events

Background/Objectives: Acute coronary syndrome (ACS) remains a leading cause of sudden cardiac death worldwide; however, limited data exist regarding the relationship between coronary arterial and coronary venous dynamics in this context. The present study aimed to evaluate whether coronary sinus flow (CSF) dynamics obtained via transthoracic echocardiography (TTE) are associated with the long-term risk of ACS and cardiovascular events. Methods: This retrospective observational cohort study included 100 patients who underwent elective coronary angiography and had their CSF parameters assessed via TTE. All participants were followed up for a duration of up to 48 months. The primary endpoint was cardiovascular mortality, while secondary endpoints comprised the occurrence of ACS, refractory angina pectoris, and cerebrovascular events. Study endpoints were evaluated by dichotomizing the population into two groups using the median CSF value as the cutoff (low: CSF ≤ median; high: CSF > median). Results: The primary endpoint did not differ significantly between the two groups; however, refractory angina was significantly more common in the high CSF group [4 (8.2%) vs. 12 (24.5%), p = 0.029]. Similarly, the high CSF group exhibited a significantly higher rate of the composite endpoint than the low CSF group [13 (26.5%) vs. 25 (51.0%), p = 0.013]. In multivariate Cox analysis, CSF was an independent predictor of the composite endpoint (HR: 1.50; 95% CI: 1.11-2.02, p = 0.009). Conclusions: Baseline CSF measured by TTE was independently associated with the composite endpoint, whereas its association with isolated ACS was limited. CSF assessment may provide incremental prognostic information alongside conventional arterial and microvascular evaluation.