The Relationship Between Coronary Sinus Dilatation And Thrombus Events In Patients With Non-valvular Atrial Fibrillation

Background: The diameter of the coronary sinus(CS)is found to increase progressively with the progression of non-valvular atrial fibrillation(NVAF).Its muscular layer is connected to the posterior wall of left atrium by numerous scattered myocardial fibers.Furthermore,frequency-dependent conduction block is commonly presented within CS and at the junction of CS and left atrium.These factors form multiple foldback loops involving pulmonary veins and right atrium.The phenomenon is closely associated with the recurrence of atrial flutter or atrial fibrillation after the electrical isolation of pulmonary veins in patients with NVAF.The CS is the central venous vessel that drains heart’s blood and has the ability to contract in line with left atrium,when its contracting ability is also affected by endothelial function.While peripheral arteries are affected by systemic inflammation,the CS is in a similar inflammatory environment to the endocardium of left atrium.The endothelial damage between CS and left atrium is also similar.However,it is still unclear whether CS dilation can be used as an equivalent indicator of left atrial dilation.Therefore,we hypothesize that the incidence of thrombotic events associated with NVAF is higher in patients with more significant CS dilation.Aims: To investigate the correlation between coronary sinus dilatation and the thrombotic events in patients with non-valvular atrial fibrillation.Methods: We retrospectively collected the clinical history,the data of serology,transesophageal ultrasound and cardiac computed tomography angiography(CCTA)of219 patients admitted to hospital from 1 January 2021 to 22 June 2022 for NVAF.The image of CS was reconstructed at diastolic phase image(75%)by using multi-planar reconstruction technology in CCTA post-processing platform,and the superior-inferior and anterior-posterior diameters of the orifice of coronary sinus(CSo)were measured by investigators independently.Moreover,the CS diameters of CSo,and 5mm,10 mm,15mm,20 mm,30mm from the CSo were also measured during the same cardiac phase.Patients with left atrial appendage thrombosis or previous atrial fibrillation related cardiogenic stroke were divided into the thrombotic event group(n=53).In contrast,patients without left atrial appendage thrombosis or previous atrial fibrillation related cardiogenic stroke were classified as the non-thrombotic event group(n=166).The differences in CS structure and related baseline characteristics between the two groups were compared.Factors that appeared statistically significant differences in the univariate analysis were included in the multivariate logistic analysis to determine whether they were independently associated with thrombotic events in patients with NVAF.And we plotted the receiver operating characteristic(ROC)curve and calculated the area under curve(AUC)to assess the value of independent risk factors in determining the presence of thrombotic events in NVAF.Results: In the thrombotic event group,the diameter of CS’s different locations was greater than the no-thrombotic event group.There was a significant difference in CS diameter at 15 mm and 20 mm from CSo between the thrombotic and no-thrombotic event group[10.62(9.19,13.30)mm vs 9.81(7.94,11.91)mm,P<0.05;10.28(8.56,12.02)mm vs 8.66(7.06,11.10)mm,P<0.05].There were also statistically significant differences between the two groups’ baseline characteristics including left ventricular ejection fraction(LVEF),history of hypertension,white blood cell count,neutrophil count,monocyte count and prothrombin time.After correcting the interference factors by multivariate logistic analysis,it was found that the CS diameter at a distance from CSo 20mm(OR=1.312,95%CI 1.001～1.720,P=0.049),LVEF(OR=0.019,95%CI0.001～0.783,P=0.037),hypertension history(OR=2.150,95%CI 1.035～4.467,P=0.040)were independently associated with thrombus events in patients with NVAF.ROC curve of the diameter of CS at a distance from CSo 20 mm showed that its AUC was 0.630(95%CI 0.547～0.714).The optimal cut-off point for CS diameter at 20 mm from CSo was 8.81 mm.At this time,the sensitivity of detecting the presence of thrombotic events in these patients was 75.0%,the specificity was 53.1%,the positive predictive value was 33.9% and the negative predictive value was 87.1%.Multivariate logistic analysis showed that LVEF was negatively correlated with thrombotic events in patients with NVAF.Therefore,we used the reciprocal of LVEF to analyze the occurrence of thrombotic events in patients with NVAF by ROC.The AUC was 0.592(95%CI 0.500～0.684).The optimal cut-off point for LVEF was 62%.When the LVEF was 62%,the sensitivity of detecting the presence of thrombotic events was 61.5%,the specificity was 61.7%,the positive predictive value was 34.0% and the negative predictive value was 83.6%.Conclusions: Firstly,the diameter of CS in the thrombotic event group presents a trend towards expansion compared with the no thrombotic event group in NVAF.The CS diameter at 20 mm from CSo is independently associated with thrombotic events and is a valuable indicator for detecting the presence of thrombotic events in NVAF.Secondly,the incidence of thrombotic events,in patients with NVAF and decompensated cardiac function,will increase with the decrease of LVEF.For patients with NVAF,combined with decompensated cardiac function or hypertension,improving the cardiac function and the level of blood pressure will further reduce the risk of thrombotic events.