Optimal uric acid reduction to improve vascular endothelial function in patients with chronic heart failure complicated by hyperuricemia.

Although an association of serum uric acid levels with endothelial function has been shown in various clinical settings, the optimal treatment target that would benefit vascular endothelial function has not been established. We, therefore, conducted a post hoc analysis of the Excited-UA study to identify an optimal target. Patients (N = 133) with chronic heart failure and comorbid hyperuricemia who enrolled in the Excited-UA study were divided into three tertiles based on their serum uric acid level 24 weeks after initiating xanthine oxidase inhibitor treatment with topiroxostat or allopurinol (i.e., groups with low, moderate, and high uric acid levels). Flow-mediated dilation (FMD) and reactive hyperemia index (RHI) values measured by reactive hyperemia peripheral arterial tonometry (RH-PAT) were compared among groups. The change from baseline in the FMD value 24 weeks after treatment was comparable among the three groups. In contrast, the change from baseline in the RHI was significantly different among the three groups (-0.153 ± 0.073, 0.141 ± 0.081 and -0.103 ± 0.104 in the low, moderate, and high uric acid level groups, respectively, P = 0.032). After adjustment for age, body mass index, and concomitant use of diuretics, which differed among the three groups, the change in the RHI in the moderate uric acid level group tended to be higher than that in the high uric acid level group (P = 0.057) and was significantly higher than that in the low uric acid level group (P = 0.020). These results indicate that targeting excessively low uric acid levels by treatment with xanthine oxidase inhibitors might be less beneficial for improving microvascular endothelial function in patients with chronic heart failure. Comparisons of the changes from baseline in vascular endothelial function parameters at 24 weeks among the 3 groups of low, moderae and high uric acid levels achieved with xanthine oxidase inhibitors. After adjustment for confounding factors, such as age, body mass index and concomitant diuretic use, which showed differences among the 3 groups, the change in RHI in the moderate uric acid level group tended to be higher than that in the high uric acid level group and was significantly higher than that in the low uric acid level group.