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.

Effects of switching from clopidogrel to prasugrel at the chronic phase after coronary stenting on antiplatelet action and vascular endothelial function: Switch-Pras study.

Compared to clopidogrel, prasugrel has a lower incidence of ischemic events following percutaneous coronary intervention (PCI) because of an early reduction during the acute phase in P2Y12 reaction units (PRU). The objective of this study was to compare the antiplatelet effect and vascular endothelial function of both drugs during the chronic phase after PCI. Patients who had undergone PCI and were confirmed to have no restenosis by follow-up coronary angiography under dual anti-platelet therapy with clopidogrel (75 mg/day) and aspirin (100 mg/day) were randomized to either continue clopidogrel or switch to prasugrel (3.75 mg/day). At baseline, prior to randomization we determined the CYP2C19 genotype. At the baseline and 24 weeks after randomization, the P2Y12 reactivity unit (PRU) was measured using the VerifyNow™ P2Y12 assay. Endothelial function was evaluated by flow-mediated vasodilation (FMD) and reactive hyperemia peripheral arterial tonometry (RH-PAT), while and circulating CD34+/CD133+/CD45low progenitor cells were measured by flow cytometric analysis. Serum high-sensitivity C-reactive protein (hsCRP) level was also measured. The PRU was reduced significantly in the prasugrel group (P = 0.0008), especially in patients who were intermediate or poor metabolizers based on the CYP2C19 genotype (P < 0.0001). This reduction was not observed in the clopidogrel group. The number of CD34+/CD133+/CD45low cells increased in the clopidogrel group (P = 0.008), but not in the prasugrel group. The hsCRP, FMD and reactive hyperemia index measured by RH-PAT did not change in either group. Prasugrel is potentially better than clopidogrel for preventing thrombotic events, although clopidogrel may have an advantage over prasugrel in terms of preventing atherosclerotic events. Proper use of thienopyridine drugs based on the CYP2C19 genotype has promising clinical potential.

Flow-Mediated Vasodilation and Reactive Hyperemia Index in Heart Failure with Reduced or Preserved Ejection Fraction.

Vascular endothelial dysfunction is part of the underlying pathophysiology of heart failure. However, there are no reports in which vascular endothelial function of both conduit arteries and microvasculature was assessed in patients with heart failure. This study was aimed to assess vascular endothelial function separately in heart failure with reduced (HFrEF) and preserved ejection fraction (HFpEF). We performed simultaneous measurement of both flow-mediated vasodilation for endothelial function of conduit arteries and reactive hyperemia-peripheral arterial tonometry for that of microvasculature in 88 consecutive patients with chronic heart failure. In 55 patients with ischemic heart disease as an underlying cause of heart failure, flow-mediated vasodilation value was comparable between the two groups of HFrEF (left ventricular ejection fraction < 50%, n = 31) and HFpEF (left ventricular ejection fraction ≥ 50%, n = 24). Reactive hyperemia index measured by reactive hyperemia peripheral arterial tonometry, however, was lower in HFrEF patients compared to HFpEF patients (P = 0.014). In contrast, among 33 patients with non-ischemic heart disease, the degree of flow-mediated vasodilation was lower in HFpEF patients (n = 18) compared with HFrEF patients (n = 15) (P = 0.009), while reactive hyperemia index was comparable between the two groups. The clinical and pathophysiological significance of endothelial function in heart failure differs between conduit artery and microvasculature, and these differences may contribute to the underlying pathophysiology of HFpEF and HFrEF, as well as in ischemic heart disease and non-ischemic heart disease.