Greater coronary lipid core plaque assessed by near-infrared spectroscopy intravascular ultrasound in patients with elevated xanthine oxidoreductase: a mechanistic insight

Association of plasma xanthine oxidoreductase activity with vascular endothelial function independent of serum uric acid level: MedCity21 health examination registry

Background

Xanthine oxidoreductase (XOR) inhibitor administration, known to reduce uric acid and reactive oxygen species (ROS) production, also improves vascular endothelial function (VEF). This cross-sectional study examined our hypothesis that XOR contributes to impaired VEF through ROS but not uric acid production.

Methods

In 395 subjects (196 males, 199 females) without urate-lowering agent administration who underwent a health examination, plasma XOR activity was determined using our highly sensitive assay based on [13C2,15N2] xanthine and liquid chromatography/triple quadrupole mass spectrometry. For VEF evaluation, flow-mediated dilatation (FMD) in the brachial artery was determined by ultrasound, with physical and laboratory measurements also obtained.

Results

The median values for plasma XOR activity, serum uric acid, and FMD were 26.6 pmol/h/mL, 5.4 mg/dL, and 6.2%, respectively. Simple regression analysis showed weak correlations of both log plasma XOR activity and serum uric acid level with FMD (r = -0.213, p < 0.001 and r = -0.139, p = 0.006, respectively). However, multivariable linear regression analyses revealed that log plasma XOR activity but not serum uric acid level remained associated with FMD (β = -0.116, p = 0.037 and β = 0.041, p = 0.549, respectively) after adjustments for various clinical parameters, with no remarkable inconsistencies for the association observed in subgroups divided based on sex or uric acid level. Finally, a series of mediation analyses showed that serum uric acid level did not meet the criteria for mediator of the association of plasma XOR activity with FMD (p = 0.538).

Conclusions

These findings suggest the possibility that XOR contributes to the pathophysiology of impaired VEF through ROS but not uric acid production.

Relation of glucose variability to vulnerable plaque formation in patients with coronary artery disease

BACKGROUND

Although glucose variability (GV) is reportedly associated with coronary plaque vulnerability, namely lipid-rich plaque, details are not fully understood. The aim of this study was to evaluate relations of GV after discharge to vulnerable plaque formation assessed by near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) in patients with and without diabetes.

METHODS

A total of 40 patients undergoing percutaneous coronary intervention under NIRS-IVUS guidance were included, among whom 13 (33%) had diabetes and 20 (50%) presented with acute myocardial infarction (MI). GV was evaluated by a flush glucose monitoring system, primarily with mean amplitude of glycemic excursion (MAGE). Lipid-rich plaque was assessed by maximum lipid core burden index in 4 mm (maxLCBI_4mm) in the target lesion using NIRS-IVUS.

RESULTS

Mean MAGE and maxLCBI_4mm were 69.7 ± 25.6 mg/dl and 508.0 ± 294.9. Intra-day GV was not significantly associated with maxLCBI_4mm in the entire study population, while MAGE was correlated with maxLCBI_4mm in non-diabetic patients (r = 0.46, p = 0.02). In patients with and without acute MI presentation, no significant relations were found between MAGE and maxLCBI_4mm.

CONCLUSION

GV was associated with lipid core plaque formation, especially in non-diabetic patients.

Impact of Serum Uric Acid Level on Systemic Endothelial Dysfunction in Patients with a Broad Spectrum of Ischemic Heart Disease

Previous studies indicated that serum uric acid (SUA) level is a marker of endothelial function in subsets of ischemic heart disease (IHD). In the present study, we aimed to evaluate the relation between the SUA level and endothelial function in patients with a broad spectrum of IHD, including obstructive coronary artery disease (CAD) and ischemia with no obstructive CAD (INOCA). Three prospective studies and one retrospective study were pooled, in which the SUA level was measured, and systemic endothelial function was assessed using the reactive hyperemia index (RHI). The primary endpoint of the present study was a correlation of the SUA level with RHI. A total of 181 patients with a broad spectrum of IHD were included, among whom, 46 (25%) had acute coronary syndrome presentation and 15 (8%) had INOCA. Overall, the SUA level was negatively correlated with the RHI (r = −0.22, p = 0.003). Multivariable analysis identified the SUA level and INOCA as significant factors associated with RHI values. In conclusion, in patients with a broad spectrum of IHD, including obstructive epicardial CAD (chronic and acute coronary syndromes) and INOCA, the SUA level was significantly and negatively correlated with systemic endothelial function assessed with the RHI. INOCA, rather than obstructive CAD, was more associated with endothelial dysfunction.

Drug-coated stent implantation vs. bypass surgery for in-stent occlusion after femoropopliteal stenting

The optimal revascularization for in-stent occlusion (ISO) lesions after femoropopliteal (FP) bare-nitinol stenting has not been established. We, therefore, investigated the comparison between drug-coated stent (DCS) implantation and bypass surgery (BSX) for ISO lesions after FP bare-nitinol stenting. This study was a dual-center, observational study from January 2004 to December 2015. A total of 172 ISO lesions were observed, and after excluding 120 ISO lesions, 52 ISO lesions (50 patients; mean age, 71.0 ± 9.2 years; male, 59.6%) after FP bare-nitinol stenting were enrolled. The included patients with clinical symptoms underwent either DCS implantation (n = 28) or BSX (n = 22). The primary endpoint was recurrent in-stent restenosis (ReISR); secondary endpoints were recurrent target lesion revascularization (ReTLR), recurrent occlusion (reocclusion) and major adverse limb events (MALE), and perioperative complications (POCs), respectively. ReISR or reocclusion was defined as ISR or occlusion after TLR. Stent restenosis was defined as a peak systolic velocity ratio (PSVR) > 2.4 on a duplex scan or ≥ 50% stenosis on angiography. Graft restenosis was defined as a PSV > 300 cm/s and velocity ratio 3.5 or uniformly low PSV < 45 cm/s throughout the entire graft based on graft surveillance. The mean follow-up period was 36.6 ± 25.5 months. At 2 years, the rates of freedom from ReISR, ReTLR, and MALE were not significantly different between the DCS implantation and BSX groups (68.9% vs. 73.7%, p = 0.81; 84.7% vs. 73.7%, p = 0.45; 84.7% vs. 78.6%, p = 0.60, respectively). However, the freedom from reocclusion rate was significantly lower in the DCS implantation group (81.6% vs. 100%, p = 0.04). The occurrence of POCs was not significantly different between the DCS implantation and BSX groups (7.1% vs 4.2%, p = 1.0). Although BSX was the gold-standard therapy for ISO lesions after FP bare-nitinol stenting, DCS implantation might be a good option because the rates of freedom from ReISR, ReTLR, and MALE were similar.