Danilo Menichelli

Gut‐Derived Serum Lipopolysaccharide is Associated With Enhanced Risk of Major Adverse Cardiovascular Events in Atrial Fibrillation: Effect of Adherence to Mediterranean Diet

Background Gut microbiota is emerging as a novel risk factor for atherothrombosis, but the predictive role of gut‐derived lipopolysaccharide (LPS) is unknown. We analyzed (1) the association between LPS and major adverse cardiovascular events (MACE) in atrial fibrillation (AF) and (2) its relationship with adherence to a Mediterranean diet (Med‐diet). Methods and Results This was a prospective single‐center study including 912 AF patients treated with vitamin K antagonists (3716 patient‐years). The primary end point was a composite of MACE. Baseline serum LPS, adherence to Med‐diet (n=704), and urinary excretion of 11‐dehydro‐thromboxane B2 (TxB2, n=852) were investigated. Mean age was 73.5 years; 42.9% were women. A total of 187 MACE (5.0% per year) occurred: 54, 59, and 74 in the first, second, and third tertile of LPS, respectively (log‐rank test P=0.004). Log‐LPS (hazard ratio 1.194, P=0.009), age (hazard ratio 1.083, P<0.001), and previous cerebrovascular (hazard ratio 1.634, P=0.004) and cardiac events (hazard ratio 1.822, P<0.001) were predictors of MACE. In the whole cohort, AF (versus sinus rhythm) (β 0.087, P=0.014) and low‐density lipoprotein cholesterol (β 0.069, P=0.049) were associated with circulating LPS. Furthermore, Med‐diet score (β −0.137, P<0.001) was predictive of log‐LPS, with fruits (β −0.083, P=0.030) and legumes (β −0.120, P=0.002) negatively associated with log‐LPS levels. Log‐LPS and log‐TxB2 were highly correlated (r=0.598, P<0.001). Log‐LPS (β 0.574, P<0.001) and Med‐diet score (β −0.218, P<0.001) were significantly associated with baseline urinary excretion of TxB2. Conclusions In this cohort of AF patients, LPS levels were predictive of MACE and negatively affected by high adherence to Med‐diet. LPS may contribute to MACE incidence in AF by increasing platelet activation.

Aging-Related Decline of Glutathione Peroxidase 3 and Risk of Cardiovascular Events in Patients With Atrial Fibrillation.

Background Experimental studies demonstrated that glutathione peroxidase 3 (GPx3), an antioxidant enzyme that catabolizes hydrogen peroxide, protects against thrombosis. Little is known about its role in cardiovascular disease. Methods and Results A prospective cohort study was conducted in 909 atrial fibrillation patients. Serum activities of GPx3, superoxide dismutase (SOD), and catalase were measured at baseline to assess the risk of cardiovascular events during a mean follow‐up of 43.4 months (3291 person‐years). Serum Nox2 and urinary excretion of 11‐deydro‐thromboxane B2 were also measured. During follow‐up 160 cardiovascular events occurred (4.9%/year). Significantly lower values of GPx3 (P<0.001) and SOD (P=0.037) were detected in patients with, compared to those without, cardiovascular events. A lower survival rate was observed in patients with GPx3 (P<0.001) and SOD (P=0.010) activities below the median, as compared to those above. In a fully adjusted Cox regression model, GPx3 was the only antioxidant enzyme predictor of cardiovascular events (hazard ratio 0.647, 95% confidence interval 0.524‐0.798, P<0.001). GPx3 was inversely associated with urinary 11‐dehydro‐thromboxane B2 (B −0.337, P<0.001) and serum Nox2 (B: −0.423, P<0.001). GPx3 activity progressively decreased with decades of age (P<0.001), with a progressive reduction in people aged ≥70 years. Conclusions This study provides evidence that a low antioxidant status, as depicted by reduced levels of GPx3, increases the risk of cardiovascular events in patients with atrial fibrillation. The age‐related decline of GPx3 may represent a mechanism for the enhanced cardiovascular risk in the elderly population.

Incidence of bleeding in patients with atrial fibrillation and advanced liver fibrosis on treatment with vitamin K or non-vitamin K antagonist oral anticoagulants

OBJECTIVES To investigate the incidence of bleeding events in atrial fibrillation (AF) patients treated with vitamin K (VKAs) or non-vitamin K antagonist oral anticoagulants (NOACs) screened for the presence of liver fibrosis (LF). BACKGROUND Previous studies provided conflicting results on bleeding risk in AF patients with liver disease on VKAs, and no data on NOACs in this setting are available. METHODS Post-hoc analysis of a prospective, observational multicentre study including 2330 AF outpatients treated with VKAs (n = 1297) or NOACs (n = 1033). Liver damage was quantified by the FIB-4 score (>3.25), a validated marker of LF. The primary endpoint was the incidence of any bleeding, according to ISTH classification. RESULTS A high FIB-4 was present in 129 (5.5%) patients: 77 (5.9%) on VKA and 52 (5.0%) on NOACs (p = 0.344). During follow-up, 357 (15.3%) patients experienced a bleeding: 261 (80 major and 180 minor) with VKAs (7.2%/year), and 96 (40 major and 56 minor) with NOACs (6.4%/year). In VKA-treated patients, but not in those on NOACs, FIB-4 >3.25 was associated with higher major bleeding (14.3% vs. 5.6%, log-rank test p < 0.001). Multivariable Cox regression model showed that FIB-4 was associated with major bleeding only in VKA-treated patients (HR: 3.075, 95% CI 1.626-5.818, p = 0.001). On multivariable analysis, FIB-4 was not significantly associated with CVEs neither in VKA or NOAC-treated patients. CONCLUSION We found a significant association between LF and major bleedings in AF patients treated with VKA, which was not evident in patients on NOACs.

Anti Xa oral anticoagulants inhibit in vivo platelet activation by modulating glycoprotein VI shedding

Anti Xa non-vitamin K oral anticoagulants (anti Xa NOACs) seem to possess antiplatelet effect in vitro, but it is unclear if this occurs also in vivo. Aim of the study was to compare the effect on platelet activation of two anti Xa NOACs, namely apixaban and rivaroxaban, to warfarin, and to investigate the potential underlying mechanism by evaluating soluble glycoprotein GPVI (sGPVI), a protein involved in platelet activation. We performed a cross-sectional including AF patients treated with warfarin (n=30), or apixaban 10mg/day (n=40), or rivaroxaban 20mg/day (n=40). Patients were balanced for sex, age and cardiovascular risk factors. Platelet activation by urinary excretion of 11-dehydro-thromboxane (Tx) B2 and soluble GPVI (sGPVI) were analysed at baseline and after 3 months of treatment. Baseline TxB2 value was 155.2±42.7ng/mg creatinine. The 3 months-variation of urinary excretion of TxB2 was -6.5% with warfarin (p=0.197), -29% with apixaban (p<0.001) and -31% with rivaroxaban (p<0.001). Use of anti Xa NOACs was independently associated to the variation of urinary TxB2 (B: -0.469, p<0.001), after adjustment for clinical characteristics; sGPVI was significantly lower in patients treated with NOACs at 3 months (p<0.001), while only a trend for the warfarin group (p=0.116) was observed. The variation of sGPVI was correlated with that of TxB2 in the NOACs group (Rs: 0.527, p<0.001). In 15 patients (5 per each group) platelet recruitment was significantly lowered at 3 months by NOACs (p<0.001), but not by warfarin. The study provides evidence that anti Xa NOACs significantly inhibit urinary TxB2 excretion compared to warfarin, suggesting that NOACs possess antiplatelet property.

Oxidative stress and cardiovascular disease: new insights

The role of oxidative stress in the onset and progression of atherosclerosis and its impact on the development of cardiovascular events has been widely described. Thus, increased oxidative stress has been described in several atherosclerotic risk factors, such as hypertension, dyslipidaemia, peripheral artery disease, metabolic syndrome, diabetes, and obesity. Among others, specific oxidative pathways involving both pro-oxidant and antioxidant enzymes seem to play a major role in the production of reactive oxidant species (ROS), such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, myeloperoxidase, superoxide dismutase, and glutathione peroxidase. In this review, we will discuss: 1) the most relevant enzyme systems involved in the formation and detoxification of ROS, 2) the relationship between oxidative stress and cardiovascular risk, and 3) therapeutic implications to modulate oxidative stress.

Silybin and metabolic disorders

Mediterranean diet represents a fundamental strategy in the prevention of cardiovascular and metabolic disorders as demonstrated by observational and interventional trials [1]. Among the most represented elements of the Mediterranean diet are polyphenols that display protective effects on cardiometabolic disorders by counteracting oxidative stress that represent a key point of the preventive strategy in this setting. Hence, oxidative stress seems to be involved in both cardiovascular and metabolic disorders [2]. Indeed, atherosclerotic disease is associated with increased level of oxidative stress [3] as well as metabolic disorders such as non-alcoholic fatty liver disease (NAFLD) [4] and diabetes [5] (Fig. 1). Amid the several natural elements proposed to be protective in these contexts is the flavolignan silybin [7]. The effect of silybin is reported on by Sciacqua and colleagues [6] in this issue of the Journal. Silybin is the major active constituent of silymarin, and it represents about 50–70% of the silymarin extract. Similar to the other flavolignans, limiting factors for the use of silybin are its low solubility in water, low bioavailability, and poor intestinal absorption [7]. To counteract this aspect, different more soluble derivatives of silybin have been synthesized. In particular, when conjugated to vitamin E and phospholipids, silybin seems to significantly improve its bioavailability. Moreover, this combination also displays increased antioxidant and antifibrotic activity [7]. In liver cells, as well as in other types of cells, the common effects of silybin may be summarized as follows: (1) antioxidant; (2) direct or indirect (through the antioxidant capability) modulator of inflammation and fibrogenesis; and (3) indirect or direct modulator of some intrahepatic metabolic pathways [7] (Fig. 1). Silybin acts as an antioxidant because it inhibits radical formation, binds some radical species (scavenger), interferes with lipid peroxidation of membranes (and, therefore, modulates membrane permeability), and increases the intracellular content of scavengers [8]. Silybin inhibits the formation of oxidative species such as superoxide anion radicals and of nitric oxide, decreases the content of malondialdehyde, and totally abolishes the decrease of antioxidants such as glutathione, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase [7]. These results, which are dose dependent, have been documented in animal and human models of cardio-metabolic diseases [7]. Silybin also displays other metabolic effects; for instance, it interferes with some mechanisms of action of insulin. In fact, it modulates the uptake of glucose in adipocytes by blocking the insulin-dependent glucose transporter 4. Several studies investigated this issue in human models. Thus, in a double-blind, randomized trial in patients with poorly controlled non-insulin-dependent diabetes mellitus and alcoholic liver disease [9], and in a randomized, double-blind, placebo-controlled trial in patients with type II diabetes [10], silybin significantly affects plasma levels of glucose and triglycerides, with a trend toward lower hemoglobin A1c levels. The silybin–vitamin E–phospholipid complex was previously tested in different metabolic settings such as patients with NAFLD demonstrating its ability in reducing insulin resistance evaluated by the HOMA test after a 6-month treatment [11]. The effect of this complex on hypertensive patients with reduced glycemic control was investigated by Sciacqua and colleagues [6]. Hypertensive patients with normal glucose tolerance (NGT) but 1-h post load plasma glucose ≥ 155 mg/dl (1-h high), during the oral glucose tolerance test (OGTT), show higher insulin resistance and multiple target organ damage, and this represents an interesting model of metabolic disorder. The authors demonstrate that after 6 months of silybin * Pasquale Pignatelli pasquale.pignatelli@uniroma1.it

Temporal trends of time in therapeutic range and incidence of cardiovascular events in patients with non-valvular atrial fibrillation

BACKGROUND Optimal time in therapeutic range (TTR) of vitamin K antagonists (VKAs) is crucial for cardiovascular events (CVEs) prevention in non-valvular atrial fibrillation (NVAF). The relationship between temporal changes of TTR and the incidence of CVEs has been poorly investigated. We investigated 1) temporal trends of TTR in a long-term follow-up of NVAF patients; 2) the incidence of CVEs according to changes of TTR. METHODS Prospective observational study including 1341 NVAF outpatients (mean age 73.5 years, 42.5% male) starting VKAs. Patients were divided into 4 groups: Group 0: Optimal TTR, consistently ≥70% (n = 241); Group 1: Temporally worsening TTR, from above to below 70% (n = 263); Group 2: Temporally improving TTR, from below to above 70% (n = 270); Group 3: Suboptimal TTR, consistently <70% (n = 567). RESULTS In a mean follow-up of 37.7 months (4214.2 patient-years), 108 CVEs occurred (2.6%/year). Survival analysis showed a graded increased risk of CVEs in relation to temporal changes in TTR, with the worst outcomes in Groups 1 and 3 (log-rank test p = 0.013). Multivariable Cox proportional hazards regression analysis showed that Group 1 vs. 0 (HR: 2.096; 95%CI 1.061-4.139, p = 0.033), Group 3 vs. 0 (HR: 2.292; 95%CI 1.205-4.361, p = 0.011), CHA2DS2VASc score (HR:1.316; 95%CI 1.153-1.501, p < 0.001) and PPIs (HR:0.453; 95%CI 0.285-0.721, p = 0.001) were independently associated with CVEs. CONCLUSION A decrease of TTR <70% over time is observed in almost 20% of NVAF patients. Patients with worsening TTR temporally (ie. from initially above 70% to below 70%) have similar risk of CVEs of patients with consistently suboptimal anticoagulation.