Dietary nitrate supplementation reduces circulating platelet-derived extracellular vesicles in coronary artery disease patients on clopidogrel therapy: a randomised, double-blind, placebo-controlled study

Extracellular vesicles (EVs) are implicated in the pathogenesis of cardiovascular disease (CVD). Specifically, platelet-derived EVs are highly pro-coagulant, promoting thrombin generation and fibrin clot formation. Nitrate supplementation exerts beneficial effects in CVD, via an increase in nitric oxide (NO) bioavailability. Clopidogrel is capable of producing NO-donating compounds, such as S-nitrosothiols (RSNO) in the presence of nitrite and low pH. The aim of this study was to assess the effect of nitrate supplementation with versus without clopidogrel therapy on circulating EVs in coronary artery disease (CAD) patients. In this randomized, double-blind, placebo-controlled study, CAD patients with (n = 10) or without (n = 10) clopidogrel therapy received a dietary nitrate supplement (SiS nitrate gel) or identical placebo. NO metabolites and platelet activation were measured using ozone-based chemiluminescence and multiple electrode aggregometry. EV concentration and origin were determined using nanoparticle tracking analysis and time-resolved fluorescence. Following nitrate supplementation, plasma RSNO was elevated (4.7 ± 0.8 vs 0.2 ± 0.5 nM) and thrombin-receptor mediated platelet aggregation was reduced (−19.9 ± 6.0 vs 4.0 ± 6.4 U) only in the clopidogrel group compared with placebo. Circulating EVs were significantly reduced in this group (−1.183e11 ± 3.15e10 vs −9.93e9 ± 1.84e10 EVs/mL), specifically the proportion of CD41+ EVs (−2,120 ± 728 vs 235 ± 436 RFU [relative fluorescence unit]) compared with placebo. In vitro experiments demonstrated clopidogrel–SNO can reduce platelet-EV directly (6.209e10 ± 4.074e9 vs 3.94e11 ±  1.91e10 EVs/mL). In conclusion, nitrate supplementation reduces platelet-derived EVs in CAD patients on clopidogrel therapy, increasing patient responsiveness to clopidogrel. Nitrate supplementation may represent a novel approach to moderating the risk of thrombus formation in CAD patients

Genetic polymorphisms and the risk of coronary artery disease

Background: Myocardial infarction involves the three processes of atheroma development, plaque rupture and formation of a thrombus. Proliferation of smooth muscle cells and vasoconstriction are important aspects of atheroma formation and are influenced by the renin-angiotensin system. Angiotensin converting enzyme (ACE) pivotal to this system has recently been shown to be influenced by an insertion/deletion (I/D) polymorphism in the ACE gene. Patients homozygous for the D allele have the highest circulating levels. Inhibition of fibrinolysis through raised levels of plasminogen activator Inhibitor (PAI- 1) has also been shown to be under the control of a PAI-1 promoter single nucleotide insertion/deletion (4G/5G) polymorphism. Patients homozygous for the 4G allele have the highest levels of circulating PAI-1. Aims: The aim of this thesis, was to investigate the role of both polymorphisms in relation to atherothrombosis in subjects with coronary artery disease (CAD). Results: 609 Caucasian patients (420 males 189 females) admitted for angiography for known or suspected coronary artery disease were recruited from two centres. Patients were classified as having no significant coronary artery disease (20%), single (21%), double (21%) and triple vessel disease (38%) on the basis of 50% stenosis. Both the ACE genotype and the PAI-1 genotype were associated with their respective circulating levels (P= 0.0008) and (P = 0.0001) respectively. There was no relationship between the ACE genotype or levels with either the degree of coronary stenosis or a history of MI. In contrast, the 4G/4G genotype was significantly related to a history of myocardial infarction, an association which was stronger in the group with pre-existing significant atheroma. Conclusions: These data suggests that the ACE genotype-activity does not influence the atherothrombotic process, whereas the PAI-1 promoter polymorphism influences the development of myocardial infarction through its effects on thrombus formation in patients with pre-existing atheroma. Conclusions These data suggests that the ACE genotype-activity does not influence the atherothrombotic process, whereas the PAI-1 promoter polymorphism influences the development of myocardial infarction through its effects on thrombus formation in patients with pre-existing atheroma

Repeat coronary angiography in patients with previously normal coronary arteries

Background: Coronary artery disease (CAD) is a major public and economic health problem. Coronary angiography is a gold standard for diagnosing CAD and is indicated in patients with 61–90% pre-test probability of the disease when the diagnosis cannot be made on clinical grounds alone and when revascularisation is being considered. The natural history of normal coronary angiogram is poorly understood. Objectives: To evaluate the progression of disease in patients with normal coronary angiography and to assess the overall survival and event-free survival from acute myocardial infarction (MI) in these patients. Methods: We interrogated the Central Cardiac Audit Database (CCAD) between November 2005 and December 2013 to identify patients with normal or ‘near-normal’ coronary angiography. Demographic, clinical and angiographic data was recorded. This database was linked with the Patient Episode Database for Wales (PEDW) and the datasets from the Office for National Statistics (for mortality) using the Secure Anonymised Information Linkage (SAIL) databank. This allowed for the extraction of information from all the sources above on the basis of the International Statistical Classification of Diseases (ICD-10) using the Structured Query Language (SQL). Results: Out of over 20,000 patients undergoing coronary angiography between November 2005 and December 2013, 5032 patients had normal coronaries and minor CAD. Of 5032 patients, 136 underwent repeat angiography, with 131 (96.3%) and 5 (3.7%) patients having two and three repeat investigations respectively. Mean time between procedures was 3.3 (±1.82) years. Of those 136 patients, at the median follow up of 6.8 years, no change in disease progression was demonstrated in 108 (79.4%) patients on the follow up studies. In the remaining 28 (20.6%) patients, normal coronaries progressed to minor CAD. No patients progressed beyond minor CAD. Patients with normal coronaries had significant better survival than patients with minor CAD (p 99.5% in both groups at the median of 5 years follow up. (p = 0.09) Conclusions: Normal coronary angiography and minor CAD is unlikely to progress to significant disease at 7 years and the incidence of MI in these patients is rare at 5 years. Therefore, repeating coronary angiography within at least 5 years is not indicated

Early Clinical Experience with a Polymer-Free Biolimus A9 Drug-Coated Stent in DES-Type Patients Who Are Poor Candidates for Prolonged Dual Anti-Platelet Therapy.

INTRODUCTION:Prolonged dual anti-platelet therapy (DAPT) may cause excess bleeding in certain patients. The biolimus-A9 drug-coated stent (BA9-DCS) has a rapid drug-elution profile allowing shortened DAPT. Data were gathered on the early experience implanting this stent in drug-eluting stent eligible patients deemed to be at high risk of bleeding. BACKGROUND AND METHODS:The demographics, procedural data and clinical outcomes were gathered prospectively for 249 patients treated with a BA9-DCS stent at 2 UK centres, and compared to a cohort of patients treated in the same period with drug-eluting stents (PCI-DES). RESULTS:Operator-defined BA9-DCS indications included warfarin therapy, age, and anaemia. Patients receiving a BA9-DCS were older (71.6±11.8 vs. 64.8±11.6yrs, p<0.001), more often female (38.2 vs. 26.8%, P<0.001), and more likely to have comorbidity including chronic kidney disease or poor LV function than PCI-DES patients. The baseline Mehran bleed risk score was also significantly higher in the BA9-DCS group (19.4±8.7 vs. 13.1±5.8, p<0.001). Of the BA9-DCS cohort, 95.5% of patients demonstrated disease fitting NICE criteria for DES placement. The number of lesions treated (1.81±1.1 vs. 1.58±0.92, p = 0.003), total lesion length (32.1±21.7 vs. 26.1±17.6mm, p<0.001), number of stents used (1.93±1.11 vs. 1.65±1.4, p = 0.007) and total stent length (37.5±20.8 vs. 32.4±20.3, p<0.01) were greater for BA9-DCS patients. DAPT was prescribed for 3.3±3.9 months for BA9-DCS patients and 11.3±2.4 months for PCI-DES patients (p<0.001). At follow up of 392±124 days despite the abbreviated DAPT course stent related event were infrequent with ischemia-driven restenosis PCI (2.8 vs. 3.4%, p = 0.838), and stent thrombosis (1.6 vs. 2.1%, p = 0.265) rates similar between the BA9-DCS ad PCI-DES groups. After propensity scoring all clinical end-points were similar between both cohorts. CONCLUSIONS:This early experience using polymer-free BA9 drug-coated stents in drug-eluting stent type patients at risk of bleeding are encouraging. Further studies are warranted

Adjusted clinical outcomes after propensity scoring in patients treated with a BA9 drug-coated stent vs. PCI-DES population.

<p>Adjusted clinical outcomes after propensity scoring in patients treated with a BA9 drug-coated stent vs. PCI-DES population.</p

Baseline demographics of patients treated with a BA9 drug-coated stent vs. PCI-DES population.

<p>Baseline demographics of patients treated with a BA9 drug-coated stent vs. PCI-DES population.</p

A) Dual anti-platelet duration (DAPT) in months by treatment group; B) Percentage of patients on DAPT at each time point by treatment group.

<p>A) Dual anti-platelet duration (DAPT) in months by treatment group; B) Percentage of patients on DAPT at each time point by treatment group.</p

Procedural data for patients treated with a BA9 drug-coated stent vs. PCI-DES population.

<p>Procedural data for patients treated with a BA9 drug-coated stent vs. PCI-DES population.</p