Thrombin-Induced Platelet-Fibrin Clot Strength Identified by Thrombelastography: A Novel Prothrombotic Marker of Coronary Artery Stent Restenosis.

BACKGROUND AND OBJECTIVE: In-stent restenosis (ISR) is a limitation of percutaneous coronary intervention and has been linked to specific clinical and angiographic variables. We aimed to simultaneously assess thrombosis biomarkers and lipid levels in patients with and without ISR. METHODS: Consecutive patients (n = 170) with a history of coronary stenting undergoing elective angiography were studied. Blood samples for thrombelastography, light transmittance aggregometry, and lipid levels were obtained prior to cardiac catheterization. RESULTS: Sixty-nine patients (41%) had ISR (>50% luminal diameter stenosis). Among patients with ISR, 40 (58%) had ISR in more than one stent bed. Patients with ISR were more often female (37.7% vs. 21.8%, P = 0.04), had higher thrombin-induced platelet-fibrin clot strength (TIP-FCS) (69.9 mm vs. 65.6 mm, P < 0.001), and a higher ApoB/A1 ratio (0.65 vs. 0.59, P = 0.03). In patients on dual antiplatelet therapy (n = 86), there were no differences in ADP-, arachidonic acid-, and collagen-induced platelet aggregation between groups. The frequency of patients with ISR increased with TIP-FCS quartiles and by ROC analysis, TIP-FCS = 67.0 mm was the cutpoint for identification of ISR (AUC = 0.80 (95%CI 0.73-0.87, P < 0.0001). By multivariate analysis, TIP-FCS ≥67.0 mm strongly associated with ISR (OR = 7.3, P = 0.004). CONCLUSION: Patients with ISR identified at the time of cardiac catheterization have a prothrombotic phenotype indicated by high TIP-FCS, a novel marker. Studies to confirm the prognostic utility of high TIP-FCS for the development of ISR are ongoing.

Association of weight gain with coronary artery disease, inflammation and thrombogenicity.

Obese individuals, despite having increased cardiovascular (CV) risk factors experience adverse CV outcomes less frequently than non-obese. Little is known about association of long-term weight gain to development of coronary artery disease (CAD), inflammation and thrombogenicity. 418 consecutive patients with suspected CAD undergoing elective cardiac catheterization were included in a sub-analysis of the multi analyte, thrombogenic, and genetic markers of atherosclerosis study. Maximum weight gain (MWG) was defined as percentage increase in weight since age 17 years to year of heaviest weight and categorized as: minor (<30 %), moderate (30-47 %), severe (>47-69 %), and extreme (>69 %). Lipid profiling was determined by vertical density gradient ultracentrifugation, thrombin-induced platelet fibrin clot strength (TIP-FCS) by thrombelastography, and urinary 11-dehydrothromboxane B2 (11-dhTxB2) by ELISA. CAD severity was defined as minimal (<20 %), moderate (20-75 %), and severe (>75 %) luminal diameter obstruction of any major coronary vessel. The mean MWG was 53 ± 33 %. Extreme MWG group had a higher incidence of diabetes mellitus (48 %), hypertension (81 %), depression (25 %), and were most often female (60 %) (p < 0.05 for all). In women, CAD severity was inversely associated to MWG (p = 0.05), whereas in men no such association was observed (p = 0.18). TIP-FCS increased in a stepwise fashion with MWG (p = 0.001). 11-dTxB2 levels were higher in the extreme MWG group, regardless of lipid lowering therapy (p < 0.05). Our data suggest that maximal weight gain since age 17 years is associated with heightened thrombogenicity, inflammation and a poorer lipid profile but not an increased risk for severe CAD development.

Pharmacology of antiplatelet agents.

Pharmacotherapies with agents that inhibit platelet function have proven to be effective in the treatment of acute coronary syndromes, and in the prevention of complications during and after percutaneous coronary intervention. Because of multiple synergetic pathways of platelet activation and their close interplay with coagulation, current treatment strategies are based not only on platelet inhibition, but also on the attenuation of procoagulant activity, inhibition of thrombin generation, and enhancement of clot dissolution. Current strategies can be broadly categorized as anticoagulants, antiplatelet agents, and fibrinolytics. This review focuses on the pharmacology of current antiplatelet therapy primarily targeting the inhibition of the enzyme cyclooxygenase 1, the P2Y12 receptor, the glycoprotein IIb/IIIa receptor, and protease-activated receptor 1.

Low-density lipoprotein 4: a novel predictor of coronary artery disease severity.

BACKGROUND: Hyperlipidemia is a well established risk factor for coronary artery disease (CAD). Severe CAD has been observed in patients with normal levels of total and low-density lipoprotein (LDL) cholesterol. Small dense LDL particle subtypes (LDL3 and LDL4) have been observed to be more oxidizable and atherogenic. We aimed to identify the role of cholesterol particle subtypes in predicting CAD severity. METHODS: Blood samples were obtained immediately before cardiac catheterization in 179 consecutive patients with suspected CAD. Detailed lipid profiling was performed using a VAP cholesterol test. CAD severity was categorized angiographically as no/minor CAD (<20% luminal diameter stenosis [LDS]), moderate CAD (20% to 74% LDS) and severe CAD (>75% LDS of any major coronary vessel). RESULTS: Patients with severe CAD had significantly higher LDL4 and triglycerides, and lower total HDL, HDL2, HDL3, LDL2 and LDL3 compared to patients with no/minor CAD (p < .05 for all). Multivariate analysis showed high LDL4 as an independent predictive of severe CAD. ROC analysis showed an area under the curve of 0.62 (p < .0001) with a cut-point of >16.9 mg/dL to predict severe CAD with a sensitivity of 53% and specificity of 79%. CONCLUSION: Elevated LDL4 levels are associated with severe CAD. Further large-scale investigations are required to evaluate the utility of LDL4 in predicting CAD severity.

Oxidized Low-Density Lipoprotein-ß2-Glycoprotein I Complex But Not Free Oxidized LDL Is Associated With the Presence and Severity of Coronary Artery Disease.

Oxidized low-density lipoprotein (oxLDL) and ß2-glycoprotein I (ß2GPI) have been identified in human atherosclerotic lesions and when complexed have been implicated as a pro-atherothrombotic antigen. We examined the association of free oxLDL and oxLDL-ß2GPI complex in patients with coronary artery disease who underwent elective cardiac catheterization. Serum was collected from patients with suspected coronary artery disease immediately before elective cardiac catheterization who were either treated (n = 385) or not treated (n = 150) with statins and from healthy volunteers (n = 134). OxLDL and oxLDL-ß2GPI complex levels were determined by enzyme-linked immunosorbent assay. Disease severity was defined angiographically as none-minimal (<20%), moderate (20% to 75%), and severe (>75%) luminal diameter obstruction of any major coronary vessel. Both oxLDL and oxLDL-ß2GPI complex were lower in patients on statins (p <0.001). In statin-naive patients, oxLDL-ß2GPI complex, but not free oxLDL, was associated with severe coronary artery disease (p = 0.036). However, no association was observed in patients on statins. LDL4 and triglycerides increased with oxLDL-ß2GPI complex quartiles (p = 0.001). OxLDL-ß2GPI complex (>0.32 U/ml) was predictive of severe atherosclerosis by receiver-operating characteristic curve analysis in statin-naive patients (area under the curve 0.66, p = 0.002). In conclusion, oxLDL-ß2GPI appears more predictive of coronary artery disease severity than oxLDL alone in statin-naive patients.

Relation of fish oil supplementation to markers of atherothrombotic risk in patients with cardiovascular disease not receiving lipid-lowering therapy.

Fish oil supplementation (FOS) is known to have cardiovascular benefits. However, the effects of FOS on thrombosis are incompletely understood. We sought to determine if the use of FOS is associated with lower indices of atherothrombotic risk in patients with suspected coronary artery disease (sCAD). This is a subgroup analysis of consecutive patients with sCAD (n=600) enrolled in the Multi-Analyte, Thrombogenic, and Genetic Markers of Atherosclerosis study. Patients on FOS were compared with patients not on FOS. Lipid profile was determined by vertical density gradient ultracentrifugation (n=520), eicosapentaenoic acid+docosahexaenoic acid was measured by gas chromatography (n=437), and AtherOx testing was performed by immunoassay (n=343). Thromboelastography (n=419), ADP- and collagen-induced platelet aggregation (n=137), and urinary 11-dehydrothromboxane B2 levels (n=259) were performed immediately before elective coronary angiography. In the total population, FOS was associated with higher eicosapentaenoic acid+docosahexaenoic acid content (p<0.001), lower triglycerides (p=0.04), total very low-density lipoprotein cholesterol (p=0.002), intermediate-density lipoprotein cholesterol (p=0.02), and AtherOx levels (p=0.02) but not in patients on lipid-lowering therapy. Patients not on lipid-lowering therapy taking FOS had lower very low-density lipoprotein cholesterol, intermediate-density lipoprotein cholesterol, remnant lipoproteins, triglycerides, low-density lipoprotein cholesterol, AtherOx levels, collagen-induced platelet aggregation, thrombin-induced platelet-fibrin clot strength, and shear elasticity (p<0.03 for all). In clopidogrel-treated patients, there was no difference in ADP-induced aggregation between FOS groups. Patients on FOS had lower urinary 11-dehydrothromboxane B2 levels regardless of lipid-lowering therapy (p<0.04). In conclusion, the findings of this study support the potential benefit of FOS for atherothrombotic risk reduction in sCAD with the greatest benefit in patients not receiving lipid-lowering therapy. Future prospective studies to compare FOS with lipid-lowering therapy and to assess the independent effects of FOS on thrombogenicity are needed.

Review of pharmacokinetic and pharmacodynamic modeling and safety of proton pump inhibitors and aspirin.

The efficacy of aspirin in primary and secondary prevention of cardiovascular diseases has been convincingly demonstrated. Gastrointestinal (GI) adverse effects with aspirin may lead to poor adherence and/or discontinuation of treatment. Proton pump inhibitors (PPIs) have been used for more than 20 years as the first choice for treating peptic ulcers and their bleeding complications, gastroesophageal reflux disease, non-steroidal anti-inflammatory drug-induced GI lesions and dyspepsia. Adherence becomes a major concern when aspirin is co-prescribed with PPIs to prevent GI adverse effects. Combining aspirin and PPIs into one tablet is an effective approach to address aspirin-related GI adverse effects and increase adherence to aspirin therapy for the prevention of cardiovascular diseases.

PA tablets: investigational compounds combining aspirin and omeprazole for cardioprotection.

For most patients with prior cardiovascular events, preventing future secondary cardiovascular events requires life-long persistence with antiplatelet therapy. PA tablets (P: proton pump inhibitors; A: aspirin) are investigational compounds that were developed to provide the cardioprotective benefits of aspirin with the upper gastrointestinal protection of a proton pump inhibitor (e.g., omeprazole). The tablets are film-coated, coordinated-release tablets for oral administration that contain 40 mg immediate-release omeprazole and either 81 or 325 mg delayed-release aspirin. The goals of the clinical development program were to demonstrate the following: improved gastrointestinal safety of PA relative to enteric-coated aspirin alone; bioequivalence and comparative bioavailability between the PA compounds and currently marketed enteric-coated aspirin; and long-term safety. Two clinical pharmacology studies were also conducted to study the potential for interaction between PA32540 and clopidogrel.