Platelet microRNA for predicting acute myocardial infarction.

Acute myocardial infarction (AMI) is one of the leading causes of morbidity and mortality worldwide, while early diagnosis still represents an upmost priority. While platelet activation is critical for AMI pathogenesis, the role of platelet microRNAs (pmiRNAs) as biomarkers for AMI is unclear. Furthermore, correlations between the levels of pmiRNAs and indices of platelet activity are also unknown. Expression of platelet miR-1, miR-21, miR-126, miR-150 and miR-223 were prospectively assessed in 20 ST-segment elevation myocardial infarction (STEMI) patients, and 40 healthy volunteers. Platelet reactive units (PRU) were assessed with cartridge analyzer, and vasodilator-stimulated phosphoprotein (VASP) was measured by flow cytometry. There were no significant changes in pmiR-1 expression. Expressions of pmiR-21 and pmiR-126 were decreased, while pmiR-150 and pmiR-223 were increased in STEMI patients when compared to controls (all p < 0.01). However, only pmiR-126 exhibited correlation with plasma cardiac troponin I (r = - 0.556, p = 0.011) in STEMI. There was no correlation between pmiRNAs with PRU or VASP during admission, or at 48 h post-stenting. Among tested pmiRNAs, pmiR-126 may serve as a potential novel biomarker for STEMI, while pmiR-1, pmiR-21, pmiR-150, and pmiR-223 were not particularly useful. Moreover, since assessed pmiRNA expression did not correlate well with platelet activity indices their potential diagnostic utility is quite limited.

Angio-Vasculogenic Properties of Endothelial-Induced Mesenchymal Stem Cells Derived From Human Adipose Tissue.

BACKGROUND: Although stem cells have been regarded as a promising therapeutic option, the marginal therapeutic effects of stem cells are limitations that must be overcome for the development of effective cell therapy. This study sought to identify the angio-vasculogenic properties of endothelial differentiated mesenchymal stem cells (MSCs) and to determine whether these cells are effective for vascular repair. METHODS AND RESULTS: Adipose MSCs were cultured for 10 days under endothelial cell (EC) culture conditions. These endothelial cell differentiated adipose MSCs (EA) and undifferentiated adipose MSCs (UA) were characterized via angiogenesis and adhesion assays. These cells were transplanted into a hindlimb ischemia (HLI) model to determine therapeutic effects and their underlying mechanisms. EA displayed low adhesion and angiogenic properties in vitro compared with UA. When implanted into mouse HLI models, EA exhibited the decreased recovery of blood perfusion in limb ischemia than uncultured UA. Histology data showed that injected EA exhibited lower retention, angiogenic cytokine levels, and neovascularization in vivo than did UA. Short-term differentiated EA display less cell engraftment and angio-vasculogenic potential, and are less effective for peripheral vascular repair than UA. CONCLUSIONS: EC differentiation of MSCs may not present an effective strategy for the promotion of therapeutic neovascularization.

Comparison of Prasugrel and Ticagrelor Antiplatelet Effects in Korean Patients Presenting With ST-Segment Elevation Myocardial Infarction.

BACKGROUND: There is insufficient data on the efficacy of prasugrel and ticagrelor in Korean patients with ST-segment elevation myocardial infarction (STEMI). METHODS AND RESULTS: I n the current double-blind, prospective pilot study, 39 patients with STEMI undergoing primary percutaneous coronary intervention were randomized to receive prasugrel 60 mg loading dose (LD) followed by 10 mg daily maintenance dose (n=19), or ticagrelor 180 mg LD followed by 90 mg twice daily maintenance dose (n=20). We assessed platelet reactivity with the VerifyNow and Vasodilator-Stimulated Phosphoprotein (VASP) P2Y12 assays. Compared to baseline platelet reactivity, both prasugrel and ticagrelor groups achieved similar and significantly lower P2Y12 reaction units (PRU) (259 [IQR: 230 to 281] vs. 28 [12 to 55] for prasugrel; 261 [196 to 286] vs. 43 [11 to 61] for ticagrelor), and platelet reactivity indexes (PRI) (51.2% [39.3 to 61.3] vs. 8.1% [6.1 to 14.7] for prasugrel; 47.5% [38.4 to 50.4] vs. 11.2% [7.1 to 15.5] for ticagrelor, all P values <0.001) at 48 h post-LD. Most patients had low platelet reactivity with 95% PRU values <85 and 82% with PRI <16%. CONCLUSIONS: Both prasugrel and ticagrelor were effective for platelet inhibition in Korean STEMI patients with almost no patients exhibiting high platelet reactivity at 48 h after the LD. Our finding of a high number of patients with very low platelet reactivity deserves further studies to assess the safety of the drugs (Prasugrel and Ticagrelor in ST-segment Elevation Myocardial Infarction Study, NCT02075125).

Comparison of pharmacodynamics between low dose ticagrelor and clopidogrel after loading and maintenance doses in healthy Korean subjects.

The novel antiplatelet agent ticagrelor has been demonstrated to exert a faster and more powerful inhibition of platelet aggregation in comparison to clopidogrel in coronary artery disease patients. However, a ticagrelor dose of 90 mg twice daily might not be suitable for patients of East Asian ethnicity, and has not been fully investigated. The aim of this study was to assess the effects of low loading doses (LD, 90 mg) and maintenance doses (MD, 90 mg daily) of ticagrelor in comparison to clopidogrel (600 mg LD, 75 mg daily MD) in healthy Korean volunteers. Twelve subjects were randomized into two groups, receiving either clopidogrel (600 mg LD, followed by 75 mg MD daily for 5 days) or ticagrelor (90 mg LD, followed by 90 mg MD daily for 5 days). Following a 2-week washout period, the treatments were switched between the groups. Three platelet function assessment methods which included light transmission aggregometry (LTA), the VerifyNow assay and multiple electrode platelet aggregometry (MEA) were then used to serially measure platelet function at various time points (baseline, 0.5, 2, 6, 24, 26, 120 and 122 h). The mean IPA to 10 µM ADP in the ticagrelor group was significantly higher than that for the clopidogrel group at the 0.5, 2, 6, 26 and 122 h time points (p ≤ 0.001). However, there was no significant difference between the two groups at the 24- and 120-hour time points (p > 0.05). The assay results produced by the other two platelet function tests (VerifyNow and MEA) were similar to those obtained by LTA. The low loading and maintenance doses of ticagrelor (90 mg LD, 90 mg daily MD) cause a more rapid and potent inhibition of platelet function when compared to clopidogrel (600 mg LD and 75 mg MD). Additionally, at the lowest value of platelet inhibition strength, oral once-daily administration of ticagrelor was no less efficacious than clopidogrel at the 24- and 120-hour time points. Due to a large diurnal variation occurring with a single daily dose, a lower dose twice-daily could be a better option for patients of East Asian ethnicity.

Pharmacodynamic study of prasugrel or clopidogrel in non-ST-elevation acute coronary syndrome with CYP2C19 genetic variants undergoing percutaneous coronary intervention (PRAISE-GENE trial).

BACKGROUND: The CYP2C19*2 or *3 loss-of-function (LOF) allele is associated with high platelet reactivity (HPR) on clopidogrel treatment. East Asians may benefit from a lower dose of prasugrel due to their more potent platelet inhibitory response. The impact of LOF alleles on the pharmacodynamic response to half-dose prasugrel in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) undergoing percutaneous coronary intervention (PCI) is unknown. METHODS: Seventy patients with the LOF alleles were assigned to half-dose prasugrel (n = 35, 30-mg load followed by 5 mg daily) or clopidogrel (n = 35, 600-mg load followed by 75 mg daily). The primary endpoint was the rate of HPR, defined as VerifyNow-P2Y12 reaction unit (PRU) >235, at 24 h post loading. RESULTS: Prasugrel achieved a lower PRU compared to clopidogrel after loading (119 [56-175] vs. 245 [189-299]), at 24 h (34 [8-58] vs. 196 [122-244]), and at 30 days (134 [98-189] vs. 203 [144-248]). Prasugrel had a lower rate of HPR after loading (5.7% vs. 57.1%, p <0.001), at 24 h (2.9% vs. 28.6%, p=0.006), and at 30 days (11.4% vs. 34.3%, p=0.004). Prasugrel had a similar rate of optimal platelet reactivity at 30 days (71.4% vs. 60.0%, p=0.450). There was no significant difference in the occurrence of periprocedural myonecrosis within 48 h after PCI with clopidogrel and prasugrel (22.9% vs. 17.1%, p>0.960). CONCLUSIONS: Half-dose prasugrel provided potent platelet inhibition in NSTE-ACS patients that were carriers of the CYP2C19*2 or *3 allele, with a lower rate of HPR. Periprocedural myonecrosis was not significantly different in the 2 groups.

CYP2C19 but not CYP2B6, CYP3A4, CYP3A5, ABCB1, PON1 or P2Y12 genetic polymorphism impacts antiplatelet response after clopidogrel in Koreans.

Clopidogrel response variability (CRV) is well documented, and may affect clinical outcomes. Impact of genetic polymorphisms is important for assessing and predicting CRV. The extensive evidence indicates the importance of CYP2C19 variants in reducing efficacy of clopidogrel. This study defined the impact of numerous genetic polymorphisms on CRV before and after percutaneous coronary interventions (PCI) exclusively in a Korean cohort assuming less genetic variability noise. One hundred and thirty-six patients of Korean origin undergoing PCI were included. Platelet reactivity was measured by VerifyNow assay before and after PCI. Genetic polymorphism of seven single nucleotides of CYP2B6, CYP2C19, CYP3A4, CYP3A5, ABCB1, PON1, and P2Y12 were evaluated and matched with platelet reactivity. Carriers of at least one CYP2C19*2 or *3 allele uniformly exhibited higher platelet reactivity compared to 0-carrier pre-PCI (odds ratio 3.1, 95% confidence interval 1.4-6.9, P < 0.01) and post-PCI (odds ratio 3.4, 95% confidence interval 1.7-6.8, P < 0.001). The carriers of other gene allele variants lack uniformed impact on CRV. The Korean carriers of CYP2C19*2 or *3 allele are linked to CRV, whereas CYP2B6, CYP3A4, CYP3A5, ABCB1, PON1, and P2Y12 failed to predict CRV. The exact clinical utility of these findings is uncertain, and requires a large randomized national trial for proof of concept.

Impact of renal impairment on platelet reactivity and clinical outcomes during chronic dual antiplatelet therapy following coronary stenting.

AIMS: Clinical utilization of dual antiplatelet therapy (DAPT) in patients with renal impairment (RI) following percutaneous coronary interventions (PCI) represents an urgent, unmet need choosing optimal agents, duration of treatment, and potential dose/regimen adjustment. The lack of any large randomized trials specifically in RI patients, and the absence of the uniformed clinical data reporting policy, clouds the reality. Moreover, triaging RI patients is problematic due to ongoing kidney deterioration, and the fact that RI patients are prone to both vascular occlusions and bleeding. METHODS AND RESULTS: Seven hundred and one Korean patients receiving DAPT with aspirin 100 mg/daily and clopidogrel 75 mg/daily after PCI were prospectively enrolled in the study. Patients were dichotomized into five groups according to RI: estimated glomerular filtration rate (eGFR) >90 mL/min/1.73 m(2) (RI1), 60-89 mL/min/1.73 m(2) (RI2), 30-59 mL/min/1.73 m(2) (RI3), <30 mL/min/1.73 m(2) (RI4), and undergoing dialysis (RI5). Major adverse clinical events (MACEs; cardiovascular death, myocardial infarction, stent thrombosis, and stroke) were collected for 1 year. Platelet reactivity by VerifyNow™ assay and eGFR were simultaneously assessed at 1 month after maintenance DAPT. Patients with RI exhibited a gradual significant increase of residual platelet reactivity during DAPT, dependent on eGFR deterioration [191 ± 72 PRU (RI1) vs. 216 ± 78 PRU (RI2) vs. 248 ± 80 PRU (RI3) vs. 264 ± 70 PRU (RI4) vs. 317 ± 96 PRU (RI5), P < 0.001] being the highest in the dialyses group. Declined eGFR has been gradually associated with advancing age (OR = 1.03, 95% CI = 1.00-1.05; P = 0.032), female gender (OR = 1.7, 95% CI = 1.1-2.5; P = 0.01), diminished smoking rates (OR = 0.6, 95% CI = 0.37-1.00; P = 0.05), hypertension (OR = 1.8, 95% CI = 1.3-2.5; P < 0.001); diabetes (OR = 1.5, 95% CI = 1.1-2.1; P = 0.007), and MACE (HR = 13.9; 95% CI = 1.6-124.3; P = 0.02 for RI4; and HR = 31.9; 95% CI = 2.9-351.9; P = 0.005 for dialysis), but not for bleeding (P = 0.143). Major adverse clinical event risks still remained significant for RI4 (P = 0.027) and RI5 (P = 0.002) by multivariate Cox hazard regression estimates. CONCLUSION: Renal impairment is associated with gradual elevation of residual platelet reactivity while on DAPT, enhancing MACE risks, but not bleeding events. These data should be confirmed in a large randomized outcome-driven trial, and may justify future maintenance-phase DAPT regimen/dose adjustment in RI patients.

Correlation between the CYP2C19 phenotype status and the results of three different platelet function tests in cardiovascular disease patients receiving antiplatelet therapy: an emphasis on newly introduced platelet function analyzer-200 P2Y test.

BACKGROUND: An association has been reported between CYP2C19 polymorphism and the altered antiplatelet activity of clopidogrel. We investigated this association using the newly introduced platelet function analyzer (PFA)-200 (INNOVANCE PFA-200 System; Siemens Healthcare, Germany) P2Y test. METHODS: Polymorphisms of CYP2C19*2, *3, *17 and the degree of inhibition of platelet function were determined in 83 patients. Three different platelet function tests were used to evaluate the degree of platelet inhibition and to check the association with genotype. RESULTS: The post-procedure PFA-200 values of extensive metabolizers (EM) patients (285.3±38.8) were higher than those of intermediate metabolizers (IM) and poor metabolizers (PM) patients (227.7±98.3 and 133.7±99.2, respectively; P=0.024). Light transmittance aggregometry (LTA) and the VerifyNow system showed that the post-procedure values for EM patients were lower than those of IM and PM patients (LTA: 24.4±15.7, 34.1±17.6, and 42.2±16.9, respectively, P<0.001; VerifyNow: 133.2±60.5, 171.5±42.6, and 218.7±59.3, respectively, P<0.001). The high residual platelet reactivity (HPR) rates were significantly different among the EM, IM, and PM groups using PFA-200 (PM:IM:EM=82.4:40.6:11.8, P<0.001). CONCLUSIONS: Approximately, 59.0% of Korean patients with cardiovascular disease receiving clopidogrel had CYP2C19 loss-of-function genotypes classified as IM or PM, and the frequency was similar to the data from Asian people. The PFA-200, LTA, and VerifyNow platelet function tests revealed evidence of a significant association between the efficacy of clopidogrel and CYP2C19 genotypes.

Concomitant nitrates enhance clopidogrel response during dual anti-platelet therapy.

BACKGROUND: Despite advances in modern anti-platelet strategies, clopidogrel still remains the cornerstone of dual anti-platelet therapy (DAPT) in patients undergoing percutaneous coronary interventions (PCI). There is some inconclusive evidence that response after clopidogrel may be impacted by concomitant medications, potentially affecting clinical outcomes. Sustained released nitrates (SRN) are commonly used together with clopidogrel in post-PCI setting for mild vasodilatation and nitric oxide-induced platelet inhibition. METHODS: We prospectively enrolled 458 patients (64.5 ± 9.6 years old, and 73.4% males) following PCI undergoing DAPT with clopidogrel and aspirin. Platelet reactivity was assessed by the VerifyNow™ P2Y12 assay at the maintenance outpatient setting. RESULTS: Concomitant SRN (n=266) significantly (p=0.008) enhanced platelet inhibition after DAPT (251.6 ± 80.9PRU) when compared (232.1 ± 73.5PRU) to the SRN-free (n=192) patients. Multivariate logistic regression analysis with the cut-off value of 253 PRU for defining heightened platelet reactivity confirmed independent correlation of more potent platelet inhibition during DAPT and use of SRN (Relative risk=1.675; Odds ratio [1.059-2.648]; p=0.027). In contrast, statins, calcium-channel blockers, beta blockers, angiotensin receptor blockers, ACE-inhibitors, diuretics, and anti-diabetic agents did not significantly impact platelet inhibition following DAPT. CONCLUSION: The synergic ability of SRN to enhance response during DAPT may have important clinical implications with regard to better cardiovascular protection, but extra bleeding risks, requiring further confirmation in a large randomized study.

Comparison of Three Tests to Distinguish Platelet Reactivity in Patients with Renal Impairment during Dual Antiplatelet Therapy.

BACKGROUND: Clopidogrel and aspirin combination remains a cornerstone for modern dual antiplatelet therapy (DAPT) following coronary stenting. Although monitoring is not currently recommended, certain high-risk cohorts may benefit from tailoring antiplatelet options to reduce thrombotic or/and hemorrhagic risks. Patients with diminished estimated glomerular filtration rate (eGFR) are prone to both vascular occlusions and bleeding events in whom monitoring may be especially advantageous. We compared the residual platelet reactivity assessed by 3 conventional tests during the maintenance antiplatelet therapy dependent on eGFR. METHODS: Post-stenting patients (n = 701) receiving aspirin 100 mg/daily and clopidogrel 75 mg/daily were prospectively enrolled in the cross-sectional single-center study. Patients were dichotomized into 5 groups: eGFR >90, 60-89, 30-59, <30 ml/min/1.73 m2, and dialysis. Platelet reactivity by VerifyNow™, light transmittance aggregometry (LTA), and Multiplate analyzer by multiple electrode platelet aggregometry (MEA) assays together with eGFR calculations were done simultaneously at 1 month after coronary stenting. RESULTS: VerifyNow assay distinguished residual platelet reactivity dependent on eGFR deterioration (191 ± 72 vs. 216 ± 78 vs. 248 ± 80 vs. 264 ± 70 vs. 317 ± 96 PRU; p < 0.001). In contrast, LTA (34.3 ± 18.1 vs. 34.7 ± 18.1 vs. 38.0 ± 16.6 vs. 33.0 ± 17.3 vs. 34.1 ± 29.3%; p = 0.242), or MEA (37.2 ± 19.6 vs. 33.8 ± 18.4 vs. 38.6 ± 21.4 vs. 36.5 ± 20.5 vs. 38.3 ± 28.3 AU/min; p = 0.086) failed to triage platelet reactivity in renal patients. Agreement among assays to identify patients with impaired platelet reactivity and eGFR during antiplatelet therapy was low. The multivariable regression analyses confirmed the VerifyNow advantage, since the differences in the platelet reactivity were highly significant for all renal impairment (RI) groups. In contrast, LTA did not distinguish RI patients, and for the MEA, only RI5 (dialysis) cohort exhibit borderline significant decline of residual platelet reactivity. CONCLUSION: Among 3 assays, VerifyNow was capable to reliably triage residual platelet reactivity in post-stenting DAPT patients dependent on the gradual decline of eGFR during therapy with clopidogrel and aspirin. These data should be confirmed in a large validation longitudinal trial, and may justify future platelet activity monitoring for potential regimen/dose adjustment in high-risk patients. The clinical implications of these data are still unclear, but may give an indication as to whether or when DAPT dose adjustment will become a reality.

Thienopyridine reloading in clopidogrel-loaded patients undergoing percutaneous coronary interventions: The PRAISE study.

OBJECTIVE: The impact of thienopyridine reloading on clinical outcomes, and residual high platelet reactivity (HPR) is unclear. We sought to compare the HRP-related effect of prasugrel and clopidogrel reloading in the already clopidogrel-loaded patients undergoing percutaneous coronary intervention (PCI). MATERIALS AND METHODS: In this prospective, two-center, randomized, open-label study, patients with HPR who had undergone PCI after a clopidogrel (300-600mg) loading dose (LD) were enrolled. Among screened (n=153), HPR was determined in seventy-six patients, who were randomized to either repeated clopidogrel (300mg LD, followed by 75mg MD daily) or prasugrel (20mg LD, followed by 5mg MD daily). The primary endpoint was HPR at 24h after PCI, as determined by the VerifyNow assay. The rates of sustained high and low platelet reactivity, periprocedural myocardial injury (PMI) and 30-day clinical outcomes were also assessed. RESULTS: Higher inhibition of platelet reactive units (PRU) was observed in the prasugrel group than after clopidogrel reloading (Pre-PCI: 284.4±32.0 vs 279.5±32.5, p=0.504; Post-PCI: 100.0±67.0 vs 202.9±65.8, p<0.001; 30days: 170.8±69.8 vs 215.1±62.4, p=0.007). There were less HRP post-PCI after prasugrel compared with the clopidogrel group (2.7 vs 36.1%, p<0.001). However, reloading with prasugrel did not reduce PMI compared to clopidogrel (36.8% vs 39.5%, p=0.813). CONCLUSION: Prasugrel reloading led to a greater reduction in HPR, but similar with clopidogrel PMI in post-PCI patients. Larger randomized evidence is needed for optimization of loading strategies with thienopyridines. CLINICAL TRIAL REGISTRATION INFORMATION: NCT01609647.

Falsely high B-type natriuretic peptide concentration in patients without heart failure attributed to AxSYM assay: case series of eight subjects.

We report a case series of eight subjects complaining of non-specific chest pain without heart failure, but with apparent high concentrations of plasma B-type natriuretic peptide (BNP). No positive clinical characteristics were identified in physical examinations, cardiac imaging, laboratory findings, or pulmonary function tests. However, we observed unusually high BNP values when analysing blood samples of the patients using the AxSYM assay, and this was not supported by readings from Triage® or ADVIA Centaur® assays on the same samples, which showed BNP within the normal range. We believe that the possibility for false readings for high BNP levels in healthy individuals measured by AxSYM assay should be taken into account by physicians in clinical practice to avoid medical errors.

Lower loading dose of prasugrel compared with conventional loading doses of clopidogrel and prasugrel in korean patients undergoing elective coronary angiography: a randomized controlled study evaluating pharmacodynamic efficacy.

BACKGROUND AND OBJECTIVES: Although prasugrel allows for rapid and potent platelet inhibition, the efficacy and safety of lower doses of prasugrel for patients of East Asian ethnicity has not yet been investigated. We compared the effect of a lower loading dose (LD) of prasugrel with conventional LDs of clopidogrel and prasugrel in Korean patients. SUBJECTS AND METHODS: Forty-three Korean patients undergoing coronary angiography were enrolled in the study. Participants were randomly administered LDs of clopidogrel 600 mg, prasugrel 30 mg or prasugrel 60 mg prior to coronary angiography. Platelet reactivity was assessed at baseline and at the time of peak platelet inhibition using light transmission aggregometry (LTA), the VerifyNow assay, and multiple electrode aggregometry. RESULTS: Although baseline platelet reactivity between the groups showed no significant differences, at the time of peak platelet inhibition, the prasugrel 30 mg (18.9±10.0%) and 60 mg groups (13.8±10.8%) showed significantly more potent platelet inhibition than the clopidogrel 600 mg group (52.9±15.8%; p<0.001) by LTA. However, there were no significant differences between the prasugrel 30 mg and 60 mg groups (p=0.549). CONCLUSION: The loading effect of prasugrel 30 mg was more potent than clopidogrel 600 mg and was not significantly different from prasugrel 60 mg.