Correlation of platelet inhibition and cerebral thromboembolic events, as expressed with number of high-intensity transient signals,during Transcatheter Aortic valve Implantation

Background It has been shown that high Residual Platelet Reactivity (RPR) may contribute to platelet aggregation which propagates thrombosis on implanted materials. Therefore, we evaluated whether high RPR may predispose to an increased number of cerebrovascular emboli during Transcatheter Aortic valve Implantation (TAVI). Methods Consecutive patients who underwent transfemoral TAVI with a self-expandable valve were prospectively studied. A loading dose of P2Y12 inhibitor 24 hours preprocedurally was given. Additionally, aspirin was started one week prior to procedure in all patients. Platelet inhibition was assessed with P2Y12 reaction units (PRU) (Verify Now assay) as well as percentage of inhibition 30 minutes prior to procedure initiation. The number of High intensity transient signals (HITS) was assessed with Rimed Digi-Lite™ transcranial Doppler, setting a threshold for detection of HITS at 3dB, continuously, on both middle cerebral arteries during the whole procedure. Two observers reviewed offline the number of HITS. Results In total, 84 patients underwent TAVI (53 males, mean age=81.9yrs old ±8,98). Mean baseline PRU and percentage of platelet inhibition was 258,24±43,03 (156–376) and 48,51%±40.05 (0–100%) respectively. In the treated patients the mean absolute total number of HITS and the number of HITS per minute recorded, was 566,63±272,32, (136–1432) and 6.7/min±3.3 (2.09–13.24) respectively. Significant positive correlation was found between baseline PRU levels and number of total HITS (r=0.261, p=0.017), (Figure 1). Multivariate regression analysis revealed that PRU was independent prognostic factor of total HITS (β=0.708, p=0.06), In order to clarify the predictive role of platelet inhibition in the total number of recorded HITS a ROC analysis was performed, obtaining an area under the curve of 0.646 (95% CI 0.518 to 0.773, p=0.047). PRU-levels≥169 were shown to predict number of HITS at the upper quartile with 76% sensitivity and 65% specificity. Conclusion High RPR after dual antiplatelet loading with a P2Y12 inhibitor and aspirin, resulted in larger burden of embolic HITS during TAVI procedure. A cut off point of 169 PRU units with 76% sensitivity and 65% specificity predicted detection of HITS at the higher quartile. PRU-HITS Correlation Funding Acknowledgement Type of funding source: None

P329Residual platelet reactivity after pre-treatment with ticagrelor prior to primary percutaneous coronary intervention is associated with suboptimal myocardial reperfusion

Background The evidence of a clinical benefit of P2Y12 inhibitor pre-treatment in primary percutaneous coronary intervention (PCI) and the relation between the level of platelet inhibition and myocardial reperfusion with newer potent P2Y12 inhibitors remain unclear. Objectives We aimed to assess the relationship between platelet reactivity at the time of primary PCI after pre-treatment with aspirin and ticagrelor and the post-PCI myocardial blush grade (MBG). Methods We prospectively included 61 patients. Platelet reaction units for ticagrelor (PRU) and aspirin reaction units (ARU) were measured using the point-of-care test VerifyNow before PCI. The high on-ticagrelor (PRU >208) and on-aspirin (ARU ≥550) platelet reactivity (HPR and HaPR) were assessed. Patients were divided into two groups according to MBG 3 or <3. Results MBG 3 was identified in 28 (46%) patients. Mean PRU was lower in such patients as compared to those with MBG <3 (155.82±90.91 vs 227.42±65.18; p=0.001) while mean ARU was similar between groups. HPR and HaPR were observed in 30 (49.2%) and 11 patients (18%), respectively. HPR but not HaPR was more frequent in the group with impaired MBG (66.7 vs 28.6%; p=0.003 and 21.2 vs 14.3%; p=0.48 respectively). Table 1. Platelet reactivity results Verify Now at admission All Final Blush <3 Final Blush 3 p n=61 (100%) n=33 (54%) n=28 (46%) PRU P2Y12 194.56±85.32 227.42±65.18 155.82±90.91 0.001 Base 193.54±49.01 194.79±45.68 192.07±53.48 0.83 Inhibition of platelet aggregation (%) 15.61±29.85 5.7±17.55 27.29±36.79 0.007 ARU 463.97±76.45 472.58±72.5 453.82±81 0.34 PRU >208 30 (49.1%) 22 (66.7%) 8 (28.6%) 0.003 ARU ≥550 11 (18%) 7 (21.2%) 4 (14.3%) 0.48 Verify Now at day 1 n=57 n=30 n=27 p PRU P2Y12 40.86±41.43 47.27±45.87 33.74±35.35 0.21 Base 196.98±36.19 193.67±30.67 200.81±41.97 0.47 Inhibition of platelet aggregation (%) 79.8±17.96 76.37±20.54 83.77±13.78 0.11 ARU = Aspirin reaction units; PRU = P2Y12 reaction units. Conclusion In conclusion, our study shows that higher PRU and the subsequent HPR at the time of primary PCI, after pretreatment with ticagrelor, are the only correlates of post PCI MBG. These findings support the earliest possible loading with ticagrelor prior to primary PCI. Acknowledgement/Funding The study was supported by grants from Terumo. The funder has no role in any step of the study.

FORMULATION OF SOLID DOSAGE FORM CONTAINING CLOPIDOGREL AND CILOSTAZOL AND ITS HPLC ANALYSIS

Objective: The verify now P2Y12 assay suggested that addition of cilostazol to clopidogrel proves to be efficious in the treatment of patients with cardiovascular disease (CVD). Based on these findings, an attempt has been made to formulate solid dosage form containing the two drugs at the recommended concentrations and develop and validate reverse phase high-performance liquid chromatography (HPLC) method for their simultaneous estimation.Methods: A combined tablet dosage form containing cilostazol (100 mg) and clopidogrel (75 mg) was formulated by direct compression method. A reverse phase HPLC method using C8 column, employing 0.025M phosphate buffer: methanol: acetonitrile (20:40:40% v/v) as mobile phase at a flow rate of 1 ml/min with ultraviolet (UV) detection at 237 nm was developed and validated as per International Council on Harmonisation (ICH) guidelines.Results: The prepared powder blend showed excellent flow properties and formulated tablet passed the standard tests for tablets. The tablets were suitably analyzed by the reverse phase HPLC method with a retention time (RT) of 3.82 and 7.72 min for cilostazol and clopidogrel respectively. The method exhibited linearity (10-100mg/ml for cilostazol and 7.5-75mg/ml for clopidogrel) with r2= 0.999 for both drugs respectively. The recoveries of cilostazol and clopidogrel were 98.97% and 98.94% respectively. The relative standard deviation (RSD) was<2% indicating good method precision. The stability indicating properties evaluated by forced degradation studies showed good separation of the drugs from their degradation products.Conclusion: A simple, precise, robust, stability-indicating HPLC method was developed for simultaneous assay of cilostazol and clopidogrel in prepared tablet formulation and validated as per ICH guidelines. This method can be employed for the analysis and stability studies of solid dosage forms containing the two drugs.

Comparison of P2Y12 receptor inhibition by clopidogrel and prasugrel in patients undergoing percutaneous coronary intervention

Dual antiplatelet treatment (DAPT) with aspirin and clopidogrel is vital after percutaneous coronary intervention (PCI). Clopidogrel and prasugrel act on P2Y12 platelet surface receptors. Both these P2Y12 inhibitors are pro-drugs and depend on cytochrome system of the liver for their conversion to active metabolite. There is growing concern regarding suboptimal response in platelet inhibition by clopidogrel. Verify Now system got approval by Federal Drug Administration, USA, for assessing platelet function as its result is almost comparable to gold standard Light Transmission Aggregometry (LTA). There are no data on the prevalence of clopidogrel resistance in Bangladeshi population. Prasugrel, as an antiplatelet drug, is a newer introduction in this country. This study will show light on the efficacy of these drugs on our population especially in patients who undergo PCI where DAPT is mandatory. A total 120 (60 diabetics ) patients with Acute Coronary Syndrome (ACS), were alternatively given 600 mg clopidogrel loading dose (LD) followed by 75 mg maintenance dose (MD) daily or 60 mg LD of prasugrel followed by 10 mg MD daily. Five samples of blood were taken at different time intervals over a period of 2 weeks. Measurement of percent inhibition of P2Y12 was done by VerifyNow. Patients who showed less than 20% inhibition (clopidogrel resistant) at any stage were switched to prasugrel. The outcomes of clopidogrel, prasugrel and clopidogrel switched to prasugrel groups were then compared. Nearly half (46.7%) of the patients in the clopidogrel group was found resistant to the drug as opposed to none in the prasugrel group. No difference was found between diabetic and non-diabetic subjects with respect to drug resistance. Intracoronary blood samples showed high degree of platelet inhibition with prasugrel. There was a gradual decline of platelet inhibition over two weeks with prasugrel. Almost fifty percent of the population is clopidogrel resistant in our study. Prasugrel is a much more potent antiplatelet drug and should be preferred in patients undergoing PCI. Prasugrel may also show resistance over time. DOI: http://dx.doi.org/10.3329/bmrcb.v39i3.20315 Bangladesh Med Res Counc Bull 2013; 39: 139-145

Η επίπτωση του πολυμορφισμού C34T του υποδοχέα P2Y12 των αιμοπεταλίων στην λειτουργικότητα των αγγείων σε στεφανιαίους ασθενείς

Η στεφανιαία νόσος (ΣΝ) αποτελεί μια από τις πιο επικίνδυνες παθήσεις του 21 αιώνα με μεγάλο κοινωνικό οικονομικό κόστος. Η καλύτερη αντιμετώπιση των ασθενών, που αποτελεί ηθική αρχή των επιστημών υγείας, έχει οδηγήσει σε αναρίθμητες μελέτες για την εύρεση καλύτερων φαρμάκων και πιο εξελιγμένων επεμβατικών τεχνικών. Τα ήδη υπάρχοντα φάρμακα αν και αποτελούν άλμα στην αντιμετώπιση του οξέος εμφράγματος του μυοκαρδίου (ΟΕΜ) έχουν ορισμένα μειονεκτήματα στην κλινική τους πράξη, όπως η αντίσταση του φαρμάκου κλοπιδογρέλη. Η αντίσταση στην κλοπιδογρέλη είναι ένα θέμα που προβληματίζει τους σημερινούς καρδιολόγους και χρήζει διερεύνησης.Σκοπός: Στην παρούσα μελέτη εξετάσθηκε η επίπτωση του πολυμορφισμού C34T του υποδοχέα P2Y12 των αιμοπεταλίων σε σταθερούς στεφανιαίους ασθενείς μετά από έμφραγμα του μυοκαρδίου στην ενδοθηλιακή λειτουργία, στην αρτηριακή σκληρία των μεγάλων αγγείων, στους δείκτες φλεγμονής, τους βιοχημικούς δείκτες στην αντιδραστικότητα των αιμοπεταλίων και στην συσχέτιση με τα καρδιαγγειακά συμβάματα. Υλικό και μέθοδος: Μελετήθηκε επίπτωση της ύπαρξης ή όχι του Τ-αλληλόμορφου για τον πολυμορφισμό C34T του υποδοχέα P2Y12 των αιμοπεταλίων στην λειτουργικότητα των μεγάλων αγγείων σε σταθερούς στεφανιαίους ασθενείς. Η εξέταση περιελάμβανε την λήψη πλήρους ιστορικού, την εκτίμηση της ενδοθηλιακής λειτουργίας μέσω της μέτρησης της ενδοθηλιοεξαρτώμενης αγγειοδιαστολής (FMD), την εκτίμηση της σκληρίας του αορτικού τοιχώματος μέσω της μέτρησης της καρωτιδομηριαίας ταχύτητας του σφυγμικού κύματος (PWV), την εκτίμηση των ανακλωμένων κυμάτων μέσω του δείκτη ενίσχυσης των ανακλωμένων κυμάτων (AIx), την εκτίμηση της κεντρικής συστολικής πίεσης και της κεντρικής πίεσης σφυγμού. Δείγματα αίματος ελήφθησαν με φλεβοκέντηση κατά τις βασικές μετρήσεις για μέτρηση φλεγμονωδών δεικτών (TNFα, IL-6, ICAM), δεικτών ηπατικής βιοχημείας, νεφρικής λειτουργίας και λιπιδαιμικού προφίλ, μια γενική αίματος και φρέσκο ολικό αίμα για το Verify Now. Τέλος αίμα φυγοκεντρήθηκε και αποθηκεύτηκε μετά από ειδική επεξεργασία για την γενετική ταυτοποίηση του πολυμορφισμού C34T. Πραγματοποιήθηκε επανέλεγχος των ασθενών για την παρατήρηση της ζωτικής και φυσικής κατάσταση, για την εμφάνιση αιμορραγιών και για την επιβίωση. Αποτελέσματα: Η ύπαρξη ή όχι του Τ αλληλόμορφου του πολυμορφισμού C34T του υποδοχέα P2Y12 των αιμοπεταλίων δεν επηρέασε το FMD (p=0,776), το AI75 (p=0.206), το PWV(p=0,604), την ΤC (p=0,685), την LDL-c (p=0,309), την HDL-c (p=0,272), τα τριγλυκερίδια (p=0,621), τον Αιματοκρίτη (HCT) (p=0,25), την Αιμοσφαιρίνη (HGB) (p=0,238), τα Αιμοπετάλια (PLT) (p=0,883), το ICAM-1 [p=0,491], τον ΤNFα [p=0,83], την IL-6 [p=0,96], το PRU (p=0,249), το πρωτογενές καταλυτικό σημείο (HR: 1.61), 95% (CI) 0.82 εν 3.18, p=0.17) και τον κίνδυνο για μείζων αιμορραγία (HR: 1.33, 95%CI 0.54 εν 3.31, p=0.52). Επηρέασε την αντίσταση στην κλοπιδογρέλη (PRU>230) (p=0,036) δείχνοντας ότι το ποσοστό των ασθενών που έχουν αντίσταση στην κλοπιδογρέλη είναι μεγαλύτερο στους ομόζυγους για το Τ αλλήλιο. Συμπέρασμα: Βρέθηκε ότι οι πάσχοντες που φέρουν τον σπάνιο τύπο του C34T έχουν αυξημένη αντίσταση στην κλοπιδογρέλη χωρίς να επηρεάζουν κάποιον από τους άλλους υπό μελέτη παράγοντες. Απαιτούνται μεγαλύτερες και αναλυτικότερες έρευνες οι οποίες να περιλαμβάνουν το γονιδιακό προφίλ του κάθε ασθενούς σε σχέση με τα γονίδια τα οποία μπορεί να οδηγούν στην αντίσταση, συσχέτιση μεταξύ της κλοπιδογρέλης και άλλων φαρμάκων αλλά και μέτρηση της κλοπιδογρέλης και με άλλους τρόπους εκτός από το Verify Now.

Haemodialysis impairs clopidogrel but not aspirin responsiveness in patients with end-stage renal disease

SummaryDual antiplatelet therapy (DAPT) with aspirin (ASA) and clopidogrel (Clp) is the standard treatment to reduce ischaemic coronary events, but in patients with end-stage renal disease (ESRD) the efficacy of Clp remains unclear. Patients with ESRD are at higher risk for coronary artery disease (CAD) and also their post-interventional outcome is worse compared to patients with normal renal function. Little is known about the influence of haemodialysis (HD) on ASA and Clp responsiveness. To assess the effect of HD on ASA- and Clp-responsiveness in patients with documented CAD and ESRD, 31 patients with ESRD (mean age 66.5 ± 1.8 years, 23 male ) on DAPT were evaluated for their ASA and Clp responsiveness with the Verify Now System (Accumetrics Inc.) We measured the antiplatelet effect in all ESRD patients at three time points: T1: just before HD; T2: directly after HD; T3: steady state on a HD free day one week after T1. In our study at baseline 10 (32.3%) patients were ASA-low responder (ASA-LR) and 14 (45.2%) patients Clp-low responder (Clp-LR). There was a significant difference in the PRU values before ( T1) and immediately after HD (T2) [PRU T1=234 (169; 274) vs PRUT2= 247 (199; 278); pT1,2=0.036; ]. Results were shown as median ARU T1 (25th, 75th percentile) or median PRU T1 (25th, 75th percentile). Hence HD seems to impair responsiveness to Clp, resulting in an increase of 6.5 % Clp-LR. No significant differences in the ARU values at the different time-points were found.