Safety and Tolerability of Inclisiran for Treatment of Hypercholesterolemia in 7 Clinical Trials.

BACKGROUND: Inclisiran is a small interfering RNA agent to lower low-density lipoprotein cholesterol. OBJECTIVES: The purpose of this study was to provide reliable evidence to date on the long-term safety profile of inclisiran. METHODS: This post hoc analysis comprised patients treated with 300 mg inclisiran sodium or placebo in the completed (ORION-1, -3, -5, -9, -10, and -11) and ongoing (ORION-8) trials. Exposure-adjusted incidence rates and Kaplan-Meier estimates of cumulative incidence of reported treatment-emergent adverse events (TEAE), abnormal laboratory measurements, and incidence of antidrug antibodies were analyzed. RESULTS: This analysis included 3,576 patients treated with inclisiran for up to 6 years and 1,968 patients treated with placebo for up to 1.5 years, with 9,982.1 and 2,647.7 patient-years of exposure, respectively. Baseline characteristics were balanced between groups. Kaplan-Meier analyses showed that TEAEs that were serious or led to discontinuation; hepatic, muscle, and kidney events; incident diabetes; and elevations of creatine kinase or creatinine accrued at a comparable rate between groups for up to 1.5 years, with similar trends continuing for inclisiran beyond this period. Numerically fewer major cardiovascular events reported as TEAEs occurred with inclisiran during this period. Treatment-induced antidrug antibodies were uncommon with inclisiran (4.6%), with few of these persistent (1.4%) and not associated with greater incidence of TEAEs leading to study drug discontinuation or serious TEAEs. CONCLUSIONS: Long-term treatment with inclisiran was well tolerated in a diverse population, without new safety signals, supporting the safety of inclisiran in patients with dyslipidemia.

Rationale and design of two trials assessing the efficacy, safety, and tolerability of inclisiran in adolescents with homozygous and heterozygous familial hypercholesterolaemia.

BACKGROUND: Inclisiran is a small interfering RNA molecule that reduces low-density lipoprotein cholesterol (LDL-C) by inhibition of proprotein convertase subtilisin/kexin type 9. This subcutaneous, twice-yearly administered agent has been shown to effectively and safely lower LDL-C in adult patients with established atherosclerotic cardiovascular disease, adults at high risk for atherosclerotic cardiovascular disease, as well as in adults with heterozygous familial hypercholesterolaemia. With the current, limited treatment options available to reach treatment goals in children with severe heterozygous familial hypercholesterolaemia, homozygous familial hypercholesterolaemia, or statin intolerance, inclisiran could be a valuable new therapeutic option. OBJECTIVES: The objective of these ongoing studies is to investigate the efficacy, safety, and tolerability of inclisiran in adolescents diagnosed with homozygous familial hypercholesterolaemia (ORION-13) or heterozygous familial hypercholesterolaemia (ORION-16). STUDY DESIGN: ORION-13 and ORION-16 are both two-part (1-year double-blind inclisiran vs. placebo/1 year open-label inclisiran) multicentre trials including adolescents aged 12 to <18 years diagnosed with familial hypercholesterolaemia. ORION-13 will include ∼12 participants diagnosed with homozygous familial hypercholesterolaemia and ORION-16 will include ∼150 participants diagnosed with heterozygous familial hypercholesteroleamia. The primary endpoint is the percentage change in LDL-C from baseline to Day 330. Secondary efficacy and safety endpoints include changes in other lipid parameters and treatment-emergent adverse events as well as laboratory parameters and vital signs. Exploratory endpoints include individual responsiveness of the participants and change in LDL-C according to the type of underlying causal mutation. CLINICAL TRIAL REGISTRATION: https://www.clinicaltrials.gov/. Unique identifier: NCT04659863 (ORION-13) and NCT04652726 (ORION-16).

Impact of high platelet turnover on the platelet transcriptome: Results from platelet RNA-sequencing in patients with sepsis.

BACKGROUND: Sepsis is associated with high platelet turnover and elevated levels of immature platelets. Changes in the platelet transcriptome and the specific impact of immature platelets on the platelet transcriptome remain unclear. Thus, this study sought to address whether and how elevated levels of immature platelets affect the platelet transcriptome in patients with sepsis. METHODS: Blood samples were obtained from patients with sepsis requiring vasopressor therapy (n = 8) and from a control group of patients with stable coronary artery disease and otherwise similar demographic characteristics (n = 8). Immature platelet fraction (IPF) was determined on a Sysmex XE 2100 analyser and platelet function was tested by impedance aggregometry. RNA from leukocyte-depleted platelets was used for transcriptome analysis by Next Generation Sequencing integrating the use of unique molecular identifiers. RESULTS: IPF (median [interquartile range]) was significantly elevated in sepsis patients (6.4 [5.3-8.7] % vs. 3.6 [2.6-4.6] %, p = 0.005). Platelet function testing revealed no differences in adenosine diphosphate- or thrombin receptor activating peptide-induced platelet aggregation between control and sepsis patients. Putative circular RNA transcripts were decreased in platelets from septic patients. Leukocyte contamination defined by CD45 abundance levels in RNA-sequencing was absent in both groups. Principal component analysis of transcripts showed only partial overlap of clustering with IPF levels. RNA sequencing showed up-regulation of 524 and down-regulation of 118 genes in platelets from sepsis patients compared to controls. Upregulated genes were mostly related to catabolic processes and protein translation. Comparison to published platelet transcriptomes showed a large overlap of changes observed in sepsis and COVID-19 but not with reticulated platelets from healthy donors. CONCLUSIONS: Patients with sepsis appear to have a less degraded platelet transcriptome as indicated by increased levels of immature platelets and decreased levels of putative circular RNA transcripts. The present data suggests that increased protein translation is a characteristic mechanism of systemic inflammation.

Antagonizing P2Y12 Receptor Inhibitors: Current and Future Options.

There are clinical scenarios where the balance between the risk of ischemic and bleeding events leads to the clinical decision to reverse the antiplatelet effect of P2Y12 receptor inhibitors. These scenarios comprise emergency situations such as active severe bleeding, urgent procedures with presumed high bleeding risk, or major trauma with (anticipated) bleeding. Supplementation of platelets has been investigated in ex vivo as well as in in vivo studies. These studies indicate that the inhibition of adenosine diphosphate-induced aggregation by the irreversibly binding thienopyridine derivatives clopidogrel and prasugrel can be reversed by administration of platelet concentrates. Supplementation of platelets in patients on prasugrel is more effective if this can be transfused > 6 hours after last dosing. Studies on the reversal effect obtained by administration of platelet concentrates in patients on ticagrelor show conflicting results. Experimental data suggest that administration of serum albumin might increase the reversal effect. A monoclonal antibody fragment (PB2452) for neutralizing ticagrelor is currently in clinical development. A recently published first in man study shows that reversal of platelet inhibition occurs within 5 minutes after start of administration and the effect is maintained for 20 to 24 hours after a 16-hour infusion which is by far the most effective approach for reversal of ticagrelor.

Evaluation of an Alternative Staining Method Using SYTO 13 to Determine Reticulated Platelets.

Reticulated platelets reflect the rate of platelet turnover and represent the youngest circulating platelets in peripheral blood. Reticulated platelets contain residual ribonucleic acid (RNA) from megakaryocytes which is lost in a time-dependent manner and can be transcribed into proteins even in the absence of a nucleus. An increased proportion of reticulated platelets is associated with higher platelet reactivity, cardiovascular events and mortality. At present, a fully automated assay system (SYSMEX haematology analyser) is available for analysis. This method, however, is not suitable for extended laboratory investigations like subsequent cell sorting. Flow cytometry analysis after staining with thiazole orange (TO) is frequently used in such settings despite several limitations. Here, we describe a new assay for determination of reticulated platelets by flow cytometry using the nucleic acid staining dye SYTO 13 and compare it with SYSMEX and TO staining as current standards. A significant correlation between immature platelet fraction (IPF) determined by SYSMEX XE-2100 analyser and results obtained with the SYTO 13-based assay was observed (r = 0.668, p < 0.001) which was stable during a reasonable time period. In contrast, the correlation between TO staining and IPF was weaker (r = 0.478, p = 0.029) and lost after 90 minutes of staining. SYTO 13 staining of platelets enabled sorting of RNAlow and RNArich platelets which was confirmed by RNA quantification of sorted platelets. Except for fixation of platelets, sorting of these platelet sub-populations was stable under various experimental settings. In summary, determination of reticulated platelets with the new SYTO 13 assay offers distinct technical advantages enabling further laboratory processing.

Haemodynamic prosthetic valve performance in patients with early leaflet thrombosis after transcatheter aortic valve implantation.

AIMS: We sought to evaluate haemodynamic prosthetic valve performance in patients with early leaflet thrombosis (LT) after transcatheter aortic valve implantation (TAVI). METHOD AND RESULTS: In this retrospective observational study, 59 patients with LT underwent clinical and echocardiographic follow-up. During a median follow-up of 383 days 41 patients received antiplatelet therapy (APT-group) and 18 patients oral anticoagulation due to atrial fibrillation (AC-group). The mean pressure gradient (MPG) at baseline did not differ between groups (P = 0.875). During follow-up, MPG increased from 11.0 (9.0; 14.5) to 13.0 mmHg (10.0; 18.0)_ in the APT-group (P = 0.010) but remained unchanged in the AC-group (P = 0.297) resulting in a significantly higher MPG in patients on antiplatelet therapy (P = 0.024). Similarly, change of MPG per year was significantly higher in the APT-group [1.4 (- 0.9; 7.0) vs. - 0.6 (- 2.5; 1.1), P = 0.014]. Seven (17.1%) patients in the APT-group and two(11.1%) patients in the AC-group developed MPGs of at least 20 mmHg (P = 0.558). Three patients (7.3%) in the APT- and none in the AC-group developed symptoms of obstructive thrombosis (P = 0.239). In our adjusted analysis, only lack of anticoagulation was significantly associated with change in gradients during follow-up (P = 0.012). CONCLUSIONS: In patients with LT, antiplatelet-, but not anticoagulant therapy, was associated with significant increases in MPG, which may lead to symptomatic obstructive valve thrombosis.

Impact of On-Clopidogrel Platelet Reactivity on Incidence of Hypoattenuated Leaflet Thickening After Transcatheter Aortic Valve Replacement.

OBJECTIVES: To assess the impact of on-clopidogrel platelet reactivity (PR) on HALT, the authors prospectively tested whether patients with below-median on-clopidogrel PR have a lower incidence of HALT compared with those with above-median on-clopidogrel PR. BACKGROUND: It is unclear whether the apparent ineffectiveness of clopidogrel in preventing hypoattenuated leaflet thickening (HALT) after transcatheter aortic valve replacement (TAVR) questions the concept of P2Y12 inhibition after TAVR or is a consequence of an inadequate response to clopidogrel in elderly patients with severe aortic stenosis. METHODS: Patients were either on long-term dual antiplatelet therapy with clopidogrel and acetylsalicylic acid or were given bolus doses of both drugs the day before TAVR. Adenosine diphosphate (ADP)-induced multielectrode impedance aggregometry was performed before TAVR. After TAVR, clopidogrel was continued in all patients. Computed tomographic angiography was performed to detect HALT. RESULTS: Of 331 patients enrolled, computed tomographic angiography was performed in 200 at 5 days (interquartile range: 4 to 6 days). Among patients with below-median ADP-induced PR (<180 AU · min), 16 were diagnosed with HALT, whereas 20 patients with above-median PR were diagnosed with HALT (p = 0.58). Among patients with high on-clopidogrel PR (>468 AU · min; n = 29), 7 (24%) displayed HALT, compared with 19 (17%) with ADP-induced PR ≤468 AU · min (p = 0.43). Consistently, ADP-induced PR as a continuous variable was not significantly associated with HALT (p = 0.75). Oral anticoagulation was associated with reduced rates of HALT (odds ratio: 0.41; 95% CI: 0.18 to 0.96; p = 0.04). CONCLUSIONS: On-clopidogrel ADP-induced PR was not significantly associated with the occurrence of HALT. In contrast, oral anticoagulation was associated with reduced rates of HALT.

Pharmacodynamic safety of clopidogrel monotherapy in patients under oral anticoagulation with a vitamin K antagonist undergoing coronary stent implantation.

Current guidelines recommend as treatment option in patients on oral anticoagulation (OAC) undergoing percutaneous coronary intervention (PCI) an antiplatelet monotherapy with clopidogrel if there is an increased risk for bleeding. However, retrospective data suggested a potential interaction of clopidogrel and the vitamin K antagonist (VKA) phenprocoumon leading to a diminished antiplatelet effect. This would increase the ischemic risk of patients treated with this combination. Thus, this prospective study sought to evaluate the pharmacodynamic effect of clopidogrel monotherapy in patients on phenprocoumon undergoing PCI and assessed clinical outcomes. This study enrolled 100 patients on aspirin plus clopidogrel (DAPT-cohort, without indication for VKA) and 100 patients on clopidogrel monotherapy plus phenprocoumon (OAC-cohort) undergoing elective PCI. Platelet reactivity was assessed by impedance aggregometry on day 1 following PCI. Ischemic (death, stroke, or myocardial infarction) and bleeding (BARC 2-5) events within 12 months were compared in a propensity score adjusted model. Platelet reactivity was not different in the OAC- and DAPT-cohort (187 [127-242] vs. 167 [126-218] AU×min; p = 0.23). Overall, 17 ischemic and 34 bleeding events were recorded during follow-up. The OAC-cohort showed a nonsignificant trend to an 80% higher incidence for ischemic and bleeding events in unadjusted analyses, which disappeared following adjustment (ischemic events HR 1.07, 95%-CI 0.32-3.59, p = 0.91; bleeding events HR 1.25, 95%-CI 0.46-3.40, p = 0.67). Following PCI, the pharmacodynamic effect of a clopidogrel monotherapy together with phenprocoumon is similar as compared to DAPT without a VKA, and not associated with an increased risk for ischemic events beyond the higher underlying baseline risk.

Uncontrolled Diabetes Mellitus Has No Major Influence on the Platelet Transcriptome.

BACKGROUND: Diabetes mellitus (DM) has been associated with increased platelet reactivity as well as increased levels of platelet RNAs in plasma. Here, we sought to evaluate whether the platelet transcriptome is altered in the presence of uncontrolled DM. METHODS: Next-generation sequencing (NGS) was performed on platelet RNA for 5 patients with uncontrolled DM (HbA1c 9.0%) and 5 control patients (HbA1c 5.5%) with otherwise similar clinical characteristics. RNA was isolated from leucocyte-depleted platelet-rich plasma. Libraries of platelet RNAs were created separately for long RNAs after ribosomal depletion and for small RNAs from total RNA, followed by next-generation sequencing. RESULTS: Platelets in both groups demonstrated RNA expression profiles characterized by absence of leukocyte-specific transcripts, high expression of well-known platelet transcripts, and in total 6,343 consistently detectable transcripts. Extensive statistical bioinformatic analysis yielded 12 genes with consistently differential expression at a lenient FDR < 0.1, thereof 8 protein-coding genes and 2 genes with known expression in platelets (MACF1 and ITGB3BP). Three of the four differentially expressed noncoding genes were YRNAs (RNY1, RNY3, and RNY4) which were all downregulated in DM. 23 miRNAs were differentially expressed between the two groups. Of the 13 miRNAs with decreased expression in the diabetic group, 8 belonged to the DLK1-DIO3 gene region on chromosome 14q32.2. CONCLUSIONS: In this study, uncontrolled DM had a remote impact on different components of the platelet transcriptome. Increased expression of MACF1, together with supporting predicted mRNA-miRNA interactions as well as reduced expression of RNYs in platelets, may reflect subclinical platelet activation in uncontrolled DM.

Impact of Reticulated Platelets on the Antiplatelet Effect of the Intravenous P2Y12-Receptor Inhibitor Cangrelor.

BACKGROUND: Reticulated platelets are associated with impaired antiplatelet response to irreversibly acting P2Y12-receptor inhibitors. However, the impact of reticluated platelets (RP) on the reversibly acting injectable P2Y12-receptor inhibitor cangrelor is unknown. Thus, this study sought to investigate the influence of RP on cangrelor and transitioning strategies to oral P2Y12-receptor inhibitors. METHODS: This study randomized 110 patients undergoing elective percutaneous coronary intervention with use of cangrelor to different oral transitioning strategies loading with prasugrel 60 mg or ticagrelor 180 mg at the start of cangrelor (n = 45 each) or loading with clopidogrel 600 mg after discontinuation of cangrelor (n = 20). ADP-induced platelet reactivity was assessed by impedance aggregometry. Reticulated platelets were analysed by an automated whole blood flow cytometry and described as immature platelet count. RESULTS: There was no correlation of reticulated platelets and ADP-induced platelet reactivity in patients under treatment with cangrelor (r = 0.06, p = 0.47). This finding was consistent in all three transitioning strategies. On day 1 following treatment with cangrelor, the correlation of reticulated platelets and platelet reactivity was detectable again in patients receiving thienopyridines but not ticagrelor (all patients r = 0.37, p < 0.001; clopidogrel: r = 0.59, p = 0.01; prasugrel: r = 0.47, p < 0.001; ticagrelor r = 0.22, p = 0.13). CONCLUSION: Platelet inhibition is not influenced by levels of reticulated platelets during infusion of cangrelor independent of oral P2Y12-receptor inhibitor transitioning strategy. These findings underline the potency of cangrelor as immediate and reversibly acting P2Y12-receptor inhibitor.

Risk of discontinuation of clopidogrel after 1 month following bare-metal stents: a propensity-score adjusted comparison with continued administration of clopidogrel after drug-eluting stents.

In patients at high risk for bleeding undergoing percutaneous coronary intervention (PCI) the use of bare-metal-stent (BMS) is considered an option that allows discontinuation of clopidogrel after 4 weeks. We sought to investigate the risk of early discontinuation of clopidogrel in patients with BMS as compared with a 6-month course of clopidogrel after DES in patients with or without high on-treatment platelet reactivity (HTPR). In 765 consecutive patients undergoing PCI after loading with clopidogrel 600 mg, HTPR was tested by optical aggregometry and defined as residual platelet reactivity > 14%. On top of aspirin 100 mg, patients received clopidogrel 75 mg for 4 weeks after BMS or 6 months after DES. The primary endpoint was all-cause mortality or myocardial infarction (MI) during 1 year. The 1-year incidence of death or MI was 3.5% with BMS (n = 484), 0.9% with DES and no HTPR (n = 211), and 7.1% with DES and HTPR (n = 70; p = 0.03). Landmark analyses for the first 6 months demonstrated that the risk of patients receiving BMS was similar as in patients receiving a DES with HTPR during this period (2.3 vs. 2.9%) but lowest in patients receiving a DES without HTPR (0.5%). The incidence of bleeding was similar in all three groups. These findings did not change after propensity score adjustment for stent type. After discontinuation of clopidogrel at 1 month, patients treated with BMS are at higher risk for death or MI than patients treated with a DES and sufficiently responding to clopidogrel planned for 6 months.ClinicalTrials.gov number NCT00457236.

Alteration of von Willebrand Factor after Transcatheter Aortic Valve Replacement in the Absence of Paravalvular Regurgitation.

Moderate or severe paravalvular regurgitation after transcatheter aortic valve implantation (TAVI) is frequently associated with a loss of high-molecular-weight multimers of von Willebrand factor (VWF) and a reduced VWF collagen-binding capacity. It is unclear whether this phenomenon can also be observed in patients with mild paravalvular regurgitation, and whether there are differences between patients undergoing conventional aortic valve replacement (AVR) or TAVI. We analysed the multimeric structure of VWF and the ratio of VWF collagen-binding capacity to VWF antigen pre- and postoperatively in 12 patients scheduled for AVR and in 31 patients scheduled for TAVI. Echocardiographic examinations were performed pre-, intra- and postoperatively. Nine patients (75%) undergoing AVR and 18 patients (58%) undergoing TAVI showed pathological VWF functionality preoperatively (p = 0.48). Five to 7 days postoperatively, VWF functionality normalised in all patients with AVR, four of them with mild paravalvular regurgitation. VWF functionality was still altered in nine patients after TAVI (p = 0.044 between groups), five of them with and four without mild paravalvular regurgitation (p = 0.1).Altered VWF functionality was observed in nearly one-third of patients after TAVI, but not after AVR. This phenomenon was not related to paravalvular regurgitation, but may indicate differences in the response of the haemostatic system to the prosthetic heart valve design or the valve replacement procedure.

On-clopidogrel platelet reactivity as predictor for long-term clinical outcome in patients after planned discontinuation of clopidogrel.

It is unknown whether the known association of high on-treatment platelet reactivity (HTPR) with worse clinical outcome in patients on clopidogrel following coronary stent implantation persists after planned discontinuation of clopidogrel. This study investigated the association of HTPR with major ischaemic events after planned discontinuation of clopidogrel. Consecutive patients undergoing elective coronary stent implantation after loading with clopidogrel 600 mg were followed for up to seven years (n=765). Platelet reactivity was tested on day 1 after coronary intervention. Clopidogrel was continued for six months after implantation of drug-eluting stents and for one month if only bare-metal stents were used. The combined primary endpoint was death of any cause or non-fatal myocardial infarction (MACE). HTPR was found in 217 of 765 patients (28 %). During a median follow-up of 5.7 years, the primary endpoint occurred in 145 subjects after planned discontinuation of clopidogrel. Patients with HTPR showed a higher incidence of MACE after discontinuation of clopidogrel. There was a significant interaction of HTPR and time following discontinuation of clopidogrel beyond one year (p for interaction 0.08). Landmark analyses confirmed that the association of HTPR and MACE was only significant within the first year (HR: 2.93, 95 %-CI 1.13-7.60, p=0.03), but not beyond the first year following discontinuation of clopidogrel (HR: 1.19, 95 %-CI 0.82-1.72, p=0.37). In conclusion, patients with HTPR persist to be at high risk for death or myocardial infarction even following planned discontinuation of clopidogrel. However, this association was only significant for the first year following discontinuation of clopidogrel.

Randomized Comparison of Oral P2Y12-Receptor Inhibitor Loading Strategies for Transitioning From Cangrelor: The ExcelsiorLOAD2 Trial.

OBJECTIVES: This randomized trial tested whether early loading with prasugrel can provide sufficient platelet inhibition even when given at the start of a 2-h infusion of cangrelor. BACKGROUND: Effective platelet inhibition with intravenous cangrelor reduces the risk of ischemic complications during percutaneous coronary intervention (PCI). Transitioning to oral therapy with clopidogrel or prasugrel is only recommended after discontinuation of cangrelor due to drug interactions. Given the long half-life of prasugrel, this drug could achieve effective platelet inhibition even when given early under cangrelor and thereby prevent a transient gap in platelet inhibition. METHODS: This trial randomized 110 P2Y12-receptor blocker-naive patients undergoing PCI with use of cangrelor to loading with prasugrel 60 mg or ticagrelor 180 mg at the start of cangrelor (n = 45 each) or loading with clopidogrel 600 mg after discontinuation of cangrelor (n = 20). The primary endpoint was the proportion of patients without high on-treatment platelet reactivity 1 h after stopping cangrelor. RESULTS: The 3 groups were well balanced with respect to clinical parameters. One hour following discontinuation of cangrelor, the primary endpoint was seen in 65.0% of patients on clopidogrel versus 95.6% with ticagrelor and 93.3% with prasugrel (p for superiority of prasugrel vs. clopidogrel = 0.003; p of prasugrel vs. ticagrelor = 0.65). The 30-day incidence of ischemic and bleeding events was similar in all groups. CONCLUSIONS: Prasugrel 60 mg given at the start of a 2-h infusion of cangrelor can provide a sufficient platelet inhibition post-cangrelor. This approach prevents the transient gap in platelet inhibition seen with oral loading after discontinuation of cangrelor. (Impact of Extent of Clopidogrel-Induced Platelet Inhibition during Elective Stent Implantation on Clinical Event Rate - Advanced Loading Strategies [ExcelsiorLOAD2]; DRKS00009739).

Impact of reticulated platelets on antiplatelet response to thienopyridines is independent of platelet turnover.

Reticulated platelets are associated with impaired antiplatelet response to thienopyridines. It is uncertain whether this interaction is caused by a decreased drug exposure due to high platelet turnover reflected by elevated levels of reticulated platelets or by intrinsic properties of reticulated platelets. This study sought to investigate if the impact of reticulated platelets on early antiplatelet response to thienopyridines is mainly caused by platelet turnover as previously suggested. Elective patients undergoing coronary intervention were randomised to loading with clopidogrel 600 mg or prasugrel 60 mg (n=200). Adenosine diphosphate (ADP)-induced platelet reactivity was determined by impedance aggregometry before, at 30, 60, 90, and 120 minutes and at day 1 after loading. Immature platelet count was assessed as marker of reticulated platelets by flow cytometry. Platelet reactivity increased with rising levels of immature platelet count in both groups. This effect was more distinctive in patients on clopidogrel as compared to patients on prasugrel. Overall, immature platelet count correlated well with on-treatment platelet reactivity at all time-points (p < 0.001). These correlations did not change over time in the entire cohort as well as in patients treated with clopidogrel or prasugrel indicating an effect independent of platelet turnover (comparison of correlations 120 minutes/day 1: p = 0.64). In conclusion, the association of immature platelet count with impaired antiplatelet response to thienopyridines is similar early and late after loading. This finding suggests as main underlying mechanism another effect of reticulated platelets on thienopyridines than platelet turnover.

Comparison of Immature Platelet Count to Established Predictors of Platelet Reactivity During Thienopyridine Therapy.

BACKGROUND: Previous data suggest that reticulated platelets significantly affect antiplatelet response to thienopyridines. It is unknown whether parameters describing reticulated platelets can predict antiplatelet response to thienopyridines. OBJECTIVES: The authors sought to determine the extent to which parameters describing reticulated platelets can predict antiplatelet response to thienopyridine loading compared with established predictors. METHODS: This study randomized 300 patients undergoing elective coronary stenting to loading with clopidogrel 600 mg, prasugrel 30 mg, or prasugrel 60 mg. Adenosine diphosphate (ADP)-induced platelet reactivity was assessed by impedance aggregometry before loading (intrinsic platelet reactivity) and again on day 1 after loading. Multiple parameters of reticulated platelets were assessed by automated whole blood flow cytometry: absolute immature platelet count (IPC), immature platelet fraction, and highly fluorescent immature platelet fraction. RESULTS: Each parameter of reticulated platelets correlated significantly with ADP-induced platelet reactivity (p < 0.01 for all 3 parameters). In a multivariable model including all 3 parameters, only IPC remained a significant predictor of platelet reactivity (p < 0.001). In models adjusting each of the 3 parameters for known predictors of on-treatment platelet reactivity including cytochrome P450 2C19 (CYP2C19) polymorphisms, age, body mass index, diabetes, and intrinsic platelet reactivity, only IPC prevailed as an independent predictor (p = 0.001). In this model, IPC was the strongest predictor of on-treatment platelet reactivity followed by intrinsic platelet reactivity. CONCLUSIONS: IPC is the strongest independent platelet count-derived predictor of antiplatelet response to thienopyridine treatment. Given its easy availability, together with its even stronger association with on-treatment platelet reactivity compared with known predictors, including the CYP2C19*2 polymorphism, IPC may become the preferred predictor of antiplatelet response to thienopyridine treatment. (Impact of Extent of Clopidogrel-Induced Platelet Inhibition During Elective Stent Implantation on Clinical Event Rate-Advanced Loading Strategies [ExcelsiorLOAD]; DRKS00006102).

Predictors of high-sensitivity cardiac troponin in stable patients undergoing coronary angiography.

AIMS: Elevated levels of high-sensitivity troponin are seen in a significant proportion of stable patients undergoing elective coronary assessment. Multiple variables have been associated with troponin levels. The present analysis sought to identify variables independently associated with elevations of troponin and their relative strength of association with this biomarker. METHODS AND RESULTS: Stable patients undergoing elective coronary angiography and echocardiographic assessment were enrolled. High-sensitivity troponin T (hsTnT) was determined before any diagnostic procedures. Multivariable linear regression models including angiographic and echocardiographic parameters were used to identify independent predictors of levels of troponin and to determine their relative contribution to levels of troponin. Out of 2,046 patients, 15% presented with levels of troponin above the upper reference limit of normal. In a combined analysis, gender followed by renal function, age, left ventricular ejection fraction, diabetes, and left ventricular mass showed the strongest association with levels of troponin. Coronary obstruction was also an independent predictor, but strength of association weakened following adjustment. CONCLUSIONS: Up to 15% of patients undergoing coronary assessment outside the setting of acute coronary syndromes present with elevated levels of cardiac troponin. These changes are independently associated with multiple clinical, laboratory, and imaging variables.

Validation of a P2Y12-receptor specific whole blood platelet aggregation assay.

Testing of P2Y12-receptor antagonist effects can support clinical decision-making. However, most platelet function assays use only ADP as agonist which is not P2Y12-receptor specific. For this reason P2Y12-receptor specific assays have been developed by adding prostaglandin E1 (PGE1) to reduce ADP-induced platelet activation via the P2Y1-receptor. The present study sought to evaluate a P2Y12-receptor specific assay for determination of pharmacodynamic and clinical outcomes. This study enrolled 400 patients undergoing coronary stenting after loading with clopidogrel or prasugrel. ADP-induced platelet reactivity was assessed by whole blood aggregometry at multiple time points with a standard ADP assay (ADPtest) and a P2Y12-receptor specific assay (ADPtest HS, both run on Multiplate Analyzer, Roche Diagnostics). Patients were clinically followed for 1 month and all events adjudicated by an independent committee. In total, 2084 pairs of test results of ADPtest and ADPtest HS were available showing a strong correlation between results of both assays (r = 0.96, p < 0.001). These findings prevailed in multiple prespecified subgroups (e.g., age; body mass index; diabetes). Calculated cutoffs for ADPtest HS and the established cutoffs of ADPtest showed a substantial agreement for prediction of ischemic and hemorrhagic events with a Cohen's κ of 0.66 and 0.66, respectively. The P2Y12-receptor specific ADPtest HS assay appears similarly predictive for pharmacodynamic and clinical outcomes as compared to the established ADPtest assay indicating its applicability for clinical use. Further evaluation in large cohorts is needed to determine if P2Y12-receptor specific testing offers any advantage for prediction of clinical outcome.