Prevalence and predictors of high-on treatment platelet reactivity with ticagrelor in ACS patients undergoing stent implantation

Platelet-derived circFAM13B associated with anti-platelet responsiveness of ticagrelor in patients with acute coronary syndrome

BACKGROUND

Platelet is enriched with Circular RNAs (circRNAs), with circFAM13B rank among the 10 most abundant circRNAs in platelets. The aim of the present study was to evaluate the predictive value of platelet-derived circFAM13B for the antiplatelet responsiveness and efficacy of ticagrelor in patients with acute coronary syndrome (ACS).

METHODS

Consecutive ACS patients treated with ticagrelor were enrolled, and the antiplatelet responsiveness of 3 days of ticagrelor maintenance treatment was assessed by measuring the adenosine diphosphate (ADP)-induced platelet inhibition rate (ADP%) using thromboelastography. The expression of circFAM13B in the patients' platelets was analyzed by quantitative real-time polymerase chain reaction. The correlation between circFAM13B expression and ticagrelor antiplatelet responsiveness, as well as the independent contribution of circFAM13B to the composite of adverse ischemic events during a follow-up period of at least 12 months was evaluated.

RESULTS

A total of 129 eligible ACS patients treated with ticagrelor were enrolled in the study. A negative correlation was found between the expression of circFAM13B and the ADP% value (r = -0.41, P < 0.001). Patients with ADP% ≥ 76% had a significantly lower level of circFAM13B compared to those with ADP% < 76% (adjusted P = 0.009). Receiver operating characteristic curve analysis demonstrated that combining circFAM13B expression > 1.05 with clinical risk factors could effectively predict the risk of adverse ischemic events (AUC = 0.81, 95% CI: 0.69 to 0.92, P < 0.001). Kaplan-Meier survival analysis showed that patients with circFAM13B > 1.05 had a significantly higher risk of adverse ischemic events compared to those with circFAM13B ≤ 1.05 (P = 0.003). Multivariate logistic hazard analysis identified circFAM13B > 1.05 as an independent risk factor for adverse ischemic events in in ticagrelor-treated ACS patients (adjusted OR: 5.60, 95% CI: 1.69-18.50; P = 0.005).

CONCLUSIONS

Platelet-derived circFAM13B could be utilized for predicting the antiplatelet responsiveness and efficacy of ticagrelor in patients with ACS.

Association of ADP-Induced Whole-Blood Platelet Aggregation with Serum Low-Density Lipoprotein Cholesterol in Patients with Coronary Artery Disease When Receiving Maintenance Ticagrelor-Based Dual Antiplatelet Therapy

The degree of platelet inhibition in patients undergoing dual antiplatelet therapy (DAPT) affects cardiovascular outcomes after acute coronary syndromes (ACS) and/or percutaneous coronary intervention. Our aim was to search for correlates of residual ex vivo platelet reactivity and circulating soluble P-selectin (sP-selectin), an index of in vivo platelet activation, in patients being treated by DAPT with ticagrelor. Adenosine diphosphate (ADP)-induced platelet aggregability (by multiple electrode aggregometry) and plasma sP-selectin were estimated in 62 stable post-ACS subjects (46 men and 16 women; mean age: 64 ± 10 years; 30 with type 2 diabetes (T2DM)) undergoing maintenance DAPT with ticagrelor and aspirin. These patients did not exhibit heart failure or other relevant coexistent diseases except for properly controlled T2DM, mild renal insufficiency, and hypertension. We also assessed this in 64 subjects on clopidogrel-based DAPT matched for age, sex, and T2DM status. ADP-induced platelet aggregation was below the optimal levels (190-460 arbitrary units (AU) * min) in most patients receiving ticagrelor-based DAPT, especially in those with below-median (<1.9 mmol/L) serum concentrations of low-density lipoprotein cholesterol (LDL-c) (128 ± 61 vs. 167 ± 73 AU * min for below-median and above-median LDL-c, respectively, p = 0.025). In contrast, platelet reactivity did not differ by LDL-c on clopidogrel-based DAPT (246 ± 101 vs. 268 ± 108 AU * min for below-median and above-median LDL-c, respectively, p > 0.4). Plasma sP-selectin was found to be unrelated to serum LDL-c when receiving DAPT with ticagrelor (p > 0.4) or clopidogrel (p > 0.8). In conclusion, our preliminary observational study suggests the association of lower residual ex vivo platelet aggregability with better LDL-c control in patients undergoing ticagrelor-based maintenance DAPT, which does not appear to be reflected by plasma sP-selectin. Whether the serum LDL-c level should be considered among the factors affecting the degree of platelet inhibition for those treated with ticagrelor-based DAPT needs to be investigated in larger studies.

The impact of high on-treatment platelet reactivity and fibrinogen levels on ischemic events in patients with ST elevation myocardial infarction: a prospective observational study

BACKGROUND

After treatment, high residual platelet reactivity (HRPR) is considered as an essential risk factor for recurrent ischemic events.

AIM

To evaluate the impact of fibrinogen on HRPR after implantation of emergency drug-eluting stents (DES) in patients treated with aspirin and clopidogrel or ticagrelor due to ST-elevation myocardial infarction (STEMI) and to explore the predictive values of HRPR and fibrinogen for adverse ischemic events at 12 months.

METHOD

This single-center prospective observational study analyzed patients with STEMI who underwent primary percutaneous coronary intervention (PCI) with second-generation DES implantation from January 2017 to December 2018. Platelet reactivity was measured by thromboelastography (TEG) at 60-72 h after primary PCI. HRPR was defined as the adenosine diphosphate-induced maximum amplitude (MA_ADP) > 47 mm.

RESULTS

A total of 919 patients were analyzed, of which 512 (55.8%) received aspirin and clopidogrel and 406 (44.2%) received aspirin and ticagrelor. Elevated fibrinogen levels were associated with an increased prevalence of HRPR (P < 0.001). High fibrinogen (quartile IV, ≥ 410 mg/dL) was an independent risk factor for HRPR after multivariate regression (odds ratio 6.556, 95% confidence interval [CI]: 3.200-13.431, P < 0.001). When analyzed by Kaplan-Meier survival curves, the combination of high fibrinogen and HRPR was strongly predictive for ischemic major adverse cardiac events at 12 months compared to the group without HRPR and with low fibrinogen (hazard ratio 9.681, 95% CI: 4.467-20.98, log-rank P < 0.001). Similar results were confirmed in subgroups according to different dual antiplatelet therapies.

CONCLUSION

A combination of high fibrinogen and HRPR may identify recurrent adverse ischemic events over 12 months. Ticagrelor exhibited more potent platelet inhibition and a better prognosis than clopidogrel.

Resistance on the Latest Oral and Intravenous P2Y12 ADP Receptor Blockers in Patients with Acute Coronary Syndromes: Fact or Myth?

Novel P2Y12 ADP receptor blockers (ADPRB) should be preferred in dual-antiplatelet therapy in patients with acute coronary syndrome. Nevertheless, there are still patients who do not respond optimally to novel ADP receptor blocker therapy, and this nonoptimal response (so-called "high on-treatment platelet reactivity" or "resistance") could be connected with increased risk of adverse ischemic events, such as myocardial re-infarction, target lesion failure and stent thrombosis. In addition, several risk factors have been proposed as factors associated with the phenomenon of inadequate response on novel ADPRB. These include obesity, multivessel coronary artery disease, high pre-treatment platelet reactivity and impaired metabolic status for prasugrel, as well as elderly, concomitant therapy with beta-blockers, morphine and platelet count for ticagrelor. There is no literature report describing nonoptimal therapeutic response on cangrelor, and cangrelor therapy seems to be a possible approach for overcoming HTPR on prasugrel and ticagrelor. However, the optimal therapeutic management of "resistance" on novel ADPRB is not clear and this issue requires further research. This narrative review article discusses the phenomenon of high on-treatment platelet reactivity on novel ADPRB, its importance in clinical practice and approaches for its therapeutic overcoming.

Low hemoglobin predicts high-platelet reactivity and major cardiovascular ischemic events at long-term follow-up among ACS patients receiving dual antiplatelet therapy with ticagrelor

BACKGROUND

Reduced levels of hemoglobin (Hb) represent an established marker of impaired outcomes and increased cardiovascular risk in patients with coronary artery disease, challenging the management of dual antiplatelet therapy (DAPT). However, while anemia has emerged as an independent predictor of suboptimal platelet inhibition in patients receiving clopidogrel, no study has so far evaluated the impact of Hb levels on high-on treatment platelet reactivity (HRPR) with ticagrelor and their prognostic consequences, that were the aim of the present study.

METHODS

Patients on DAPT with ASA + Ticagrelor (90 mg/twice a day) after percutaneous coronary revascularization for ACS were scheduled for platelet function assessment 30-90 days post-discharge. Aggregation tests were performed by multiple electrode aggregometry. Suboptimal platelet inhibition (HRPR-high residual platelet reactivity was defined if above the lower limit of normality (417 AU*min). The primary study endpoint was defined as the occurrence of major cardiovascular events (a composite of cardiovascular death, recurrent acute coronary syndrome [MI], target vessel revascularization) at longest available follow-up.

RESULTS

We included 397 patients that were divided according to tertiles values of Hb (< 12.7, 12-7-14.09, ≥14.1 g/dl). Patients with lower Hb were older and displayed a more severe cardiovascular risk profile. Mean levels of platelet reactivity were enhanced in patients with lower Hb after stimulation with TRAP peptide (TRAP test, p = .03) and ADP (p = .02). Elevated platelet reactivity (HRPR) on Ticagrelor was more frequent among patients with reduced Hb (16.4% vs. 12% vs. 5.4%, p = .005, adjusted OR [95%CI] = 1.71[0.996;3.01], p = .056). At a mean follow-up of 820.9 ± 553.4 days, 21.4% of the patients experienced the primary composite endpoint, with a higher rate of events in patients with lower Hb (27.6% vs. 22.6% vs. 13.5%, p = .006, adjusted HR [95%CI] = 1.51[1.12; 2.03], p = .006), mainly driven by a higher rate of recurrent ACS. After correction for baseline differences lower Hb tertiles but not HRPR emerged as independent predictor of MACE (adjusted HR [95%CI] = 0.98[0.50; 1.92], p = .95).

CONCLUSIONS

In the present study, we demonstrated that among patients on DAPT with ASA and ticagrelor after PCI for ACS, lower Hb levels are independently associated with a higher rate of HRPR and an increased rate of major ischemic events, and especially for recurrent ACS, although with no impact on survival. Neutral prognostic effect of HRPR was observed across Hb tertiles.

Ticagrelor and prasugrel in acute coronary syndrome: a single-arm crossover platelet reactivity study

AIM

To compare the degree of platelet inhibition between ticagrelor and prasugrel in patients undergoing percutaneous coronary intervention for acute coronary syndrome.

METHODS

Platelet function was assessed by impedance aggregometry after 30-90 days of therapy with acetylsalicylic acid and ticagrelor and over 15 days after switching to prasugrel. High-on-treatment platelet reactivity (HRPR) was defined for ADP test results above the upper limit of normal.

RESULTS

A total of 105 patients were included, 81.9% males and 33.3% people with diabetes, with a mean age of 60.8 ± 8.1 years. Mean platelet reactivity was not significantly different between the two antiplatelet strategies, as the prevalence of HRPR (8.6 vs 12.3%, P = 0.50). Switching between the two antiplatelet agents was safe and well tolerated, and effectively reduced platelet reactivity in over 95% of the patients (only 3.8% of the study population displaying ineffective response to both drugs).

CONCLUSION

Ticagrelor and prasugrel have a similar effect on platelet reactivity. Switching between the two drugs can be safely done.

Platelet reactivity in response to aspirin and ticagrelor in African-Americans and European-Americans

Platelet gene polymorphisms are associated with variable on-treatment platelet reactivity and vary by race. Whether differences in platelet reactivity and aspirin or ticagrelor exist between African-American and European-Americans remains poorly understood. Biological samples from three prior prospective antiplatelet challenge studies at the Duke Clinical Research Unit were used to compare platelet reactivity between African-American and European-American subjects. Platelet reactivity at baseline, on-aspirin, on-ticagrelor, and the treatment effect of aspirin or ticagrelor were compared between groups using an adjusted mixed effects model. Compared with European-Americans (n = 282; 50% female; mean ± standard deviation age, 50 ± 16), African-Americans (n = 209; 67% female; age 48 ± 12) had lower baseline platelet reactivity with platelet function analyzer-100 (PFA-100) (p < 0.01) and with light transmission aggregometry (LTA) in response to arachidonic acid (AA), adenosine diphosphate (ADP), and epinephrine agonists (p < 0.05). African-Americans had lower platelet reactivity on aspirin in response to ADP, epinephrine, and collagen (p < 0.05) and on ticagrelor in response to AA, ADP, and collagen (p < 0.05). The treatment effect of aspirin was greater in European-Americans with an AA agonist (p = 0.002). Between-race differences with in vitro aspirin mirrored those seen in vivo. The treatment effect of ticagrelor was greater in European-Americans in response to ADP (p < 0.05) but with collagen, the treatment effect was greater for African-Americans (p < 0.05). Platelet reactivity was overall lower in African-Americans off-treatment, on aspirin, and on ticagrelor. European-Americans experienced greater platelet suppression on aspirin and on ticagrelor. The aspirin response difference in vivo and in vitro suggests a mechanism intrinsic to the platelet. Whether the absolute level of platelet reactivity or the degree of platelet suppression after treatment is more important for clinical outcomes is uncertain.

Impact of the rs73598374 polymorphism of the adenosine deaminase gene on platelet reactivity and long-term outcomes among patients with acute coronary syndrome treated with ticagrelor

BACKGROUND

The positive interaction of ticagrelor with the metabolism of adenosine has been claimed for the large antithrombotic and antiischemic benefits of this antiplatelet agent in acute coronary syndromes (ACS). Adenosine catabolism is regulated by the activity of the adenosine deaminase enzyme (ADA), for which several polymorphisms have been identified. Therefore, the aim of our study was to explore the impact of the rs73598374 polymorphism of ADA gene on platelet reactivity in ACS patients treated with ticagrelor.

METHODS

We included consecutive patients receiving ASA and ticagrelor after an ACS and coronary intervention. Platelet reactivity was evaluated by impedance aggregometry at 30-90 days post-discharge. The genetic analysis was carried out by PCR and RFLP. Clinical endpoints were mortality, cardiovascular death, recurrent myocardial infarction or coronary revascularization at the maximum available follow-up.

RESULTS

Our population is represented by 464 patients, of whom 33.4% were A-heterozygotes and 6 homozygotes. A-allele carriers showed a greater prevalence of renal failure (p = 0.02) and a lower rate of previous coronary artery bypass graft (p = 0.03) and statin treatment (p = 0.02). No differences in the mean values of platelet reactivity or HRPR on ticagrelor were found according to the ADA genotype (11.3%vs13.9%, p = 0.45; adjusted OR[95% CI] = 1.17[0.64-2.14], p = 0.61). At follow up, patients carrying the A-allele showed a non-significantly lower incidence of ACS and repeated unplanned revascularization, although with no effect on mortality.

CONCLUSIONS

In the present study the rs73598374 polymorphism of the ADA gene did not affect platelet reactivity or the long-term prognosis in patients with ACS receiving dual antiplatelet therapy with ASA and ticagrelor.

Dual Antiplatelet Therapy Duration in Acute Coronary Syndrome Patients: The State of the Art and Open Issues

Conflicting results have been reported so far in pooled analyses and studies evaluating the optimum duration of dual antiplatelet therapy (DAPT) in acute coronary syndrome (ACS) patients. However, randomized clinical trials dedicated to this specific setting of higher thrombotic risk patients have only recently been completed, pointing at the noninferiority of a shorter strategy as compared to the traditional 12-month DAPT, furthermore allowing to reduce the risk of major bleeding complications. Therefore, a reconsideration of current clinical practice and guidelines should be certainly be advocated in light of the most recent updates, especially among ACS patients treated with percutaneous coronary intervention (PCI) and modern drug-eluting stents (DES). Our aim was to provide a comprehensive review of the available evidence on the optimal DAPT duration in ACS patients.

Gender Differences in Platelet Reactivity in Diabetic Patients Receiving Dual Antiplatelet Therapy

BACKGROUND

Increased comorbidities and a perceived high-bleeding risk often prevent the use of dual antiplatelet therapy (DAPT) in female patients. However, more aggressive antiplatelet treatment would certainly offer additional outcome benefits in coronary artery disease, especially among diabetic patients. The aim of the present study was to evaluate the gender differences in high-residual on treatment platelet reactivity (HRPR) among diabetic patients treated with DAPT.

METHODS

Our population is represented by a consecutive cohort of diabetic patients treated with DAPT (ASA + clopidogrel, ticagrelor or dose-adjusted prasugrel) for an acute coronary syndrome or elective PCI, undergoing platelet reactivity assessment at 30-90 days post-discharge. Aggregation was assessed by multiple-electrode aggregometry and in diabetic patients naïve to antiplatelet therapy, by light transmission aggregometry, surface expression of P-selectin and plasma concentration of Thromboxane B2.

RESULTS

We included 472 patients, 113 (23.9%) women. Female gender was associated with more advanced age, and increased comorbidities. Mean platelet reactivity did not differ according to gender. The rate of HRPR was similar in women as compared to men (for ASA: adjusted OR[95%CI] = 0.59[0.27-1.33], p = 0.21, for ADP-antagonists: adjusted OR[95%CI] = 1.24[0.25-1.80], p = 0.27), however, the benefits of the new ADP-antagonists on platelet reactivity were lower in women than in men (p interaction = 0.01). No impact of gender on platelet reactivity was confirmed among 50 diabetic patients naïve to antiplatelet therapy.

CONCLUSIONS

Among diabetic patients receiving dual antiplatelet therapy gender does not affect platelet reactivity or high-on treatment platelet reactivity. However, the enhanced platelet inhibition provided by the new-ADP antagonists of new-ADP antagonists could be mitigated in women.

Homocysteine levels and platelet reactivity in coronary artery disease patients treated with ticagrelor

BACKGROUND AND AIM

Recurrent atherothrombotic events have been reported in certain higher risk subsets of patients even with ticagrelor, a potent first-line antiplatelet agent for the management of patients with acute coronary syndrome (ACS). Hyperhomocysteinemia is a known determinant of platelet function abnormalities. Therefore, the aim of our study was to evaluate the impact of homocysteine (Hcy) levels on platelet reactivity in patients receiving Ticagrelor.

METHODS AND RESULTS

Patients with ACS undergoing percutaneous coronary revascularization and on dual antiplatelet therapy with ASA + Ticagrelor (90mg/twice a day) were scheduled for platelet function assessment 30-90 days post-discharge. Aggregation tests were performed by Multiple Electrode Aggregometry (MEA). Suboptimal platelet inhibition HRPR-high residual platelet reactivity was defined if above the lower limit of normality (417 AU*min). We included 432 patients, divided according to Hcy tertiles. Higher Hcy levels were associated with age, renal failure, creatinine levels and use diuretics (p < 0.001). Patients with higher Hcy levels displayed a higher platelet reactivity at COL test (p = 0.002), and ADP test (p = 0.04), with a linear relationship between Hcy and platelet aggregation after stimulation with collagen (r = 0.202, p < 0.001), thrombin receptor peptide (r = 0.104, p = 0.05) and ADP (r = 0.145, p = 0.006). However, Hcy levels did not significantly affect the rate of HRPR with Ticagrelor (9.9% vs 13.7% vs 10.7%, p = 0.89; adjusted OR [95% CI] = [0.616-1.51], p = 0.99).

CONCLUSIONS

Among patients with ACS, despite the elevated platelet reactivity associated to hyperhomocysteinemia, DAPT with ticagrelor could overcome such phenomenon, achieving an adequate platelet inhibition in the majority of the patients.

The impact of clinical and genetic factors on ticagrelor and clopidogrel antiplatelet therapy

Aim: To determine clinically significant factors which may alter the effect of dual antiplatelet therapy with aspirin and ticagrelor or clopidogrel in patients who had undergone percutaneous coronary intervention and stent implantation. Materials & methods: The study included 378 patients. All the patients had undergone percutaneous coronary intervention and stent implantation. Platelet aggregation and genotyping for CYP2C19 *2 (rs4244285) and CYP4F2 (rs2108622, rs1558139, rs3093135 and rs2074902) was performed. Results: Significantly lower platelet aggregation values (%agr) were detected in ticagrelor users who carried CYP4F2 rs3093135 TT variant (14.67 ± 5.07%agr) versus AA (22.88 ± 6.30%agr), p = 0.0004, or AT (20.56 ± 6.51%agr), p = 0.0126. Conclusion: Results of the current study showed that CYP4F2 rs3093135 TT variant carriers had a higher antiplatelet effect of ticagrelor, and more frequently had nonprocedural bleeding during ticagrelor therapy, as compared with AA and AT variant carriers.

Parathyroid Hormone Levels and High-Residual Platelet Reactivity in Patients Receiving Dual Antiplatelet Therapy With Acetylsalicylic Acid and Clopidogrel or Ticagrelor

BACKGROUND

High-residual-on-treatment platelet reactivity still represents a challenging issue, potentially vanishing the benefits of dual antiplatelet treatment in patients with coronary artery disease. However, very few is known on the determinants of suboptimal response to antiplatelet agents. Recent interests have emerged on the potential prothrombotic effect of parathyroid hormone (PTH). Therefore, the aim of the present study was to assess the impact of parathyroid hormone (PTH) on platelet reactivity in patients receiving DAPT after an acute coronary syndrome or PCI.

METHODS

Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30- to 90-days postdischarge. By whole blood impedance aggregometry, HRPR was considered for ASPI test >862 AU*min (for ASA) and ADP test values ≥417 AU*min (for ADP antagonists).

RESULTS

We included 362 patients on DAPT, 125 (34.5%) receiving clopidogrel, and 237 (65.5%) on ticagrelor. Patients were divided according to PTH quartiles values (<45.8; 45.8-60.3; 60.4-88; ≥88.1 pg/mL). Higher PTH was associated with older age (P = 0.001); renal failure (P < 0.001), higher HDL cholesterol (P = 0.006) and creatinine (P < 0.001) and lower 25-OH cholecalciferol (P < 0.001). Suboptimal response to ASA was infrequent (2.8%), and not influenced by the levels of PTH (P = 0.57). ADP-mediated platelet aggregation was significantly increased in patients with higher PTH (P = 0.03), with an absolute increase in the prevalence of HRPR to ADP antagonists for higher PTH (24.7% vs. 40%, P = 0.007 for 4th vs. 1-3rd quartiles, adjusted OR[95%CI] = 2.04[1.14-3.64], P = 0.02). By the use of the ROC curve, we identified PTH levels above 96.7 pg/mL as the best predictor of HRPR with ADP antagonists (adjusted OR[95%CI] = 2.52[1.31-4.87], P = 0.006). Higher rate of HRPR was confirmed for PTH >96.7 pg/mL among the subgroup of patients on clopidogrel (51.5 vs. 85.7%, P = 0.001; adjusted OR[95%CI] = 12.5[2.6-60.9], P = 0.002), but not among ticagrelor-treated patients (11.3 vs. 16.7%, P = 0.31; adjusted OR[95%CI] = 1.55[0.56-4.6], P = 0.42).

CONCLUSION

In patients receiving dual antiplatelet therapy for coronary artery disease, higher PTH levels are associated with an increased ADP-mediated platelet reactivity and suboptimal response to clopidogrel, especially for values above 96.7 pg/mL, while not influencing the effectiveness of ASA and ticagrelor.

Validation of a New ELISA-Based Vasodilator-Associated Stimulated Phosphoprotein Phosphorylation Assay to Assess Platelet Reactivity Index in a Chinese Population

The level of platelet reactivity during P2Y12-adenosine diphosphate receptor antagonist is associated with ischemic and bleeding risks following percutaneous coronary intervention in acute coronary syndrome. Determining platelet reactivity inhibition may be valuable for confirming effective platelet inhibition for individual patients and identifying patients at risk of bleeding. The enzyme-linked immunosorbent assay (ELISA)-based vasodilator-stimulated phosphoprotein (VASP) assay offers unique advantages over other methods and has not been used in the Chinese population. We enrolled 10 healthy volunteers and 54 patients with acute coronary syndrome. The volunteers received no treatment, and patients were administered a loading dose of clopidogrel or ticagrelor. The platelet reactivity index (PRI) was measured using flow cytometry (FC)-VASP and ELISA-VASP at baseline and 8-hour postloading dose. Blood samples of healthy volunteers and clopidogrel- or ticagrelor-treated patients were frozen and stored for 1, 2, and 4 weeks after initial activation. All frozen samples were tested using ELISA-VASP. The PRI assessed by FC-VASP and ELISA-VASP correlated well showing a high degree of consistency in identifying high or low on-treatment platelet reactivity. No significant time-dependent changes in PRI results were observed in frozen samples stored up to 4 weeks compared to nonfrozen samples. The PRI of ticagrelor-treated patients was lower than that of clopidogrel-treated patients. The ELISA-VASP effectively assesses the PRI, and results obtained from frozen specimens are unaffected by storage and shipment prior to assay. Ticagrelor was superior to clopidogrel in decreasing the PRI.

Relationship between ADP-induced platelet-fibrin clot strength and anti-platelet responsiveness in ticagrelor treated ACS patients

BACKGROUND

Ticagrelor provides enhanced antiplatelet efficacy but increased risk of bleeding and dyspnea. This study aimed to display the relationship between ADP-induced platelet-fibrin clot strength (MAADP) and clinical outcomes in acute coronary syndrome (ACS) patients treated by ticagrelor.

METHODS

Consecutive Chinese-Han patients with ACS who received maintenance dose of ticagrelor on top of aspirin were recruited. After 5-day ticagrelor maintenance treatment, MAADP measured by thrombelastography (TEG) were recorded for the evaluation of ticagrelor anti-platelet reactivity. Pre-specified cutoffs of MAADP > 47 mm for high on-treatment platelet reactivity (HTPR) and MAADP < 31 mm for low on-treatment platelet reactivity (LTPR) were applied for evaluation. The occurrences of primary ischemic cardiovascular events (including a composite of cardiac death, non-fatal myocardial infarction and stroke), the Thrombolysis in Myocardial Infarction (TIMI) defined bleeding events, and ticagrelor related dyspnea were recorded after a follow-up of three months.

RESULTS

Overall, 176 ACS patients (Male: 79.55%, Age: 59.91 ± 10.54 years) under ticagrelor maintenance treatment were recruited. The value of MAADP ranged from 4.80% to 72.90% (21.27% ± 12.07% on average), with the distribution higher skewed towards the lower values. Using the pre-specific cutoffs for HTPR and LTPR, seven patients (3.98%) were identified as HTPR and 144 patients (81.82%) as LTPR. After a follow-up of three months in 172 patients, major cardiovascular events occurred in no patient, but TIMI bleeding events in 81 (47.09%) with major bleedings in three patients. All patients with major bleedings were classified as LTPR. Ticagrelor related dyspnea occurred in 31 (18.02%) patients, with 30 (21.28%) classified as LTPR and no one as HTPR (P = 0.02).

CONCLUSIONS

In ticagrelor treated ACS patients, MAADP measured by TEG might be valuable for the prediction of major bleeding and ticagrelor related dyspnea. Due to the small number of patients with HTPR after ticagrelor maintenance treatment, larger scale study should be warranted to verify the relationship between MAADP defined HTPR and ticagrelor related ischemic events.

Serum uric acid levels during dual antiplatelet therapy with ticagrelor or clopidogrel: Results from a single-centre study

BACKGROUND AND AIMS

New antithrombotic therapies have significantly improved the outcomes of patients with acute coronary syndrome (ACS), where the introduction of ticagrelor has provided the greatest mortality benefits. However, ticagrelor treatment has been associated with a potential increase in the serum uric acid (SUA) levels, which may influence endothelial dysfunction and prothrombotic status, thereby affecting the risk of acute cardiovascular events in patients requiring dual antiplatelet therapy (DAPT). The present study aimed to compare the impact of antiplatelet agents such as ticagrelor or clopidogrel on SUA levels and their effect on platelet reactivity.

METHODS AND RESULTS

We included patients admitted for ACS or elective percutaneous coronary intervention (PCI) and discharged with ASA (acetylsalicylic acid; 100-160 mg) and clopidogrel (75 mg) or ticagrelor (90 mg twice a day). Chemistry was assessed at admission (baseline) and after a 30-90-day period of DAPT (together with platelet reactivity). The absolute and percentage variations of SUA after DAPT introduction were considered. Multiple-electrode aggregometry was used to assess platelet function. A total of 378 patients were enrolled, with 145 treated with aspirin and clopidogrel (AC) and 233 with aspirin and ticagrelor (AT). The AC patients were older (p = 0.003) and more often showed elective PCI as an indication to DAPT (<0.001); they received chronic therapy with ARB (angiotensin II receptor blocker; p = 0.001), nitrates (p = 0.044), CCB (calcium channel blocker; p = 0.005) and diuretics (p = 0.044). The AT patients displayed a higher percentage of ACS diagnosis (p < 0.001) and received chronic therapy with ACE (angiotensin-converting enzyme) inhibitors (p = 0.001), beta blockers (p = 0.001) and statins (p = 0.013). The AC patients displayed higher platelet reactivity at COL (collagen) test, ASPI test and ADP (adenosine diphosphate) test (p = 0.03, 0.001 and <0.001, respectively) and a higher percentage of HRPR (high residual platelet reactivity) in the ADP test (p = 0.001). No difference was found in the baseline uric acid and creatinine levels between AC and AT patients. At 30-90 days, a significant absolute and percentage increase in the SUA levels was found in AT as compared to AC patients (0.204 mg/dl vs. -0.165 mg/dl, p = 0.034; 6.26% vs. -0.005%, p = 0.018, respectively). Results were not influenced by variations in renal function. At multivariate analysis, in fact, ticagrelor therapy emerged as an independent predictor of increase in the uric acid levels (odds ratio (OR; 95% confidence interval (CI)) = 2.79 (1.66-4.67), p < 0.001). However, the variation in the SUA levels did not affect platelet reactivity or HRPR in both AC and AT patients.

CONCLUSION

An increase in the SUA levels at 30-90 days was observed in patients receiving chronic DAPT with ticagrelor, but not clopidogrel treatment. However, the changes in the SUA levels do not influence platelet aggregation.