Sub-acute stent thrombosis secondary to ticagrelor resistance-Myth or reality!!

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.

Double Trouble: Interrupting DAPT and COVID-19

Cardiovascular disorders have been described as relevant risk factor for severe COVID infection. Stent thrombosis is a life-threatening complication that may occur subacutely. We present an interesting case of a middle-aged woman who developed acute stent thrombosis while interrupting dual antiplatelet therapy (DAPT) ticagrelor, during an episode of coronavirus disease (COVID-19). In our case, the patient’s not-compliance to DAPT, associated with COVID-19 infection and a hyperinflammatory and hypercoagulable state associated with it played a major role in the development of stent thrombosis. The hypercoagulable and hyperinflammatory state associated with COVID-19 has important implications for cardiac patients, especially those undergoing complex coronary intervention, predisposing them to an increased risk of post-PCI complications.

Double Whammy: Subacute Stent Thrombosis While Being Adherent to Dual Antiplatelet Therapy Including Ticagrelor, Followed by Multiple Coronary Artery Aneurysms in a COVID-19 Patient

Coronavirus disease 2019 (COVID-19), although predominantly a respiratory illness, can have important cardiovascular implications, which include the development of myocardial injury/myocarditis, acute coronary syndromes, arrhythmias, pericarditis, and the occurrence of arterial and venous thrombosis. We describe a rare case of a middle-aged COVID-19 patient who developed sub-acute stent thrombosis after implantation of second-generation drug-eluting stents (DES) despite being adherent to dual antiplatelet therapy including ticagrelor and who subsequently developed multiple coronary artery aneurysms within a few weeks of the DES implantation.

Clopidogrel Versus Ticagrelor for Antiplatelet Therapy in Transcarotid Artery Revascularization (TCAR) in the Society for Vascular Surgery Vascular Quality Initiative

OBJECTIVE

Transcarotid artery revascularization (TCAR) with dynamic flow reversal is a hybrid technique for operative management of carotid artery stenosis. Dual antiplatelet therapy is recommended for patients undergoing TCAR; however, nonresponders to these medications may be predisposed to perioperative thromboembolic complications. Prevalent in up to 44-66% of patients taking clopidogrel, high on-treatment platelet reactivity (HTPR) may thus be responsible for a portion of adverse cerebrovascular events in TCAR. A previous single-institution study has demonstrated the use of ticagrelor as a viable alternative to clopidogrel for antiplatelet therapy in patients undergoing TCAR; however, large-scale comparisons between clopidogrel and ticagrelor are needed to confirm the safety of ticagrelor outside of highly selected patients and providers.

METHODS

Data from patients enrolled in the Society for Vascular Surgery Vascular Quality Initiative undergoing TCAR with a perioperative antiplatelet therapy regimen including either clopidogrel or ticagrelor from January 2015 to March 2021 were analyzed and compared. Multivariable logistic regression and propensity score matching were used to evaluate the primary 30-day outcomes of stroke, major bleeding event, and combined stroke/myocardial infarction (MI)/death rate while adjusting for baseline characteristics of the patients.

RESULTS

A total of 11973 patients underwent TCAR with a dual antiplatelet therapy regimen that included clopidogrel versus 426 patients with ticagrelor. Compared to clopidogrel, patients on ticagrelor were significantly more likely to have coronary artery disease (51% vs 66% [P = <.001]), particularly unstable angina or MI within 6 months (3% vs 9% [P = <.001]), and more likely to have insulin-dependent diabetes mellitus (14% vs 19% [P = <.001]). The unadjusted 30-day rates of stroke, major bleeding, and combined stroke/MI/death were not statistically significant among both groups (1.3% vs 0.5% [P = .14], 2.4% vs 1.4% [P = .18], and 1.9% vs 1.6% [P = .71], respectively). After multivariable adjustment and propensity matching, these remained statistically insignificant.

CONCLUSIONS

Despite a substantially higher medical risk in patients undergoing TCAR with ticagrelor, 30-day rates of stroke, major bleeding events, and combined stroke/MI/death were similar between patients on ticagrelor and clopidogrel as part of adjunctive antiplatelet therapy. Randomized prospective trials, and studies with larger sample sizes and longer follow-up will be needed to better examine the outcome differences in TCAR between these two medications.

Viscoelastic Hemostatic Assays and Platelet Function Testing in Patients with Atherosclerotic Vascular Diseases

Platelets play crucial role in acute vascular atherosclerotic diseases, including myocardial infarction and stroke. Additionally, platelet aggregation is a key target of antiplatelet agents, forming the keystone of pharmacotherapy of various atherosclerotic cardiovascular diseases. Thromboelastography and thromboelastometry, representing currently available viscoelastic hemostatic assays (VHA), are designed as whole blood, real-time analyzers of clot formation and clot resolution. These assays could, in theory, overcome some limitations of currently available platelet function testing assays. This article reviews the current experience with the use of VHA for platelet function testing and for monitoring of the response to antiplatelet therapy.

Outcomes and strategy of tailored antiplatelet therapy with ticagrelor in patients undergoing transcarotid artery revascularization

OBJECTIVE

Antiplatelet drug resistance is associated with periprocedural ischemic complications in patients undergoing intravascular stent implantation. Nonresponders are subject to increased risk of stent thrombosis and in-stent stenosis, and high on-treatment platelet reactivity (HTPR) is present in up to 44% of patients taking clopidogrel, a widely used component of dual antiplatelet therapy (DAPT). Evidence points to ticagrelor as a viable alternative to overcome HTPR on clopidogrel. Studies have shown fewer thromboembolic events with ticagrelor therapy; however, results on bleeding risk are mixed, and its safety and efficacy in hybrid operative techniques have yet to be established. Transcarotid artery revascularization (TCAR) is a hybrid procedure to treat severe carotid stenosis. The objective of this study was to establish the safety and efficacy of ticagrelor as part of DAPT in patients undergoing TCAR and to develop a protocol to ensure adequate antithrombotic protection throughout the operative course.

METHODS

Data were collected retrospectively for patients undergoing TCAR on DAPT of aspirin and ticagrelor for symptomatic (≥50%) or asymptomatic (≥80%) carotid stenosis. Preoperative platelet reactivity was determined using Thromboelastography with Platelet Mapping (Haemonetics Corporation, Braintree, Mass), with adequate platelet reactivity defined as maximal amplitude produced by adenosine diphosphate <50 mm. The primary safety end point was 30-day major bleeding event rate. Primary efficacy end points were 30-day incidence of ipsilateral cerebrovascular ischemic event (stroke or transient ischemic attack), myocardial infarction, and death. Secondary end points were postoperative length of hospital stay, procedure time, and clamp/flow reversal time.

RESULTS

Sixty-seven TCAR procedures with patients receiving periprocedural DAPT of ticagrelor and aspirin were performed during the study period. Patients had an average age of 79 years, and 28 (42%) were symptomatic. The mean procedure time was 45.8 ± 9.2 minutes, with a mean clamp/flow reversal time of 4.8 ± 1.5 minutes, and mean postoperative length of hospital stay of 3.1 ± 2.2 days for inpatients and 1.3 ± 0.8 days for outpatients. Technical success was achieved in all cases, with no 30-day major bleeding events and no occurrence of ipsilateral cerebrovascular ischemic event, myocardial infarction, or death.

CONCLUSIONS

Initial experience with ticagrelor as part of DAPT in patients undergoing TCAR demonstrated its safety and efficacy in both symptomatic and asymptomatic disease. No bleeding events or thromboembolic complications occurred. Furthermore, a protocol to administer ticagrelor to assay for HTPR on ticagrelor and consequent medication and patient management is proposed. Ticagrelor may represent a safe and effective alternative to overcome clopidogrel nonresponsiveness in DAPT regimens for TCAR.

A 70-Year-Old Female with Unexpected Platelet Function Testing Results

A 70-year-old female with a history of hypertension and left A2 segment aneurysm was scheduled for pipeline embolization device (PED) placement. Preinterventional antiplatelet prophylaxis included aspirin and ticagrelor. Unexpectedly, after 13 days of treatment, VerifyNow showed a P2Y12 reaction unit (PRU) value of 216, approximately >5 times the mean PRU of other patients on aspirin and ticagrelor. We confirmed platelet reactivity and ticagrelor resistance with light transmission aggregometry. Antiplatelet therapy was switched to prasugrel, and aspirin was continued. Eight days later, the P2Y12 reaction value (PRU) was 164. PED was placed without complications. Unlike clopidogrel, ticagrelor is a direct P2Y12 inhibitor that does not require metabolism to an active metabolite. Ticagrelor resistance is very rarely reported. To the best of our knowledge, there has been no case of ticagrelor resistance reported in the context of pre-PED placement prophylaxis.

One-Month Outcomes of Cases Receiving Ticagrelor after Percutaneous Coronary Intervention; a Case Series

INTRODUCTION

Ticagrelor is the first reversibly binding oral P2Y12 receptor antagonist that can block ADP-induced platelet aggregation. This study aimed to describe one-month follow-up findings of cases undergoing ticagrelor therapy after percutaneous coronary intervention (PCI).

METHODS

This case series was performed on acute coronary syndrome (ACS) patients who were candidates for PCI and received aspirin plus ticagrelor after PCI. Patients were followed for one month and their outcomes were described.

RESULTS

156 cases with the mean age of 59.74 ± 9.24 years were studied (63% male). 45 (28.8%) cases complained of dyspnea (39 cases with mild and 6 cases with severe dyspnea). Bleeding occurred in 4 (2.5%) cases (intra-cranial hemorrhage (ICH) in one, hematuria in two, and skin hemorrhage in one case). There were no cases with bradycardia or thrombosis. One (0.6%) patient developed drug hypersensitivity reaction, which manifested as skin rash. The use of drug was stopped in 10 (6.4%) cases due to severe dyspnea (n= 6), ICH (n=1), skin rash (n=1), and concomitant left ventricular (LV) clot (n=2).

CONCLUSION

The most important finding of one-month ticagrelor consumption were dyspnea, bleeding, and hypersensitivity reaction. No case of bradycardia and stent thrombosis was detected. In our study , iranian population has more susceptibility to dyspnea than PLATO result. The rate of drug discontinuation in this series of cases was 6.4 %.