P2Y12 platelet reactivity after thrombolytic therapy for ST-segment elevation myocardial infarction

Role of ticagrelor in the peri-thrombolytic phase for patients with ST-segment elevation myocardial infarction: a comprehensive review

Recent years have seen ticagrelor, a potent P2Y12 inhibitor, emerge as a significant advancement in the peri-thrombolytic management of patients with ST-segment elevation myocardial infarction (STEMI), offering a promising alternative to traditional antiplatelet drugs like clopidogrel. This review critically examines the efficacy and safety of ticagrelor during the peri-thrombolytic phase in STEMI patients, drawing on evidence from key clinical trials such as TREAT and MIRTOS, as well as other relevant studies. These investigations underscore ticagrelor's superior platelet inhibition capabilities, which are crucial for minimizing thrombotic complications post-thrombolysis without increasing bleeding risks. Despite its potential, clopidogrel remains the guideline-recommended choice for such patients, leaving the appropriateness of ticagrelor in this context open to debate. By summarizing the current evidence and identifying gaps in our understanding, this study advocates for targeted research to clarify the long-term benefits and optimal deployment of ticagrelor, highlighting its evolving significance in cardiovascular care.

Post-PCI corrected TIMI Frame Count predicts left ventricular global longitudinal strain at 90 days post-STEMI in thrombolysis-treated patients: A pre-specified analysis of the MIRTOS study

Introduction

Ticagrelor has been established as the P2Y12-inhibitor of choice in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI); however, its use has not been adequately studied in the context of thrombolysis. In the present study, we sought to investigate whether the administration of ticagrelor together with thrombolysis could result in a greater degree of left ventricular systolic function recovery compared to clopidogrel, at 90 days post-STEMI, as well as to evaluate post-PCI corrected TIMI Frame Count (CTFC) as a predictive marker of myocardial recovery in thrombolysis-treated patients.

Material and methods

In this pre-specified analysis of the MIRTOS trial, the degree of change in left ventricular ejection fraction (ΔLVEF) and left ventricular longitudinal strain (ΔLV-GLS) from baseline to 90 days post-randomization in all patients who underwent conventional and speckle-tracking echocardiography at both timepoints was compared between the ticagrelor and clopidogrel groups. In addition, speckle-tracking echocardiographic measurements were evaluated for any correlations to post-PCI CTFC.

Results

No statistically significant differences were detected between the ticagrelor and clopidogrel groups for ΔLVEF (+3.61 ± 5.08 % versus +2.21 ± 4.78 %; P = 0.18) and ΔLV-GLS (-1.53 ± 2.7 % versus -1.21 ± 3.05 %; P = 0.73). A strong negative correlation was found between post-PCI CTFC and the absolute value of LV-GLS at 90 days post-randomization (r = -0.33, P = 0.014).

Conclusions

Our work suggests that both P2Y12-inhibitors are accompanied with a similar degree of myocardial recovery in the context of lytic therapy. Importantly, post-PCI microvascular integrity is a predictor of 3-month left ventricular systolic function in STEMI patients initially treated with thrombolysis.

Assessment of myocardial salvage in patients with STEMI undergoing thrombolysis: ticagrelor versus clopidogrel

Background

In the setting of ST-segment elevation myocardial infarction (STEMI), the faster and stronger antiplatelet action of ticagrelor compared to clopidogrel, as well as its pleiotropic effects, could result in a greater degree of cardioprotection and final infarct size (FIS) limitation. The aim of our study was to comparatively evaluate the effect of ticagrelor and clopidogrel on myocardial salvage index (MSI) in STEMI patients undergoing thrombolysis.

Methods

Forty-two STEMI patients treated with thrombolysis were randomized to receive clopidogrel (n = 21) or ticagrelor (n = 21), along with aspirin. Myocardial area at risk (AAR) was calculated according to the BARI and the APPROACH jeopardy scores. FIS was quantified by cardiac magnetic resonance imaging (CMR) performed 5–6 months post-randomization. MSI was calculated as (AAR-FIS)/AAR × 100%. Primary endpoint of our study was MSI. Secondary endpoints were FIS and CMR-derived left ventricular ejection fraction (LVEF) at 5 –6 months post-randomization.

Results

By using the BARI score for AAR calculation, mean MSI was 52.25 ± 30.5 for the clopidogrel group and 54.29 ± 31.08 for the ticagrelor group (p = 0.83), while mean MSI using the APPROACH score was calculated at 51.94 ± 30 and 53.09 ± 32.39 (p = 0.9), respectively. Median CMR-derived FIS—as a percentage of LV—was 10.7% ± 8.25 in the clopidogrel group and 12.09% ± 8.72 in the ticagrelor group (p = 0.6). Mean LVEF at 5–6 months post-randomization did not differ significantly between randomization groups.

Conclusions

Our results suggest that the administration of ticagrelor in STEMI patients undergoing thrombolysis offer a similar degree of myocardial salvage, compared to clopidogrel.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02735-1.

Effects of Ticagrelor and Clopidogrel on Coronary Microcirculation in Patients with Acute Myocardial Infarction

Introduction

Clopidogrel has been demonstrated to be effective in improving coronary microcirculation (CM) among patients with ST-elevation myocardial infarction (STEMI) treated with fibrinolytics. Ticagrelor is a more potent adenosine diphosphate (ADP) receptor blocker proven to be superior to clopidogrel among patients with acute coronary syndromes. The present study aimed to compare the effects of ticagrelor and clopidogrel on CM in patients with STEMI treated with fibrinolytics.

Methods

The present study prospectively included 48 patients participating in the TREAT trial, which randomly assigned patients with STEMI undergoing fibrinolysis to ticagrelor versus clopidogrel. The primary endpoint of this study was the evaluation of the CM using the global myocardial perfusion score index (global MPSI) obtained by myocardial contrast echocardiography (MCE). Platelet aggregation to ADP was evaluated by Multiplate® and expressed as area under the curve (AUC).

Results

The global MPSI demonstrated no differences between the groups [mean 1.4 (1.2–1.5) in the ticagrelor group and 1.2 (1.2–1.5) in the clopidogrel group (p = 0.41)]. Platelet aggregability was lower in the ticagrelor group (18.1 ± 9.7 AUC), compared to the clopidogrel group (26.1 ± 12.5 AUC, p = 0.01).

Conclusion

We found no improvement in coronary microcirculation with ticagrelor compared to clopidogrel among patients with STEMI treated with fibrinolytics, despite the fact that platelet aggregation to ADP was lower with ticagrelor.

Clinical Trials Registration

NCT03104062.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02061-0.

Residual platelet reactivity, thrombus burden and myocardial reperfusion in patients treated by PCI after successful pre-hospital fibrinolysis compared to primary PCI

We compared residual platelet reactivity and post PCI atherothrombotic burden using OFDI in patients successfully treated by primary PCI versus pharmacoinvasive approach (PI) defined as PCI after successful pre-hospital fibrinolysis. Despite pre-hospital P2Y12-inhibitor loading dose, high rates of high on-treatment platelet reactivity were found at the time of PCI in both groups. Primary PCI patients had higher post stenting thrombus burden and lower rates of final normal myocardial blush grade compared to PI. These findings support the use of a pharmacoinvasive reperfusion strategy especially when primary PCI cannot be timely performed.

Complete Revascularization in Patients Undergoing a Pharmacoinvasive Strategy for ST-Segment-Elevation Myocardial Infarction: Insights From the COMPLETE Trial

[Figure: see text].

Ticagrelor versus clopidogrel in patients with STEMI treated with thrombolysis: the MIRTOS trial

AIMS

We aimed to demonstrate whether coronary microvascular function is improved after ticagrelor administration compared to clopidogrel administration in STEMI subjects undergoing thrombolysis.

METHODS AND RESULTS

MIRTOS is a multicentre study of ticagrelor versus clopidogrel in STEMI subjects treated with fibrinolysis. We enrolled 335 patients <75 years old with STEMI eligible for thrombolysis, of whom 167 were randomised to receive clopidogrel and 168 to receive ticagrelor together with thrombolysis. Primary outcome was the difference in post-PCI corrected TIMI frame count (CTFC). All clinical events were recorded in a three-month follow-up period. From the 335 patients who were randomised, 259 underwent PCI (129 clopidogrel and 130 ticagrelor) and 154 angiographies were analysable for the study primary endpoint. No significant difference was found between the clopidogrel (n=85) and ticagrelor (n=69) groups for CTFC (24.33±17.35 vs 28.33±17.59, p=0.10). No significant differences were observed in MACE and major bleeding events between randomisation groups (OR 2.0, 95% CI: 0.18-22.2, p=0.99).

CONCLUSIONS

Thrombolysis with ticagrelor in patients <75 years old was not able to demonstrate superiority compared to clopidogrel in terms of microvascular injury, while there was no difference between the two groups in MACE and major bleeding events.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02429271. EudraCT Number 2014-004082-25.

Ticagrelor versus clopidogrel in the management of acute myocardial infarction

Hypothesis: In the care of acute myocardial infarction, ticagrelor attenuates post-ischemic myocardial damage and inhibits platelet activity to a greater extent than clopidogrel. Methods: Scholarly articles published in the last 10 years were compiled from a PubMed MeSH search focusing on acute coronary infarction and the antiplatelet therapies clopidogrel and ticagrelor. The databases used were PubMed, Google Scholar, Dynamed, and EBSCOhost. Eight articles were chosen based on subject matter related to the hypothesis, including cardioprotective effects, mortality benefits, platelet reactivity, angiographic effects, and electrocardiography changes. Results: Evidence from randomized clinical trials demonstrates that ticagrelor reduces infarct size, prevents remodeling, and reduces mortality rate after acute myocardial infarction to a greater extent than clopidogrel. However, some angiography studies show no difference between the two treatment regimes. Two articles show that ticagrelor is more effective in treating individuals with high platelet reactivity (HPR). In addition, there is some evidence of increased dyspnea and significant bleeding with ticagrelor. Discussion: Although there is growing evidence that ticagrelor is the better antiplatelet drug post-acute coronary infarction, more research needs to be done to determine the situations in which ticagrelor provides the optimal treatment regime in regards to cardioprotective effects, antiplatelet effects and an overall decrease in mortality. Conclusion: Ticagrelor was found to be superior to clopidogrel in relation to cardioprotective effects, mortality, and antiplatelet activity.

Point of Care Tests VerifyNow P2Y12 and INNOVANCE PFA P2Y Compared to Light Transmittance Aggregometry After Fibrinolysis

Detection of high on-treatment platelet reactivity (HPR) by point-of-care tests has not been validated after successful fibrinolysis for ST-elevation myocardial infarction. We assessed the validity of the point-of-care VerifyNow P2Y12 (VN) and INNOVANCE PFA P2Y (PFA) tests on HPR compared to light transmittance aggregometry (LTA) in these patients. The HPR was identified in 10 (34.5%) patients, 15 (51.7%) patients, and 14 (50%) patients using LTA, VN, and PFA, respectively. Discrepancies were observed between the tests despite significant correlations between platelet reactivity measures by LTA and VN (r = 0.74; P < .0001) and LTA and PFA (r = .75; P < .0001). Compared to LTA, VN and PFA were associated with a 92% and 53% and 92% and 64% positive predictive value (PPV) and negative predictive value (NPV), respectively, in detecting HPR. When combined, VN and PFA results yielded 90% and 100% PPV and NPV values if discrepancies between the 2 tests were considered as non-HPR. The VN or PFA identify patients without HPR correctly but overestimate the proportion of HPR patients. The association of the 2 tests, in case of HPR, improves the accuracy of the detection of HPR.

Effects of ticagrelor versus clopidogrel on platelet function in fibrinolytic-treated STEMI patients undergoing early PCI

OBJECTIVES

Patients undergoing PCI early after fibrinolytic therapy are at high risk for both thrombotic and bleeding complications. We sought to assess the pharmacodynamic effects of ticagrelor versus clopidogrel in the fibrinolytic-treated STEMI patients undergoing early PCI.

METHODS AND RESULTS

Patients undergoing PCI within 24 hours of tenecteplase (TNK), aspirin, and clopidogrel for STEMI were randomized to receive additional clopidogrel 300 mg followed by 75 mg daily or ticagrelor 180 mg followed by 90 mg twice daily. The platelet reactivity units (PRU) were measured with the VerifyNow Assay before study drug administration (baseline) at 4 and 24 hours post-PCI. The primary end point was PRU ≤208 at 4 hours. A total of 140 patients (74 in ticagrelor and 66 in clopidogrel group) were enrolled. The mean PRU values at baseline were similar for the 2 groups (257.8±52.9 vs 259.5±56.7, P=.85, respectively). Post-PCI, patients on ticagrelor, compared to those on clopidogrel, had significantly lower PRU at 4 hours (78.7±88 vs 193.6±86.5, respectively, P<.001) and at 24 hours (34.5±35.0 and 153.5±75.5, respectively, P<.001). The primary end point was observed in 87.8% (n=65) in the ticagrelor-treated patients compared to 57.6% (n=38) of clopidogrel-treated patients, P<.001.

CONCLUSION

Fibrinolysis-treated STEMI patients who received clopidogrel and aspirin at the time of fibrinolysis and were undergoing early PCI frequently had PRU >208. In this high-risk population, ticagrelor provides more prompt and potent platelet inhibition compared with clopidogrel (Funded by Astra Zeneca; NCT01930591, https://clinicaltrials.gov/ct2/show/NCT01930591).

Effects of P2Y12 receptor inhibition in patients with ST-segment elevation myocardial infarction

In ST-segment elevation myocardial infarction (STEMI), an effective antiplatelet treatment adjunctive to primary percutaneous coronary intervention is of utmost importance. High dose of clopidogrel, prasugrel, or ticagrelor provides a faster, more potent, and more consistent platelet inhibition than standard clopidogrel. Oral P2Y12 inhibitors have been studied in large clinical trials and are in use in clinical practice. Intravenously administered P2Y12 inhibitors such as cangrelor have also been tested. However, statistically significant anti-ischemic superiority of stronger platelet inhibition regimens versus standard clopidogrel has not been proved exclusively in patients receiving primary percutaneous coronary intervention. Whether orally administered antiplatelet agents suffice in patients with STEMI has been recently disputed, mainly because of their delayed onset of action. Platelet reactivity variability before P2Y12 blockade and its evolution over time, genetic predisposition, antiplatelet agent used, timing, and method of platelet function testing significantly affect the rates of high on-treatment platelet reactivity. Although ominous signs of greater bleeding potential of stronger antiplatelet regimens have not appeared in STEMI, this should be carefully tested.