Randomised trial to compare a protective effect of Clopidogrel Versus TIcagrelor on coronary Microvascular injury in ST-segment Elevation myocardial infarction (CV-TIME trial)

What do we know about platelets in myocardial ischemia-reperfusion injury and why is it important?

Myocardial ischemia-reperfusion injury (MIRI), the joint result of ischemic injury and reperfusion injury, is associated with poor outcomes in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Accumulating evidence demonstrates that activated platelets directly contribute to the pathogenesis of MIRI through participating in the formation of microthrombi, interaction with leukocytes, secretion of active substances, constriction of microvasculature, and activation of spinal afferent nerves. The molecular mechanisms underlying the above detrimental effects of activated platelets include the homotypic and heterotypic interactions through surface receptors, transduction of intracellular signals, and secretion of active substances. Revealing the roles of platelet activation in MIRI and the associated mechanisms would provide potential targets/strategies for the clinical evaluation and treatment of MIRI. Further studies are needed to characterize the temporal (ischemia phase vs. reperfusion phase) and spatial (systemic vs. local) distributions of platelet activation in MIRI by multi-omics strategies. To improve the likelihood of translating novel cardioprotective interventions into clinical practice, basic researches maximally replicating the complexity of clinical scenarios would be necessary.

The effect of ticagrelor on coronary microvascular function after PCI in patients with ACS compared to clopidogrel: A systematic review and meta-analysis

BACKGROUND

The function of coronary microcirculation is an important factor in predicting the prognosis of patients with acute coronary syndrome (ACS) who receive percutaneous coronary intervention (PCI) therapy. Ticagrelor, a type of oral P2Y12 inhibitor, is widely prescribed to ACS patients and can improve prognosis compared to clopidogrel. However, the efficacy of ticagrelor on coronary microcirculation, compared to clopidogrel, remains unclear. The objective of this meta-analysis was to determine the efficacy of ticagrelor on coronary microcirculation.

METHODS

The PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov databases were comprehensively searched to identify studies until November 2022. Data was pooled using the fixed effects model or random effects model based on the level of heterogeneity. Sensitivity analyses were performed to measure the effects of potential confounders.

RESULTS

After screening, 16 trials with a total of 3676 participants were ultimately included in the analysis. The meta-analysis revealed that compared to clopidogrel, patients receiving ticagrelor exhibited a more significant reduction in the IMR (WMD: -6.23, 95% CI: -8.41 to -4.04), a reduction in the cTFC (WMD: -1.88; 95% CI: -3.32 to -0.45), and greater increases in CFR (WMD: 0.38; 95% CI: 0.18 to 0.57), MBG (RR 1.29, 95% CI 1.12 to 1.48), and TIMI (RR 1.03, 95% CI 1.00 to 1.06).

CONCLUSION

Our findings suggest that, compared to clopidogrel, ticagrelor has a significant effect in reducing coronary microcirculatory resistance, enhancing coronary blood flow reserve, and improving myocardial perfusion.

Ticagrelor vs. clopidogrel for coronary microvascular dysfunction in patients with STEMI: a meta-analysis of randomized controlled trials

Purpose

Approximately half of ST-segment elevation myocardial infarction (STEMI) patients who undergo revascularization present with coronary microvascular dysfunction. Dual antiplatelet therapy, consisting of aspirin and a P2Y12 inhibitor (e.g., clopidogrel or ticagrelor), is recommended to reduce rates of cardiovascular events after STEMI. The present study performed a pooled analysis of randomized controlled trials (RCTs) to compare effects of ticagrelor and clopidogrel on coronary microcirculation dysfunction in STEMI patients who underwent the primary percutaneous coronary intervention.

Methods

The PubMed, Embase, Cochrane Library, and Web of Science databases were searched for eligible RCTs up to September 2022, with no language restriction. Coronary microcirculation indicators included the corrected thrombolysis in myocardial infarction (TIMI) frame count (cTFC), myocardial blush grade (MBG), TIMI myocardial perfusion grade (TMPG), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR).

Results

Seven RCTs that included a total of 957 patients (476 who were treated with ticagrelor and 481 who were treated with clopidogrel) were included. Compared with clopidogrel, ticagrelor better accelerated microcirculation blood flow [cTFC = -2.40, 95% confidence interval (CI): -3.38 to -1.41, p < 0.001] and improved myocardial perfusion [MBG = 3, odds ratio (OR) = 1.99, 95% CI: 1.35 to 2.93, p < 0.001; MBG ≥ 2, OR = 2.57, 95% CI: 1.61 to 4.12, p < 0.001].

Conclusions

Ticagrelor has more benefits for coronary microcirculation than clopidogrel in STEMI patients who undergo the primary percutaneous coronary intervention. However, recommendations for which P2Y12 receptor inhibitor should be used in STEMI patients should be provided according to results of studies that investigate clinical outcomes.

Angiography derived assessment of the coronary microcirculation: is it ready for prime time?

INTRODUCTION

Non-obstructive coronary arteries (NOCA) are present in 39.7% to 62.4% of patients who undergo elective angiography. Coronary microcirculation (<400 µm) is not visible on angiography therefore functional assessment, invasive or non-invasive plays a prior role to help provide a more personalized diagnosis of angina.

AREA COVERED

In this review, we revise the pathophysiology, clinical importance and invasive assessment of the coronary microcirculation, and discuss angiography-derived indices of microvascular resistance. A comprehensive literature review over four decades is also undertaken.

EXPERT OPINION

The coronary microvasculature plays an important role in flow autoregulation and metabolic regulation. Invasive assessment of microvascular resistance is a validated modality with independent prognostic value, nevertheless, its routine application is hampered by the requirement of intravascular instrumentation and hyperaemic agents. The angiography-derived index of microvascular resistance has emerged as a promising surrogate in pilot studies, however, more data are needed to validate and compare the diagnostic and prognostic accuracy of different equations as well as to illustrate the relationship between angiography-derived parameters for epicardial coronary arteries and those for the microvasculature.

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.

Impact of Ticagrelor Versus Clopidogrel on Coronary Microvascular Function After Non-ST-Segment-Elevation Acute Coronary Syndrome

BACKGROUND

Coronary microvascular dysfunction after acute coronary syndrome is an important predictor of long-term prognosis. Data is lacking on the effects of oral P2Y₁₂-inhibitors on coronary microvascular function in non-ST-segment-elevation acute coronary syndrome. The aim of this study was to compare the acute effects of ticagrelor versus clopidogrel pretreatment on coronary microvascular function in non-ST-segment-elevation acute coronary syndrome patients.

METHODS

Hospitalized non-ST-segment-elevation acute coronary syndrome patients were randomized (1:1) to ticagrelor or clopidogrel. The index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio were obtained using an intracoronary pressure-temperature sensor-tipped wire.

RESULTS

In total, 128 patients were randomized between March 2018 and July 2020. Mean age 59.2±11.8 years, 84% were male, mean Global Registry of Acute Coronary Events score was 93.7±24.5. Intracoronary physiological measurements were obtained in 118 patients (60 ticagrelor, 58 clopidogrel). In the infarct-related artery, the ticagrelor group had lower baseline index of microcirculatory resistance (22.0 [13.0-34.9] versus 27.7 [19.3-29.8]; P=0.02) and higher baseline resistive reserve ratio (3.0 [2.3-4.4] versus 2.4 [1.7-3.4]; P=0.01) compared with the clopidogrel group. A total of 88 patients underwent percutaneous coronary intervention (PCI; 45 ticagrelor, 43 clopidogrel). The ticagrelor group had lower post-PCI index of microcirculatory resistance (22.0 [15.0-29.0] versus 27.0 [18.5-47.5]; P=0.02) and higher post-PCI resistive reserve ratio (3.0 [1.8-3.8] versus 1.8 [1.5-3.4]; P=0.006) compared with the clopidogrel group. The coronary flow reserve was not significantly different between the 2 groups at baseline or post-PCI. No between-group differences were seen in any of the indices in the non-infarct-related artery.

CONCLUSIONS

In non-ST-segment-elevation acute coronary syndrome patients, ticagrelor significantly improved coronary microvascular function before and after PCI compared with clopidogrel.

REGISTRATION

URL: https://www.anzctr.org.au; Unique identifier: ACTRN12618001610224.

The Effect of Ticagrelor on Endothelial Function Compared to Prasugrel, Clopidogrel, and Placebo: A Systematic Review and Meta-Analysis

Background/Objective

Endothelial dysfunction is associated with the long-term outcomes in patients with coronary artery disease (CAD). Recent evidence suggests that ticagrelor, a potent antiplatelet agent, improves endothelial function. However, several studies demonstrated contrasting results. The objective of this meta-analysis was to determine the efficacy of ticagrelor treatment on endothelial function.

Materials and Methods

A systematic literature study was conducted on databases including PubMed, Web of Science, EMBASE, Scopus, and the Cochrane Library. A historical search was performed for a reference list of the selected studies as of August 2021. The randomized controlled trials (RCTs) were assessed using the Cochrane tool. The weighted mean difference (WMD) 95% CI was treated as the overall effect size, and data were pooled using the fixed-effect model or random-effect model according to the heterogeneity. Subgroup and sensitivity analyses were performed to measure the effects of potential confounders.

Results

A total of 21 studies were included. The meta-analysis indicated that ticagrelor resulted in a significant increase of flow-mediated dilation (FMD) (WMD: 1.48; 95% CI: 0.36, 2.60), reactive hyperemia index (RHI) (WMD: 0.06; 95% CI: 0.00, 0.13), and circulating progenitor endothelial cells (CEPCs) (WMD: 13.84; 95% CI: 5.70, 21.98), and a reduction in the index of microvascular resistance (IMR) (WMD: −15.39; 95% CI: −25.11, −5.68).

Conclusion

Ticagrelor has a significant effect on some markers of endothelial function in patients with CAD. However, the results should be interpreted with caution due to the heterogeneity and limited studies.

Novel Applications for Invasive and Non-invasive Tools in the Era of Contemporary Percutaneous Coronary Revascularisation

Percutaneous coronary intervention (PCI) is an expanding treatment option for patients with coronary artery disease (CAD). It is considered the default strategy for the unstable presentation of CAD. PCI techniques have evolved over the last 4 decades with significant improvements in stent design, an increase in functional assessment of coronary lesions, and the use of intra-vascular imaging. Nonetheless, the morbidity and mortality related to CAD remain significant. Advances in technology have allowed a better understanding of the nature and progression of CAD. New tools are now available that reflect the pathophysiological changes at the level of the myocardium and coronary atherosclerotic plaque. Certain changes within the plaque would render it more prone to rupture leading to acute vascular events. These changes are potentially detected using novel tools invasively, such as near infra-red spectroscopy, or non-invasively using T2 mapping cardiovascular magnetic resonance imaging (CMR) and ¹⁸F-Sodium Fluoride positron emission tomography/ computed tomography. Similarly, changes at the level of the injured myocardium are feasibly assessed invasively using index microcirculatory resistance or non-invasively using T1 mapping CMR. Importantly, these changes could be detected immediately with the opportunity to tailor treatment to those considered at high risk. Concurrently, novel therapeutic options have demonstrated promising results in reducing future cardiovascular risks in patients with CAD. This Review article will discuss the role of these novel tools and their applicability in employing a mechanical and pharmacological treatment to mitigate cardiovascular risk in patients with CAD.

Platelet Reactivity Was Not Associated with Infarct Size after Primary Percutaneous Coronary Intervention

Potent antiplatelet therapy after primary percutaneous coronary intervention (PCI) has the potential to reduce infarct size. This study analyzed the association between on-treatment platelet reactivity and myocardial infarct size in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI. In this single-center, retrospective study, 253 patients who underwent primary PCI for STEMI were divided into two groups according to platelet reactivity measurements (53 patients in the high platelet reactivity [HPR] group and 200 in the non-HPR group). Technetium Tc-99m tetrofosmin single-photon emission computed tomography (SPECT) was performed before hospital discharge. We measured the infarct size using SPECT imaging and serial cardiac biomarker levels, and compared the infarct sizes of each group. The patients with HPR were older (65.5±13.2 vs. 60.6±12.1 years, p=0.011) than the patients with non-HPR. On the other hand, the non-HPR group had a higher incidence of smoking (26.4% vs. 51.0%, p=0.001) than the HPR group. Infarct size was similar between the two groups (22.6±17.3% vs. 24.8±17.7%, p=0.416). Multivariate analysis revealed that onset to balloon time >240 min (odds ratio [OR]=1.92; 95% confidence interval [CI]=1.08-3.40; p=0.025) and anterior infarction (OR=5.28; 95% CI=3.05-9.14; p<0.001) were independent predictors of large (>22%) infarct size. HPR was not a predictor of infarct size assessed by SPECT. The two groups also showed analogous cumulative creatinine kinase-myocardial band and troponin T levels. In conclusion, compared to non-HPR, HPR showed no significant association with myocardial infarct size measured by SPECT imaging in early phase of MI.

Impact of a micro-net mesh technology covering stent on coronary microvascular dysfunction in patients with high thrombus burden

BACKGROUND

Highly thrombotic coronary lesions continue to be a serious and clinically significant problem that is not effectively and completely addressed by current technology.

OBJECTIVES

We aimed to investigate whether a micro-net mesh (MNM) technology covering stent could preserve the index of microcirculatory resistance (IMR) after percutaneous coronary intervention (PCI) in patients with high thrombus burden.

METHODS AND RESULTS

Fifty-two patients with non-ST elevation myocardial infarction or ST Elevation Myocardial Infarction and high thrombus burden (TIMI thrombus grade ≥ 3) were randomized into two groups, PCI with a MNM covering stent (MNM group, n = 25) and PCI with any commercially available stent (DES group, n = 27). As the primary endpoint, IMR was measured immediately after PCI using a pressure-temperature sensor-tipped coronary wire. The secondary endpoint was left ventricular ejection fraction (LVEF) at 6 months of follow-up. The IMR in the MNM group was significantly lower in comparison to the DES group (33.2 [21.3, 48.9] vs. 57.2 [39.9, 98.0], p = 0.005). No significant differences were observed in baseline LVEF (54.5 ± 10.2% vs. 53.1 ± 6.87%, p = .57), while LVEF was significantly improved at follow-up in the MNM group (61.1 ± 7.1% vs. 53.9 ± 6.35%, p = .0001).

CONCLUSION

MNM technology significantly improved coronary microvascular dysfunction after PCI in patient with acute coronary syndrome and appears as a useful technological option for thrombus management.

The Role of Genetic Polymorphism and Other Factors on Clopidogrel Resistance (CR) in an Asian Population with Coronary Heart Disease (CHD)

Clopidogrel is a widely-used antiplatelet drug. It is important for the treatment and prevention of coronary heart disease. Clopidogrel can effectively reduce platelet activity and therefore reduce stent thrombosis. However, some patients still have ischemic events despite taking the clopidogrel due to the alteration in clopidogrel metabolism attributable to various genetic and non-genetic factors. This review aims to summarise the mechanisms and causes of clopidogrel resistance (CR) and potential strategies to overcome it. This review summarised the possible effects of genetic polymorphism on CR among the Asian population, especially CYP2C19 *2 / *3 / *17, where the prevalence rate among Asians was 23.00%, 4.61%, 15.18%, respectively. The review also studied the effects of other factors and appropriate strategies used to overcome CR. Generally, CR among the Asian population was estimated at 17.2-81.6%. Therefore, our overview provides valuable insight into the causes of RC. In conclusion, understanding the prevalence of drug metabolism-related genetic polymorphism, especially CYP2C19 alleles, will enhance clinical understanding of racial differences in drug reactions, contributing to the development of personalised medicine in Asia.

The effect of antiplatelet drug on coronary endothelial and microvascular function: comparison with ticagrelor and clopidogrel

BACKGROUND/AIMS

Coronary endothelial and microvascular function play important roles in cardiovascular disease. We aimed to evaluate the effect of ticagrelor on coronary artery function and tested the antiplatelet effect of low dose ticagrelor in East-Asian patients.

METHODS

Sixty-one consecutive patients with non-significant coronary disease were included in the study. Initially, patients were randomized in 1:1:1 ratio to receive drugs: ticagrelor 90 mg twice a day (bid; n = 22), ticagrelor 45 mg bid (n = 19) or clopidogrel 75 mg once a day (qd; n = 20) and then divided into two groups (ticagrelor vs clopidogrel) for evaluation of coronary artery function, and three groups for evaluation of antiplatelet function. Endothelial dysfunction was measured by coronary flow reserve (CFR), and changes in the levels of asymmetric dimethylarginine (ADMA), cluster of differentiation (CD) 40 ligand, and P-selectin. Microvascular function was evaluated as index of microvascular resistance (IMR). Platelet reactivity was assessed by VerifyNow P2Y12 assay.

RESULTS

The levels of CFR, ADMA, and CD 40 ligand were not different between the two groups. However, P-selectin was lower in the ticagrelor group compared with clopidogrel group. IMR was significantly lower in the ticagrelor group compared with clopidogrel group (median, 15.0 [interquartile range, 12.0 to 21.0] vs. 47.5 [23.0 to 67.5], p = 0.014). There was significant difference in platelet inhibition among the three groups (ticagrelor 90 mg bid vs. ticagrelor 45 mg bid vs. clopidogrel 75 mg qd; 85.57 ± 47.63 vs. 120.33 ± 51.09 vs. 256.42 ± 55.10, p < 0.001).

CONCLUSION

It is hypothesized that ticagrelor might ameliorate the coronary microvascular function. When compared with clopidogrel, low dose ticagrelor exhibited satisfactory antiplatelet effect in the present study.

Effect of Smoking on Outcomes of Primary PCI in Patients With STEMI

BACKGROUND

Smoking is a well-established risk factor for ST-segment elevation myocardial infarction (STEMI); however, once STEMI occurs, smoking has been associated with favorable short-term outcomes, an observation termed the "smoker's paradox." It has been postulated that smoking might exert protective effects that could reduce infarct size, a strong independent predictor of worse outcomes after STEMI.

OBJECTIVES

The purpose of this study was to determine the relationship among smoking, infarct size, microvascular obstruction (MVO), and adverse outcomes after STEMI.

METHODS

Individual patient-data were pooled from 10 randomized trials of patients with STEMI undergoing primary percutaneous coronary intervention. Infarct size was assessed at median 4 days by either cardiac magnetic resonance imaging or technetium-99m sestamibi single-photon emission computed tomography. Multivariable analysis was used to assess the relationship between smoking, infarct size, and the 1-year rates of death or heart failure (HF) hospitalization and reinfarction.

RESULTS

Among 2,564 patients with STEMI, 1,093 (42.6%) were recent smokers. Smokers were 10 years younger and had fewer comorbidities. Infarct size was similar in smokers and nonsmokers (adjusted difference: 0.0%; 95% confidence interval [CI]: -3.3% to 3.3%; p = 0.99). Nor was the extent of MVO different between smokers and nonsmokers. Smokers had lower crude 1-year rates of all-cause death (1.0% vs. 2.9%; p < 0.001) and death or HF hospitalization (3.3% vs. 5.1%; p = 0.009) with similar rates of reinfarction. After adjustment for age and other risk factors, smokers had a similar 1-year risk of death (adjusted hazard ratio [adjHR]: 0.92; 95% CI: 0.46 to 1.84) and higher risks of death or HF hospitalization (adjHR: 1.49; 95% CI: 1.09 to 2.02) as well as reinfarction (adjHR: 1.97; 95% CI: 1.17 to 3.33).

CONCLUSIONS

In the present large-scale individual patient-data pooled analysis, recent smoking was unrelated to infarct size or MVO, but was associated with a worse prognosis after primary PCI in STEMI. The smoker's paradox may be explained by the younger age and fewer cardiovascular risk factors in smokers compared with nonsmokers.

Impact of Targeted Therapies for Coronary Microvascular Dysfunction as Assessed by the Index of Microcirculatory Resistance

Coronary microvascular dysfunction (CMD) has emerged as an important therapeutic target in the contemporary management of ischemic heart disease. However, due to a lack of a reliable traditional "gold standard" test for CMD, optimal treatment remains undefined. The index of microcirculatory resistance (IMR) is an intra-coronary wire-based technique that provides a more reliable and quantitative assessment of CMD and has been increasingly used as a preferred endpoint for evaluating CMD treatment strategies in recent studies. IMR can help diagnose CMD in angina patients with non-obstructive epicardial coronary disease, predict peri-procedural myocardial infarction in stable patients undergoing coronary stenting, and predict long-term prognosis after acute myocardial infarction. Studies of IMR in the setting of non-ST-elevation acute coronary syndromes are still lacking. This review critically appraises the current published literature evaluating targeted therapies for CMD using IMR as the assessment tool and provides insights into evidence gaps in this important field. The index of microcirculatory resistance has rapidly evolved from a research tool to being the new "gold standard" test for evaluating coronary microvascular dysfunction.

The Potential Use of the Index of Microcirculatory Resistance to Guide Stratification of Patients for Adjunctive Therapy in Acute Myocardial Infarction

The goal of reperfusion therapies in ST-segment elevation myocardial infarction has evolved to include effective reperfusion of the microcirculation subtended by the culprit epicardial coronary artery. The index of microcirculatory resistance is measured using a pressure- and temperature-sensing coronary guidewire and quantifies microvascular dysfunction. The index of microcirculatory resistance is an independent predictor of microvascular obstruction, infarct size, and adverse clinical outcomes. It has the advantage of being immediately measurable in the catheterization laboratory, before the results of blood biomarkers or noninvasive imaging become available. This provides an opportunity for additional intervention that may alter outcomes. In this review, the authors provide a critical appraisal of the published research on the emerging role of the index of microcirculatory resistance as a tool to guide the stratification of patients for adjunctive therapeutic strategies in acute ST-segment elevation myocardial infarction.

Outcomes Related to Antiplatelet Therapy in a High-Risk ST-Segment Elevation Myocardial Infarction Population: A Retrospective Real-World Analysis of an Italian ECMO Center

AIM

To evaluate outcomes related to antiplatelet therapy in patients with ST-elevation myocardial infarction (STEMI) admitted to the San Gerardo Hospital in Monza, an extracorporeal membrane oxygenation (ECMO) reference center in the Monza-Brianza area.

METHODS

This retrospective study enrolled patients with STEMI hospitalized between 2013 and 2017.

RESULTS

This study included 653 patients (mean age: 67.5 years, 71% male). Across the study period, ticagrelor use showed consistent increases, from 22% of patients during 2013 to 85% in 2017. Cardiac arrest prehospitalization occurred in 100 patients (15.3%), either at home (n = 85, 13.0%) or during transfer (n = 15, 2.3%); 46 patients underwent ECMO for refractory cardiac arrest. Rates of 90-day survival (hazard ratio [HR]: 2.4, 95% confidence interval [CI]: 1.3-4.4, P = .004) and ST resolution (odds ratio [OR]: 2.5, 95% CI: 1.6-4.1, P = .000) were higher with ticagrelor than with other antiplatelet agents. When analyzed by each agent, patients on ticagrelor had longer survival (HR: 0.4, 95% CI: 0.2-0.8, P = .008) than patients on clopidogrel and more frequent ST resolution than those on clopidogrel or prasugrel (OR: 0.4, 95% CI: 0.2-0.7, P = .002 and OR: 0.4, 95% CI: 0.2-0.7, P = .006). There was no difference in mortality between ticagrelor and prasugrel.

CONCLUSIONS

Changes in the treatment of high-risk patients with STEMI over time are in line with changes in treatment guidelines. In these patients, ticagrelor is associated with significantly improved 90-day mortality compared with clopidogrel.

Evaluation of Microvascular Injury in Revascularized Patients With ST-Segment-Elevation Myocardial Infarction Treated With Ticagrelor Versus Prasugrel

BACKGROUND

Despite successful restoration of epicardial vessel patency with primary percutaneous coronary intervention, coronary microvascular injury occurs in a large proportion of patients with ST-segment-elevation myocardial infarction, adversely affecting clinical and functional outcome. Ticagrelor has been reported to increase plasma adenosine levels, which might have a protective effect on the microcirculation. We investigated whether ticagrelor maintenance therapy after revascularized ST-segment-elevation myocardial infarction is associated with less coronary microvascular injury compared to prasugrel maintenance therapy.

METHODS

A total of 110 patients with ST-segment-elevation myocardial infarction received a loading dose of ticagrelor and were randomized to maintenance therapy of ticagrelor (n=56) or prasugrel (n=54) after primary percutaneous coronary intervention. The primary outcome was coronary microvascular injury at 1 month, as determined with the index of microcirculatory resistance in the infarct-related artery. Cardiovascular magnetic resonance imaging was performed during the acute phase and at 1 month.

RESULTS

The primary outcome of index of microcirculatory resistance was not superior in ticagrelor- or prasugrel-treated patients (ticagrelor, 21 [interquartile range, 15-39] U; prasugrel, 18 [interquartile range, 11-29] U; P=0.08). Recovery of microcirculatory resistance over time was not better in patients with ticagrelor versus prasugrel (ticagrelor, -13.9 U; prasugrel, -13.5 U; P=0.96). Intramyocardial hemorrhage was observed less frequently in patients receiving ticagrelor (23% versus 43%; P=0.04). At 1 month, no difference in infarct size was observed (ticagrelor, 7.6 [interquartile range, 3.7-14.4] g, prasugrel 9.9 [interquartile range, 5.7-16.6] g; P=0.17). The occurrence of microvascular obstruction was not different in patients on ticagrelor (28%) or prasugrel (41%; P=0.35). Plasma adenosine concentrations were not different during the index procedure and during maintenance therapy with ticagrelor or prasugrel.

CONCLUSIONS

In patients with ST-segment-elevation myocardial infarction, ticagrelor maintenance therapy was not superior to prasugrel in preventing coronary microvascular injury in the infarct-related territory as assessed by the index of microcirculatory resistance, and this resulted in a comparable infarct size at 1 month.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02422888.

Comparison of the Effects of Ticagrelor and Clopidogrel on Microvascular Dysfunction in Patients With Acute Coronary Syndrome Using Invasive Physiologic Indices

Background:

Ticagrelor reduced the rate of myocardial infarction and death compared with clopidogrel in patients with acute coronary syndrome. However, little is understood about chronic treatment of ticagrelor on microvascular dysfunction. The objective of this study was to assess the impact of ticagrelor maintenance treatment on microvascular system and coronary flow in comparison with clopidogrel.

Methods:

This study was a nonblinded, open-label, parallel-group, prospective, randomized controlled trial that enrolled 120 patients with acute coronary syndrome requiring stent implantation. Patients were randomized into the ticagrelor (180 mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300 to 600 mg loading dose, 75 mg daily thereafter) group. The primary end point was coronary microvascular dysfunction as measured by an index of microcirculatory resistance (IMR) at 6 months after treatment.

Results:

The baseline clinical characteristics and physiological parameters, such as fractional flow reserve, coronary flow reserve, and IMR, did not differ between the ticagrelor and clopidogrel groups. Six-month follow-up physiological data showed that the IMR value was significantly lower in the ticagrelor group than the clopidogrel group (15.57±5.65 versus 21.15±8.39, P <0.01), and coronary flow reserve was higher in the ticagrelor group than in the clopidogrel group (3.85±0.72 versus 3.37±0.76, P <0.01). However, there was no difference in fractional flow reserve (0.87±0.08 versus 0.87±0.09, P =0.94) between the 2 groups. The improvement in IMR after 6 months of treatment was higher in the ticagrelor group ( P <0.01). Analyses of 223 nonculprit vessels of registered patients based on physiological results showed no differences in baseline fractional flow reserve (0.93±0.13 versus 0.92±0.09, P =0.58), coronary flow reserve (3.62±1.27 versus 3.51±1.24, P =0.16), or IMR (21.37±12.37 versus 24.19±21.08, P =0.22) or in follow-up fractional flow reserve (0.91±0.09 versus 0.91±0.08, P =0.67), coronary flow reserve (3.91±1.22 versus 3.75±1.16, P =0.36), or IMR (19.43±10.32 versus 21.52±18.90, P =0.34) between the 2 groups.

Conclusions:

Compared with clopidogrel, 6 months of ticagrelor therapy significantly improved microvascular dysfunction in acute coronary syndrome patients with stent implantation.

Clinical Trial Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02618733.

The impact of CYP2C19*2, CYP4F2*3, and clinical factors on platelet aggregation, CYP4F2 enzyme activity, and 20-hydroxyeicosatetraenoic acid concentration in patients treated with dual antiplatelet therapy

: The aim of the current study was to evaluate the impact of CYP2C192 (rs4244285), CYP4F23 (rs2108622), and nongenetic factors on platelet aggregation and to investigate the mechanism of CYP4F2's effect on platelet aggregation in the patients treated with dual antiplatelet therapy. A total of 146 patients were included in this study. Ticagrelor or clopidogrel were administered in a loading dose of 180 mg and 600 mg, respectively, in combination with aspirin (300 mg). Blood samples for analysis were taken the next morning after antiplatelet therapy induction. Clopidogrel users with the CYP2C1912 variant had higher platelet aggregation values (median 43, range 30-54%) compared with 11 wild-type carriers (median 33, range 15-77%; P = 0.009). Carriers of the CYP4F213 variant had higher platelet aggregation values than carriers of the 33 variant (median 34, range 8-70% vs. median 24.5, range 10-47%, P = 0.016, respectively). Higher CYP4F2 concentrations were detected in clopidogrel users than in ticagrelor users (median 3.6, range 1.6-22.0 ng/ml vs. median 2.3, range 1.6-27.2 ng/ml, P = 0.056, respectively) and in carriers of the CYP4F213 variant compared with carriers of the 11 variant (median 4.3, range 1.6-27.2 ng/ml vs. median 2.4, range 1.6-22.0 ng/ml, P = 0.009, respectively). No correlation between plasma 20-hydroxyeicosatetraenoic acid and CYP4F2 enzyme concentrations were detected (r = -0.045, P = 0.587). Our results proved that CYP2C192 might significantly affect antiplatelet function of clopidogrel. Plasma CYP4F2 concentrations were significantly lower in ticagrelor users than in clopidogrel users.

Design and Rationale for comParison Between ticagreLor and clopidogrEl on mIcrocirculation in Patients with Acute cOronary Syndrome Undergoing Percutaneous Coronary Intervention (PLEIO) Trial

It has been previously demonstrated that ticagrelor can reduce mortality compared to clopidogrel in acute coronary syndrome (ACS) patients. However, the mechanism for this mortality reduction remains uncertain. The objective of the present study is to assess the impact of chronic ticagrelor treatment on microvascular circulation. A total of 120 participants aged 20–85 years with clinical diagnosis of ACS will be randomized in a 1:1 fashion to the following two groups: ticagrelor 90 mg twice daily; clopidogrel 75 mg once daily. To evaluate the status of microcirculation, the primary end point is coronary microvascular dysfunction measured using an index of microcirculatory resistance (IMR) at 6 months after receiving the study agent. The purpose of this trial is to investigate whether ticagrelor, beyond its antiplatelet efficacy, could improve coronary microcirculation more effectively than clopidogrel for patients with ACS.

Invasive Assessment of the Coronary Microvasculature

Traditionally, invasive coronary physiological assessment has focused on the epicardial coronary artery. More recently, appreciation of the importance of the coronary microvasculature in determining patient outcomes has grown. Several invasive modalities for interrogating microvascular function have been proposed. Angiographic techniques have been limited by their qualitative and subjective nature. Doppler wire-derived coronary flow reserve has been applied in research studies, but its clinical role has been limited by its lack of reproducibility, its lack of a clear normal value, and the fact that it is not specific for the microvasculature but interrogates the entire coronary circulation. The index of microcirculatory resistance—a thermodilution-derived measure of the minimum achievable microvascular resistance—is relatively easy to measure, more reproducible, has a clearer normal value, and is independent of epicardial coronary artery stenosis. The index of microcirculatory resistance has been shown to have prognostic value in patients with ST-segment–elevation myocardial infarction and cardiac allograft vasculopathy after heart transplantation. Emerging data demonstrate its role in evaluating patients with chest pain and nonobstructive coronary artery disease. Increasingly, the index of microcirculatory resistance is used as a reference standard for invasively assessing the microvasculature in clinical trials.

Comparison of the Infarct Size between the Loading of Ticagrelor and Clopidogrel in Patients with Acute Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

Background and Objectives

Ticagrelor is considered a potent antiplatelet agent compared to clopidogrel. However, there are no studies regarding the effect of ticagrelor loading on infarct size in patients with ST-segment elevation myocardial infarction (STEMI) in a primary percutaneous coronary intervention (PCI) setting.

Subjects and Methods

In this single-center, randomized, open-label study, 188 patients who underwent primary PCI for STEMI were enrolled (92 patients in the clopidogrel group and 96 in the ticagrelor group) and compared the infarct size by technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomography (SPECT) and serial cardiac biomarker levels between the groups. SPECT was performed at a median of 2 days after PCI.

Results

Baseline clinical and procedural characteristics were similar between the groups. Infarct size on SPECT, was similar between the 2 groups (28.1%±34.5% vs. 32.8%±29.2%; p=0.169). At all time-points after PCI (8, 24, and 48 hours), the peak levels of creatine kinase-myocardial band (CK-MB) and troponin T were lower in the clopidogrel group. The clopidogrel group showed lower cumulative troponin T levels than the ticagrelor group (12.59±10.66 vs. 17.67±19.51 ng/mL; p=0.029).

Conclusion

Ticagrelor loading before primary PCI was not associated with reduced myocardial infarct size during the first 48 hours, compared to clopidogrel loading.

PRotective Effect on the coronary microcirculation of patients with DIabetes by Clopidogrel or Ticagrelor (PREDICT): study rationale and design. A randomized multicenter clinical trial using intracoronary multimodal physiology

Background

In diabetic patients a predisposed coronary microcirculation along with a higher risk of distal particulate embolization during primary percutaneous intervention (PCI) increases the risk of peri-procedural microcirculatory damage. However, new antiplatelet agents, in particular Ticagrelor, may protect the microcirculation through its adenosine-mediated vasodilatory effects.

Methods

PREDICT is an original, prospective, randomized, multicenter controlled study designed to investigate the protective effect of Ticagrelor on the microcirculation during PCI in patient with diabetes mellitus type 2 or pre-diabetic status. The primary endpoints of this study aim to test (i) the decrease in microcirculatory resistance with antiplatelet therapy (Ticagrelor > Clopidogrel; mechanistic effect) and (ii) the relative microcirculatory protection of Ticagrelor compared to Clopidogrel during PCI (Ticagrelor < Clopidogrel; protective effect).

Conclusions

PREDICT will be the first multicentre clinical trial to test the adenosine-mediated vasodilatory effect of Ticagrelor on the microcirculation during PCI in diabetic patients. The results will provide important insights into the prospective beneficial effect of this drug in preventing microvascular impairment related to PCI (http://www.clinicaltrials.gov No. NCT02698618).

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0543-5) contains supplementary material, which is available to authorized users.

Reperfusion ventricular arrhythmia bursts identify larger infarct size in spite of optimal epicardial and microvascular reperfusion using cardiac magnetic resonance imaging

AIMS

Ventricular arrhythmia (VA) bursts following recanalisation in acute ST-elevation myocardial infarction (STEMI) are related to larger infarct size (IS). Inadequate microvascular reperfusion, as determined by microvascular obstruction (MVO) using cardiac magnetic resonance imaging (CMR), is also known to be associated with larger IS. This study aimed to test the hypothesis that VA bursts identify larger infarct size in spite of optimal microvascular reperfusion.

METHODS

All 65 STEMI patients from the Maastricht ST elevation (MAST) study with brisk epicardial flow (TIMI 3), complete ST recovery post-percutaneous coronary intervention and early CMR were included. Using 24-hour Holter registrations from the time of admission, VA bursts were identified against subject-specific Holter background VA rates using a statistical outlier method. MVO and final IS were determined using delayed enhancement CMR.

RESULTS

MVO was present in 37/65 (57%) of patients. IS was significantly smaller in the group without MVO (median 9.4% vs. 20.5%; p < 0.001). IS in the group with MVO did not differ depending on VA burst ( n = 28/37; median 20.8% vs. 19.7%; p = 0.64). However, in the group without MVO, VA burst was associated with significantly larger IS ( n = 17/28; median 10.5% vs. 4.1%; p = 0.037). In multivariable analyses, VA burst as well as anterior infarct location remained independent predictors of larger infarct size.

CONCLUSION

In the presence of suboptimal reperfusion with MVO by CMR, VA burst does not further define MI size. However, with optimal TIMI 3 reperfusion and optimal microvascular perfusion (i.e. no MVO), VA burst is associated with larger IS, indicating that VA burst is a marker of additional cell death.

A review of strategies for infarct size reduction during acute myocardial infarction

Advances in medical and interventional therapy over the last few decades have revolutionized the treatment of acute myocardial infarction. Despite the ability to restore epicardial coronary artery patency promptly through percutaneous coronary intervention, tissue level damage may continue. The reported 30-day mortality after all acute coronary syndromes is 2 to 3%, and around 5% following myocardial infarction. Post-infarct complications such as heart failure continue to be a major contributor to cardiovascular morbidity and mortality. Inadequate microvascular reperfusion leads to worse clinical outcomes and potentially strategies to reduce infarct size during periods of ischemia-reperfusion can improve outcomes. Many strategies have been tested, but no single strategy alone has shown a consistent result or benefit in large scale randomised clinical trials. Herein, we review the historical efforts, current strategies, and potential novel concepts that may improve myocardial protection and reduce infarct size.

Comparative Prognostic Utility of Indexes of Microvascular Function Alone or in Combination in Patients With an Acute ST-Segment-Elevation Myocardial Infarction

BACKGROUND

Primary percutaneous coronary intervention is frequently successful at restoring coronary artery blood flow in patients with acute ST-segment-elevation myocardial infarction; however, failed myocardial reperfusion commonly passes undetected in up to half of these patients. The index of microvascular resistance (IMR) is a novel invasive measure of coronary microvascular function. We aimed to investigate the pathological and prognostic significance of an IMR>40, alone or in combination with a coronary flow reserve (CFR≤2.0), in the culprit artery after emergency percutaneous coronary intervention for acute ST-segment-elevation myocardial infarction.

METHODS

Patients with acute ST-segment-elevation myocardial infarction were prospectively enrolled during emergency percutaneous coronary intervention and categorized according to IMR (≤40 or >40) and CFR (≤2.0 or >2.0). Cardiac magnetic resonance imaging was acquired 2 days and 6 months after myocardial infarction. All-cause death or first heart failure hospitalization was a prespecified outcome (median follow-up, 845 days).

RESULTS

IMR and CFR were measured in the culprit artery at the end of percutaneous coronary intervention in 283 patients with ST-segment-elevation myocardial infarction (mean±SD age, 60±12 years; 73% male). The median IMR and CFR were 25 (interquartile range, 15-48) and 1.6 (interquartile range, 1.1-2.1), respectively. An IMR>40 was a multivariable associate of myocardial hemorrhage (odds ratio, 2.10; 95% confidence interval, 1.03-4.27; P=0.042). An IMR>40 was closely associated with microvascular obstruction. Symptom-to-reperfusion time, TIMI (Thrombolysis in Myocardial Infarction) blush grade, and no (≤30%) ST-segment resolution were not associated with these pathologies. An IMR>40 was a multivariable associate of the changes in left ventricular ejection fraction (coefficient, -2.12; 95% confidence interval, -4.02 to -0.23; P=0.028) and left ventricular end-diastolic volume (coefficient, 7.85; 95% confidence interval, 0.41-15.29; P=0.039) at 6 months independently of infarct size. An IMR>40 (odds ratio, 4.36; 95% confidence interval, 2.10-9.06; P<0.001) was a multivariable associate of all-cause death or heart failure. Compared with an IMR>40, the combination of IMR>40 and CFR≤2.0 did not have incremental prognostic value.

CONCLUSIONS

An IMR>40 is a multivariable associate of left ventricular and clinical outcomes after ST-segment-elevation myocardial infarction independently of the infarction size. Compared with standard clinical measures of the efficacy of myocardial reperfusion, including the ischemic time, ST-segment elevation, angiographic blush grade, and CFR, IMR has superior clinical value for risk stratification and may be considered a reference test for failed myocardial reperfusion.

CLINICAL TRIAL REGISTRATION

URL: https//www.clinicaltrials.gov. Unique identifier: NCT02072850.