Novel role of platelet reactivity in adverse left ventricular remodelling after ST-segment elevation myocardial infarction: The REMODELING Trial

The pathological mechanisms and potential therapeutic drugs for myocardial ischemia reperfusion injury

BACKGROUND

Cardiovascular disease is the main cause of death and disability, with myocardial ischemia being the predominant type that poses a significant threat to humans. Reperfusion, an essential therapeutic approach, promptly reinstates blood circulation to the ischemic myocardium and stands as the most efficacious clinical method for myocardial preservation. Nevertheless, the restoration of blood flow associated with this process can potentially induce myocardial ischemia-reperfusion injury (MIRI), thereby diminishing the effectiveness of reperfusion and impacting patient prognosis. Therefore, it is of great significance to prevent and treat MIRI.

PURPOSE

MIRI is an important factor affecting the prognosis of patients, and there is no specific in-clinic treatment plan. In this review, we have endeavored to summarize its pathological mechanisms and therapeutic drugs to provide more powerful evidence for clinical application.

METHODS

A comprehensive literature review was conducted using PubMed, Web of Science, Embase, Medline and Google Scholar with a core focus on the pathological mechanisms and potential therapeutic drugs of MIRI.

RESULTS

Accumulated evidence revealed that oxidative stress, calcium overload, mitochondrial dysfunction, energy metabolism disorder, ferroptosis, inflammatory reaction, endoplasmic reticulum stress, pyroptosis and autophagy regulation have been shown to participate in the process, and that the occurrence and development of MIRI are related to plenty of signaling pathways. Currently, a range of chemical drugs, natural products, and traditional Chinese medicine (TCM) preparations have demonstrated the ability to mitigate MIRI by targeting various mechanisms.

CONCLUSIONS

At present, most of the research focuses on animal and cell experiments, and the regulatory mechanisms of each signaling pathway are still unclear. The translation of experimental findings into clinical practice remains incomplete, necessitating further exploration through large-scale, multi-center randomized controlled trials. Given the absence of a specific drug for MIRI, the identification of therapeutic agents to reduce myocardial ischemia is of utmost significance. For the future, it is imperative to enhance our understanding of the pathological mechanism underlying MIRI, continuously investigate and develop novel pharmaceutical agents, expedite the clinical translation of these drugs, and foster innovative approaches that integrate TCM with Western medicine. These efforts will facilitate the emergence of fresh perspectives for the clinical management of MIRI.

High platelet reactivity is a predictor of left ventricular remodelling in patients with acute myocardial infarction

AIMS

Acute myocardial infarction (AMI) is associated with left ventricular remodelling (LVR), which leads to progressive heart failure. Platelets play a pivotal role in promoting systemic and cardiac inflammatory responses during the complex process of myocardial wound healing or repair following AMI. This study aimed to investigate the impact of platelet reactivity immediately after primary percutaneous coronary intervention (PCI) on LVR in AMI patients with ST-segment (STEMI) and non-ST-segment elevation (NSTEMI).

METHODS AND RESULTS

This prospective, single-centre, observational study included 182 patients with AMI who underwent primary PCI (107 patient with STEMI and 75 patients with NSTEMI). Patients were administered a loading dose of aspirin plus prasugrel before the procedure, and platelet reactivity was assessed using the VerifyNow P2Y12 assay immediately after PCI. Echocardiography was performed before discharge and during the chronic phase (8 ± 3 months after discharge). LVR was defined as a relative ≥20% increase in left ventricular end-diastolic volume index (LVEDVI). LVR in chronic phase was found in 34 patients (18.7%) whose platelet reactivity was significantly higher than those without LVR (259.6 ± 61.5 and 213.1 ± 74.8 P2Y12 reaction units [PRU]; P = 0.001). The occurrence of LVR did not differ between patients with STEMI and patients with NSTEMI (21.5% and 14.7%; P = 0.33). The optimal cut-off value of platelet reactivity for discriminating LVR was ≥245 PRU. LVEDVI significantly decreased at chronic phase in patients without high platelet reactivity (<245 PRU) (from 49.2 ± 13.5 to 45.4 ± 15.8 mL/m² ; P = 0.02), but not in patients with high platelet reactivity (≥d245 PRU) (P = 0.06). Multivariate logistic analysis showed that high platelet reactivity was an independent predictor of LVR after adjusting for LVEDVI before discharge (odds ratio, 4.13; 95% confidence interval, 1.85-9.79).

CONCLUSIONS

High platelet reactivity measured immediately after PCI was a predictor of LVR in patients with AMI during the chronic phase. The role of antiplatelet therapy on inflammation in the myocardium is a promising area for further research.

Protective Value of Aspirin Loading Dose on Left Ventricular Remodeling After ST-Elevation Myocardial Infarction

Aims

Left ventricular (LV) remodeling after ST-elevation myocardial infarction (STEMI) is a complex process, defined as changes of LV volumes over time. CMR feature tracking analysis (CMR-FT) offers an accurate quantitative assessment of LV wall deformation and myocardial contractile function. This study aimed to evaluate the role of myocardial strain parameters in predicting LV remodeling and to investigate the effect of Aspirin (ASA) dose before primary coronary angioplasty (pPCI) on myocardial injury and early LV remodeling.

Methods and Results

Seventy-eight patients undergoing CMR, within 9 days from symptom onset and after 6 months, were enrolled in this cohort retrospective study. We divided the study population into three groups based on a revised Bullock's classification and we evaluated the role of baseline CMR features in predicting early LV remodeling. Regarding CMR strain analysis, worse global circumferential and longitudinal strain (GCS and GLS) values were associated with adverse LV remodeling. Patients were also divided based on pre-pPCI ASA dosage. Significant differences were detected in patients receiving ASA 500 mg dose before pPCI, which showed lower infarct size extent and better strain values compared to those treated with ASA 250 mg. The stepwise multivariate logistic regression analysis, adjusted for covariates, indicated that a 500 mg ASA dose remained an inverse independent predictor of early adverse LV remodeling.

Conclusion

GCS and GLS have high specificity to detect early LV adverse remodeling. We first reported a protective effect of ASA loading dose of 500 mg before pPCI on LV myocardial damage and in reducing early LV adverse remodeling.

IL-6, IL-1RA and Resistin as Predictors of Left Ventricular Remodelling and Major Adverse Cardiac Events in Patients with Acute ST Elevation Myocardial Infarction

Despite continuous advances in diagnostic and therapeutic methods, acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality worldwide. Considering the role of inflammation in AMI etiopathogenesis, we aimed to explore the role of a group of three inflammatory cytokines (IL-1RA, IL-6 and resistin) as an independent prognostic factor for LVR assessed by 3D echocardiography and MACE in patients with STEMI. We enrolled 41 patients with STEMI who underwent primary PCI. We assessed the occurrence of LVR (defined as an increase of over 20% in end-diastolic left ventricular volume at 6 months compared with baseline values) and MACE. Using the enzyme-linked immunosorbent assays (ELISA) method, we measured plasmatic levels of IL-6, IL-1RA and resistin (within 48 h after AMI and at 6 months). Out of 41 STEMI patients, 20.5% presented signs of LVR at follow up, and in 24.4%, MACE occurred. In univariate logistic regression analysis, baseline levels of IL-6 (OR = 1.042, p = 0.004), IL-1RA (OR = 1.004, p = 0.05) and resistin (OR = 1.7, p = 0.007) were all significantly associated with LVR. ROC analysis showed that the three cytokines as a group (AUC 0.946, p = 0.000) have a better predictive value for LVR than any individual cytokine. The group of cytokines also proved to have a better predictive value for MACE together than separately (AUC = 0.875, p = 0.000 for ROC regression model). IL-6, IL-1RA and resistin plasma levels at baseline have a good predictive value both as independent variables and also as a group for the development of adverse LVR and MACE at 6 months follow up after STEMI.

Prognostic implication of systemic inflammatory state on antiplatelet effect in patients after percutaneous coronary intervention for ST-elevation myocardial infarction: A retrospective cohort study

Patients with ST-elevation myocardial infarction (STEMI) show an inflammatory response. The level of systemic inflammation is known to affect platelet aggregation function and antiplatelet therapy, which leads to different clinical prognosis. This study aims to evaluate the prognostic implication of systemic inflammatory state in patients with STEMI undergoing percutaneous coronary intervention.In this study, 203 patients with STEMI who underwent primary percutaneous coronary intervention were included. The patients were divided into 3 groups based on the inflammation levels assessed by tertiles of high-sensitivity C-reactive protein (hs-CRP) level on admission. Platelet aggregation evaluation was performed by residual platelet reactivity, which was assessed by the value of residual ADP-induced light transmittance aggregometry after clopidogrel maintenance dose therapy and in follow-up. Major adverse cardiac events (MACEs) were defined to include all-cause mortality, cardiovascular mortality, reinfarction, target vessel revascularization (TVR), cardiopulmonary resuscitation, advanced heart failure, ventricular fibrillation or ventricular tachycardia, and atrioventricular block.Levels of white blood cell was observed to be significantly higher at high tertile levels. Residual ADP-induced platelet aggregation was significantly higher at high tertile levels after clopidogrel maintenance dose therapy and in follow-up. Multivariate analysis identified that reperfusion time, alanine aminotransferase, platelet count, ADP-induced light transmittance aggregometry in follow-up and hs-CRP was independent predictors of MACEs. Platelet inhibition function of clopidogrel decreases progressively at different inflammation levels. The different levels of hs-CRP were demonstrated to be associated with MACEs at follow-up assessments.The presence of hs-CRP was not only significantly associated with platelet inhibition function, but was also a prognostic marker in STEMI.

Effect of Ticagrelor on Left Ventricular Remodeling in Patients With ST-Segment Elevation Myocardial Infarction (HEALING-AMI)

OBJECTIVES

The aim of this study was to evaluate the effect of ticagrelor versus clopidogrel on left ventricular (LV) remodeling after reperfusion of ST-segment elevation myocardial infarction (STEMI) in humans.

BACKGROUND

Animal studies have demonstrated that ticagrelor compared with clopidogrel better protects myocardium against reperfusion injury and improves remodeling after myocardial infarction.

METHODS

In this investigator-initiated, randomized, open-label, assessor-blinded trial performed at 10 centers in Korea, patients were enrolled if they had naive STEMI successfully treated with primary percutaneous coronary intervention (PCI) and at least 6-month planned duration of dual-antiplatelet treatment. The coprimary endpoints were LV remodeling index (LVRI) (a relative change of LV end-diastolic volume) measured on 3-dimensional echocardiography and N-terminal pro-B-type natriuretic peptide level at 6 months.

RESULTS

Among initially enrolled patients with STEMI (n = 336), 139 in each group completed the study. LVRI at 6 months was numerically lower with ticagrelor versus clopidogrel (0.6 ± 18.6% vs. 4.5 ± 16.5%; p = 0.095). Ticagrelor significantly reduced the 6-month level of N-terminal pro-B-type natriuretic peptide (173 ± 141 pg/ml vs. 289 ± 585 pg/ml; p = 0.028). These differences were prominent in patients with pre-PCI TIMI (Thrombolysis In Myocardial Infarction) flow grade 0. By multivariate analysis, ticagrelor versus clopidogrel reduced the risk for positive LV remodeling (LVRI >0%) (odds ratio: 0.56; 95% confidence interval: 0.33 to 0.95; p = 0.030). The LV end-diastolic volume index remained unchanged during ticagrelor treatment (from 54.7 ± 12.2 to 54.2 ± 12.2 ml/m²; p = 0.629), but this value increased over time during clopidogrel treatment (from 54.6 ± 11.3 to 56.4 ± 13.9 ml/m²; p = 0.056) (difference -2.3 ml/m²; 95% confidence interval: -4.8 to 0.2 ml/m²; p = 0.073). Ticagrelor reduced LV end-systolic volume index (from 27.0 ± 8.5 to 24.7 ± 8.4 ml/m²; p < 0.001), whereas no reduction was seen with clopidogrel (from 26.2 ± 8.9 to 25.6 ± 11.0 ml/m²; p = 0.366) (difference -1.8 ml/m²; 95% confidence interval: -3.5 to -0.1 ml/m²; p = 0.040).

CONCLUSIONS

Ticagrelor was superior to clopidogrel for LV remodeling after reperfusion of STEMI with primary PCI. (High Platelet Inhibition With Ticagrelor to Improve Left Ventricular Remodeling in Patients With ST Segment Elevation Myocardial Infarction [HEALING-AMI]; NCT02224534).

A review of the effects of ticagrelor on adenosine concentration and its clinical significance

BACKGROUND

Ticagrelor is an oral antiplatelet drug that can reversibly bind to the platelet P2Y12 receptor. Ticagrelor is metabolized mainly by CYP3A4 and produces a rapid blood concentration-dependent platelet inhibitory effect. Unlike other P2Y12 receptor antagonists, many clinical features of ticagrelor are not related to P2Y12 receptor antagonism.

PURPOSE

This review aims to gather existing literature on the clinical effects of ticagrelor after inhibiting adenosine uptake.

METHODOLOGY

The current study reviewed literature related to the effects of ticagrelor on adenosine metabolism. The review also examined the drug's biological effects and clinical characteristics to see how it could be used in a clinical setting.

RESULTS

Many studies have shown that ticagrelor can inhibit equilibrative nucleoside transporter 1 (ENT1). This inhibition leads to intracellular adenosine uptake, increased adenosine half-life and plasma concentration levels and an enhanced adenosine-mediated biological effect.

CONCLUSIONS

Based on the studies reviewed, it was found that ticagrelor essentially inhibits adenosine absorption of adenosine into cells through ENT1, which increases the concentration in the blood and subsequently increases the protection of the heart muscle by adenosine. It also prevents platelet aggregation, and extends the biological effects of coronary arteries. Moreover, it leads to a lower mortality rate in acute coronary syndrome (ACS) patients.

Targeted pharmacotherapy for ischemia reperfusion injury in acute myocardial infarction

INTRODUCTION

Achieving reperfusion immediately after acute myocardial infarction improves outcomes; despite this, patients remain at a high risk for mortality and morbidity at least for the first year after the event. Ischemia-reperfusion injury (IRI) has a complex pathophysiology and plays an important role in myocardial tissue injury, repair, and remodeling.

AREAS COVERED

In this review, the authors discuss the various mechanisms and their pharmacological agents currently available for reducing myocardial ischemia-reperfusion injury (IRI). They review important original investigations and trials in various clinical databases for treatments targeting IRI.

EXPERT OPINION

Encouraging results observed in many preclinical studies failed to show similar success in attenuating myocardial IRI in large-scale clinical trials. Identification of critical risk factors for IRI and targeting them individually rather than one size fits all approach should be the major focus of future research. Various newer therapies like tocilizumab, anakinra, colchicine, revacept, and therapies targeting the reperfusion injury salvage kinase pathway, survivor activating factor enhancement, mitochondrial pathways, and angiopoietin-like peptide 4 hold promise for the future.

Rationale and Design of the High Platelet Inhibition with Ticagrelor to Improve Left Ventricular Remodeling in Patients with ST-Segment Elevation Myocardial Infarction (HEALING-AMI) Trial

BACKGROUND AND OBJECTIVES

Impaired recovery from left ventricular (LV) dysfunction is a major prognostic factor after myocardial infarction (MI). Because P2Y₁₂ receptor blockade inhibits myocardial injury, ticagrelor with off-target properties may have myocardial protection over clopidogrel. In animal models, ticagrelor vs. clopidogrel protects myocardium against reperfusion injury and improves remodeling after MI. We aimed to investigate the effect of ticagrelor on sequential myocardial remodeling process after MI.

METHODS

High platelet inhibition with ticagrelor to improve LV remodeling in patients with ST-segment elevation MI (HEALING-AMI) is an investigator-initiated, randomized, open-label, assessor-blinded, multi-center trial done at 10 sites in Korea. Patients will be enrolled if they have ST-segment elevation MI (STEMI) treated with primary percutaneous coronary intervention and a planned duration of dual antiplatelet treatment of at least 6 months. Screened patients will be randomly assigned (1:1) using an internet-based randomization with a computer-generated blocking with stratification across study sites to either ticagrelor or clopidogrel treatment. The co-primary primary endpoints are LV remodeling index with three-dimensional echocardiography and the level of N-terminal prohormone B-type natriuretic peptide (NT-proBNP) at 6 months representing post-MI remodeling processes. Changes of LV end-systolic/diastolic volume indices and LV ejection fraction between baseline and 6-month follow-up will be also evaluated. Analysis is per protocol.

CONCLUSIONS

HEALING-AMI is testing the effect of ticagrelor in reducing adverse LV remodeling following STEMI. Our trial would show the benefit of ticagrelor vs. clopidogrel related to the recovery of post-MI LV dysfunction beyond potent platelet inhibition.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02224534.

The Platelet Response to Tissue Injury

In recent years, various studies have increasingly explained platelet functions not only in their central role as a regulator in cellular hemostasis and coagulation. In fact, there is growing evidence that under specific conditions, platelets act as a mediator between the vascular system, hemostasis, and the immune system. Therefore, they are essential in many processes involved in tissue remodeling and tissue reorganization after injury or inflammatory responses. These processes include the promotion of inflammatory processes, the contribution to innate and adaptive immune responses during bacterial and viral infections, the modulation of angiogenesis, and the regulation of cell apoptosis in steady-state tissue homeostasis or after tissue breakdown. All in all platelets may contribute to the control of tissue homeostasis much more than generally assumed. This review summarizes the current knowledge of platelets as part of the tissue remodeling network and seeks to provide possible translational implications for clinical therapy.