Impact of early abciximab administration on infarct size in patients with ST-elevation myocardial infarction

Acute Coronary Syndromes (ACS)-Unravelling Biology to Identify New Therapies-The Microcirculation as a Frontier for New Therapies in ACS

In acute coronary syndrome (ACS) patients, restoring epicardial culprit vessel patency and flow with percutaneous coronary intervention or coronary artery bypass grafting has been the mainstay of treatment for decades. However, there is an emerging understanding of the crucial role of coronary microcirculation in predicting infarct burden and subsequent left ventricular remodelling, and the prognostic significance of coronary microvascular obstruction (MVO) in mortality and morbidity. This review will elucidate the multifaceted and interconnected pathophysiological processes which underpin MVO in ACS, and the various diagnostic modalities as well as challenges, with a particular focus on the invasive but specific and reproducible index of microcirculatory resistance (IMR). Unfortunately, a multitude of purported therapeutic strategies to address this unmet need in cardiovascular care, outlined in this review, have so far been disappointing with conflicting results and a lack of hard clinical end-point benefit. There are however a number of exciting and novel future prospects in this field that will be evaluated over the coming years in large adequately powered clinical trials, and this review will briefly appraise these.

Sonothrombolysis in the ambulance for ST-elevation myocardial infarction: rationale and protocol

Background

Treatment of ST-elevation myocardial infarction (STEMI) has improved over the years. Current challenges in the management of STEMI are achievement of early reperfusion and the prevention of microvascular injury. Sonothrombolysis has emerged as a potential treatment for acute myocardial infarction, both for epicardial recanalisation as well as improving microvascular perfusion. This study aims to determine safety and feasibility of sonothrombolysis application in STEMI patients in the ambulance.

Methods

Ten patients with STEMI will be included and treated with sonothrombolysis in the ambulance during transfer to the PCI centre. Safety will be assessed by the occurrence of ventricular arrhythmias and shock during sonothrombolysis intervention. Feasibility will be assessed by the extent of protocol completion and myocardial visibility. Efficacy will be determined by angiographic patency rate, ST-elevation resolution, infarct size and left ventricular volumes, and function measured with cardiovascular magnetic resonance imaging, and contrast and strain echocardiography. A comparison will be made with matched controls using an existing STEMI database.

Discussion

Sonothrombolysis is a novel technique for the treatment of cardiovascular thromboembolic disease. The first clinical trials on its use for STEMI have demonstrated promising results. This study will be the first to examine the feasibility of in-ambulance sonothrombolysis for STEMI.

Trial registration

EU Clinical Trials Register (identifier: 2019-001883-31), registered 2020-02-25.

Antithrombotic therapy before, during and after emergency angioplasty for ST elevation myocardial infarction

The first three hours after symptom onset hold the maximum potential for myocardial reperfusion and salvage in ST-elevation myocardial infarction (STEMI) patients. During this period timely primary percutaneous coronary intervention (PPCI) or, when PPCI is not promptly feasible, pre-hospital administration of fibrinolyis or a glycoprotein IIb/IIIa-inhibitor (GPI) have been shown to restore coronary patency and reperfusion and even result in myocardial infarction (MI) abortion. On the other hand, oral antiplatelet therapy may not yet guarantee sufficient platelet inhibition. Patients presenting after this golden time have less, if any, benefit from an aggressive antithrombotic treatment prior to PPCI. Antithrombotic treatment during primary angioplasty should be tailored on the basis of the coronary thrombotic burden, vascular approach and the patient's risk of bleeding complications. A GPI-based approach may be favourable in patients presenting early with large MI and high thrombus burden, whereas a bivalirudin-based approach without GPI may be preferred in patients with higher bleeding risk. There are no data to support the use of GPI in bailout conditions. The powerful oral P2Y₁₂ inhibitors, prasugrel and ticagrelor, have been clearly shown to prevent stent thrombosis and recurrent ischaemic events after emergency percutaneous coronary intervention in STEMI patients. Open issues remaining are the treatment of patients with high bleeding risk, such as the elderly and those requiring anticoagulation, as well as the duration of dual antiplatelet therapy after STEMI.

Coronary microvascular obstruction in acute myocardial infarction

The success of a primary percutaneous intervention (PCI) in the setting of ST elevation myocardial infarction depends on the functional and structural integrity of coronary microcirculation. Coronary microvascular dysfunction and obstruction (CMVO) occurs in up to half of patients submitted to apparently successful primary PCI and is associated to a much worse outcome. The current review summarizes the complex mechanisms responsible for CMVO, including pre-existing coronary microvascular dysfunction, and highlights the current limitations in the assessment of microvascular function. More importantly, at the light of the substantial failure of trials hitherto published on the treatment of CMVO, this review proposes a novel integrated therapeutic approach, which should overcome the limitations of previous studies.

Pharmacologic Therapy for Reducing Myocardial Infarct Size in Clinical Trials

In patients with acute ST-segment elevation myocardial infarction, early, successful, and durable reperfusion therapy optimizes the likelihood of favorable outcomes. Fibrinolysis and primary percutaneous coronary intervention improve survival compared to no reperfusion therapy in large part by reducing infarct size (IS) and preserving left ventricular ejection fraction. There is direct correlation between IS and clinical outcomes. In this article, we will review some of the more promising pharmacological agents geared toward reduction in IS, discuss the major pathways that can lead to this desirable outcome, and evaluate the results of clinical trials performed with these and other compounds.

Current state of clinical translation of cardioprotective agents for acute myocardial infarction

There is continued interest in the concept of limiting myocardial infarct size with adjunctive agents administered along with reperfusion injury; however, there remains considerable controversy in the literature. The purpose of this article is to review the medical literature on clinical trials performed during the past 3 years that have attempted to reduce myocardial infarct size by administration of adjunctive therapies along with reperfusion therapy. A PubMed-driven literature search revealed a host of clinical trials focusing on the following prominent types of therapies: endogenous conditioning (postconditioning and remote ischemic conditioning); rapid cooling; pharmacological therapy (cyclosporine, abciximab, clopidogrel, tirofiban, erythropoietin, thrombus aspiration, adenosine, glucose-insulin-potassium, statins, antidiabetic agents, FX06, iron chelation, and ranolazine). Although there remains some controversy, quite a few of these studies showed that adjunctive therapy further reduced myocardial infarct size when coupled with reperfusion. Antiplatelet agents are emerging as some of the newest agents that seem to have cardioprotective capabilities. Postconditioning has become a bit more controversial in the clinical literature; remote conditioning, early and rapid cooling, adenosine, and ranolazine are intriguing therapies deserving of larger studies. Certain agents and maneuvers, such as erythropoietin, protein kinase C δ inhibitors, iron chelation, and intra-aortic balloon counterpulsation, perhaps should be retired. The correct adjunctive therapy administered along with reperfusion has the capability of further reducing myocardial injury during ST-segment-elevation myocardial infarction.

Strategies TO reduce time delays in patients with AcuTe coronary heart disease treated with primary PCI--the STOP WATCH study: a multistage action research project

OBJECTIVE

To identify, evaluate and reduce system delay times in an ST-elevation myocardial infarction (STEMI) network by targeted reorganisation of logistics and personal feedback to staff on time delays.

DESIGN

Multistage action research project. Three study phases were used (exploration, tailored intervention and evaluation).

SETTING

Single centre study, Sweden.

PATIENTS

Consecutive patients (N=156) with prehospital STEMI onset treated with primary percutaneous coronary intervention (PCI).

INTERVENTIONS

Areas of delays were identified through participant observations and collaborative discussions. To increase the awareness of delay factors, continuous feedback on time delays was given. Elements of the logistics' reorganisation were (1) prioritised ECG recording by emergency medical services personnel, (2) central evaluation of ECG in all patients and (3) start of PCI procedure when two of three PCI team members were on site. Multiple key time measurements were made before (N=67) and after (N=89) the intervention.

MAIN OUTCOMES

Time difference (minutes) in system delay between the preintervention and postintervention phases.

RESULTS

Time from first medical contact (FMC) to a patent artery and time from FMC-to-catheter laboratory (cath-lab) arrival decreased by 6 and 12 min, respectively (ns). Time from FMC-to-ECG recording remained unchanged after the intervention. Time from ECG to decision for primary PCI was reduced by 6 min, p=0.004 and time from ECG-to-cath-lab arrival by 11 min, p=0.02. Total time from diagnosis to a patent artery decreased by 11 min (ns).

CONCLUSIONS

Identification of time delays in an STEMI network with awareness of delay factors, reorganisation of logistics and continuous feedback can reduce system delay times significantly.

Early glycoprotein IIb-IIIa inhibitors in primary angioplasty-abciximab long-term results (EGYPT-ALT) cooperation: individual patient's data meta-analysis

BACKGROUND

Even although time to treatment has been shown to be a determinant of mortality in primary angioplasty, the potential benefits are still unclear from early pharmacological reperfusion by glycoprotein (Gp) IIb-IIIa inhibitors. Therefore, the aim of this meta-analysis was to combine individual data from all randomized trials conducted on upstream as compared with late peri-procedural abciximab administration in primary angioplasty.

METHODS

The literature was scanned using formal searches of electronic databases (MEDLINE and EMBASE) from January 1990 to December 2010. All randomized trials on upstream abciximab administration in primary angioplasty were examined. No language restrictions were enforced.

RESULTS

We included a total of seven randomized trials enrolling 722 patients, who were randomized to early (n = 357, 49.4%) or late (n = 365, 50.6%) peri-procedural abciximab administration. No difference in baseline characteristics was observed between the two groups. Follow-up data were collected at a median (25th-75th percentiles) of 1095 days (720-1967). Early abciximab was associated with a significant reduction in mortality (primary endpoint) [20% vs. 24.6%; hazard ratio (HR) 95% confidence interval (CI) = 0.65 (0.42-0.98) P = 0.02, P(het) = 0.6]. Furthermore, early abciximab administration was associated with a significant improvement in pre-procedural thrombolysis in myocardial infarction (TIMI) 3 flow (21.6% vs. 10.1%, P < 0.0001), post-procedural TIMI 3 flow (90% vs. 84.8%, P = 0.04), an improvement in myocardial perfusion as evaluated by post-procedural myocardial blush grade (MBG) 3 (52.0% vs. 43.2%, P = 0.03) and ST-segment resolution (58.4% vs. 43.5%, P < 0.0001) and significantly less distal embolization (10.1% vs. 16.2%, P = 0.02). No difference was observed in terms of major bleeding complications between early and late abciximab administration (3.3% vs. 2.3%, P = 0.4).

CONCLUSIONS

This meta-analysis shows that early upstream administration of abciximab in patients undergoing primary angioplasty for ST-segment elevation myocardial infarction (STEMI) is associated with significant benefits in terms of pre-procedural epicardial re-canalization and ST-segment resolution, which translates in to significant mortality benefits at long-term follow-up.