Open-label, randomized, placebo-controlled evaluation of intracoronary adenosine or nitroprusside after thrombus aspiration during primary percutaneous coronary intervention for the prevention of microvascular obstruction in acute myocardial infarction: the REOPEN-AMI study (Intracoronary Nitroprusside Versus Adenosine in Acute Myocardial Infarction)

Adenosine in Interventional Cardiology: Physiopathologic and Pharmacologic Effects in Coronary Artery Disease

This review article focuses on the role of adenosine in coronary artery disease (CAD) diagnosis and treatment. Adenosine, an endogenous purine nucleoside, plays crucial roles in cardiovascular physiology and pathology. Its release and effects, mediated by specific receptors, influence vasomotor function, blood pressure regulation, heart rate, and platelet activity. Adenosine therapeutic effects include treatment of the no-reflow phenomenon and paroxysmal supraventricular tachycardia. The production of adenosine involves complex cellular pathways, with extracellular and intracellular synthesis mechanisms. Adenosine's rapid metabolism underscores its short half-life and physiological turnover. Furthermore, adenosine's involvement in side effects of antiplatelet therapy, particularly ticagrelor and cangrelor, highlights its clinical significance. Moreover, adenosine serves as a valuable tool in CAD diagnosis, aiding stress testing modalities and guiding intracoronary physiological assessments. Its use in assessing epicardial stenosis and microvascular dysfunction is pivotal for treatment decisions. Overall, understanding adenosine's mechanisms and clinical implications is essential for optimizing CAD management strategies, encompassing both therapeutic interventions and diagnostic approaches.

Treatment and Care of Patients with ST-Segment Elevation Myocardial Infarction-What Challenges Remain after Three Decades of Primary Percutaneous Coronary Intervention?

Primary percutaneous coronary intervention (pPCI) has revolutionized the prognosis of ST-segment elevation myocardial infarction (STEMI) and is the gold standard treatment. As a result of its success, the number of pPCI centres has expanded worldwide. Despite decades of advancements, clinical outcomes in STEMI patients have plateaued. Out-of-hospital cardiac arrest and cardiogenic shock remain a major cause of high in-hospital mortality, whilst the growing burden of heart failure in long-term STEMI survivors presents a growing problem. Many elements aiming to optimize STEMI treatment are still subject to debate or lack sufficient evidence. This review provides an overview of the most contentious current issues in pPCI in STEMI patients, with an emphasis on unresolved questions and persistent challenges.

Coronary microvascular obstruction and dysfunction in patients with acute myocardial infarction

Despite prompt epicardial recanalization in patients presenting with ST-segment elevation myocardial infarction (STEMI), coronary microvascular obstruction and dysfunction (CMVO) is still fairly common and is associated with poor prognosis. Various pharmacological and mechanical strategies to treat CMVO have been proposed, but the positive results reported in preclinical and small proof-of-concept studies have not translated into benefits in large clinical trials conducted in the modern treatment setting of patients with STEMI. Therefore, the optimal management of these patients remains a topic of debate. In this Review, we appraise the pathophysiological mechanisms of CMVO, explore the evidence and provide future perspectives on strategies to be implemented to reduce the incidence of CMVO and improve prognosis in patients with STEMI.

Chinese expert consensus on the diagnosis and treatment of coronary microvascular diseases (2023 Edition)

Since the four working groups of the Chinese Society of Cardiology issued first expert consensus on coronary microvascular diseases (CMVD) in 2017, international consensus documents on CMVD have increased rapidly. Although some of these documents made preliminary recommendations for the diagnosis and treatment of CMVD, they did not provide classification of recommendations and levels of evidence. In order to summarize recent progress in the field of CMVD, standardize the methods and procedures of diagnosis and treatment, and identify the scientific questions for future research, the four working groups of the Chinese Society of Cardiology updated the 2017 version of the Chinese expert consensus on CMVD and adopted a series of measures to ensure the quality of this document. The current consensus has raised a new classification of CMVD, summarized new epidemiological findings for different types of CMVD, analyzed key pathological and molecular mechanisms, evaluated classical and novel diagnostic technologies, recommended diagnostic pathways and criteria, and therapeutic strategies and medications, for patients with CMVD. In view of the current progress and knowledge gaps of CMVD, future directions were proposed. It is hoped that this expert consensus will further expedite the research progress of CMVD in both basic and clinical scenarios.

The effect of nicorandil on cardiac function and clinical outcomes in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention: a randomised trial

BACKGROUND

We investigated the effect of nicorandil on infarct size, cardiac function assessed by cardiac magnetic resonance imaging (CMR) and outcomes in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI).

METHODS

In a prospective, randomised, controlled trial, 83 patients with STEMI receiving primary PCI were randomised into the nicorandil (n =  40) or placebo (n  =  43) groups. Nicorandil was administered in the emergency room before primary PCI as an intravenous bolus of 4 mg followed by a continuous infusion of 6 mg/h for 24 h and as 2-mg intracoronary injections prior to balloon dilatation and coronary stenting. Nicorandil was continued orally at 10-20 mg/d for 6 months. Infarct size and cardiac function were measured by CMR at 5 d and 6 months after primary PCI. Furthermore, major adverse cardiac events (MACEs) including all-cause death, nonfatal myocardial infarction (MI), any revascularisation, stroke, and definite/probable stent thrombosis (ST) were compared.

RESULTS

There were no significant differences in baseline clinical characteristics between the groups. Infarct size at baseline and 6 months as well as infarct size changes during 6 months as measured by CMR were similar between the groups. Similarly, other CMR parameters were comparable at baseline and 6 months between the groups. MACEs occurred in four patients (4.8%) during 6 months. No significant difference in the risk of MACEs was observed between the groups.

CONCLUSIONS

Treatment with nicorandil for 6 months after primary PCI was not associated with any improvement in infarct size, CMR-determined cardiac function, and outcomes in STEMI patients.

Coronary No-Reflow after Primary Percutaneous Coronary Intervention-Current Knowledge on Pathophysiology, Diagnosis, Clinical Impact and Therapy

Coronary no-reflow (CNR) is a frequent phenomenon that develops in patients with ST-segment elevation myocardial infarction (STEMI) following reperfusion therapy. CNR is highly dynamic, develops gradually (over hours) and persists for days to weeks after reperfusion. Microvascular obstruction (MVO) developing as a consequence of myocardial ischemia, distal embolization and reperfusion-related injury is the main pathophysiological mechanism of CNR. The frequency of CNR or MVO after primary PCI differs widely depending on the sensitivity of the tools used for diagnosis and timing of examination. Coronary angiography is readily available and most convenient to diagnose CNR but it is highly conservative and underestimates the true frequency of CNR. Cardiac magnetic resonance (CMR) imaging is the most sensitive method to diagnose MVO and CNR that provides information on the presence, localization and extent of MVO. CMR imaging detects intramyocardial hemorrhage and accurately estimates the infarct size. MVO and CNR markedly negate the benefits of reperfusion therapy and contribute to poor clinical outcomes including adverse remodeling of left ventricle, worsening or new congestive heart failure and reduced survival. Despite extensive research and the use of therapies that target almost all known pathophysiological mechanisms of CNR, no therapy has been found that prevents or reverses CNR and provides consistent clinical benefit in patients with STEMI undergoing reperfusion. Currently, the prevention or alleviation of MVO and CNR remain unmet goals in the therapy of STEMI that continue to be under intense research.

A historical literature review of coronary microvascular obstruction and intra-myocardial hemorrhage as functional/structural phenomena

The analysis of experimental data demonstrates that platelets and neutrophils are involved in the no-reflow phenomenon, also known as microvascular obstruction (MVO). However, studies performed in the isolated perfused hearts subjected to ischemia/reperfusion (I/R) do not suggest the involvement of microembolization and microthrombi in this phenomenon. The intracoronary administration of alteplase has been found to have no effect on the occurrence of MVO in patients with acute myocardial infarction. Consequently, the major events preceding the appearance of MVO in coronary arteries are independent of microthrombi, platelets, and neutrophils. Endothelial cells appear to be the target where ischemia can disrupt the endothelium-dependent vasodilation of coronary arteries. However, reperfusion triggers more pronounced damage, possibly mediated by pyroptosis. MVO and intra-myocardial hemorrhage contribute to the adverse post-infarction myocardial remodeling. Therefore, pharmacological agents used to treat MVO should prevent endothelial injury and induce relaxation of smooth muscles. Ischemic conditioning protocols have been shown to prevent MVO, with L-type Ca ²⁺ channel blockers appearing the most effective in treating MVO.

The SALINE Technique for the Treatment of the No-Reflow Phenomenon during Percutaneous Coronary Intervention in STEMI

BACKGROUND

Primary percutaneous coronary intervention (pPCI) performed for STEMI may be complicated by the "no-reflow" phenomenon.

AIMS

A super-selective intracoronary injection of saline solution through a thrombus aspiration catheter (SALINE technique), was investigated for the treatment of no-reflow as compared with the standard care of therapy (SCT).

METHODS

Among the 1471 patients with STEMI undergoing pPCI between May 2015 and June 2020, 168 patients developed no-reflow. Primary endpoints were the incidence of ST-segment resolution (STR) ≥ 70% at 90 min after PCI and the rate of flow restoration (TIMI flow grade 3 with an MBG > 1). The secondary endpoint was the incidence of major adverse cardiac and cerebrovascular events at 3 years follow-up.

RESULTS

After propensity score matching analysis, patients treated with SALINE showed STR ≥ 70% in twelve out of the sixteen patients (75.0%), compared to only three patients out of the sixteen in the SCT control group (19.0%), (p < 0.004). SALINE was associated with a higher probability of final TIMI flow grade 3 with an MBG > 1, as shown in fourteen out of sixteen patients (87.5%), as compared to only seven out of sixteen patients in the SCT group (43.8%), (p < 0.03). MACCE at 3 years follow-up occurred in only one patient (6.3%) in the SALINE group, as compared to eight patients (50%) in the SCT group (p = 0.047).

CONCLUSIONS

The SALINE technique showed to be a safe and effective strategy to reduce "no-reflow" in STEMI patients as assessed by significant STR, improvement of TIMI flow grade, and better 3-year outcomes.

Adenosine as adjunctive therapy in acute coronary syndrome: a meta-analysis of randomized controlled trials

AIMS

Adenosine has been tested in several randomized controlled trials (RCTs) to minimize the incidence of coronary microvascular obstruction (CMVO). The aim of this study was to pool all the RCTs comparing intracoronary or intravenous adenosine versus placebo in patients with acute coronary syndrome (ACS) undergoing myocardial revascularization.

METHODS AND RESULTS

PubMed and Scopus electronic databases were scanned for eligible studies up to 5th June 2022. A total of 26 RCTs with 5843 patients were included. Efficacy endpoints were major adverse cardiac events (MACE), all-cause death, non-fatal myocardial infarction, and heart failure. Atrioventricular blocks and ventricular fibrillation/sustained ventricular tachycardia (VF/SVT) were the safety endpoints. Myocardial blush grade, thrombolysis in myocardial infarction (TIMI) flow grade, left ventricular ejection fraction (LVEF), infarct size, and ST-segment resolution were also assessed. Adenosine administration was not associated with any clinical benefit in terms of MACE, all-cause death, non-fatal myocardial infarction, and heart failure. However, adenosine was associated with an increased rate of advanced atrioventricular blocks and of VF/SVT in studies with total mean ischaemic time >3 h, compared to placebo. Remarkably, among patients undergoing percutaneous coronary intervention, adenosine was associated with reduced myocardial blush grade 0-1 and TIMI flow grade 0-2, compared to placebo. Furthermore, adenosine did not show favourable effects on LVEF and infarct size.

CONCLUSION

Adenosine infusion, as adjunctive therapy in ACS, was associated with an increased risk of advanced atrioventricular blocks and increased rates of adenosine-triggered ventricular arrhythmias in patients with long ischaemic time, without providing any clinical benefit compared to placebo.

High mobility group box 1 derived mainly from platelet microparticles exacerbates microvascular obstruction in no reflow

INTRODUCTION

No reflow manifests coronary microvascular injury caused by continuous severe myocardial ischemia and reperfusion. Microvascular obstruction (MVO) has emerged as one fundamental mechanism of no reflow. However, the underlying pathophysiology remains incompletely defined. Herein, we explore the contribution of high mobility group box 1 (HMGB1), derived mainly from platelet microparticles exacerbating MVO in no reflow.

MATERIALS AND METHODS

44 STEMI patients undergoing successful primary percutaneous coronary intervention (PCI) were included in our study. Plasma HMGB1 levels in both the peripheral artery (PA) and infarct-related coronary artery (IRA) were measured by ELISA. Flow cytometry and confocal microscopy assessed the level of HMGB1⁺ platelet derived microparticles (PMPs) and platelet activation. Flow cytometry and western blot evaluated the procoagulant activity (PCA) and the release of inflammatory factors of human microvascular endothelial cells (HCEMCs).

RESULTS

HMGB1 levels were significantly higher in the IRA in no-reflow patients. The levels of HMGB1⁺ PMPs were considerably higher in the IRA of patients with no reflow and were strongly associated with platelet activation. Moreover, our results show that HMGB1 interacts with human microvascular endothelial cells primarily through TLR4, inducing HCMEC proinflammatory, procoagulant phenotype, and monocyte recruitment, accelerating microvascular obstruction and facilitating the development of no reflow.

CONCLUSION

Our results illustrate a novel mechanism by which HMGB1, derived mainly from PMPs, plays a crucial role in the pathogenesis of no-reflow, revealing a novel therapeutic target.

Functional angiography-derived index of microcirculatory resistance validated with microvascular obstruction in cardiac magnetic resonance after STEMI

INTRODUCTION AND OBJECTIVES

The index of microcirculatory resistance (IMR) measured after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is associated with microvascular obstruction (MVO) and adverse clinical events. To evaluate MVO after successful primary PCI for STEMI without pressure wires or hyperemic agents, we investigated the feasibility and usefulness of functional angiography-derived IMR (angio-IMR).

METHODS

The current study included a total of 285 STEMI patients who underwent primary PCI and cardiac magnetic resonance (CMR). Angio-IMR of the culprit vessel after successful primary PCI was calculated using commercial software. MVO, infarct size, and myocardial salvage index were assessed using CMR, which was obtained a median of 3.0 days [interquartile range, 3.0-5.0] after primary PCI.

RESULTS

Among the total population, 154 patients (54.0%) showed elevated angio-IMR (> 40 U) in the culprit vessel. MVO was significantly more prevalent in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (88.3% vs 32.1%, P <.001). Infarct size, extent of MVO, and area at risk were significantly larger in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (P <.001 for all). Angio-IMR showed a significantly higher discriminatory ability for the presence of MVO than thrombolysis in myocardial infarction flow grade or myocardial blush grade (area under the curve: 0.821, 0.504, and 0.496, respectively, P <.001).

CONCLUSIONS

Angio-IMR was significantly associated with CMR-derived infarct size, extent of MVO, and area at risk. An elevated angio-IMR (> 40 U) after primary PCI for STEMI was highly predictive of the presence of MVO in CMR. This trial was registered at ClnicalTrialsgov (Identifier: NCT04828681).

Small molecules as modulators of regulated cell death against ischemia/reperfusion injury

Ischemia/reperfusion (IR) injury contributes to disability and mortality worldwide. Due to the complicated mechanisms and lack of proper therapeutic targets, few interventions are available that specifically target the pathogenesis of IR injury. Regulated cell death (RCD) of endothelial and parenchymal cells is recognized as the promising intervening target. Recent advances in IR injury suggest that small molecules exhibit beneficial effects on various RCD against IR injury, including apoptosis, necroptosis, autophagy, ferroptosis, pyroptosis, and parthanatos. Here, we describe the mechanisms behind these novel promising therapeutic targets and explain the machinery powering the small molecules. These small molecules exert protection by targeting endothelial or parenchymal cells to alleviate IR injury. Therapies of the ideal combination of small molecules targeting multiple cell types have shown potent synergetic therapeutic effects, laying the foundation for novel strategies to attenuate IR injury.

“No-Reflow” Phenomenon: A Contemporary Review

Primary percutaneous angioplasty (pPCI), represents the reperfusion strategy of choice for patients with STEMI according to current international guidelines of the European Society of Cardiology. Coronary no-reflow is characterized by angiographic evidence of slow or no anterograde epicardial flow, resulting in inadequate myocardial perfusion in the absence of evidence of mechanical vessel obstruction. No reflow (NR) is related to a functional and structural alteration of the coronary microcirculation and we can list four main pathophysiological mechanisms: distal atherothrombotic embolization, ischemic damage, reperfusion injury, and individual susceptibility to microvascular damage. This review will provide a contemporary overview of the pathogenesis, diagnosis, and treatment of NR.

Complementary Pharmacotherapy for STEMI Undergoing Primary PCI: An Evidence-Based Clinical Approach

Antithrombotic therapy is the cornerstone of pharmacological treatment in patients undergoing primary percutaneous coronary intervention (PCI). However, the acute management of ST elevation myocardial infarction (STEMI) patients includes therapy for pain relief and potential additional strategies for cardioprotection. The safety and efficacy of some commonly used treatments have been questioned by recent evidence. Indeed a concern about morphine use is the interaction between opioids and oral P2Y₁₂ inhibitors; early beta-blocker treatment has shown conflicting results for the improvement of clinical outcomes; and supplemental oxygen therapy lacks benefit in patients without hypoxia and may be of potential harm. Other additional strategies remain disappointing; however, some treatments may be selectively used. Therefore, we intend to present a critical updated review of complementary pharmacotherapy for a modern treatment approach for STEMI patients undergoing primary PCI.

Pathophysiology, Diagnosis, and Management of Coronary No-Reflow Phenomenon

Coronary no-reflow phenomenon is a lethal mechanism of ongoing myocardial injury following successful revascularization of an infarct-related coronary artery. Incidence of this phenomenon is high following percutaneous intervention and is associated with adverse in-hospital and long-term outcomes. Several mechanisms such as ischemia-reperfusion injury and distal microthromboembolism in genetically susceptible patients and those with preexisting endothelial dysfunction have been implicated. However, the exact mechanism in humans is still poorly understood. Several investigative and treatment strategies within and outside the cardiac catheterization laboratory have been proposed, but they have not uniformly shown success in reducing mortality or in preventing adverse left ventricular remodeling resulting from this condition. The aim of this article is to provide a brief and concise review of the current understanding of the pathophysiology, clinical predictors, and investigations and management of coronary no-reflow phenomenon.

A fresh look at coronary microembolization

Mechanical stress from haemodynamic perturbations or interventional manipulation of epicardial coronary atherosclerotic plaques with inflammatory destabilization can release particulate debris, thrombotic material and soluble substances into the coronary circulation. The physical material obstructs the coronary microcirculation, whereas the soluble substances induce endothelial dysfunction and facilitate vasoconstriction. Coronary microvascular obstruction and dysfunction result in patchy microinfarcts accompanied by an inflammatory reaction, both of which contribute to progressive myocardial contractile dysfunction. In clinical studies, the benefit of protection devices to retrieve atherothrombotic debris during percutaneous coronary interventions has been modest, and the treatment of microembolization has mostly relied on antiplatelet and vasodilator agents. The past 25 years have witnessed a relative proportional increase in non-ST-segment elevation myocardial infarction in the presentation of acute coronary syndromes. An associated increase in the incidence of plaque erosion rather than rupture has also been recognized as a key mechanism in the past decade. We propose that coronary microembolization is a decisive link between plaque erosion at the culprit lesion and the manifestation of non-ST-segment elevation myocardial infarction. In this Review, we characterize the features and mechanisms of coronary microembolization and discuss the clinical trials of drugs and devices for prevention and treatment.

Predictive value of C-reactive protein/albumin ratio for no-reflow in patients with non-ST-elevation myocardial infarction

Introduction: The focus of this research was to explore the link between CRP (C-reactive protein) /albumin ratio (CAR), a novel inflammatory response marker, and no-reflow (NR) phenomena in non-ST elevation myocardial infarction (non-STEMI) patients during percutaneous coronary intervention (PCI). Methods: The current study recruited 209 non-STEMI participants who underwent PCI. The patients were divided into two groups based on their post-intervention Thrombolysis in Myocardial Infarction (TIMI) flow grade; those with and without NR. Results: In all, 30 non-STEMI patients (6.9%) had NR after PCI. CAR values were substantially greater in the NR group. The CAR was identified to be a determinant of the NR (OR: 1.250, 95% CI: 1.033-1.513, P=0.02), although CRP and albumin were not independently related with NR in the multivariate analysis. In our investigation, low density lipoprotein-cholesterol levels and high thrombus burden were also predictors of the occurrence of NR. According to receiver operating characteristic curve evaluation, the optimal value of CAR was>1.4 with 60% sensitivity and 47% specificity in detecting NR in non-STEMI patients following PCI. Conclusion: To the best of knowledge, this is the first investigation to demonstrate that the CAR, a new and useful inflammatory marker, can be utilized as a predictor of NR in patients with non-STEMI prior to PCI.

[Our enemy : the clot. Coronary thrombosis : strategy and therapeutic arsenal]

Intra coronary thrombus is  frequently encountered during acute coronary syndromes revascularisation procedures. It can also be encountered during angioplasty procedures in a stable angina context, although at a much lesser frequency.In both situations, it harbors a risk of poor angiographic result and poor prognosis. Intracoronnary thrombus may cause coronary occlusion at the angioplasty site or distal embolic  flow obstruction. Per procedure thrombus prevention rests on an prior optimal anti thrombotic treatment and in some circumstances the choice to defer the revascularisation procedure in the complex high risk setting. Treating the initiated thrombus remains controversial concerning thrombectomy and GPIIBIIIa inhibitors which are still in use in common practice. No reflow phenomenon is a particularly complex setting during cornary angioplasties, partially but not solely related to a thrombotic complication. It's treatment remains unclear in the absence of related oriented studies.The current mechanical and pharmacological antithrombotic therapies must remain common practice and used appropriately as of the clinical and angiographic setting, until further scientific outbrakes.

The effectiveness of alprostadil in treating coronary microcirculation dysfunction following ST-segment elevation myocardial infarction in a pig model

Though alprostadil has been reported to improve the impaired microcirculation of patients with pulmonary arterial hypertension, its effectiveness as a treatment for coronary microvasculature dysfunction (CMD) following ST-segment elevation myocardial infarction (STEMI) is unknown. A total of 18 miniature pigs with CMD following STEMI were randomized into three groups that received an intracoronary injection of 5 ml of normal saline, 2 mg of nicorandil or 10 µg of alprostadil immediately after measurement of the index of microcirculatory resistance (IMR) and then an intravenous drip containing 5 ml of normal saline, 2 mg of nicorandil or 10 µg of alprostadil once a day for 6 days. The IMR, cardiac function using ultrasound, infarct areas and heparanase levels in infarct areas were measured and compared between the three groups. The IMR decreased markedly 10 min after alprostadil or nicorandil intracoronary injection (both P<0.05) but not following saline injection (P>0.05). After 7 days, the IMR was substantially lower in the alprostadil and nicorandil groups compared with the saline group (both P<0.05) and the ejection fraction was considerably higher in the alprostadil and nicorandil groups compared with the saline group (both P<0.05). Differences in infarct areas and the relative heparanase expression levels among the 3 groups were similar to the differences in the ejection fraction. No significant differences in the above assessment indexes were identified in the alprostadil and nicorandil groups. Alprostadil infusion improved coronary microcirculation function, reduced the infarct area and limited left ventricular dilatation in a pig coronary microvasculature dysfunction model following STEMI.

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.

Reducing Cardiac Injury during ST-Elevation Myocardial Infarction: A Reasoned Approach to a Multitarget Therapeutic Strategy

The significant reduction in ‘ischemic time’ through capillary diffusion of primary percutaneous intervention (pPCI) has rendered myocardial-ischemia reperfusion injury (MIRI) prevention a major issue in order to improve the prognosis of ST elevation myocardial infarction (STEMI) patients. In fact, while the ischemic damage increases with the severity and the duration of blood flow reduction, reperfusion injury reaches its maximum with a moderate amount of ischemic injury. MIRI leads to the development of post-STEMI left ventricular remodeling (post-STEMI LVR), thereby increasing the risk of arrhythmias and heart failure. Single pharmacological and mechanical interventions have shown some benefits, but have not satisfactorily reduced mortality. Therefore, a multitarget therapeutic strategy is needed, but no univocal indications have come from the clinical trials performed so far. On the basis of the results of the consistent clinical studies analyzed in this review, we try to design a randomized clinical trial aimed at evaluating the effects of a reasoned multitarget therapeutic strategy on the prevention of post-STEMI LVR. In fact, we believe that the correct timing of pharmacological and mechanical intervention application, according to their specific ability to interfere with survival pathways, may significantly reduce the incidence of post-STEMI LVR and thus improve patient prognosis.

Robotic-assisted PCI: The future of coronary intervention?

Robotic percutaneous coronary intervention (R-PCI) is a novel approach to performing percutaneous coronary intervention (PCI) whereby the operator can utilise remotely controlled technology to manipulate guidewires and catheter devices. This enables the procedure to be undertaken from within a radiation-shielded cockpit. Success in early trials has led to the release of commercially available robotic platforms which have now received regulatory approval and are available for use in clinical practice. Recent trials evaluating R-PCI have demonstrated high technical success rates with low complication rates. Despite this, a significant number of cases, particularly those with complex anatomy, still require at least partial conversion to a manual procedure. Advantages of R-PCI include accurate stent placement, reduced operator radiation exposure and a presumed reduction in orthopedic injuries. Limitations include current incompatibility with certain intravascular imaging catheters and the inability to manipulate multiple guidewires and stents simultaneously. Patients presenting with ST-elevation myocardial infarction requiring primary-PCI have also largely been excluded from existing R-PCI studies. Given these caveats, R-PCI remains a novel technology and has yet to become commonplace in cardiac catheterisation laboratories, however with increasing safety and feasibility data emerging, it is possible that R-PCI may form part of standard practice in the future.

Pathophysiology, Diagnosis, and Management of Coronary No-Reflow Phenomenon

Coronary no-reflow phenomenon is a lethal mechanism of ongoing myocardial injury, following successful revascularization of an infarct-related coronary artery. Incidence of this phenomenon is high following percutaneous intervention, and is associated with adverse in-hospital and long-term outcomes. Several mechanisms such as ischemia-reperfusion injury and distal microthromboembolism in genetically susceptible patients and those with preexisting endothelial dysfunction have been implicated. However, the exact mechanism in humans is still poorly understood. Several investigative and treatment strategies within and outside the cardiac catheterization laboratory have been proposed, but have not uniformly shown success in reducing mortality or in preventing adverse left ventricular remodeling resulting from this condition. The aim of this article is to provide a brief and concise review of the current understanding of the pathophysiology, clinical predictors, and investigations and management of coronary no-reflow phenomenon.

Novel Guidewire Design and Coating for Continuous Delivery of Adenosine During Interventional Procedures

Background

The “no‐reflow phenomenon” compromises percutaneous coronary intervention outcomes. There is an unmet need for a device that prevents no‐reflow phenomenon. Our goal was to develop a guidewire platform comprising a nondisruptive hydrophilic coating that allows continuous delivery of adenosine throughout a percutaneous coronary intervention.

Methods and Results

We developed a guidewire with spaced coils to increase surface area for drug loading. Guidewires were plasma treated to attach hydroxyl groups to metal surfaces, and a methoxy–polyethylene glycol–silanol primer layer was covalently linked to hydroxyl groups. Using polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl acetate, a drug layer containing jet‐milled adenosine was hydrogen‐bonded to the polyethylene glycol–silanol layer and coated with an outer diffusive barrier layer. Coatings were processed with a freeze/thaw curing method. In vitro release studies were conducted followed by in vivo evaluation in pigs. Coating quality, performance, and stability with sterilization were also evaluated. Antiplatelet properties of the guidewire were also determined. Elution studies with adenosine‐containing guidewires showed curvilinear and complete release of adenosine over 60 minutes. Porcine studies demonstrated that upon insertion into a coronary artery, adenosine‐releasing guidewires induced immediate and robust increases (2.6‐fold) in coronary blood flow velocity, which were sustained for ≈30 minutes without systemic hemodynamic effects or arrhythmias. Adenosine‐loaded wires prevented and reversed coronary vasoconstriction induced by acetylcholine. The wires significantly inhibited platelet aggregation by >80% in vitro. Guidewires passed bench testing for lubricity, adherence, integrity, and tracking.

Conclusions

Our novel drug‐releasing guidewire platform represents a unique approach to prevent/treat no‐reflow phenomenon during percutaneous coronary intervention.

No-reflow phenomenon in ST-segment elevation myocardial infarction: still the Achilles' heel of the interventionalist

Improvements in systems, technology and pharmacotherapy have significantly changed the prognosis over recent decades in patients presenting with ST-segment elevation myocardial infarction. These clinical achievements have, however, begun to plateau and it is becoming increasingly necessary to consider novel strategies to further improve outcomes. Approximately a third of patients treated by primary percutaneous coronary intervention for ST-segment elevation myocardial infarction will suffer from coronary no-reflow (NR), a condition characterized by poor myocardial perfusion despite patent epicardial arteries. The presence of NR impacts significantly on clinical outcomes including left ventricular dysfunction, heart failure and death, yet conventional management algorithms neither assess the risk of NR nor treat NR. This review will provide a contemporary overview on the pathogenesis, diagnosis and treatment of NR.

Initiate Danhong Injection before or after percutaneous coronary intervention for microvascular obstruction in ST-elevation myocardial infarction (DIRECTION): study protocol for a randomized controlled trial

BACKGROUND

No treatment has convincingly been proven to be beneficial for microvascular obstruction (MVO) in patients with ST-elevation myocardial infarction (STEMI). Several studies have described the effects of Danhong Injection. However, evidence of a rigorously designed verification study is still lacking, and the intervention timing of Danhong Injection is uncertain.

METHODS

The DIRECTION study is a multicenter, prospective, randomized, evaluator-blind study. A total of 336 patients with STEMI receiving percutaneous coronary intervention (PCI) will be randomly assigned to conventional treatment, the preoperative Danhong Injection, or the postoperative Danhong Injection. The primary outcome is rate of ST-segment resolution (STR) ≥ 70% at 90 min after PCI. The secondary outcomes are the degree of STR, Thrombolysis in Myocardial Infarction (TIMI) flow grade, TIMI myocardial perfusion grade, left ventricular ejection fraction, N-terminal prohormone brain natriuretic peptide, high-sensitivity C-reactive protein, and infarct size expressed as area under the curve for cardiac troponin I (cTnI) and for creatine kinase MB. The major adverse cardiovascular events and hospital readmission events will be recorded. Health quality will be assessed with the 12-item Short Form Health Survey. The safety outcomes include bleeding events, adverse events, and abnormal changes in routine blood tests. Psychological status and dietary patterns will be evaluated using Hamilton Depression Rating Scale and Food Frequency Questionnaire as the relevant indicators.

DISCUSSION

This trial will evaluate the efficacy and safety of Danhong Injection, as well as its optimal timing of intervention to prevent MVO in patients with STEMI.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1900021440. Registered on February 21, 2019.

2019 Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology Guidelines on the Acute Management of ST-Elevation Myocardial Infarction: Focused Update on Regionalization and Reperfusion

Rapid reperfusion of the infarct-related artery is the cornerstone of therapy for the management of acute ST-elevation myocardial infarction (STEMI). Canada's geography presents unique challenges for timely delivery of reperfusion therapy for STEMI patients. The Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology STEMI guideline was developed to provide advice regarding the optimal acute management of STEMI patients irrespective of where they are initially identified: in the field, at a non-percutaneous coronary intervention-capable centre or at a percutaneous coronary intervention-capable centre. We had also planned to evaluate and incorporate sex and gender considerations in the development of our recommendations. Unfortunately, inadequate enrollment of women in randomized trials, lack of publication of main outcomes stratified according to sex, and lack of inclusion of gender as a study variable in the available literature limited the feasibility of such an approach. The Grading Recommendations, Assessment, Development, and Evaluation system was used to develop specific evidence-based recommendations for the early identification of STEMI patients, practical aspects of patient transport, regional reperfusion decision-making, adjunctive prehospital interventions (oxygen, opioids, antiplatelet therapy), and procedural aspects of mechanical reperfusion (access site, thrombectomy, antithrombotic therapy, extent of revascularization). Emphasis is placed on integrating these recommendations as part of an organized regional network of STEMI care and the development of appropriate reperfusion and transportation pathways for any given region. It is anticipated that these guidelines will serve as a practical template to develop systems of care capable of providing optimal treatment for a wide range of STEMI patients.

Optimized Treatment of ST-Elevation Myocardial Infarction

Primary percutaneous coronary intervention is nowadays the preferred reperfusion strategy for patients with acute ST-segment-elevation myocardial infarction, aiming at restoring epicardial infarct-related artery patency and achieving microvascular reperfusion as early as possible, thus limiting the extent of irreversibly injured myocardium. Yet, in a sizeable proportion of patients, primary percutaneous coronary intervention does not achieve effective myocardial reperfusion due to the occurrence of coronary microvascular obstruction (MVO). The amount of infarcted myocardium, the so-called infarct size, has long been known to be an independent predictor for major adverse cardiovascular events and adverse left ventricular remodeling after myocardial infarction. Previous cardioprotection studies were mainly aimed at protecting cardiomyocytes and reducing infarct size. However, several clinical and preclinical studies have reported that the presence and extent of MVO represent another important independent predictor of adverse left ventricular remodeling, and recent evidences support the notion that MVO may be more predictive of major adverse cardiovascular events than infarct size itself. Although timely and complete reperfusion is the most effective way of limiting myocardial injury and subsequent ventricular remodeling, the translation of effective therapeutic strategies into improved clinical outcomes has been largely disappointing. Of importance, despite the presence of a large number of studies focused on infarct size, only few cardioprotection studies addressed MVO as a therapeutic target. In this review, we provide a detailed summary of MVO including underlying causes, diagnostic techniques, and current therapeutic approaches. Furthermore, we discuss the hypothesis that simultaneously addressing infarct size and MVO may help to translate cardioprotective strategies into improved clinical outcome following ST-segment-elevation myocardial infarction.

Editor's Choice- Pathophysiology and therapy of myocardial ischaemia/reperfusion syndrome

There is a need to find interventions able to reduce the extent of injury in reperfused ST-segment elevation myocardial infarction (STEMI) beyond timely reperfusion. In this review, we summarise the clinical impact of STEMI from epidemiological, clinical and biological perspectives. We also revise the pathophysiology underlying the ischaemia/reperfusion syndrome occurring in reperfused STEMI, including the several players involved in this syndrome, such as cardiomyocytes, microcirculation and circulating cells. Interventions aimed to reduce the resultant infarct size, known as cardioprotective therapies, are extensively discussed, putting the focus on both mechanical interventions (i.e. ischaemic conditioning) and promising pharmacological therapies, such as early intravenous metoprolol, exenatide and other glucose modulators, N-acetylcysteine as well as on some other classic therapies which have failed to be translated to the clinical arena. Novel targets for evolving therapeutic interventions to ameliorate ischaemia/reperfusion injury are also discussed. Finally, we highlight the necessity to improve the study design of future randomised clinical trials in the field, as well as to select patients better who can most likely benefit from cardioprotective interventions.

Cardioprotection of PLGA/gelatine cardiac patches functionalised with adenosine in a large animal model of ischaemia and reperfusion injury: A feasibility study

The protection from ischaemia‐reperfusion‐associated myocardial infarction worsening remains a big challenge. We produced a bioartificial 3D cardiac patch with cardioinductive properties on stem cells. Its multilayer structure was functionalised with clinically relevant doses of adenosine. We report here the first study on the potential of these cardiac patches in the controlled delivery of adenosine into the in vivo ischaemic‐reperfused pig heart. A Fourier transform infrared chemical imaging approach allowed us to perform a characterisation, complementary to the histological and biochemical analyses on myocardial samples after in vivo patch implantation, increasing the number of investigations and results on the restricted number of pigs (n = 4) employed in this feasibility step. In vitro tests suggested that adenosine was completely released by a functionalised patch, a data that was confirmed in vivo after 24 hr from patch implantation. Moreover, the adenosine‐loaded patch enabled a targeted delivery of the drug to the ischaemic‐reperfused area of the heart, as highlighted by the activation of the pro‐survival signalling reperfusion injury salvage kinases pathway. At 3 months, though limited to one animal, the used methods provided a picture of a tissue in dynamic conditions, associated to the biosynthesis of new collagen and to a non‐fibrotic outcome of the healing process underway. The synergistic effect between the functionalised 3D cardiac patch and adenosine cardioprotection might represent a promising innovation in the treatment of reperfusion injury. As this is a feasibility study, the clinical implications of our findings will require further in vivo investigation on larger numbers of ischaemic‐reperfused pig hearts.

Microvesicles (MIVs) secreted from adipose-derived stem cells (ADSCs) contain multiple microRNAs and promote the migration and invasion of endothelial cells

Extracellular vesicles (EVs) such as microvesicles (MIVs) play an important role in intercellular communications. MIVs are small membrane vesicles sized 100–1000 nm in diameter that are released by many types of cells, such as mesenchymal stem cells (MSCs), tumor cells and adipose-derived stem cells (ADSC). As EVs can carry out autocrine and paracrine functions by controlling multiple cell processes, it is conceivable that EVs can be used as delivery vehicles for treating several clinical conditions, such as to improve cardiac angiogenesis after myocardial infarction (MI). Here, we seek to investigate whether ADSC-derived MIVs contain microRNAs that regulate angiogenesis and affect cell migration of endothelial cells. We first characterized the ADSC-derived MIVs and found that the MIVs had a size range of 100–300 nm, and expressed the MIV marker protein Alix. We then analyzed the microRNAs in ADSCs and ADSC-derived MIVs and demonstrated that ADSC-derived MIVs selectively released a panel of microRNAs, several of which were related to angiogenesis, including two members of the let-7 family. Furthermore, we demonstrated that ADSC-derived MIVs promoted the cell migration and invasion of the HUVEC endothelial cells. The PKH26-labeled ADSC-derived MIVs were effectively uptaken into the cytoplasm of HUVEC cells. Collectively, our results demonstrate that the ADSC-derived MIVs can promote migration and invasion abilities of endothelial cells, suggesting pro-angiogenetic potential. Future studies should focus on investigating the roles and mechanisms through which ADSC-derived MIVs regulate angiogenesis.

Do We Need Potent Intravenous Antiplatelet Inhibition at the Time of Reperfusion During ST-Segment Elevation Myocardial Infarction?

Acute myocardial infarction (MI) is still a large source of morbidity and mortality worldwide. Although early reperfusion therapy has been prioritized in the modern era of percutaneous coronary intervention and thrombolysis, attempts at incremental improvements in clinical outcomes by reducing MI size have not been successful so far. Herein, we review the studies that have evaluated immediate-onset antiplatelet therapy as attempts to improve meaningful clinical outcomes in ST-segment elevation MI (STEMI). Unfortunately, many of the adjunctive pharmacotherapies have proven to be disappointing. Recent studies performed in the background of routine oral administration of P2Y₁₂ adenosine receptor inhibitors, which may take several hours to take full effect, and aspirin have largely shown no improvement in outcomes, despite an earlier onset of antiplatelet activity of the investigative agents. Further progress in improving outcomes during STEMI may depend on exploring therapeutics that modulate the pathophysiology of microvascular damage during ischemia-reperfusion injury, a phenomenon whose effects evolve over hours to days. We speculate that the dynamic nature of the no-reflow phenomenon may be an explanation for these disappointing results with the intravenous antiplatelet agents. We hope that appreciation for what has not worked in this domain may direct future research efforts to focus on novel pathways. Myocardial ischemia and reperfusion injury are very much still a lingering issue. Despite significant improvements in door-to-balloon times, rates of in-hospital mortality for STEMI remain unchanged. Outcomes following successfully reperfused STEMI are likely determined by the initial size of myocardial necrosis (ie, cardiomyocyte death during the period of ongoing ischemia), patency of the infarct-related epicardial coronary artery, possible reperfusion injury, the microvascular no-reflow phenomenon, and adverse remodeling after infarction.

The predictors of no reflow phenomenon after percutaneous coronary intervention in patients with ST elevation myocardial infarction: A meta-analysis

OBJECTIVE

To investigate the no reflow risk factors after percutaneous coronary intervention in ST elevation myocardial infarction patients.

METHOD

Sample size, mean±standard deviation (SD) or frequencies (percent) of normal and no reflow groups were extracted from each study.

RESULTS

Of 27 retrospective and prospective studies, we found that increasing risks of no reflow were associated with advanced age, male, family history of coronary artery disease, smoking, diabetes mellitus, hypertension, delayed reperfusion, killip class ≥2, elevated blood glucose, increased creatinine, elevated creatine kinase (CK), higher heart rate, decreased left ventricular ejection fraction (LVEF), collateral flow ≤1, longer lesion length, multivessel disease, reference luminal diameter, initial thrombolysis in myocardial infarction (TIMI) flow, and high thrombus burden. Moreover, initial TIMI flow ≤1 and high thrombus burden had the greater impact on no reflow (OR95%CI=3.83 [2.77-5.29], p<0.0001 and 3.69 [2.39-5.68], p<0.0001, respectively).

CONCLUSION

Our meta-analysis reveals that initial TIMI flow ≤1 and high thrombus burden are the most impacted no reflow risk factors.

The pathophysiology of acute myocardial infarction and strategies of protection beyond reperfusion: a continual challenge

The incidence of ST segment elevation myocardial infarction (STEMI) has decreased over the last two decades in developed countries, but mortality from STEMI despite widespread access to reperfusion therapy is still substantial as is the development of heart failure, particularly among an expanding older population. In developing countries, the incidence of STEMI is increasing and interventional reperfusion is often not available. We here review the pathophysiology of acute myocardial infarction and reperfusion, notably the temporal and spatial evolution of ischaemic and reperfusion injury, the different modes of cell death, and the resulting coronary microvascular dysfunction. We then go on to briefly characterize the cardioprotective phenomena of ischaemic preconditioning, ischaemic postconditioning, and remote ischaemic conditioning and their underlying signal transduction pathways. We discuss in detail the attempts to translate conditioning strategies and drug therapy into the clinical setting. Most attempts have failed so far to reduce infarct size and improve clinical outcomes in STEMI patients, and we discuss potential reasons for such failure. Currently, it appears that remote ischaemic conditioning and a few drugs (atrial natriuretic peptide, exenatide, metoprolol, and esmolol) reduce infarct size, but studies with clinical outcome as primary endpoint are still underway.

Effect of intracoronary agents on the no-reflow phenomenon during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction: a network meta-analysis

Background

Despite the restoration of epicardial flow after primary percutaneous coronary intervention (PPCI), myocardial reperfusion remains impaired in a significant proportion of patients. We performed a network meta-analysis to assess the effect of 7 intracoronary agents (adenosine, anisodamine, diltiazem, nicorandil, nitroprusside, urapidil, and verapamil) on the no-reflow phenomenon in patients with ST-elevation myocardial infarction (STEMI) undergoing PPCI.

Methods

Database searches were conducted to identify randomized controlled trials (RCTs) comparing the 7 agents with each other or with standard PPCI. Outcome measures included thrombolysis in myocardial infarction flow grade (TFG), ST-segment resolution (STR), left ventricular ejection fraction (LVEF), major adverse cardiovascular events (MACEs), and adverse events.

Results

Forty-one RCTs involving 4069 patients were analyzed. The addition of anisodamine to standard PPCI for STEMI was associated with improved post-procedural TFG, more occurrences of STR, and improvement of LVEF. The cardioprotective effect of anisodamine conferred a MACE-free survival benefit. Additionally, nitroprusside was regarded as efficient in improving coronary flow and clinical outcomes. Compared with standard care, adenosine, nicorandil, and verapamil improved coronary flow but had no corresponding benefits regarding cardiac function and clinical outcomes. The ranking probability for the 7 treatment drugs showed that anisodamine consistently ranked the highest in efficacy outcomes (TFG < 3, STR, LVEF, and MACEs). No severe adverse events, such as hypotension and malignant arrhythmia, were observed in patients treated with anisodamine. Network meta-regression analysis showed that age, the time to reperfusion, and study follow-up did not affect the treatment effects.

Conclusions

The intracoronary administration of anisodamine appears to improve myocardial reperfusion, cardiac function, and clinical outcomes in patients with STEMI undergoing PPCI. Given the limited quality and quantity of the included studies, more rigorous RCTs are needed to verify the role of this inexpensive and well-tolerated regimen.

Electronic supplementary material

The online version of this article (10.1186/s12872-017-0722-z) contains supplementary material, which is available to authorized users.

Management of No-Reflow Phenomenon in the Catheterization Laboratory

At the conclusion of a primary percutaneous coronary intervention for ST-segment elevation myocardial infarction, and after the cardiologist makes certain that there is no residual stenosis following stenting, assessment of coronary flow becomes the top priority. The presence of no-reflow is a serious prognostic sign. No-reflow can result in poor healing of the infarct and adverse left ventricular remodeling, increasing the risk for major adverse cardiac events, including congestive heart failure and death. To achieve normal flow, features associated with a high incidence of no-reflow must be anticipated, and measures must be undertaken to prevent its occurrence. In this review, the authors discuss various preventive strategies for no-reflow as well as pharmacological and nonpharmacological interventions that improve coronary blood flow, such as intracoronary adenosine and nitroprusside. Nonpharmacological therapies, such as induced hypothermia, were successful in animal studies, but their effectiveness in reducing no-reflow in humans remains to be determined.

The Coronary Circulation as a Target of Cardioprotection

The atherosclerotic coronary vasculature is not only the culprit but also a victim of myocardial ischemia/reperfusion injury. Manifestations of such injury are increased vascular permeability and edema, endothelial dysfunction and impaired vasomotion, microembolization of atherothrombotic debris, stasis with intravascular cell aggregates, and finally, in its most severe form, capillary destruction with hemorrhage. In animal experiments, local and remote ischemic pre- and postconditioning not only reduce infarct size but also these manifestations of coronary vascular injury, as do drugs which recruit signal transduction steps of conditioning. Clinically, no-reflow is frequently seen after interventional reperfusion, and it carries an adverse prognosis. The translation of cardioprotective interventions to clinical practice has been difficult to date. Only 4 drugs (brain natriuretic peptide, exenatide, metoprolol, and esmolol) stand unchallenged to date in reducing infarct size in patients with reperfused acute myocardial infarction; unfortunately, for these drugs, no information on their impact on the ischemic/reperfused coronary circulation is available.

Efficacy and safety of intracoronary verapamil versus sodium nitroprusside for the prevention of microvascular obstruction during primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

OBJECTIVE

The aim of this study was to compare the role of intracoronary (IC) verapamil versus sodium nitroprusside (SNP) in the prevention of microvascular obstruction (MVO) during a primary percutaneous coronary intervention (pPCI).

BACKGROUND

A head-to-head comparison between verapamil and SNP in the prevention of MVO lacks evidence.

PATIENTS AND METHODS

Sixty patients with ST-segment elevation myocardial infarction were randomized to receive IC verapamil (n=30) versus SNP (n=30) during pPCI. The primary outcome was the incidence of angiographic MVO as defined by Thrombolysis In Myocardial Infarction flow less than 3 or Thrombolysis In Myocardial Infarction flow 3 with myocardial blush grade less than 2. The secondary outcomes were the percentage of ST-segment resolution on 12-lead ECG, left ventricular ejection fraction and wall motion score index by two-dimensional echocardiography at 3-5 days after pPCI, as well as major adverse cardiovascular events at 30 days. Safety outcomes were the incidence of hypotension and/or bradycardia during pPCI.

RESULTS

Verapamil was associated with lower incidence of angiographic MVO compared with SNP (13.3 vs. 40%, respectively; P=0.02), as well as superior ST-segment resolution greater than or equal to 70% (33.3 vs. 6.7%, respectively; P=0.01). There was a trend towards improved left ventricular ejection fraction with verapamil (42.6±4.9 vs. 40.4±4.7%, respectively; P=0.09), but with similar wall motion score index (1.43±0.1 vs. 1.45±0.2, respectively; P=0.14). Both groups had similar 30-day major adverse cardiovascular events (3.3 vs. 6.7%, respectively; P=0.55). Verapamil was associated with lower incidence of hypotension compared with SNP (3.3 vs. 20%, respectively; P=0.04).

CONCLUSION

In pPCI, IC verapamil results in significant improvements in MVO with a better safety profile compared with SNP. Larger trials should be conducted to confirm these results.

Limitation of Infarct Size and No-Reflow by Intracoronary Adenosine Depends Critically on Dose and Duration

OBJECTIVES

In the absence of effective clinical pharmacotherapy for prevention of reperfusion-mediated injury, this study re-evaluated the effects of intracoronary adenosine on infarct size and no-reflow in a porcine model of acute myocardial infarction using clinical bolus and experimental high-dose infusion regimens.

BACKGROUND

Despite the clear cardioprotective effects of adenosine, when administered prior to ischemia, studies on cardioprotection by adenosine when administered at reperfusion have yielded contradictory results in both pre-clinical and clinical settings.

METHODS

Swine (54 ± 1 kg) were subjected to a 45-min mid-left anterior descending artery occlusion followed by 2 h of reperfusion. In protocol A, an intracoronary bolus of 3 mg adenosine injected over 1 min (n = 5) or saline (n = 10) was administered at reperfusion. In protocol B, an intracoronary infusion of 50 μg/kg/min adenosine (n = 15) or saline (n = 21) was administered starting 5 min prior to reperfusion and continued throughout the 2-h reperfusion period.

RESULTS

In protocol A, area-at-risk, infarct size, and no-reflow were similar between groups. In protocol B, risk zones were similar, but administration of adenosine resulted in significant reductions in infarct size from 59 ± 3% of the area-at-risk in control swine to 46 ± 4% (p = 0.02), and no-reflow from 49 ± 6% of the infarct area to 26 ± 6% (p = 0.03).

CONCLUSIONS

During reperfusion, intracoronary adenosine can limit infarct size and no-reflow in a porcine model of acute myocardial infarction. However, protection was only observed when adenosine was administered via prolonged high-dose infusion, and not via short-acting bolus injection. These findings warrant reconsideration of adenosine as an adjuvant therapy during early reperfusion.