A systematic observation of vasodynamics from different segments along the cerebral vasculature in the penumbra zone of awake mice following cerebral ischemia and recanalization

Different segments of the cerebral vascular network may react distinctly to brain ischemia and recanalization. However, there are limited systematic observations of these vascular responses in mice under a physiological state following ischemic stroke. Herein, we aimed to investigate the vasodynamics among several segments along the cerebral vessels in awake mice following cerebral ischemia/recanalization via two-photon imaging. Plasma in the blood vessels were labelled with fluorescein isothiocyanate dextran. Smooth muscle cells and pericytes were labelled via a genetic mouse line (PDGFRβ-tdTomato). We observed a no-reflow phenomenon in downstream microcirculation, and the vasodynamics of different segments of larger cerebral vessels varied in the penumbra area following cerebral ischemia-reperfusion. Despite obtaining reperfusion from the middle cerebral artery, there were significant constrictions of the downstream blood vessels in the ischemic penumbra zone. Interestingly, we observed an extensive constriction of the capillaries 3 hours following recanalization, both at the site covered by pericyte soma and by the pericyte process alone. In addition, we did not observe a significant positive correlation between the changed capillary diameter and pericyte coverage along the capillary. Taken together, abnormal constrictions and vasodynamics of cerebral large and small vessels may directly contribute to microcirculation failure following recanalization in ischemic stroke.

Mechanisms of the "No-Reflow" Phenomenon After Acute Myocardial Infarction: Potential Role of Pericytes

Pericytes contract during myocardial ischemia resulting in capillary constriction and no reflow. Reversing pericyte contraction pharmacologically reduces no reflow and infarct size. These findings open up an entire new venue of research aimed at altering pericyte function in myocardial ischemia and infarction.

Safety and efficacy of intracoronary recombinant human prourokinase administration in patients with acute myocardial infarction and ST‑segment elevation: A meta‑analysis of randomized controlled trials

Slow blood flow or no reflow following percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI) typically leads to an adverse prognosis. However, it is controversial whether to use prourokinase (Pro-UK) during PCI in patients with acute STEMI. The present meta-analysis compared the efficacy and safety of intracoronary Pro-UK administration in patients with acute STEMI. Published randomized controlled trials (RCTs) were analyzed to compare Pro-UK with non-Pro-UK treatment in patients with acute STEMI. PubMed, Cochrane Library and China National Knowledge Infrastructure were searched and meta-analysis was performed using Review Manager 5.3 software. A total of 13 RCTs were selected and 1,797 patients were considered in the meta-analysis, including 897 patients who received Pro-UK intervention and 900 patients who were in the control group. No significant heterogeneity was identified across these selected studies. Pro-UK therapy significantly decreased the incidence of major adverse cardiac events [risk ratio (RR), 0.68; 95% CI, 0.56-0.82, P<0.0001], left ventricular end-diastolic diameter [standardized mean difference (SMD), -0.26; 95% CI, -0.40 - -0.12; P=0.0003], corrected thrombolysis in myocardial infarction (TIMI) frame count [SMD, -0.45; 95% CI, -0.62 - -0.28; P<0.00001] and cardiac troponin I [SMD, -0.31; 95% CI, -0.46 - -0.17; P<0.0001]. In addition, Pro-UK administration increased TIMI grade 3 flow (RR, 1.16; 95% CI, 1.07-1.25; P=0.0003), TIMI myocardial perfusion grade 3 (RR: 1.39, 95% CI: 1.12-1.74, P=0.004), ST-segment resolution (RR, 1.23; 95% CI, 1.10-1.36; P=0.0002) and left ventricular ejection fraction (SMD, 0.38; 95% CI, 0.27-0.49; P<0.00001). No significant difference was identified in bleeding (RR, 1.12; 95% CI, 0.85-1.47; P=0.41). The present meta-analysis determined that intracoronary Pro-UK administration is efficacious and safe to decrease slow blood flow or no reflow phenomena following PCI and improve the prognosis of patients with acute STEMI.

Management of no Reflow during Percutaneous Transcoronary Angioplasty with Catheter-Directed Intracoronary Thrombolysis: A Retrospective Observational Study

Background

Intracoronary thrombus is common in patients with ST-elevation myocardial infarction (STEMI). Percutaneous coronary intervention (PCI) is the treatment of choice for these patients. Intracoronary thrombus is still a challenge during PCI in STEMI, even with dual antiplatelets, glycoprotein IIb/IIIa inhibitor, and anticoagulation. Intracoronary thrombus can cause distal or nonculprit vessel embolization and no-reflow state. No reflow results in large infarct size, adverse left ventricular remodeling, arrhythmias, and death. Recently, catheter-directed intracoronary thrombolysis (ICT) is gaining acceptance in patients with no-reflow due to a large thrombus burden.

Aim

Evaluation of catheter-directed ICT in patients with acute STEMI who develop no reflow due to large thrombus burden during PCI.

Materials and Methods and Results

This was a retrospective observational study conducted after approval of the institutional ethics committee in a tertiary care hospital of north India from April 15, 2021 to April 14, 2022, included 1020 adult patients who had undergone coronary evaluation. 37.25% patients had PCI, among these 10% had PCI for acute STEMI. Thrombolysis in myocardial infarction (TIMI) Grade 5 in 79.17% and Grade 4 in 20.83%. ICT was done with low-dose tenecteplase (15 ± 5 mg). The TIMI flow III in 91.67% and II in 8.33% of patients was achieved after intracoronary thrombolysis. Major risk factor was tobacco smoking in 41.67%, and the major complication was left ventricular failure in 33.33%.

Conclusions

Catheter-directed ICT is safe and effective in reducing thrombus burden, thus improving myocardial reperfusion in STEMI. This condition has a grave prognosis and can lead to adverse cardiac outcomes. There are many drugs that have been tried to manage no reflow. The use of ICT to treat no-reflow state can be life saving with minimal systemic side effects.

Saphenous Vein Graft Intervention

Even though saphenous vein grafts (SVGs) are the most commonly used surgical conduits, their long-term patency is limited by accelerated atherosclerosis often resulting in acute coronary syndrome or asymptomatic occlusion. SVG intervention is associated with 2 significant challenges: a significant risk of distal embolization with resultant periprocedural myocardial infarction in the short-term and restenosis in the long-term. Several individual trials have compared bare metal stents with drug-eluting stents for SVG intervention. This review article discusses the pathophysiology of SVG lesions, indications for SVG intervention, and the challenges encountered, and also technical considerations for SVG intervention and the supporting evidence.

CRP Albumin Ratio May Predict No Reflow in Patients Undergoing Percutaneous Coronary Intervention for Saphenous Vein Graft Stenosis

Many hypotheses have been proposed to explain no-reflow (NR). Some of these hypotheses, state that NR may be caused by damage to the vascular endothelium and an inflammatory process. In a recent study that did not include patients with coronary artery bypass graft (CABG), the ratio of C-reactive protein (CRP) to albumin (CAR) was found to be associated with NR. Our study aims to evaluate the relationship between CAR and NR in patients who underwent percutaneous coronary intervention (PCI) for saphenous vein graft (SVG). In this retrospective study, among the patients with CABG who underwent primary or elective coronary angiography, 242 patients who underwent PCI to the SVG were selected. The incidence of NR was 19.8% (n = 48). Diabetes mellitus, left ventricular ejection fraction (LVEF), stent length, and CAR were found as independent predictors of NR in multivariate logistic regression analysis (P < .05). Using a cut-off level of .930, the CAR predicted NR with a sensitivity of 75% and a specificity of 73% (AUC: .814, 95% CI: .749-.879, P < .001). The CAR was a better predictor than both stent length and LVEF. CAR was found to be the strongest predictor of NR in our study.

The Reduction of Mortality in Acute Myocardial Infarction: From Bed Rest to Future Directions

Despite the reduction of mortality secondary to cardiovascular diseases observed in the last decades, ischemic heart disease remains the most common cause of death worldwide. Among the spectrum of ischemic heart disease, myocardial infarction accounts for most deaths. Since the introduction of the coronary care units in the 1960s, and until the latest antithrombotic drugs, myocardial infarction survival improved by 40-50%. However long-term mortality after myocardial infarction has not improved as short-term mortality. Moreover, the decline of mortality has apparently reached a "plateau" in the past 15 years. In this review we describe the steps of the improvement in ischemic heart disease mortality, from the bed rest to the possible future of treating microcirculation. In fact, coronary artery disease is not only a disease of large vessels that can be visualized with coronary angiography. The small network of pre-arterioles and arterioles that supply the myocardium can be also affected in ischemic heart disease. Thus, despite the introduction of effective recanalization strategies for epicardial coronary arteries such as thrombolysis and, more recently, primary percutaneous intervention, some patients may not achieve effective myocardial reperfusion due to microvascular dysfunction or damage after myocardial myocardial infarction. This phenomenon is named no reflow. We believe that no reflow, through the incomplete reperfusion that can account for a higher rate of adverse event in the follow up, should be regarded as one of the open issues in the modern treatment of myocardial infarction.

Mechanism and potential treatment of the "no reflow" phenomenon after acute myocardial infarction: role of pericytes and GPR39

The "no reflow" phenomenon, where the coronary artery is patent after treatment of acute myocardial infarction (AMI) but tissue perfusion is not restored, is associated with worse outcome. The mechanism of no reflow is unknown. We hypothesized that pericytes contraction, in an attempt to maintain a constant capillary hydrostatic pressure during reduced coronary perfusion pressure, causes capillary constriction leading to no reflow and that this effect is mediated through the orphan receptor, GPR39, present in pericytes. We created AMI (coronary occlusion followed by reperfusion) in GPR39 knock out mice and littermate controls. In a separate set of experiments, we treated wild-type mice undergoing coronary occlusion with vehicle or VC43, a specific inhibitor of GPR39, before reperfusion. We found that no reflow zones were significantly smaller in the GPR39 knockouts compared with controls. Both no reflow and infarct size were also markedly smaller in animals treated with VC43 compared with vehicle. Immunohistochemistry revealed greater capillary density and larger capillary diameter at pericyte locations in the GPR39-knockout and VC43-treated mice compared with controls. We conclude that GPR39-mediated pericyte contraction during reduced coronary perfusion pressure causes capillary constriction resulting in no reflow during AMI and that smaller no reflow zones in GPR39-knockout and VC43-treated animals are associated with smaller infarct sizes. These results elucidate the mechanism of no reflow in AMI, as well as providing a therapeutic pathway for the condition.NEW & NOTEWORTHY The mechanism of "no reflow" phenomenon, where the coronary artery is patent after treatment of acute myocardial infarction but tissue perfusion is not restored, is unknown. This condition is associated with worse outcome. Here, we show that GPR39-mediated pericyte contraction during reduced coronary perfusion pressure causes capillary constriction resulting in no reflow. Smaller no-reflow zones in GPR39-knockout animals and those treated with a GPR39 inhibitor are associated with smaller infarct size. These results could have important therapeutic implications.

Impact of target vessel choice on outcomes following percutaneous coronary intervention in patients with a prior coronary artery bypass graft

OBJECTIVES

To evaluate and compare characteristics and clinical outcomes of percutaneous coronary intervention (PCI) among target vessel types in patients with a prior coronary artery bypass graft (CABG) surgery.

BACKGROUND

Patients with a prior CABG often require repeat revascularization with PCI. Graft PCI has been associated with worse outcomes compared to native vessel PCI, yet the optimal PCI strategy in prior CABG patients remains unknown.

METHODS

We stratified prior CABG patients who underwent PCI at a tertiary-care center between 2009 and 2017 by target vessel type: native vessel, venous graft, and arterial graft. The primary outcome of major adverse cardiac events (MACE) was a composite of all-cause death, myocardial infarction, stent thrombosis, or target vessel revascularization up to 1 year post-PCI.

RESULTS

Prior CABG patients (n = 3983) represented 19.5% of all PCI interventions during the study period. PCI was most frequently performed on native vessels (n = 2928, 73.5%) followed by venous (n = 883, 22.2%) and arterial grafts (n = 172, 4.3%). Procedural success and complications were similar among the groups; however, slow- and no-reflow phenomenon was more common in venous graft PCI compared to native vessel PCI (OR 4.78; 95% CI 2.56-8.95; p < 0.001). At 1 year, there were no significant differences in MACE or in its individual components.

CONCLUSIONS

Target vessel choice did not appear to affect MACE at 1 year in a large cohort of patients with prior CABG undergoing PCI. Whether PCI of surgical grafts versus native arteries truly results in similar outcomes warrants further investigation in randomized controlled trials.

[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.

Neutrophils Obstructing Brain Capillaries Are a Major Cause of No-Reflow in Ischemic Stroke

Despite successful clot retrieval in large vessel occlusion stroke, ∼50% of patients have an unfavorable clinical outcome. The mechanisms underlying this functional reperfusion failure remain unknown, and therapeutic options are lacking. In the thrombin-model of middle cerebral artery (MCA) stroke in mice, we show that, despite successful thrombolytic recanalization of the proximal MCA, cortical blood flow does not fully recover. Using in vivo two-photon imaging, we demonstrate that this is due to microvascular obstruction of ∼20%-30% of capillaries in the infarct core and penumbra by neutrophils adhering to distal capillary segments. Depletion of circulating neutrophils using an anti-Ly6G antibody restores microvascular perfusion without increasing the rate of hemorrhagic complications. Strikingly, infarct size and functional deficits are smaller in mice treated with anti-Ly6G. Thus, we propose neutrophil stalling of brain capillaries to contribute to reperfusion failure, which offers promising therapeutic avenues for ischemic stroke.

Platelet-Lymphocyte ratio is a predictor for the development of no-reflow phenomenon in patients with ST-segment elevation myocardial infarction after thrombus aspiration

BACKROUND

We aimed to evaluate the utility of the preprocedural platelet-lymphocyte ratio (PLR) for predicting the no-reflow phenomenon after thrombus aspiration during percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI).

METHOD

We retrospectively analyzed postprocedural thrombolysis in myocardial infarction (TIMI) flow grades and myocardial blush grades (MBG) of 247 patients who underwent a PCI procedure with thrombus aspiration.We divided these patients into two groups according to whether they had no-reflow (TIMI < 3, MBG < 2) or not (TIMI 3, MBG ≥ 2).

RESULTS

No-reflow developed in 43 (17%) patients.Preprocedural PLR was significantly higher in the no-reflow group (183.76 ± 56.65 vs 118.32 ± 50.42 p < 0.001).Independent predictors of no-reflow were as follows: higher preprocedural platelet-lymphocyte ratio (PLR) (OR = 1.018; 95% CI = 1.004, 1.033; p = 0.013),mean corpuscular volume (MCV) (OR = 1.118; 95% CI = 1.024, 1.220; p = 0.012) and SYNTAX Score-2 (OR = 1.073; 95% CI = 1.005, 1.146; p = 0.036). PLR of 144 had 79% sensitivity and 75% specificity for the prediction of no-reflow.

CONCLUSION

PLR is a reliable predictor for no-reflow in STEMI patients undergoing thrombus aspiration.

Deferred Stenting for Heavy Thrombus Burden During Percutaneous Coronary Intervention for ST-Elevation MI

Patients with ST-elevation MI (STEMI) usually have a huge thrombus burden in the infarct-related artery. Stenting may lead to high chances of the slow-flow/no-reflow phenomenon that leads to periprocedural MI and adverse cardiovascular events. Deferred stenting may be beneficial in this situation as the thrombus burden will reduce, mitigating the slow-flow/no-reflow phenomenon. However, routine deferral of stenting in patients with STEMI has not been found to be beneficial, but when the patient is properly selected, deferred stenting has the potential for reducing the final infarct size. The authors report the safety and feasibility of deferred stenting after 5 days of prolonged anticoagulation in a 45-year-old smoker with STEMI who had a large thrombus load shown on an angiogram. They review the registries, trials and meta-analyses on deferred stenting in the literature and analyse the benefits and harms of the strategy. They also propose an algorithm for applying a strategy for deferred stenting in clinical practice based on the available data.

Intracoronary Administration of Allogeneic Cardiosphere-Derived Cells Immediately Prior to Reperfusion in Pigs With Acute Myocardial Infarction Reduces Infarct Size and Attenuates Adverse Cardiac Remodeling

BACKGROUND

Allogeneic cardiosphere-derived cells (CDCs) exert cardioprotective effects when administered intracoronarily after reperfusion in animal models of acute myocardial infarction (AMI). The "no-reflow" phenomenon develops rapidly post-reperfusion and may undermine the efficacy of cell therapy, due to poor cell delivery in areas of microvascular obstruction (MVO). We hypothesized that CDC-induced cardioprotection would be enhanced by cell administration prior to reperfusion, when microvasculature is still relatively intact, to facilitate widespread cell delivery within the ischemic area.

METHODS AND RESULTS

We studied 81 farm pigs; 55 completed the specified protocols. A dose-optimization study in infarcted pigs demonstrated that the doses of 5 million and 10 million CDCs are the maximum safe doses that can be administered intracoronarily at 5 minutes prior to and at 5 minutes post-reperfusion, respectively, without aggravating MVO. Quantification of acute cell retention by polymerase chain reaction demonstrated that cell delivery prior to reperfusion resulted in higher cardiac cell retention compared to delivery post-reperfusion. We then performed a randomized, placebo-controlled study to assess the long-term efficacy of intracoronary infusion of 5 million allogeneic CDCs, delivered at 5 minutes prior to reperfusion, in a porcine model of AMI. The CDC therapy resulted in decreased scar size, improved regional systolic function, and attenuation of adverse cardiac remodeling (manifested as preserved global systolic function, preserved end-systolic volume, and decreased interstitial fibrosis) compared to placebo at 30 days post-MI.

CONCLUSIONS

Dose-optimized intracoronary infusion of allogeneic CDCs prior to reperfusion in a porcine model of AMI is feasible, safe and confers long-term benefits.

Impact of electrical defibrillation on infarct size and no-reflow in pigs subjected to myocardial ischemia-reperfusion without and with ischemic conditioning

Ventricular fibrillation (VF) occurs frequently during myocardial ischemia-reperfusion (I/R) and must then be terminated by electrical defibrillation. We have investigated the impact of VF/defibrillation on infarct size (IS) or area of no reflow (NR) without and with ischemic conditioning interventions. Anesthetized pigs were subjected to 60/180 min of coronary occlusion/reperfusion. VF, as identified from the ECG, was terminated by intrathoracic defibrillation. The area at risk (AAR), IS, and NR were determined by staining techniques (patent blue, triphenyltetrazolium chloride, and thioflavin-S). Four experimental protocols were analyzed: I/R (n = 49), I/R with ischemic preconditioning (IPC; n = 22), I/R with ischemic postconditioning (POCO; n = 22), or I/R with remote IPC (RIPC; n = 34). The incidence of VF was not different between I/R (44%), IPC (45%), POCO (50%), and RIPC (33%). IS was reduced by IPC (23 ± 12% of AAR), POCO (31 ± 16%), and RIPC (22 ± 13%, all P < 0.05 vs. I/R: 41 ± 12%). NR was not different between protocols (I/R: 17 ± 15% of AAR, IPC: 15 ± 18%, POCO: 25 ± 16%, and RIPC: 18 ± 17%). In pigs with defibrillation, IS was 50% larger than in pigs without defibrillation but independent of the number of defibrillations. Analysis of covariance confirmed the established determinants of IS, i.e., AAR, residual blood flow during ischemia (RMBFi), and a conditioning protocol, and revealed VF/defibrillation as a novel covariate. VF/defibrillation in turn was associated with larger AAR and lower RMBFi. Lack of dose-response relation between IS and the number of defibrillations excluded direct electrical injury as the cause of increased IS. Obviously, AAR size and RMBFi account for both IS and the incidence of VF. IS and NR are mechanistically distinct phenomena.NEW & NOTEWORTHY Ventricular fibrillation/defibrillation is associated with increased infarct size. Electrical injury is unlikely the cause of such association, since there is no dose-response relation between infarct size and number of defibrillations. Ventricular fibrillation, in turn, is associated with a larger area at risk and lower residual blood flow.

Neutrophil/Lymphocyte Ratio as a Predictor of In-Hospital Major Adverse Cardiac Events, New-Onset Atrial Fibrillation, and No-Reflow Phenomenon in Patients with ST Elevation Myocardial Infarction

BACKGROUND

Neutrophil/lymphocyte (N/L) ratio represents the balance between neutrophil and lymphocyte counts in the body and can be utilized as an index for systemic inflammatory status. The no-reflow phenomenon is defined as inadequate myocardial perfusion through a given segment of the coronary circulation without angiographic evidence of mechanical vessel obstruction. Systemic inflammatory status has been associated with new-onset atrial fibrillation (NOAF) as well as no-reflow.

AIM

To evaluate the predictive value of N/L ratio for in-hospital major adverse events, NOAF, and no-reflow in patients with ST elevation myocardial infarction (STEMI).

PATIENTS

Two hundred consecutive patients with STEMI presenting to Alexandria Main University Hospital and International Cardiac Center Hospital, Alexandria, Egypt, from April 2013 to October 2013 were included in this study.

METHODS

Laboratory investigation upon admission included complete blood count with mean platelet volume (MPV) and N/L ratio, and random plasma glucose (RPG) level. The results of coronary angiography indicating the infarct-related artery (IRA), initial thrombolysis in myocardial infarction (TIMI) flow in the IRA, and the TIMI flow after stenting were recorded. The patients were studied according to the presence of various clinical and laboratory variables, such as age, gender, pain-to-balloon time, location of the infarction, RPG level and complete blood count including N/L ratio and MPV on admission, and initial TIMI flow in the IRA. They were also evaluated for the final TIMI flow after the primary percutaneous coronary intervention, incidence of NOAF, and the incidence of in-hospital major adverse cardiac events (MACE).

RESULTS

The incidence rate of no-reflow, NOAF, and in-hospital MACE was 13.2%, 8%, and 5%, respectively, with cardiac death as the predominant form of in-hospital MACE. The group of no-reflow, NOAF, and/or MACE showed significantly older age (62.29 ± 7.90 vs 56.30 ± 10.34, P = 0.014), longer pain-to-balloon time (15.90 ± 7.87 vs 6.08 ± 3.82 hours, P < 0.001), higher levels of RPG, N/L ratio (8.19 ± 3.05 vs 5.44 ± 3.53, P, 0.001), and MPV (11.90 ± 2.09 vs 8.58 ± 1.84 fL, P < 0.001) on admission. After adjustment of confounding factors, the independent predictors of NOAF, no-reflow, and in-hospital MACE were higher N/L ratio (odds ratio [OR] = 3.5, P = 0.02) and older age (OR = 3.1, P = 0.04).

CONCLUSIONS

Older patient age, longer pain-to-balloon time, hyperglycemia, higher N/L ratio, and MPV on admission are useful predictive factors for the occurrence of no-reflow postprimary percutaneous coronary intervention, NOAF, and/or in-hospital MACE. N/L ratio is a new strong independent predictor of no-reflow, NOAF, and/or in-hospital MACE in patients with STEMI. The use of this simple routine biomarker may have a potential therapeutic implication in preventing NOAF and improving prognosis in STEMI revascularized patients.

Morphological predictors for no reflow phenomenon after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction caused by plaque rupture

AIMS

Myocardial no reflow after percutaneous coronary intervention (PCI) is associated with poor outcome. Patients with ST-segment elevation myocardial infarction (STEMI) caused by plaque rupture are at high risk for no reflow. However, specific morphologic characteristics associated with no reflow are unknown in this population. The aim of this study is to identify the morphological characteristics of culprit plaques associated with no reflow in patients with STEMI caused by plaque rupture using both optical coherence tomography (OCT) and intravascular ultrasound (IVUS).

METHODS AND RESULTS

We enrolled 145 patients with STEMI who underwent both OCT and IVUS within 12 h of symptom onset. Among these patients, we excluded those with plaque erosion and calcified nodule and included 72 patients who had plaque rupture as an underlying mechanism for STEMI. Myocardial no reflow, defined as Thrombolysis in Myocardial Infarction flow grade 0-2 and/or myocardial blush grade 0-1 after PCI, was observed in 28 patients (38.9%). Onset to recanalization time was similar between the groups with and without no reflow. Receiver-operating curve analysis revealed OCT-derived lipid index > 3500 [area under curve (AUC) 0.77, P < 0.001] and IVUS-derived plaque burden > 81.5% (AUC 0.70, P = 0.002) were the best discriminators for myocardial no reflow.

CONCLUSION

No reflow occurred in nearly 40% of patients with STEMI caused by plaque rupture. Large lipid index and plaque burden were critical morphological discriminators between no reflow and normal flow.

Distal coronary embolization following acute myocardial infarction increases early infarct size and late left ventricular wall thinning in a porcine model

BACKGROUND

Distal coronary embolization (DCE) of thrombotic material occurs frequently during percutaneous interventions for acute myocardial infarction and can alter coronary flow grades. The significance of DCE on infarct size and myocardial function remains unsettled. The aims of this study were to evaluate the effects of DCE sufficient to cause no-reflow on infarct size, cardiac function and ventricular remodeling in a porcine acute myocardial infarction model.

METHODS AND RESULTS

Female Yorkshire pigs underwent 60 min balloon occlusion of the left anterior descending coronary artery followed by reperfusion and injection of either microthrombi (prepared from autologous porcine blood) sufficient to cause no-reflow (DCE), or saline (control). Animals were sacrificed at 3 h (n = 5), 3 days (n = 20) or 6 weeks (n = 20) post-AMI. Cardiovascular magnetic resonance (CMR), serum troponin-I, and cardiac gelatinase (MMP) and survival kinase (Akt) activities were assessed. At 3d, DCE increased infarct size (CMR: 18.8% vs. 14.5%, p = 0.04; serum troponin-I: 13.3 vs. 6.9 ng/uL, p < 0.05) and MMP-2 activity levels (0.81 vs. 0.49, p = 0.002), with reduced activation of Akt (0.06 versus 0.26, p = 0.02). At 6 weeks, there were no differences in infarct size, ventricular volume or ejection fraction between the two groups, although infarct transmurality (70% vs. 57%, p< 0.04) and ventricular thinning (percent change in mid anteroseptal wall thickness:-25.6% vs. 0.7%, p = 0.03) were significantly increased in the DCE group.

CONCLUSIONS

DCE increased early infarct size, but without affecting later infarct size, cardiac function or ventricular volumes. The significance of the later remodelling changes (ventricular thinning and transmurality) following DCE, possibly due to changes in MMP-2 activity and Akt activation, merits further study.

Intracoronary administration of anisodamine and nicorandil in individuals undergoing primary percutaneous coronary intervention for acute inferior myocardial infarction: A randomized factorial trial

In acute inferior myocardial infarction (AIMI), numerous conventional drugs that are used to improve the myocardial microcirculation can significantly reduce blood pressure (BP) and coronary perfusion pressure, aggravate bradyarrhythmia and cause a deterioration in the hemodynamic state of the whole body, which greatly limits the application of these drugs in clinical settings. The aim of the present study was to assess the effect of anisodamine and nicorandil regimens on the prevention of no-reflow (NR) and the amelioration of myocardial reperfusion in patients with AIMI undergoing primary percutaneous coronary intervention (PCI). A total of 104 consecutive patients with AIMI were included in this study and randomly assigned to one of four groups: A (control group), B (anisodamine group), C (nicorandil group) and D (anisodamine and nicorandil group). Patients underwent PCI via transradial artery access and the angiographic results were evaluated. Coronary diastolic BP (DBP) and systolic and mean BPs were measured by invasive catheterization. The primary end-point was a post-PCI Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG) of 3. Composite end-points (mortality + new MI + target vessel revascularization) were evaluated during the hospital stay and 30 days after discharge. Following the procedure, the proportion of patients achieving TMPG 3 was significantly higher in group D than that in the other groups (P=0.014); furthermore, the incidence of a postprocedural TIMI score of 3 was the highest in group D. Three days after the procedure, the peak creatine kinase-MB and cardiac troponin I levels were the lowest and the left ventricular ejection fraction was the highest in group D. A thrombus score of 3/4 and low DBP were the independent risk factors for poor myocardial reperfusion (expressed as TMPG <3), while 2 mg anisodamine plus 2 mg nicorandil prior to PCI was protective for optimal myocardial reperfusion following the procedure. The combination of anisodamine and nicorandil can effectively ameliorate myocardial reperfusion and protect cardiac function in patients with AIMI undergoing primary PCI.

Clinical efficacy of thrombus aspiration on 5-year clinical outcomes in patients with ST-segment elevation acute myocardial infarction undergoing percutaneous coronary intervention

Background

Adjunctive thrombus aspiration (TA) during primary percutaneous coronary intervention (PCI) was reported to promote better coronary and myocardial reperfusion. However, long-term mortality benefit of TA remains controversial. The objective of this study is to investigate the clinical impact of TA on long-term clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI.

Methods and Results

The CREDO-Kyoto AMI Registry is a large-scale cohort study of acute myocardial infarction patients undergoing coronary revascularization in 2005–2007 at 26 hospitals in Japan. Among 5429 patients enrolled in the registry, the current study population consisted of 3536 patients who arrived at the hospital within 12 hours after the symptom onset and underwent primary PCI. Clinical outcomes were compared between the 2 patient groups with or without TA. During primary PCI procedures, 2239 out of 3536 (63%) patients underwent TA (TA group). The cumulative 5-year incidence of all-cause death was significantly lower in the TA group than in the non-TA group (18.5% versus 23.9%, log-rank P<0.001). After adjusting for confounders, however, the risk for all-cause death in the TA group was not significantly lower than that in the non-TA group (hazard ratio: 0.90, 95% CI: 0.76 to 1.06, P=0.21). The adjusted risks for cardiac death, myocardial infarction, stroke, and target-lesion revascularization were also not significantly different between the 2 groups.

Conclusions

Adjunctive TA during primary PCI was not associated with better 5-year mortality in STEMI patients.

Predictors of delayed and no-reflow as recognized with Thrombolysis in Myocardial Infarction [TIMI] flow grade following Primary Percutaneous Coronary Angioplasty

Background: Initial percutaneous coronary interference (PCI) is still connected by a noticeable incidence of suboptimal coronary flow thrombolysis in infarction of myocardial (TIMI). The predictors of slow and no-reflow in cases that supported initial PCI in our institute was searched for and the relationship of these parameters with major adverse cardiovascular effects (MACE) was assessed. Material and Method: 397 patients with AMI displaying in 24 hours of the sign opening were retrospectively enrolled and underwent primary PCI between March 2006 and March 2012. Demographic, clinical, and procedural data were retrieved from our institutional databank. The baseline and post-PCI flow of blood in the revascularized artery was ranked based on the TIMI grading method. The follow-up visits were performed after one, six and twelve month from hospitalization. All the mortalities and complications were recorded within this period for evaluate the MACE. Results: The frequency of diabetes mellitus and renal failure were importantly larger in cases with a TIMI flow of 0-1 (p=0.03 & p=.01, respectively). Similarly, level of serum creatine were importantly larger in cases with a TIMI flow of 0-1. The predictors for TIMI flow included that utilize of Adenosin or Integrilin, diabetes mellitus, POIT, long tubular lesion, and injury at LAD territory. The incidence of MACE was significantly higher in patients with a TIMI flow of 0-1 (P=0.001) and the survival in this subgroup was significantly poorer (Hazard ratio=4.96; P<0.001). Conclusion: A low TIMI flow is accompanied by a poorer survival and a higher MACE and is influenced by some clinical and vascular characteristics.

Assessment of No-Reflow Phenomenon by Myocardial Blush Grade and Pulsed Wave Tissue Doppler Imaging in Patients with Acute Coronary Syndrome

Background:

No-reflow phenomenon is a complication of myocardial revascularization and it is associated with a worse prognosis.

Materials and Methods:

A prospective study was carried out enrolling patients with acute myocardial infarction (64 patients, 49 male and 15 female, median age 64.9 ± 10.61 years), both STEMI and NSTEMI, who underwent myocardial revascularization with percutaneous coronary intervention (PCI). TIMI flow and Myocardial Blush Grade (MBG) were assessed at baseline (T0), in addition to tissue Doppler imaging (TDI) and electrocardiogram. Cardiological evaluation was also performed at T1 (one month after PCI) and T2 (every year after revascularization for a mean follow-up of 24.9 months ± 6.93 months). Patients were divided into two groups on the basis of MBG.

Results:

In the present study, we found at T1 a significant association between MBG and dyslipidemia (P = 0,038) and NYHA class and MBG (P = 0,040), among clinical variables and cardiovascular risk factors. Moreover, a statistically significant relationship was observed between MBG and a new echocardiographic index of systolic and diastolic dysfunction, the EAS index measured with tissue Doppler imaging (P = 0,013). At T2, the EAS parameter was also significantly impaired in patients with reduced MBG, compared to patients with normal MBG (P = 0,003).

Conclusions:

This study demonstrates that the combined evaluation of systolic and diastolic dysfunction by EAS index, according to the literature, could detect a subclinical ventricular dysfunction due to a perfusion defect. Therefore, EAS index could be a useful parameter to be measured in the follow-up of patients undergoing revascularization.

Serial measurement of hFABP and high-sensitivity troponin I post-PCI in STEMI: how fast and accurate can myocardial infarct size and no-reflow be predicted?

The objective of this study was to compare heart-specific fatty acid binding protein (hFABP) and high-sensitivity troponin I (hsTnI) via serial measurements to identify early time points to accurately quantify infarct size and no-reflow in a preclinical swine model of ST-elevated myocardial infarction (STEMI). Myocardial necrosis, usually confirmed by hsTnI or TnT, takes several hours of ischemia before plasma levels rise in the absence of reperfusion. We evaluated the fast marker hFABP compared with hsTnI to estimate infarct size and no-reflow upon reperfused (2 h occlusion) and nonreperfused (8 h occlusion) STEMI in swine. In STEMI (n = 4) and STEMI + reperfusion (n = 8) induced in swine, serial blood samples were taken for hFABP and hsTnI and compared with triphenyl tetrazolium chloride and thioflavin-S staining for infarct size and no-reflow at the time of euthanasia. hFABP increased faster than hsTnI upon occlusion (82 ± 29 vs. 180 ± 73 min, P < 0.05) and increased immediately upon reperfusion while hsTnI release was delayed 16 ± 3 min (P < 0.05). Peak hFABP and hsTnI reperfusion values were reached at 30 ± 5 and 139 ± 21 min, respectively (P < 0.05). Infarct size (containing 84 ± 0.6% no-reflow) correlated well with area under the curve for hFABP (r(2) = 0.92) but less for hsTnI (r(2) = 0.53). At 50 and 60 min reperfusion, hFABP correlated best with infarct size (r(2) = 0.94 and 0.93) and no-reflow (r(2) = 0.96 and 0.94) and showed high sensitivity for myocardial necrosis (2.3 ± 0.6 and 0.4 ± 0.6 g). hFABP rises faster and correlates better with infarct size and no-reflow than hsTnI in STEMI + reperfusion when measured early after reperfusion. The highest sensitivity detecting myocardial necrosis, 0.4 ± 0.6 g at 60 min postreperfusion, provides an accurate and early measurement of infarct size and no-reflow.

Temporal evolution and functional outcome of no reflow: sustained and spontaneously reversible patterns following successful coronary recanalisation

OBJECTIVE

To identify in humans the temporal patterns of no reflow and their functional implications.

METHODS

24 patients with first acute myocardial infarction and successful coronary recanalisation by recombinant tissue-type plasminogen activator (n = 15) or primary percutaneous transluminal coronary angioplasty (n = 9) were studied by myocardial contrast echocardiography within 24 hours of recanalisation and at one month's follow up. Myocardial contrast echocardiography was performed by intermittent harmonic power Doppler and intravenous Levovist. The regional contrast score index (CSI) was calculated within dysfunctioning myocardium. Videointensity was measured (dB) within risk and control areas and their ratio was calculated.

RESULTS

In 8 patients reflow was observed at 24 hours and persisted at one month. Conversely in 16 patients areas of no reflow were detectable at 24 hours. At one month, no reflow was spontaneously reversible in 9 patients (mean (SD) CSI and videointensity ratio improved from 2.5 (0.5) to 1.4 (0.6) and from 0.6 (0.1) to 0.7 (0.1), respectively; p < 0.05) and was sustained in the remaining 7 patients (CSI and videointensity ratio remained unchanged from 2.6 (0.6) to 2.6 (0.5) and from 0.5 (0.2) to 0.5 (0.2), respectively; NS). Left ventricular function improved significantly in patients with reflow and reversible no reflow. Volumes were enlarged only in patients with sustained no reflow.

CONCLUSIONS

No reflow detected at 24 hours may be sustained or spontaneously reversible at one month. Such reversibility of the phenomenon is associated with preserved left ventricular volumes and function. Clarification of the mechanisms of delayed reversibility may lead to tailored treatment of no reflow even in the subacute phase of myocardial infarction.