Long-term clinical outcomes of transient and persistent no-reflow following percutaneous coronary intervention (PCI): a multicentre Australian registry

No-Reflow Prediction in Acute Coronary Syndrome During Percutaneous Coronary Intervention: The NORPACS Risk Score

BACKGROUND

Suboptimal coronary reperfusion (no reflow) is common in acute coronary syndrome percutaneous coronary intervention (PCI) and is associated with poor outcomes. We aimed to develop and externally validate a clinical risk score for angiographic no reflow for use following angiography and before PCI.

METHODS

We developed and externally validated a logistic regression model for prediction of no reflow among adult patients undergoing PCI for acute coronary syndrome using data from the Melbourne Interventional Group PCI registry (2005-2020; development cohort) and the British Cardiovascular Interventional Society PCI registry (2006-2020; external validation cohort).

RESULTS

A total of 30 561 patients (mean age, 64.1 years; 24% women) were included in the Melbourne Interventional Group development cohort and 440 256 patients (mean age, 64.9 years; 27% women) in the British Cardiovascular Interventional Society external validation cohort. The primary outcome (no reflow) occurred in 4.1% (1249 patients) and 9.4% (41 222 patients) of the development and validation cohorts, respectively. From 33 candidate predictor variables, 6 final variables were selected by an adaptive least absolute shrinkage and selection operator regression model for inclusion (cardiogenic shock, ST-segment-elevation myocardial infarction with symptom onset >195 minutes pre-PCI, estimated stent length ≥20 mm, vessel diameter <2.5 mm, pre-PCI Thrombolysis in Myocardial Infarction flow <3, and lesion location). Model discrimination was very good (development C statistic, 0.808; validation C statistic, 0.741) with excellent calibration. Patients with a score of ≥8 points had a 22% and 27% risk of no reflow in the development and validation cohorts, respectively.

CONCLUSIONS

The no-reflow prediction in acute coronary syndrome risk score is a simple count-based scoring system based on 6 parameters available before PCI to predict the risk of no reflow. This score could be useful in guiding preventative treatment and future trials.

The predictive value of the HALP score for no-reflow phenomenon and short-term mortality in patients with ST-elevation myocardial infarction

OBJECTIVE

ST-elevation myocardial infarction (STEMI) is a medical emergency demanding immediate intervention, and primary percutaneous coronary intervention (pPCI) is the standard of care for this condition. While PCI has proven highly effective, a subset of patients experience the devastating no-reflow phenomenon, and some face increased short-term mortality. The Hemoglobin, Albumin, Lymphocyte, and Platelet (HALP) score, a novel biomarker-based tool, has recently surfaced as an innovative predictor of these adverse outcomes. This study aims to investigate the groundbreaking findings that designate a low HALP score as a robust risk factor for no-reflow and short-term mortality in STEMI patients.

METHODS

1817 consecutive STEMI patients who underwent pPCI were included in this retrospective study, and the patients were divided into two groups according to whether no-reflow developed or not, and the HALP scores of the groups were compared. In addition, short-term mortality was compared between the study groups according to their HALP score values. The predictive ability of the HALP score for no-reflow was evaluated using a receiver operating characteristic curve.

RESULTS

No-reflow developed in 198 (10.1%) of the patients included in the study. HALP score value was found to be significantly lower in the no-reflow group (27 ± 13 vs 47 ± 24, p < 0.001). After multivariable adjustment, the HALP score was an independent predictor of no-reflow (OR, 0.923, 95% CI, 0.910-0.935, p < 0.001). Furthermore, the HALP score showed good discrimination for no-reflow (AUC, 0.771, 95% CI, 0.737-0.805, p < 0.001). In addition, HALP score was determined to be an independent predictor for short-term mortality (HR, 0.955, 95% CI, 0.945-0.966, p < 0.001).

CONCLUSIONS

HALP score can independently predict the development of no-reflow and short-term mortality in STEMI patients undergoing pPCI.

The impact of primary percutaneous coronary intervention strategies during ST-elevation myocardial infarction on the prevalence of coronary microvascular dysfunction

Coronary microvascular dysfunction (CMD) is a common complication of ST-segment elevation myocardial infarction (STEMI) and can lead to adverse cardiovascular events. This is a non-randomized, observational, prospective study of STEMI patients with multivessel disease who underwent primary PCI, grouped based on whether they underwent balloon pre-dilatation stenting or direct stenting of the culprit lesion. Coronary physiology measurements were performed 3 months post-PCI including coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) measurements at the culprit vessel. The primary endpoint was the prevalence of CMD at 3 months, defined as IMR ≥ 25 or CFR < 2.0 with a normal fractional flow reserve. Secondary endpoints included major adverse cardiovascular events (MACE) at 12 months. Two hundred ten patients were enrolled; most were men, 125 (59.5%), with a median age of 65 years. One hundred twelve (53.2%) underwent balloon pre-dilatation before stenting, and 98 (46.7%) underwent direct stenting. The prevalence of CMD at 3 months was lower in the direct stenting group than in the balloon pre-dilatation stenting group (12.24% vs. 40.18%; p < 0.001). Aspiration thrombectomy and administration of intracoronary glycoprotein IIb/IIIa inhibitors were associated with lower odds of CMD (OR = 0.175, p = 0.001 and OR = 0.113, p = 0.001, respectively). Notably, MACE in patients who underwent direct stenting was lower than in those who underwent balloon pre-dilatation before stenting (14.29% vs. 26.79%; p = 0.040). In STEMI patients with multivessel disease, direct stenting of the culprit lesion, aspiration thrombectomy and administration of intracoronary glycoprotein IIb/IIIa inhibitors were associated with a lower prevalence of CMD at 3 months and lower incidence of MACE at 12 months compared with balloon pre-dilatation stenting.This trial is registered at https://ichgcp.net/clinical-trials-registry/NCT05406297 .

Relationship between systemic immune-inflammation index and no-reflow in percutaneous coronary intervention for saphenous grafts

Objective: In this study, we investigated the occurrence of no-reflow (NR) in percutaneous coronary intervention (PCI) for saphenous vein grafts (SVGs) and its relationship with a new systemic immune-inflammation index (SII) that determines inflammation. Methods: We studied 303 patients with acute coronary syndrome without ST elevation who underwent PCI for SVG disease. Results: NR formation during SVG PCI was significantly higher in patients with high SII (p < 0.001). NR occurrence was 12.8% when SII was ≤548 and 41.9% when SII was >548. Conclusion: Our study is the first to investigate SII as the state of inflammation and its effect on the SVG PCI. Patients with higher SII have a higher risk of NR during an SVG for PCI.

[Intra-aortic balloon pump in patients with myocardial infarction and cardiogenic shock of stages A and B]

This article presents two clinical cases of patients with myocardial infarction and stage A (at risk) and B (beginning) cardiogenic shock who underwent intra-aortic balloon counterpulsation (IABP). In patients with a high risk of classic cardiogenic shock and/or the no-reflow phenomenon, stenting of the infarct-related coronary artery during this type of mechanical circulatory support was performed without complications. Theoretical and practical aspects of using IABP at different stages of cardiogenic shock are discussed.

The role of myocardial work in evaluating coronary microcirculation of STEMI patients after percutaneous coronary intervention

BACKGROUND

Despite of restoring epicardial infarct-related artery(IRA) patency after myocardial infarction, microvascular reperfusion were not achieved sometimes, and the deterioration of myocardial perfusion persists in a considerable number of patients. This phenomenon is known as microvascular obstruction (MVO). MVO is often observed in ST-Segment Elevation Myocardial Infarction(STEMI) patients, even if percutaneous coronary intervention (PCI) was successful. In addition, some evidence has indicated that the presence of MVO predicted poor clinical outcomes independent of myocardial infarct size. Noninvasive as well as invasive modes for assessing microvascular perfusion(MVP) are complex, time consuming, and expensive have, there is yet no simple method available at present to assess coronary microcirculation. In this research, we attempt to evaluate the usefulness of left ventricular myocardial work (LVMW), a new index of myocardial performance, for the assessment of MVP in STEMI patients after PCI.

METHODS

Forty-seven patients with STEMI treated by PCI were enrolled and underwent a transthoracic doppler echocardiography (TTE) within 24-72 hours after PCI. IRA were left anterior descending (LAD) artery (29,62%), left circumflex (LCX) artery(9,19%), right coronary artery (RCA) (9,19%) respectively. Myocardial contrast echocardiography (MCE) was used to evaluate MVP after PCI, then perfusion score index (PSI) was calculated referring to whether the ultrasonic enhancing agents was replenishment or not. Patients were divided into normal MVP and impaired MVP group according to PSI. Left ventricular global longitudinal strain (GLS) was generated by speckle tracking echocardiography(STE) and pressure-strain loops (PSLs) was used to generate global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). GLS and the MW parameters (GWI, GCW, GWW, GWE) were compared between groups. Receiver operating characteristic (ROC) curves were calculated by plotting sensitivity versus (1-specificity), allowing calculation of the area under the curve (AUC) and the identification of LVMW parameters and GLS cutoff thresholds that best identify STEMI patients with impaired MVP after PCI.

RESULTS

In this study, a statistically significant difference was observed in GWI (1163±405 mm Hg% vs 1617±363 mm Hg%), GCW (1296±430 mm Hg% vs 1789±406 mm Hg%), GWE (83±8.52% vs 90±5.58%) and GLS (11.56±3.29 vs 16.65±3.59) between impaired MVP group and normal MVP group. However, there is no statistical significance difference in left ventricular ejection fraction (LVEF), and GWW. ROC analysis revealed that GCW (cut-off value: 1326 mm Hg%, AUC: .80, sensitivity: 95% and specificity: 56%), GWI (cut-off value: 1281 mm Hg%, AUC: .81, sensitivity: 90% and specificity: 70%), GWE (cut-off value: 90%, AUC: .77, sensitivity: 65% and specificity: 78%) and GLS (cut-off value: 12.5, AUC: .86, sensitivity: 90% and specificity: 67%) have appreciable AUC, sensitivity, and specificity to identify STEMI patients with impaired MVP after PCI.

CONCLUSION

Measuring LVMW indices of STEMI patients after PCI may add adjuvant value for the assessment of MVP.

Relationship Between Plasma Total Homocysteine Levels and Mean Corrected TIMI Frame Count in Patients with Acute Myocardial Infarction

Objective

To explore the relationship between the plasma total homocysteine (tHcy) levels and slow coronary flow (SCF) measured by mean corrected TIMI frame count (CTFC) in patients with acute myocardial infarction (AMI).

Methods

Ninety-one patients with primary myocardial infarction were enrolled in this study. The quantitative measurement of coronary blood flow was performed using the mean CTFC method. Plasma tHcy levels were determined using enzymatic assay from venous blood samples. Multivariable linear regression models indicated were used to estimate the effect size (β) of plasma tHcy levels on mean CTFC levels.

Results

Compared with patients with the mean CTFC ≤23.61 frames per second (FPS) group, there were increased plasma tHcy levels in patients of the second, third and highest mean CTFC quartiles (P < 0.001). Linear regression models indicated that plasma tHcy levels were positively associated with mean CTFC levels (adjusted-β per SD increase: 1.96, 95% CI 1.20 to 2.73, P < 0.001). Compared to the tHcy ≤12.30 μmol/L group, the third and highest tHcy-quartile groups had higher mean CTFC levels (adjusted-β: 2.52, 95% CI 0.39 to 4.65, P = 0.023; adjusted-β: 5.07, 95% CI 2.98 to 7.16, P < 0.001, respectively; P for trend <0.001). Moreover, this positive relationship was modified by diabetes mellitus (P-value for interaction was 0.046).

Conclusion

We found a positive relationship between plasma tHcy levels and mean CTFC levels in patients with AMI. Moreover, diabetes mellitus played an interactive role in this positive association between the plasma tHcy levels and mean CTFC levels.

Prophylactically injection of Nicorandil to reduce no-reflow phenomenon during PCI in acute STEMI patients: Protocol of a double-blinded, randomized, placebo-controlled trial

INTRODUCTION

An acute ST-elevation myocardial infarction (STEMI) is a very serious type of heart attack and a profoundly life-threatening medical emergency, and percutaneous coronary intervention (PCI) is the preferred strategy. However, in patients undergoing primary PCI, 30% to 40% may suffer the no-reflow phenomenon (NRP), and it could expand the myocardial infarction area and accompanied with high rehospitalization rate and fatality rate. In this study, we try to conduct a double blinded, randomized, placebo-controlled trial to observe whether the prophylactically intracoronary administration of Nicorandil could reduce the occurrence of NRP in STEMI patients undergoing PCI.

METHODS

Simple randomization in a 1:1 ratio will be made in blocks of variable size according to a random numbers generated by Excel 2010 to divide the patients to treatment group (Nicorandil) and control group (Saline). The outcomes are the occurrence of NRP, levels of interleukin-6 and HS-CRP, cTnT, and CK-MB before, and every 4 hours following PCI, and major adverse cardiovascular events at day 30. SPSS 23.0 (IBM, Chicago, IL) will be used, and P-value < .05 will be considered statistically significant.

CONCLUSIONS

The findings will determine the efficacy of prophylactically intracoronary administration of Nicorandil to reduce the occurrence of NRP during PCI in acute STEMI patients.

TRIAL REGISTRATION

OSF Registration number: DOI 10.17605/OSF.IO/QPF3V.

The Dynamic Inflammatory Tissue Microenvironment: Signality and Disease Therapy by Biomaterials

Tissue regeneration is an active multiplex process involving the dynamic inflammatory microenvironment. Under a normal physiological framework, inflammation is necessary for the systematic immunity including tissue repair and regeneration as well as returning to homeostasis. Inflammatory cellular response and metabolic mechanisms play key roles in the well-orchestrated tissue regeneration. If this response is dysregulated, it becomes chronic, which in turn causes progressive fibrosis, improper repair, and autoimmune disorders, ultimately leading to organ failure and death. Therefore, understanding of the complex inflammatory multiple player responses and their cellular metabolisms facilitates the latest insights and brings novel therapeutic methods for early diseases and modern health challenges. This review discusses the recent advances in molecular interactions of immune cells, controlled shift of pro- to anti-inflammation, reparative inflammatory metabolisms in tissue regeneration, controlling of an unfavorable microenvironment, dysregulated inflammatory diseases, and emerging therapeutic strategies including the use of biomaterials, which expand therapeutic views and briefly denote important gaps that are still prevailing.

Clinical outcomes following ST-elevation myocardial infarction secondary to stent thrombosis treated by percutaneous coronary intervention

OBJECTIVES

To assess the clinical outcomes of patients presenting with ST-elevation myocardial infarction (STEMI) secondary to stent thrombosis (ST) compared to those presenting with STEMI secondary to a de novo culprit lesion and treated by percutaneous coronary intervention (PCI).

BACKGROUND

ST is an infrequent but serious complication of PCI with substantial associated morbidity and mortality, however with limited data.

METHODS

We studied consecutive patients who underwent PCI for STEMI from 2005 to 2013 enrolled prospectively in the Melbourne Interventional Group registry. Patients were divided into two groups: the ST group comprised patients where the STEMI was due to ST and the de novo group formed the remainder of the STEMI cohort and all patients were treated by PCI. The primary endpoint was 30-day all-cause mortality.

RESULTS

Compared to the de novo group (n = 3,835), the ST group (n = 128; 3.2% of STEMI) had higher rates of diabetes, hypertension and dyslipidemia, established cardiovascular diseases, myocardial infarction, and peripheral vascular disease, all p < .01. Within the ST group, very-late ST was the most common form of ST, followed by late and early ST (64, 19, and 17%, respectively). There was no significant difference in the primary outcome between the ST group and the de novo group (4.7 vs. 7.1%, p = .29). On multivariate analysis, ST was not an independent predictor of 30-day mortality (odds ratio: 0.62, 95% confidence interval: 0.07-1.09, p = .068).

CONCLUSION

The short-term prognosis of patients with STEMI secondary to ST who were treated by PCI was comparable to that of patients with STEMI due to de novo lesions.

No-Reflow after PPCI-A Predictor of Short-Term Outcomes in STEMI Patients

The no-reflow phenomenon following primary percutaneous coronary intervention (PPCI) in acute ST-elevation myocardial infarction (STEMI) patients is a predictor of unfavorable prognosis. Patients with no-reflow have many complications during admission, and it is considered a marker of short-term mortality. The current research emphasizes the circumstances of the incidence and complications of the no-reflow phenomenon in STEMI patients, including in-hospital mortality. In this case-control study, conducted over two and a half years, there were enrolled 656 patients diagnosed with STEMI and reperfused through PPCI. Several patients (n = 96) developed an interventional type of no-reflow phenomenon. One third of the patients with a no-reflow phenomenon suffered complications during admission, and 14 succumbed. Regarding complications, the majority consisted of arrhythmias (21.68%) and cardiogenic shock (16.67%). The anterior localization of STEMI and the left anterior descending artery (LAD) as a culprit lesion were associated with the highest number of complications during hospitalization. At the same time, the time interval >12 h from the onset of the typical symptoms of myocardial infarction (MI) until revascularization, as well as multiple stents implantations during PPCI, correlated with an increased incidence of short-term complications. The no-reflow phenomenon in patients with STEMI was associated with an unfavorable short-term prognosis.

[The Clinical Value of no-Reflow Phenomenon in the Routing Operation of The Regional Vascular Center]

Coronary no-reflow phenomenon (CNR) is a complication of primary percutaneous coronary intervention (PCI). According to different reports, CNR occurs in 10 to 60 % of cases. Despite the long history of studying this phenomenon many issues remain unsolved. This article presents a clinical case of electrocardiographically confirmed ST-segment elevation myocardial infarction. In this case, the CNR phenomenon occurred during PCI and was associated with heart rhythm disorders, left ventricular (LV) cavity dilatation with a decrease in LV contractility, and formation of intracavitary thrombus. The patient asked for medical care late, which could influence the development of CNR. This case demonstrates the clinical significance, diagnostic characteristics, and successful drug correction of the no-reflow phenomenon.

Outcomes of cardiogenic shock complicating acute coronary syndromes

OBJECTIVES

We aimed to assess the outcomes of cardiogenic shock (CS) complicating acute coronary syndromes (ACS).

BACKGROUND

CS remains the leading cause of mortality in patients presenting with ACS despite advances in care.

METHODS

We studied 13,184 patients undergoing percutaneous coronary intervention (PCI) for all subtypes of ACS enrolled prospectively in a large multicentre Australian registry (Melbourne Interventional Group registry) from 2005 to 2013. All-cause mortality was obtained via linkage to the National Death Index. Patients were divided into those with and those without CS.

RESULTS

Compared to the non-CS group (n = 12,548, 95.2%), the CS group (n = 636, 4.8%) had a higher proportion of out-of-hospital cardiac arrest (OHCA) (31.1 vs. 2.2%) and ST-elevation myocardial infarction (STEMI) presentation (89 vs. 34%), both p < .01. Patients in the CS group had higher rates of in-hospital (40.4 vs. 1.2%) and 30-day (41 vs. 1.7%) mortality compared to the non-CS group. Long-term mortality over a median follow-up of 4.2 years was higher in the CS group (50.6 vs. 13.8%), p < .001. Trends of in-hospital and 30-day mortality rates of CS complicating ACS were relatively stable from 2005 to 2013. Predictors of long-term NDI-linked mortality within the CS group include severe left ventricular systolic dysfunction (HR 3.0), glomerular filtration rate (GFR) <30 (HR 2.56), GFR 30-59 (HR 1.94), OHCA (HR 1.46), diabetes (HR 1.44), and age (HR 1.02), all p < .05.

CONCLUSIONS

Rates of CS-related mortality complicating ACS have remained very high and steady over nearly a decade despite progress in STEMI systems of care, PCI techniques, and medical therapy.

Prognostic Value of Pre-Infarction Angina Combined with Mean Platelet Volume to Lymphocyte Count Ratio for No-Reflow and Short-Term Mortality in Patients with ST-Segment Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Background

The aim of the present study was to investigate the clinical predictive value of pre-infarction angina (PIA) combined with mean platelet volume to lymphocyte count ratio (MPVLR) for no-reflow phenomenon and short-term mortality in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI).

Material/Methods

A total of 1009 STEMI patients who had undergone PCI were enrolled and subdivided into 4 groups based on the occurrence of PIA and the presence of MPVLR above or below the cutoff value. Analysis of the predictors of the no-reflow phenomenon and 90-day mortality was conducted. Further, evaluation and comparison of the clinical predictive value of PIA, MPVLR, and their combination were done.

Results

Both MPVLR (odds ratio [OR]=1.476, 95% confidence interval [CI]: 1.401 to 1.756, P<0.001; hazard ratio [HR]=1.430, 95% CI: 1.287 to 1.643, P<0.001) and PIA (OR=0.905, 95% CI: 0.783 to 0.986, P<0.001; HR=0.878, 95% CI: 0.796 to 0.948, P<0.001) were independent predictors of no-reflow phenomenon and 90-day mortality. Spearman’s rank correlation test revealed that MPVLR (r=−0.297, P<0.001), monocyte to lymphocyte count ratio (MLR) (r=−0.211, P<0.001) and neutrophil to lymphocyte count ratio (NLR) (r=−0.389, P<0.001) in peripheral blood were significantly negatively correlated with postoperative left ventricular ejection fraction (LVEF). Upon comparing the area under curve (AUC), the MPVLR combined with PIA achieved better performance in differentiating no-reflow phenomenon (AUC=0.847, 95% CI: 0.821 to 0.874) and 90-day mortality (AUC=0.790, 95% CI: 0.725 to 0.855), than the GRACE score, MPVLR and PIA alone, and had similar performance to all other pairwise combinations of the GRACE score, MPVLR and PIA.

Conclusions

High MPVLR and PIA were independent predictors of the no-reflow phenomenon and 90-day mortality in patients with STEMI after PCI. Moreover, Combined application of MPVLR and PIA can effectively predict the occurrence of the no-reflow phenomenon and 90-day mortality.

ST-segment elevation myocardial infarction

ST-segment elevation myocardial infarction (STEMI) is the most acute manifestation of coronary artery disease and is associated with great morbidity and mortality. A complete thrombotic occlusion developing from an atherosclerotic plaque in an epicardial coronary vessel is the cause of STEMI in the majority of cases. Early diagnosis and immediate reperfusion are the most effective ways to limit myocardial ischaemia and infarct size and thereby reduce the risk of post-STEMI complications and heart failure. Primary percutaneous coronary intervention (PCI) has become the preferred reperfusion strategy in patients with STEMI; if PCI cannot be performed within 120 minutes of STEMI diagnosis, fibrinolysis therapy should be administered to dissolve the occluding thrombus. The initiation of networks to provide around-the-clock cardiac catheterization availability and the generation of standard operating procedures within hospital systems have helped to reduce the time to reperfusion therapy. Together with new advances in antithrombotic therapy and preventive measures, these developments have resulted in a decrease in mortality from STEMI. However, a substantial amount of patients still experience recurrent cardiovascular events after STEMI. New insights have been gained regarding the pathophysiology of STEMI and feed into the development of new treatment strategies.

Assessing and managing coronary microcirculation dysfunction in acute ST-segment elevation myocardial infarction

INTRODUCTION

Microvascular dysfunction in the setting of acute ST-segment elevation myocardial infarction (STEMI) is an indicator of poor long-term prognosis. Prompt assessment and pharmacological or procedural therapy (prophylactic or post onset of dysfunction) may improve outcomes in STEMI post-primary percutaneous intervention. Areas covered: The aim of this review is to provide a comprehensive analysis of the evidence available about the assessment and management of coronary microcirculatory injury/dysfunction in STEMI. We also aim to elucidate the possible strategies that could be applied in clinical practice to support the application of already available or novel therapeutic strategies for the prevention and management of microvascular impairment. Expert commentary: There are multiple established methods in assessing microvascular dysfunction, both non-invasively and invasively. Invasive physiological measurements allow real-time assessment of microvascular dysfunction and have prognostic cut-off values. Multiple therapeutic modalities exist for both preventing and treating microvascular dysfunction. These can be either pharmacological or mechanical, and there is no algorithm to guide if, how and when to apply them. Future research into both procedural and pharmacological therapy guided by physiological measurements is needed, with the aim of recognizing high-risk patients who would benefit from therapy.

No-reflow phenomenon in the heart and brain

The no-reflow phenomenon refers to the observation that when an organ is made ischemic by occlusion of a large artery supplying it, restoration of patency in that artery does not restore perfusion to the microvasculature supplying the parenchyma of that organ. This has been observed after prolonged arterial occlusions in the heart (30–90 min), brain, skin, and kidney. In experimental models, zones of no reflow in the heart are characterized by ultrastructural microvascular damage, including focal endothelial swelling obstructing the lumen of small vessels. Blood elements such as neutrophil plugs, platelets, and stacking of erythrocytes have also been implicated. No reflow is associated with poor healing of the myocardial infarction. In patients, no reflow is associated with a poor clinical outcome independent of infarct size, suggesting that therapy for no reflow may be an important approach to improving outcome for ST elevation myocardial infarction. No reflow occurs after reperfusion of experimental cerebral ischemia and may be observed after only 5-min episodes of ischemia. Aggregation of blood elements may play a greater role than in cardiac no reflow. No reflow in the brain may involve cortical spreading depression with disturbed local vascular control and high, vasculotonic levels of extracellular K+ concentration, postischemic swelling in endothelial cells and abutting end feet of pericytes, pericyte contraction and death, interstitial edema with collapse of cerebral capillaries, and inflammatory reaction. New guidelines suggesting that reperfusion for stroke may be considered as late as 24 h after the onset of symptoms suggest that clinicians may be seeing more no reflow in the future.