Clinical implications of the 'no reflow' phenomenon. A predictor of complications and left ventricular remodeling in reperfused anterior wall myocardial infarction

Incidence, predictors and outcomes of stress hyperglycemia in patients with ST elevation myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

Stress hyperglycemia is a common finding during ST elevation myocardial infarction in diabetic patients and is associated with a worse outcome. However, there are limited data about stress hyperglycemia in non-diabetic patients and its outcome especially in patients undergoing primary percutaneous coronary intervention.

METHODS

The study was conducted on 660 patients with ST elevation myocardial infarction who were managed with primary percutaneous coronary intervention. Patients were classified into two groups according to the presence of stress hyperglycemia: group I (patients with stress hyperglycemia) and group II (patients without stress hyperglycemia). Patients were analysed for clinical outcome including mortality and the occurrence of major adverse cardiac events.

RESULTS

Incidence of stress hyperglycemia was 16.8%, multivariate regression analysis identified the independent predictors of stress hyperglycemia, that were family history of diabetes mellitus odds ratio 1.697 (95% confidence interval: 1.077-2.674, p = 0.023), body mass index >24 kg/m² odds ratio 1.906 (95% confidence interval: 1.244-2.922, p = 0.003) and cardiogenic shock on admission odds ratio 2.517 (95% confidence interval: 1.162-5.451, p = 0.019). Mortality, cardiogenic shock, contrast induced nephropathy and no reflow phenomenon were significantly higher in stress hyperglycemia group with p value = 0.027, 0.001, 0.020 and 0.037, respectively.

CONCLUSION

Stress hyperglycemia in non-diabetic patients with ST elevation myocardial infarction undergoing primary percutaneous coronary intervention is associated with increased incidence of no reflow phenomenon, contrast induced nephropathy, cardiogenic shock and higher mortality.

Relationship between the ST-Segment Resolution and Microvascular Dysfunction in Patients Who Underwent Primary Percutaneous Coronary Intervention

Objectives

Incomplete ST-segment elevation resolution (STR) occasionally occurs despite successful revascularization of epicardial coronary artery after primary percutaneous coronary intervention (PPCI). The aim of this study was to evaluate the relationship between the degree of STR and the severity of microvascular dysfunction.

Methods

A total of 73 consecutive patients with ST-segment elevation myocardial infarction (STEMI) who underwent successful PPCI were evaluated. Serial 12-lead electrocardiography was performed at baseline and at 90 minutes after PPCI. Microvascular dysfunction was assessed by index of microvascular resistance (IMR) immediately after PPCI.

Results

Patients were classified into 2 groups: 50 patients with complete STR (STR ≥50%) and 23 patients with incomplete STR (STR <50%). The incomplete STR group had a higher IMR value and lower left ventricular ejection fraction (LVEF), compared with the complete STR group. The degree of STR was significantly correlated with IMR (r = −0.416, P=0.002) and LVEF (r = 0.300, P=0.011). These correlations were only observed in patients with left anterior descending artery (LAD) infarction but not observed in patients with non-LAD infarction. A cutoff IMR value was 27.3 for predicting incomplete STR after PPCI.

Conclusion

Incomplete STR after PPCI in patients with STEMI reflects the presence of microvascular and left ventricular dysfunction, especially in patients with LAD infarction.

Impact of intracoronary contrast injection pressure on reperfusion during primary percutaneous coronary intervention in acute ST-segment elevation myocardial infarction: A prospective randomized pilot study

Background

Distal embolization of plaque and thrombotic debris in the infarct-related artery (IRA) may lead to microvascular obstruction resulting in impaired myocardial reperfusion.

The aim of the study was to assess the impact of contrast injection pressure in IRA, during primary percutaneous coronary intervention (PCI), on myocardial reperfusion in patients with acute ST-segment elevation myocardial infarction (STEMI).

Methods

This prospective, randomized, open label, pilot trial evaluated acute STEMI patients who underwent primary PCI, with blinded evaluation of end points. Patients were assigned to higher injection pressure group A (550 pound/inch²) or lower injection pressure group B (200 pound/inch²). Primary endpoint was the postprocedural incidence of restored myocardial perfusion defined as myocardial blush grade (MBG) 3.

Results

Study included 100 consecutive acute STEMI patients, with median age of 63 (56–72) years (77% men) who were randomized to higher and lower injection pressure group. Baseline demographic, clinical and angiographic characteristics did not differ significantly between the groups. There were no significant differences between the study groups regarding difference in achieved MBG 3 (33 vs 36 patients, p = 0.247) nor regarding the ST-segment deviation score neither immediately after (3 vs 4 mm, p > 0.3) nor 24 h after primary PCI (2 vs 3 mm, p > 0.3).

Conclusion

There was no impact of lower intracoronary contrast injection pressure in comparison to higher injection pressure, during primary PCI in patients with acute STEMI, on myocardial reperfusion as assessed by MBG or ST segment changes in the ECG.

The study was registered at registry ClinicalTrials.gov with the registration number: NCT03445364, on February 26th 2018.

The Effect of Stent Artefact on Quantification of Plaque Features Using Optical Coherence Tomography (OCT): A Feasibility and Clinical Utility Study

BACKGROUND

Optical coherence tomography (OCT) can detect detailed plaque features in native coronary arteries. Stent struts cause shadows that partially obscure the vessel wall, but plaque features can still be seen. We investigated the impact of stent artefact on plaque quantification and whether the plaque behind struts is associated with microvascular dysfunction.

METHODS

Patients retrospectively recruited from two centres, underwent OCT pre- and post-stenting on the same vessel segment. Lipid (LA) and calcium (CA) were measured as arcs. Macrophages, microchannels and cholesterol crystals were counted. Subsequently, we determined whether stented plaque features were associated with reduced Thrombolysis in Myocardial Infarction (TIMI) flow grade in consecutive patients who underwent OCT post-stenting.

RESULTS

In 52 patients the lipid arc was similar pre- vs post-stent: median (55º [13º-93º] vs. 40º [18º-87°]; difference 1º [-7º to 16º], p = NS). Pre- and post-stent lipid were strongly correlated (r = 0.92, p < 0.001). In a further 128 patients those with reduced (TIMI ≤ II) vs normal flow post percutaneous coronary intervention (PCI) showed more plaque behind struts: lipid (89º [50º-139º] vs 62º [29º-88°]; p < 0.001); and calcium (24º [6º-45º] vs 7° [0º-34º]; p = 0.031). Multivariate logistic regression analysis showed that abnormal TIMI flow post-stenting was associated with diabetes (Odds ratio [OR] 2.87, CI 1.01-8.19, p = 0.048), LA (OR 1.29, 95% CI 1.14-1.38, p < 0.001) and CA (OR 1.26, CI 1.07-1.40, p = 0.005).

CONCLUSIONS

Plaque behind the struts can be accurately quantified using OCT. Furthermore, OCT plaque features in stented segments are associated with microvascular dysfunction post PCI.

Multilayer longitudinal strain can help predict the development of no-reflow in patients with acute coronary syndrome without ST elevation

No-reflow (NR) is one of the major complications of primary percutaneous coronary intervention (PCI) in patients with non-ST-segment elevation myocardial infarction (NSTEMI). We aim to assess the value of multilayer longitudinal strain parameter to predict NR in patients with NSTEMI and preserved ejection fraction. 230 consecutive patients who were admitted to the emergency department and diagnosed with NSTEMI were prospectively included in this study. Echocardiography was performed 1 h before angiography. Specific analysis for endocardial, mid-myocardial and epicardial layers were performed by two-dimensional (2D) speckle tracking echocardiography (STE) for multilayer longitudinal strain. NR was described as flow grade of ≤ TIMI 2 when mechanical occlusions like dissection, intimal tear, arterial spasm and thromboembolism during angiography were excluded. 49 of 168 patients admitted to the study had NR. No significant differences were observed between the groups regarding age and gender. Multilayer longitudinal strain imaging (endocard, midmyocard and epicard) revealed lower strain values particularly in endocardial layer in patients with NR (GLS-endocard: - 14.14 ± 1.39/- 17.41 ± 2.34, p < 0.001; GLS-midmyocard: - 14.81 ± 1.40/17.81 ± 2.22, p < 0.001; GLS-epicard: - 16.14 ± 1.38/18.22 ± 2.00, p < 0.001). GLS-endocard, GLS-midmyocard, GLS-epicard and ST depression were found to be statistically significant independents parameters respectively to predict NR phenomenon (GLS-endocard: OR: 2.193, p < 0.001; GLS-midmyocard: OR: 1.510, p: 0.016; GLS-epicard: OR: 1.372, p: 0.035; ST depression: OR: 3.694, p: 0.014). We revealed that left ventricular strain study with speckle tracking echocardiography predicts NR formation. This noninvasive method may be useful for detecting NR formation in patients with NSTEMI.

The cyclooxygenase-1/mPGES-1/endothelial prostaglandin EP4 receptor pathway constrains myocardial ischemia-reperfusion injury

The use of nonsteroidal anti-inflammatory drugs that inhibit cyclooxygenase (COX)-1 and COX-2, increases heart failure risk. It is unknown whether microsomal (m) prostaglandin (PG) E synthase (S)-1, a target downstream of COX, regulates myocardial (M) ischemia/reperfusion (I/R) injury, a key determinant of heart failure. Here we report that COX-1 and mPGES-1 mediate production of substantial amounts of PGE₂ and confer cardiac protection in MI/R. Deletion of mPges-1 impairs cardiac microvascular perfusion and increases inflammatory cell infiltration in mouse MI/R. Consistently, mPges-1 deletion depresses the arteriolar dilatory response to I/R in vivo and to acetylcholine ex vivo, and enhances leukocyte-endothelial cell interaction, which is mediated via PGE receptor-4 (EP4). Furthermore, endothelium-restricted Ep4 deletion impairs microcirculation, and exacerbates MI/R injury, irrespective of EP4 agonism. Treatment with misoprostol, a clinically available PGE analogue, improves microcirculation and reduces MI/R injury. Thus, mPGES-1, a key microcirculation protector, constrains MI/R injury and this beneficial effect is partially mediated via endothelial EP4.

The use of nonsteroidal anti-inflammatory drugs inhibiting COX-1/2 is associated with an increased risk of heart failure. Here the authors show that mPGES-1, a therapeutic target downstream of COX enzymes, protects from cardiac ischemia/reperfusion injury, limiting leukocyte-endothelial interactions and preserving microvascular perfusion partly via the endothelial EP4 receptor.

Comparison of 0.9-mm and 1.4-mm catheters in excimer laser coronary angioplasty for acute myocardial infarction

Excimer laser coronary angioplasty (ELCA) is a unique revascularization modality that can vaporize plaque and thrombus. Compared to thrombus aspiration therapy, ELCA is reported to provide better microcirculation and reduced peripheral embolism in treatment for acute coronary syndrome. Excimer laser catheters come in various sizes, and we sought to compare the 0.9- and 1.4-mm-diameter catheters. We retrospectively enrolled 90 acute myocardial infarction (AMI) patients who underwent primary percutaneous coronary intervention with excimer laser from August 2013 to March 2017 in our hospital. Patients were grouped by diameter of catheter that had been used, the 0.9 mm group (n = 51) and 1.4 mm group (n = 39). We evaluated myocardial perfusion, procedural success rate, short-term outcome, lesion crossability, and complications between the two groups. The percentage of patients whose final thrombolysis in myocardial infarction (TIMI) grade was 3 (0.9 mm 86.3% vs 1.4 mm 89.7% p = 0.75) and final myocardial blush grade (MBG) was 3 (0.9 mm 72.5% vs 1.4 mm 69.2% p = 0.82) was similarly high for both groups. Procedural success rate, in-hospital major adverse cardiac events (MACE), lesion crossability, and complications were also similar. This study showed that efficacy of 0.9 and 1.4 mm excimer laser catheter was equivalent in ELCA for AMI patients. If one takes into account lesion crossability, debulking effects, and the stunned platelets phenomenon, the 0.9 mm excimer laser catheter is sufficient for ELCA in AMI patients.

ROUTINELY AVAILABLE BIOMARKERS AS LONG-TERM PREDICTORS OF DEVELOPING SYSTOLIC DYSFUNCTION IN COMPLETELY REVASCULARIZED PATIENTS WITH ACUTE ST ELEVATION MYOCARDIAL INFARCTION

The aim of this study was to assess the efficacy of high-sensitivity C-reactive protein (hsCRP), cardiac troponin T (cTnT) and creatine kinase (CK) as long-term predictors of reduced systolic function in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) with complete revascularization. This prospective study evaluated consecutive patients with acute STEMI who had normal left ventricular ejection fraction (LVEF ≥50%) at admission with single-vessel disease and underwent complete revascularization. Blood samples were collected from admission to day 7. The primary endpoint was reduction of LVEF <50% after 12 months. The study included 47 patients, median age 59±10 years, 74.5% of them men. Patients who developed systolic dysfunction (LVEF <50%) had significantly higher mean values of cTnT after 24 hours (5.11 vs. 2.82 µg/L, p=0.010) and peak values of CK (3375.5 vs. 1865 U/L, p=0.008). There was no significant relation between hsCRP and development of reduced LVEF (p=0.541). In conclusion, cTnT and CK could serve as long-term predictors of reduced left ventricular systolic function (<50%) in acute STEMI patients with normal systolic function at admission, single-vessel coronary disease and complete revascularization during primary PCI.

Primary percutaneous coronary intervention in ST-elevation myocardial infarction with an ectatic infarct-related artery

OBJECTIVE

The aim of this study was to describe the procedural characteristics, myocardial perfusion, and long-term outcomes in ST-elevation myocardial infarction patients with an ectatic infarct-related artery (IRA).

PATIENTS AND METHODS

The retrospective analysis included 1270 consecutive ST-elevation myocardial infarction patients treated by primary percutaneous coronary intervention who were categorized according to the coronary anatomy of the IRA as follows: ectatic group (n=91) and control group (n=1179).

RESULTS

Compared with the control group, patients in the ectatic group experienced lower Thombolysis in myocardial infarction grade 3 flow rate after percutaneous coronary intervention (64.8 vs. 88.2%: ectatic group vs. nonectatic group, P<0.001) and more frequent distal embolization (44.4 vs. 11.1%, P<0.001). ECG ST resolution was significantly lower in the ectatic group (P<0.001). Paradoxically, the left ventricular ejection fraction values at discharge were significantly higher in the ectatic group (P=0.032) and the infarct size assessed within 6-12 months after discharge tended to be smaller (P=0.06). The 30-day mortality rate was not significantly different between the two groups (3.3 vs. 5.0%, P=0.378) as well as Kaplan-Meier analysis for long-term overall survival in both groups (P=0.8).

CONCLUSION

Patients with ectatic IRA were characterized by discrepancies between high angiographic thrombus burden in a larger vessel and impact on left ventricular function that may influence their long-term survival.

Molecular Imaging of VWF (von Willebrand Factor) and Platelet Adhesion in Postischemic Impaired Microvascular Reflow

BACKGROUND

Complete mechanistic understanding of impaired microvascular reflow after myocardial infarction will likely lead to new therapies for reducing infarct size. Myocardial contrast echocardiography perfusion imaging and molecular imaging were used to evaluate the contribution of microvascular endothelial-associated VWF (von Willebrand factor) and platelet adhesion to microvascular no-reflow.

METHODS AND RESULTS

Myocardial infarction was produced by transient LAD ligation in WT (wild type) mice, WT mice treated with the VWF proteolytic enzyme ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13), and ADAMTS13-deficient (ADAMTS13-/-) mice. Myocardial contrast echocardiography perfusion imaging and molecular imaging of VWF and platelet GP (glycoprotein) Ibα were performed 30 minutes after ischemia-reperfusion. Infarct size was measured at 3 days. Mortality during ischemia-reperfusion incrementally increased in WT+ADAMTS13, WT, and ADAMTS13-/- mice (14%, 43%, and 63%, respectively; P<0.05). For WT mice, molecular imaging signal for platelets and VWF in the postischemic risk area was 4- to 5-fold higher ( P<0.05) compared with both the remote nonischemic regions or to sham-treated mice. Signal enhancement in the risk area was completely abolished by ADAMTS13 treatment for both platelets (12.8±3.3 versus -1.0±4.4 IU; P<0.05) and VWF (13.9±4.0 versus -1.0±3.0 IU; P<0.05). ADAMTS13-/- compared with WT mice had 2- to 3-fold higher risk area signal for platelets (33.1±8.5 IU) and VWF (30.9±1.9 IU). Microvascular reflow in the risk area incrementally decreased for WT+ADAMTS13, WT, and ADAMTS13-/- mice ( P<0.05), whereas infarct size incrementally increased ( P<0.05).

CONCLUSIONS

Mechanistic information on microvascular no-reflow is possible by combining perfusion and molecular imaging. In reperfused myocardial infarction, excess endothelial-associated VWF and secondary platelet adhesion in the risk area microcirculation contribute to impaired reflow and are modifiable.

Combined Therapy with SS31 and Mitochondria Mitigates Myocardial Ischemia-Reperfusion Injury in Rats

Myocardial ischemia-reperfusion (IR) injury contributes to adverse cardiac outcomes after myocardial ischemia, cardiac surgery, or circulatory arrest. In this study, we evaluated the ability of combined SS31-mitochondria (Mito) therapy to protect heart cells from myocardial IR injury. Adult male SD rats (n = 8/each group) were randomized: group 1 (sham-operated control), group 2 (IR, 30-min ischemia/72 h reperfusion), group 3 (IR-SS31 (2 mg intra-peritoneal injection at 30 min/24 h/48 h after IR)), group 4 (IR-mitochondria (2 mg/derived from donor liver/intra-venous administration/30 min after IR procedure)), and group 5 (IR-SS31-mitochondria). In H9C2 cells, SS31 suppressed menadione-induced oxidative-stress markers (NOX-1, NOX-2, oxidized protein) while it increased SIRT1/SIRT3 expression and ATP levels. In adult male rats 72 h after IR, left ventricular ejection fraction (LVEF) was highest in sham-operated control animals and lowest in the IR group. LVEF was also higher in IR rats treated with SS31-Mito than untreated IR rats or those treated with Mito or SS31 alone. Areas of fibrosis/collagen-deposition showed the opposite pattern. Likewise, levels of oxidative-stress markers (NOX-1, NOX-2, oxidized protein), inflammatory markers (MMP-9, CD11, IL-1β, TNF-α), apoptotic markers (mitochondrial-Bax, cleaved-caspase-3, PARP), fibrosis markers (p-Smad3, TGF-β), DNA-damage (γ-H2AX), sarcomere-length, and pressure/volume overload markers (BNP, β-MHC) all showed a pattern opposite that of LVEF. Conversely, anti-apoptotic (BMP-2, Smad1/5) and energy integrity (PGC-1α/mitochondrial cytochrome-C) markers exhibited a pattern identical to that of LVEF. This study demonstrates that the combined SS31-Mito therapy is superior to either therapy alone for protecting myocardium from IR injury and indicates that the responsible mechanisms involved increased SIRT1/SIRT3 expression, which suppresses inflammation and oxidative stress and protects mitochondrial integrity.

Efficacy and safety of thrombus aspiration in ST-segment elevation myocardial infarction: an updated systematic review and meta-analysis of randomised clinical trials

BACKGROUND:

The role of thrombus aspiration plus primary percutaneous coronary intervention in ST-segment elevation myocardial infarction remains controversial.

METHODS:

We performed a meta-analysis of 25 randomised controlled trials in which 21,740 ST-segment elevation myocardial infarction patients were randomly assigned to thrombus aspiration plus primary percutaneous coronary intervention or primary percutaneous coronary intervention. Study endpoints were: death, myocardial infarction, stent thrombosis and stroke.

RESULTS:

On pooled analysis, the risk of death (4.3% vs. 4.8%, odds ratio (OR) 0.90, 95% confidence interval (CI) 0.79-1.03; P=0.123), myocardial infarction (2.4% vs. 2.5%, OR 0.95, 95% CI 0.80-1.13; P=0.57) and stent thrombosis (1.3% vs. 1.6%, OR 0.80, 95% CI 0.63-1.01; P=0.066) was similar between thrombus aspiration plus primary percutaneous coronary intervention and primary percutaneous coronary intervention. The risk of stroke was higher in the thrombus aspiration plus primary percutaneous coronary intervention than the primary percutaneous coronary intervention group (0.84% vs. 0.59%, OR 1.401, 95% CI 1.004-1.954; P=0.047). However, on sensitivity analysis after removing the TOTAL trial, thrombus aspiration plus primary percutaneous coronary intervention was not associated with an increased risk of stroke (OR 1.01, 95% CI 0.58-1.78). The weak association between thrombus aspiration and stroke was also confirmed by the fact that the lower bound of the 95% CI was slightly below unity after removing either the study by Kaltoft or the ITTI trial. There was no interaction between the main study results and follow-up, evidence of coronary thrombus, or study sample size.

CONCLUSIONS:

In patients with ST-segment elevation myocardial infarction, thrombus aspiration plus primary percutaneous coronary intervention does not reduce the risk of death, myocardial infarction or stent thrombosis. Thrombus aspiration plus primary percutaneous coronary intervention is associated with an increased risk of stroke; however, this latter finding appears weak.

Cardiosphere-Derived Cells and Ischemic Heart Failure

After a myocardial infarction, heart tissue becomes irreversibly damaged, leading to scar formation and inevitably ischemic heart failure. Of the many available interventions after a myocardial infarction, such as percutaneous intervention or pharmacological optimization, none can reverse the ischemic insult on the heart and restore cardiac function. Thus, the only available cure for patients with scarred myocardium is allogeneic heart transplantation, which comes with extensive costs, risks, and complications. However, multiple studies have shown that the heart is, in fact, not an end-stage organ and that there are endogenous mechanisms in place that have the potential to spark regeneration. Stem cell therapy has emerged as a potential tool to tap into and activate this endogenous framework. Particularly promising are stem cells derived from cardiac tissue itself, referred to as cardiosphere-derived cells (CDCs). CDCs can be extracted and isolated from the patient's myocardium and then administered by intramyocardial injection or intracoronary infusion. After early success in the animal model, multiple clinical trials have demonstrated the safety and efficacy of autologous CDC therapy in humans. Clinical trials with allogeneic CDCs showed early promising results and pose a potential "off-the-shelf" therapy for patients in the acute setting after a myocardial infarction. The mechanism responsible for CDC-induced cardiac regeneration seems to be a combination of triggering native cardiomyocyte proliferation and recruitment of endogenous progenitor cells, which most prominently occurs via paracrine effects. A further understanding of the mediators involved in paracrine signaling can help with the development of a stem cell-free therapy, with all the benefits and none of the associated complications.

Prognostic significance of fragmented QRS in patients with ST-elevation myocardial infarction undergoing revascularization

BACKGROUND & OBJECTIVES

This longitudinal study was carried out to evaluate the prognostic significance of fragmented QRS (fQRS) in patients with acute ST elevation myocardial infarction (STEMI) undergoing revascularization.

METHODS

This study included 103 STEMI patients belonging to Killip class I and II who underwent primary revascularization. All patients underwent twelve lead ECG at admission before PCI. Serial ECG were done after PCI at 3 hours, 6 hours, 24 hours, 48 hours and at discharge for detection of fQRS and echocardiography on day 3 post revascularization. Patients developing fQRS within 48 hours and with persistence of fQRS till discharge were included in "persistent fQRS" group. They were followed up after 30 days for major adverse cardiac events (MACE) and assessment of LV function by echocardiography.

RESULTS

fQRS was present in 64 patients (61.5%) of study population with 37 patients (57.8%) having persistent fQRS. MACE rates were low (4.8%) and did not differ with respect to fQRS. fQRS significantly correlated with LV dysfunction at 30 days on univariate analysis (p-0.003) but not on multivariate analysis (p -0.10). fQRS was significantly related to impaired myocardial reperfusion as assessed by ΣSTR (percent of total ST segment resolution) (adjusted odds ratio, 95% CI [4.265 (1.034 - 17.58)], p = 0.04).

CONCLUSION

In our study, fQRS did not predict MACE and LV dysfunction in acute STEMI patients belonging to Killip class I and II on short term follow-up of 30 days. But, fQRS independently predicted impaired microvascular myocardial reperfusion as assessed by ΣSTR.

Strain analysis is superior to wall thickening in discriminating between infarcted myocardium with and without microvascular obstruction

OBJECTIVES

The aim of the present study was to evaluate the diagnostic performances of strain and wall thickening analysis in discriminating among three types of myocardium after acute myocardial infarction: non-infarcted myocardium, infarcted myocardium without microvascular obstruction (MVO) and infarcted myocardium with MVO.

METHODS

Seventy-one patients with a successfully treated ST-segment elevation myocardial infarction underwent cardiovascular magnetic resonance imaging at 2-6 days after reperfusion. The imaging protocol included conventional cine imaging, myocardial tissue tagging and late gadolinium enhancement. Regional circumferential and radial strain and associated strain rates were analyzed in a 16-segment model as were the absolute and relative wall thickening.

RESULTS

Hyperenhancement was detected in 418 (38%) of 1096 segments and was accompanied by MVO in 145 (35%) of hyperenhanced segments. Wall thickening, circumferential and radial strain were all significantly diminished in segments with hyperenhancement and decreased even further if MVO was also present (all p < 0.001). Peak circumferential strain (CS) surpassed all other strain and wall thickening parameters in its ability to discriminate between hyperenhanced and non-enhanced myocardium (all p < 0.05). Furthermore, CS was superior to both absolute and relative wall thickening in differentiating infarcted segments with MVO from infarcted segments without MVO (p = 0.02 and p = 0.001, respectively).

CONCLUSIONS

Strain analysis is superior to wall thickening in differentiating between non-infarcted myocardium, infarcted myocardium without MVO and infarcted myocardium with MVO. Peak circumferential strain is the most accurate marker of regional function.

KEY POINTS

• CMR can quantify regional myocardial function by analysis of wall thickening on cine images and strain analysis of tissue tagged images. • Strain analysis is superior to wall thickening in differentiating between different degrees of myocardial injury after acute myocardial infarction. • Peak circumferential strain is the most accurate marker of regional function.

The value of real-time myocardial contrast echocardiography for detecting coronary microcirculation function in coronary artery disease patients

Objective:

The aim of this study was to evaluate the value of real-time myocardial contrast echocardiography (RT-MCE) for detecting coronary microcirculation (CM) function in coronary artery disease (CAD) patients.

Methods:

Sixty-five consecutive patients were divided into CAD (n=52) and no-CAD (n=13) groups using coronary angiography (CAG). All patients underwent RT-MCE at rest and CAG within 1 week after RT-MCE. The ventricular segments in CAD patients were divided semi-quantitatively into ischemic and non-ischemic myocardial groups based on RT-MCE images. Myocardial blood volume (A), myocardial blood flow velocity (β), and mean myocardial blood flow (A×β) were obtained. The Gensini scores were calculated for CAD patients. The receiver operating characteristic (ROC) curve areas of A, β, and A×β were calculated to assess CM function in CAD patients.

Results:

A total of 798 and 204 segments were investigated in the CAD and non-CAD groups, respectively. In CAD patients, 332 ischemic and 466 non-ischemic segments were identified. The values of A, β, and A×β were significantly different among non-CAD, CAD, ischemic, and non-ischemic groups. ROC curve areas of A, β, and A×β were 0.85, 0.79, and 0.83, respectively, and significant differences were observed in these values among three Gensini score groups of the CAD patients.

Conclusion:

Varying degrees of CM function deterioration was observed in CAD patients both in ischemic and non-ischemic areas, with the deterioration being more sever in the former.

MiR-124 aggravates failing hearts by suppressing CD151-facilitated angiogenesis in heart

Heart failure (HF) is the final common pathway of various cardiovascular diseases. Although it is well documented that reduction of cardiac angiogenesis contributes to the progression from adaptive cardiac hypertrophy to HF, the molecular mechanisms remain unknown. In the present study, we found that cardiac expression of miR-124 was increased in patients and mice with HF. Recombinant adeno-associated virus (rAAV)-mediated miR-124 over-expression aggravated angiotensin II (Ang II) infusion-induced cardiac dysfunction and abnormal cardiac angiogenesis in mice. In vitro, transfection of miR-124 mimics significantly promoted apoptosis and reduced viability, migration, tube formation, and nitric oxide release in endothelial cells. In addition, CD151 was identified as a direct target of miR-124. Endothelial cell injury caused by CD151 silencing was mimicked by miR-124 over-expression. Re-expression of CD151 attenuated miR-124-mediated suppression of cardiac angiogenesis and cardiac dysfunction in Ang II-treated mice. Our observations suggest that miR-124 is an important negative regulator of cardiac angiogenesis and cardiac function, likely by suppressing the expression of CD151 in heart cells. Modulation of miR-124 levels may provide new strategies and targets for HF therapy.

Microvascular Obstruction in Acute Myocardial Infarction

Introduction: The no-reflow phenomenon has been described in 20–40% of patients with acute ST-segment elevation myocardial infarction, despite restoration of TIMI 3 myocardial flow. It is associated with adverse left ventricular remodeling and an unfavorable long-term prognosis.

Case presentation: A 45-year-old gentleman was admitted one hour after the onset of an acute anterior ST-segment elevation myocardial infarction. Emergency coronary angiography was performed, and a severe stenosis of the left anterior descending artery was identified. The lesion was crossed with a pressure-wire, and a drug-eluting stent was directly implanted, with restoration of TIMI 3 epicardial flow. Predilatation was not performed. Coronary wedge pressure was measured during stent deployment. The mean pressure value was 27 mmHg. However, a tall systolic wave was identified in the morphology of the pressure curve. Myocardial blush grade and ST-segment resolution were concordant with early micro-vascular obstruction. Similarly, at transthoracic Doppler echocardiography, the flow in the left anterior descending artery revealed the same pattern. An apical left ventricular aneurysm was echocardiographically detected. The MRI described extensive interstitial edema that affected the anterior, septal, and apical regions of the left ventricle. Areas of intramyocardial hemorrhage and microvascular obstruction were also detected. According to recent literature data, the morphology of the coronary wedge pressure wave suggested at least the presence of pre-procedural distal embolization.

Conclusions: In the setting of acute myocardial infarction, the integrity of coronary microvasculature is an important issue. The distal coronary pressure wave pattern before primary percutaneous revascularization can be a deciding factor for an early therapeutic approach.

Which admission electrocardiographic parameter is more powerful predictor of no-reflow in patients with acute anterior myocardial infarction who underwent primary percutaneous intervention?

BACKGROUND

Acute transmural ischemia due to left anterior descending artery (LAD) occlusion changes precordial R and Q wave durations owing to depressed intramyocardial activation. We investigated the prognostic value of sum of precordial Q wave duration/sum of precordial R wave duration ratio (Q/R) in patients with first acute anterior myocardial infarction (AAMI) treated with primary percutaneous coronary intervention (PPCI).

METHODS

In this prospective analysis, we evaluated the no-reflow predictive value of Q/R on 403 patients with first AAMI. Patients were divided into two as no-reflow group (n=32) and control (n=371) group according to post-PPCI flow status.

RESULTS

The patients in the no-reflow group had significantly higher Q/R on admission electrocardiography (ECG) compared to patients in the control group (p<0.001). When admission ECG parameters were compared according to no-reflow prediction, Q/R was stronger than other well-accepted parameters. The best cut-off value of the Q/R to predict no-reflow was 1.08 with 76% sensitivity and 73% specificity (AUC: 0.78; 95% CI: 0.72-0.83; p<0.001).

CONCLUSION

In patients with first AAMI treated with PPCI, Q/R in admission ECG may have a role as an independent predictive marker of no-reflow.

The Role of Nitric Oxide during Sonoreperfusion of Microvascular Obstruction

Rationale: Microembolization during PCI for acute myocardial infarction can cause microvascular obstruction (MVO). MVO severely limits the success of reperfusion therapies, is associated with additional myonecrosis, and is linked to worse prognosis, including death. We have shown, both in in vitro and in vivo models, that ultrasound (US) and microbubble (MB) therapy (termed “sonoreperfusion” or “SRP”) is a theranostic approach that relieves MVO and restores perfusion, but the underlying mechanisms remain to be established.

Objective: In this study, we investigated the role of nitric oxide (NO) during SRP.

Methods and results: We first demonstrated in plated cells that US-stimulated MB oscillations induced a 6-fold increase in endothelial nitric oxide synthase (eNOS) phosphorylation in vitro. We then monitored the kinetics of intramuscular NO and perfusion flow rate responses following 2-min of SRP therapy in the rat hindlimb muscle, with and without blockade of eNOS with LNAME. Following SRP, we found that starting at 6 minutes, intramuscular NO increased significantly over 30 min and was higher than baseline after 13 min. Concomitant contrast enhanced burst reperfusion imaging confirmed that there was a marked increase in perfusion flow rate at 6 and 10 min post SRP compared to baseline (>2.5 fold). The increases in intramuscular NO and perfusion rate were blunted with LNAME. Finally, we tested the hypothesis that NO plays a role in SRP by assessing reperfusion efficacy in a previously described rat hindlimb model of MVO during blockade of eNOS. After US treatment 1, microvascular blood volume was restored to baseline in the MB+US group, but remained low in the LNAME group. Perfusion rates increased in the MB+US group after US treatment 2 but not in the MB+US+LNAME group.

Conclusions: These data strongly support that MB oscillations can activate the eNOS pathway leading to increased blood perfusion and that NO plays a significant role in SRP efficacy.

Usefulness of Mean Platelet Volume-to-Lymphocyte Ratio for Predicting Angiographic No-Reflow and Short-Term Prognosis After Primary Percutaneous Coronary Intervention in Patients With ST-Segment Elevation Myocardial Infarction

Primary percutaneous coronary intervention (pPCI) is associated with improved prognosis in patients with ST-segment elevation myocardial infarction (STEMI). However, no-reflow phenomenon limits the benefit of revascularization and predicts adverse outcomes. The specific mechanism for its occurrence is still not entirely clear, and it is believed at present that platelet activation and inflammation play a pivotal role in developing no-reflow. Both increased mean platelet volume (MPV), which is a platelet activation marker, and lymphopenia, which is an inflammation marker, have been linked to adverse events and poor prognosis after STEMI. Recently, MPV-to-lymphocyte ratio (MPVLR) has emerged as a novel marker of poor short- and long-term prognosis in diabetic patients with STEMI who underwent pPCI. In this study, we aimed to investigate whether MPVLR predicts angiographic no-reflow and in-hospital mortality in all STEMI patients. From January 2014 to January 2017, a total of 1,206 patients who underwent pPCI, admitted within 12 hours from symptom onset, were enrolled and divided into 2 groups based on the final thrombolysis in myocardial infarction (TIMI) flow grading. No-reflow was defined as post-pPCI TIMI grade 0, 1, and 2 flows and normal-reflow was defined as TIMI 3 flow. The incidence of no-reflow was 16.1% (n = 198). The MPVLR values were higher in no-reflow group than in normal-reflow group (p <0.001). In multivariate analysis, MPVLR was an independent predictor of angiographic no-reflow. Furthermore, in multivariable Cox regression models adjusted for potential confounders, MPVLR was independently and positively associated with the hazard of 30-day all-cause mortality. In conclusion, the MPVLR was a strong independent predictor for angiographic no-reflow and short-term mortality in patients with STEMI who underwent pPCI.

Bivalirudin infusion to reduce ventricular infarction: the open-label, randomised Bivalirudin Infusion for Ventricular InfArction Limitation (BIVAL) study

AIMS

The aim of the study was to investigate whether bivalirudin versus unfractionated heparin (UFH) reduces infarct size (IS) for primary percutaneous coronary intervention (PPCI) in large acute myocardial infarction (AMI).

METHODS AND RESULTS

This multicentre open-label trial randomised 78 patients undergoing PPCI for large AMI to bivalirudin or UFH. The primary endpoint was IS, assessed by cardiac magnetic resonance (CMR) five days after PPCI. Secondary endpoints included index of microcirculatory resistance (IMR), CMR-assessed microvascular obstruction (MVO) and ejection fraction, and biomarkers for thrombin activity and cell injury. No difference was observed in mean IS at five days (25.0±19.7 g for bivalirudin vs. 27.1±20.7 g for UFH; p=0.75). Early MVO was numerically lower with bivalirudin (5.3±5.8 g vs. 7.7±6.3 g; p=0.17), with no significant difference in ejection fraction at 90 days (54.6±12.0% vs. 49.1±12.1%; p=0.11). In the biomarkers, thrombin-antithrombin complexes were reduced by 4.8 ug/L over the first day for bivalirudin versus an increase of 1.9 ug/L in the heparin arm (p=0.0003). Acute IMR was lower (43.5±21.6 vs. 68.7±35.8 mmHg×s, respectively; p=0.014). In a planned interim analysis, an approximate 11% reduction in IS was observed with bivalirudin; the trial was discontinued for futility.

CONCLUSIONS

This study did not achieve its primary endpoint of significant infarct size reduction in PPCI by prolonged bivalirudin infusion compared to UFH, even though complete thrombin inhibition was achieved in the acute phase, with a lower myocardial microcirculation resistance at the end of the procedure.

Unmet goals in the treatment of Acute Myocardial Infarction: Review

Reperfusion therapy decreases myocardium damage during an acute coronary event and consequently mortality. However, there are unmet needs in the treatment of acute myocardial infarction, consequently mortality and heart failure continue to occur in about 10% and 20% of cases, respectively. Different strategies could improve reperfusion. These strategies, like generation of warning sign recognition and being initially assisted and transferred by an emergency service, could reduce the time to reperfusion. If the first electrocardiogram is performed en route, it can be transmitted and interpreted in a timely manner by a specialist at the receiving center, bypassing community hospitals without percutaneous coronary intervention capabilities. To administer thrombolytic therapy during transport to the catheterization laboratory could reduce time to reperfusion in cases with expected prolonged transport time to a percutaneous coronary intervention center or to a center without primary percutaneous coronary intervention capabilities with additional expected delay, known as pharmaco-invasive strategy. Myocardial reperfusion is known to produce damage and cell death, which defines the reperfusion injury. Lack of resolution of ST segment is used as a marker of reperfusion failure. In patients without ST segment resolution, mortality triples. It is important to note that, until recently, reperfusion injury and no-reflow were interpreted as a single entity and we should differentiate them as different entities; whereas no-reflow is the failure to obtain tissue flow, reperfusion injury is actually the damage produced by achieving flow. Therefore, treatment of no-reflow is obtained by tissue flow, whereas in reperfusion injury the treatment objective is protection of susceptible myocardium from reperfusion injury. Numerous trials for the treatment of reperfusion injury have been unsuccessful. Newer hypotheses such as “ controlled reperfusion”, in which the interventional cardiologist assumes not only the treatment of the culprit vessel but also the way to reperfuse the myocardium at risk, could reduce reperfusion injury.

Lymphocyte Communication in Myocardial Ischemia/Reperfusion Injury

SIGNIFICANCE

Myocardial ischemia/reperfusion (I/R) is an important complication of reperfusion therapy for myocardial infarction (MI). It is a complex process involving metabolic and immunological factors. To date, no effective treatment has been identified. Recent Advances: Previous research has focused on the role of innate immune cells in I/R injury. In recent years, increasing evidence has accumulated for an important role for adaptive immune cells, particularly T lymphocytes. Data from ST elevation MI patients have identified prognostic significance for lymphocyte counts, particularly postreperfusion lymphopenia. Dynamic changes in circulating CD4⁺ T cell subsets occurring early after reperfusion are associated with development of I/R injury in the form of microvascular obstruction. Transcoronary gradients in cell counts suggest sequestration of these cells into the reperfused myocardium. These findings support existing data from mouse models indicating a role for CD4⁺ T cells in I/R injury. It is clear, however, the effects of lymphocytes in the ischemic myocardium are time and subset specific, with some having protective effects, while others are pathogenic.

CRITICAL ISSUES

An understanding of the cellular events that lead to accumulation of lymphocytes in the myocardium, and their actions once there, is key to manipulating this process. Chemokines produced in response to ischemia and cellular injury have an important role, while lymphocyte-derived cytokines are critical in the balance between inflammation and healing.

FUTURE DIRECTIONS

Further research into the involvement of lymphocytes in myocardial I/R injury may allow development of targeted therapies, opening a new avenue of considerable therapeutic potential. Antioxid. Redox Signal. 26, 660-675.

Predictors of no- reflow during primary angioplasty for acute myocardial infarction, from Medical College Hospital, Trivandrum

Background

Primary angioplasty (PCI) for acute myocardial infarction is associated with no-reflow phenomenon, in about 5–25% of cases. Here we analysed the factors predicting no reflow .

Methods

This was a case control study of consecutive patients with acute myocardial infarction who underwent Primary PCI from August 2014 to February 2015.

Results

Of 181 patients who underwent primary PCI, 47 (25.9%) showed an angiographic no-reflow phenomenon. The mean age was 59.19 ± 10.25 years and females were 11%.

Univariate predictors of no reflow were age >60 years (OR = 6.146, 95%CI 2.937–12.86, P = 0<0.001), reperfusion time >6 h (OR = 21.94, 95%CI 9.402–51.2, P = < 0.001), low initial TIMI flow (≤1) (OR = 12.12, 95%CI 4.117–35.65, P < 0.001), low initial TMPG flow (≤1) (OR = 36.19, 95%CI 4.847–270.2, P < 0.001) a high thrombus burden (OR = 11.04,95%CI 5.124–23.8, P < 0.001), a long target lesion (OR = 8.54, 95%CI 3.794–19.23, P < 0.001), Killip Class III/IV(OR = 2.937,95%CI 1.112–7.756,P = 0.025) and overlap stenting(OR = 3.733,95%CI 1.186–11.75,P = 0.017).

Multiple stepwise logistic regression analysis predictors were: longer reperfusion time > 6 h (OR = 13.844, 95%CI 3.214–59.636, P = <0.001), age >60 years (OR = 8.886, 95%CI 2.145–36.80, P = 0.003), a long target lesion (OR = 8.637, 95%CI 1.975–37.768, P = 0.004), low initial TIMI flow (≤1) (OR = 20.861, 95%CI 1.739–250.290, P = 0.017).

Conclusions

It is important to minimize trauma to the vessel, avoid repetitive balloon dilatations use direct stenting and use the shortest stent if possible.

Plasma big endothelin-1 levels at admission and future cardiovascular outcomes: A cohort study in patients with stable coronary artery disease

BACKGROUND

Big endothelin-1 (ET-1) has been proposed as a novel prognostic indicator of acute coronary syndrome, while its predicting role of cardiovascular outcomes in patients with stable coronary artery disease (CAD) is unclear.

METHODS AND RESULTS

A total of 3154 consecutive patients with stable CAD were enrolled and followed up for 24months. The outcomes included all-cause death, non-fatal myocardial infarction, stroke and unplanned revascularization (percutaneous coronary intervention and coronary artery bypass grafting). Baseline big ET-1 was measured using sandwich enzyme immunoassay method. Cox proportional hazard regression analysis and Kaplan-Meier analysis were used to evaluate the prognostic value of big ET-1 on cardiovascular outcomes. One hundred and eighty-nine (5.99%) events occurred during follow-up. Patients were divided into two groups: events group (n=189) and non-events group (n=2965). The results indicated that the events group had higher levels of big ET-1 compared to non-events group. Multivariable Cox proportional hazard regression analysis showed that big ET-1 was positively and statistically correlated with clinical outcomes (Hazard Ratio: 1.656, 95% confidence interval: 1.099-2.496, p=0.016). Additionally, the Kaplan-Meier analysis revealed that patients with higher big ET-1 presented lower event-free survival (p=0.016).

CONCLUSIONS

The present study firstly suggests that big ET-1 is an independent risk marker of cardiovascular outcomes in patients with stable CAD. And more studies are needed to confirm our findings.

Salvianolate reduces murine myocardial ischemia and reperfusion injury via ERK1/2 signaling pathways in vivo

OBJECTIVE

To analyze the effects of salvianolate on myocardial infarction in a murine in vivo model of ischemia and reperfusion (I/R) injury.

METHODS

Myocardial I/R injury model was constructed in mice by 30 min of coronary occlusion followed by 24 h of reperfusion and pretreated with salvianolate 30 min before I/R (SAL group). The SAL group was compared with SHAM (no I/R and no salvianolate), I/R (no salvianolate), and ischemia preconditioning (IPC) groups. Furthermore, an ERK1/2 inhibitor PD98059 (1 mg/kg), and a phosphatidylinositol-3-kinase (PI3-K) inhibitor, LY294002 (7.5 mg/kg), were administered intraperitoneal injection (i.p) for 30 min prior to salvianolate, followed by I/R surgery in LY and PD groups. By using a double staining method, the ratio of the infarct size (IS) to left ventricle (LV) and of risk region (RR) to LV were compared among the groups. Correlations between IS and RR were analyzed. Western-blot was used to detect the extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (AKT) phosphorylation changes.

RESULTS

There were no significant differences between RR to LV ratio among the SHAM, I/R, IPC and SAL groups (P>0.05). The SAL and IPC groups had IS of 26.1%±1.4% and 22.3%±2.9% of RR, respectively, both of which were significantly smaller than the I/R group (38.5%±2.9% of RR, P<0.05, P<0.01, respectively). Moreover, the phosphorylation of ERK1/2 was increased in SAL group (P<0.05), while AKT had no significant change. LY294002 further reduced IS, whereas the protective role of salvianolate could be attenuated by PD98059, which increased the IS. Additionally, the IS was not linearly related to the RR (r=0.23, 0.45, 0.62, 0.17, and 0.52 in the SHAM, I/R, SAL, LY and PD groups, respectively).

CONCLUSION

Salvianolate could reduce myocardial I/R injury in mice in vivo, which involves an ERK1/2 pathway, but not a PI3-K signaling pathway.

The Open Artery Hypothesis: Beneficial Effects and Long-term Prognostic Importance of Patency of the Infarct-Related Coronary Artery

There seem to be additional mechanisms of benefit in patients receiving late reperfusion therapy in a time when the opportunity for myocardial salvage has been missed. Previous studies have demonstrated that the restoration of blood flow in the infarct-related coronary artery in patients with acute myocardial infarction improves left ventricular function and reduces mortality. Initially, it was thought that survival was improved because viable myocardium was salvaged. However, data obtained over the past several years have suggested that the restoration of antegrade flow in the infarct-related artery may improve survival via a mechanism independent of the influence on left ventricular function. Clinical interest in the open artery hypothesis has recently resurfaced owing to a substantial improvement in technical aspects of percutaneous coronary interventions (PCI). Observational data suggest a role for late intervention as safer and more effective mechanical reperfusion practices have emerged. Long-term clinical benefits have been shown from balloon angioplasty late after myocardial infarction (MI). Therefore, patients with failed thrombolysis or those with late-presenting MI may still benefit from PCI by mechanisms independent of myocardial salvage. There is accumulative evidence on this matter. Possible mechanisms include reduction of ventricular remodeling, diminished ventricular instability reducing the incidence of arrhythmias, and provision of collaterals to other territories in the event of further coronary artery occlusion. However, caution must be exercised in interpreting the results of studies examining the open artery hypothesis. This hypothesis can be tested in its purest sense in animal experiments; however, the clinical situation is much more complex. Patients may have acute-on-chronic coronary artery occlusion in the presence of multivessel disease and well-developed collateral channels. The pattern of necrosis may also be different with areas of necrosis separated by islands of ischemic, stunned, hibernating, or normal cells. Therefore, the patency of the infarct-related coronary artery in single or multivessel disease days to weeks after infarction markedly influences long-term prognosis unrelated to improvement of left ventricular function. Current technology has made it feasible to open and maintain patency of most occluded infarct-related arteries. However, the hypothesis that late mechanical reperfusion in patients with asymptomatic occluded infarct-related artery will improve long-term clinical outcomes remains to be proved and is currently being tested in a large randomized trial.

The Effect of Interventional Treatment in Acute Myocardial Infarction on ST Resolution: A Comparison of Coronary Angioplasty with Excimer Laser Angioplasty

The treatment methods for acute myocardial infarction (MI) have started to change in the new millennium. Myocardial perfusion (ST-segment resolution) is the target rather than achieving TIMI-III flow in the infarct-related artery. In this study the authors compared the effect of percutaneous transluminal coronary angioplasty (PTCA) and excimer laser angioplasty (ELCA), which was accepted as one of the thrombolysis methods, on ST-segment resolution. A stent was applied after ELCA to 36 patients (4 women, 32 men; mean age 50.44 ±9.8 years) in group I and a stent was applied after balloon angioplasty to 44 patients (5 women, 39 men; mean age 50.77 ±12.2 years) in group II. Fisher’s exact test was used in the analysis of data, and p<0.05 was accepted as significant. There was no difference between the groups with respect to symptom duration, time to angioplasty, risk factors, infarct localization, stent diameter, and length. TIMI-III flow was achieved in 33 patients (92%) in group I and in 40 patients (91%) in group II. There was no statistical difference in TIMI flow between the groups. In group I, complete ST resolution was observed in 75% (27/36) of the patients, partial resolution in 22% (8/36), and resolution was unsuccessful in 3% (1/36). In group II, complete, partial, and unsuccessful ST resolution were 41% (18/44), 45% (20/44), and 14% (6/44), respectively. The mean ST resolution was 82.78 ±11.8% in group I and 66.36 ±10% in group II (p=0.001). ST segment resolution, which is a good predictor of tissue perfusion, was higher with ELCA than with balloon angioplasty. These findings should be supported by large randomized studies.

Effect of Thrombus Composition and Viscosity on Sonoreperfusion Efficacy in a Model of Micro-Vascular Obstruction

Distal embolization of micro-thrombi during stenting for myocardial infarction causes micro-vascular obstruction (MVO). We have previously shown that sonoreperfusion (SRP), a microbubble (MB)-mediated ultrasound (US) therapy, resolves MVO from venous micro-thrombi in vitro in saline. However, blood is more viscous than saline, and arterial thrombi that embolize during stenting are mechanically distinct from venous clot. Therefore, we tested the hypothesis that MVO created with arterial micro-thrombi are more resistant to SRP therapy compared with venous micro-thrombi, and higher viscosity further increases the US requirement for effective SRP in an in vitro model of MVO. Lipid MBs suspended in plasma with adjusted viscosity (1.1 cP or 4.0 cP) were passed through tubing bearing a mesh with 40-μm pores to simulate a micro-vascular cross-section; upstream pressure reflected thrombus burden. To simulate MVO, the mesh was occluded with either arterial or venous micro-thrombi to increase upstream pressure to 40 mmHg ± 5 mmHg. Therapeutic long-tone-burst US was delivered to the occluded area for 20 min. MB activity was recorded with a passive cavitation detector. MVO caused by arterial micro-thrombi at either blood or plasma viscosity resulted in less effective SRP therapy compared to venous thrombi. Higher viscosity further reduced the effectiveness of SRP therapy. The passive cavitation detector showed a decrease in inertial cavitation when viscosity was increased, while stable cavitation was affected in a more complex manner. Overall, these data suggest that arterial thrombi may require higher acoustic pressure US than venous thrombi to achieve similar SRP efficacy; increased viscosity decreases SRP efficacy; and both inertial and stable cavitation are implicated in observed SRP efficacy.

Percutaneous Mechanical Reperfusion During Acute Myocardial Infarction

The treatment of acute myocardial infarction has progressed from bedrest to mechanical, catheter-based reperfusion. The authors review the use of percutaneous coronary intervention (PCI) as a primary treatment for acute myocardial infarction and the use of adjunctive agents. The most recent American College of Cardiology/ American Heart Association (ACC/AHA) guidelines for the use of PCI in ST segment elevation myocardial infarction (MI) advocate the use of PCI as primary therapy at those centers in which the procedure can be performed within accepted standards. Because a majority of hospitals (80%) do not have the capability of performing primary PCI, most patients are treated with thrombolytic therapy. PCI should be considered in those patients treated with thrombolytic therapy who have persistent or recurrent ischemia and/or cardiogenic shock. For patients with non-ST elevation MI, the use of an invasive strategy (early angiography and PCI if needed) has recently shown to be beneficial. Although revascularization is the basis of the acute therapy of MI, additional pharmacologic therapy in the acute setting is now recognized as a key to favorable long-term outcome.

QRS duration: a novel marker of microvascular reperfusion as assessed by myocardial blush grade in ST elevation myocardial infarction patients undergoing a primary percutaneous intervention

Objectives

Prolonged QRS duration is a predictor of poor prognosis in patients with coronary artery disease. The association between the duration of QRS and myocardial reperfusion is not very well understood. Our aim was to assess the relationship between the measurements of QRS duration and myocardial blush grade (MBG) in patients with ST elevation myocardial infarction (STEMI) who were treated with a primary percutaneous intervention.

Patients and methods

A total of 213 patients (mean age: 57.5±11 years) with STEMI were included. ECG recordings were obtained for the evaluation of the QRS duration before and after primary percutaneous coronary intervention. Angiographic assessment in the infarct-related artery was performed using the MBG. Patients were categorized into two groups of those with impaired microvascular reperfusion (MBG: 0–1) and those with normal microvascular reperfusion (MBG: 2–3).

Results

Overall, 105 and 108 patients had an MBG of 0–1 or 2–3, respectively. There is no significant difference between patient’s characteristics. Despite the absence of a difference between two groups in terms of the QRS duration at presentation (P: 0.57), patients with impaired microvascular reperfusion were found to have longer QRS duration at immediately postprocedure (P: 0.003) and postprocedure 60 min time-points (P<0.001). Correlation analyses showed a positive correlation between pain-to-balloon time and QRS duration at postprocedure 60 min time-points (r: 0.137 and P: 0.04).

Conclusion

Our results suggest that longer QRS duration after angioplasty seemed to indicate the presence of impaired microvascular reperfusion in patients with STEMI.

Early Administration of Intracoronary Nitroprusside Compared with Thrombus Aspiration in Myocardial Perfusion for Acute Myocardial Infarction: A 3-Year Clinical Follow-Up Study

BACKGROUND

Intracoronary nitroprusside and thrombus aspiration have been demonstrated to improve myocardial perfusion during percutaneous coronary interventions (PCI) for ST-segment elevation acute myocardial infarction (STEMI) However, no long-term clinical studies have been performed comparing these approaches.

METHODS

A single medical center retrospective study was conducted to evaluate the effects of intracoronary nitroprusside administration before slow/no-reflow phenomena versus thrombus aspiration during primary PCI. Forty-three consecutive patients with STEMI were enrolled in the intracoronary nitroprusside treatment group. One hundred twenty-four consecutive STEMI patients who received thrombus aspiration were enrolled; ninety-seven consecutive STEMI patients who did not receive either thrombus aspiration or intracoronary nitroprusside treatment were enrolled and served as control subjects. Patients with cardiogenic shock, who had received platelet glycoprotein IIb/IIIa inhibitor, or intra-aortic balloon pump insertion were excluded. Thrombolysis in Myocardial Infarction (TIMI) flow grade, corrected TIMI frame count and TIMI myocardial perfusion grade (TMPG) were assessed prior to and following PCI by two independent cardiologists blinded to the procedures. The rate of major adverse cardiac events (MACE) at 30 days, 1 year, and 3 years after study enrollment as a composite of recurrent myocardial infarction, target-vessel revascularization, and cardiac death were recorded.

RESULTS

The control group had a significantly lower pre-PCI TIMI flow (≤ 1; 49.5% vs. 69.8% vs. 77.4%; p = < 0.001) compared with the nitroprusside and thrombus aspiration groups. The thrombus aspiration group had a significantly higher pre-PCI thrombus score (> 4; 98.4% vs. 88.4% vs. 74.3%; p = < 0.001) and post-PCI TMPG (3; 39.5% vs. 16.3% vs. 20.6%; p = 0.001) compared with the nitroprusside and control groups. No significant differences were noted in the post-PCI thrombus score, 30-day, 1-year and 3-year MACE rate, and Kaplan-Meier curve among 3 groups of patients.

CONCLUSIONS

Although thrombus aspiration provided improved TMPG compared with early administration of intracoronary nitroprusside and neither of both during primary PCI, it did not have a significant impact on 30-day, 1-year and 3-year MACE rate.

KEY WORDS

Acute myocardial infarction; Intracoronary nitroprusside; Thrombus aspiration.

Renal Dysfunction on Admission Predicts No-Reflow Phenomenon in Patients Undergoing Manual Thrombus Aspiration during Primary Percutaneous Coronary Intervention

BACKGROUND

No-reflow is a frequent complication during percutaneous coronary intervention (PCI) for acute ST segment elevation myocardial infarction (STEMI). Available data is limited regarding its impact on short-term outcomes in patients undergoing manual thrombus aspiration. Renal impairment is also associated with higher complication rates in STEMI. Herein, we aimed to evaluate the impact of baseline renal dysfunction on the no- reflow phenomenon and the association of no-reflow phenomenon with early clinical outcomes.

METHODS

A total of 94 consecutive STEMI patients who underwent primary stent-based PCI and thrombus aspiration were enrolled. No-reflow was established by the use of angiographic and electrocardiographic reperfusion criteria, respectively. Additionally angiographic and clinical follow-up data were also recorded.

RESULTS

In our study, the no-reflow phenomenon was observed in 10 patients (11%) angiographically and in 23 patients (24%) electrocardiographically. Whereas, the the estimated glomerular filtration rate (eGFR) [odds ratio (OR) 10.4], hypertension (OR 6.2), previous MI (OR 6.5), previous PCI history, (OR 4.2), predilatation (OR 7.2), final balloon pressure (OR 0.9) were found to be the significant predictors of angiographic no-reflow, only reperfusion time was the predictor of electrocardiographic no-reflow (OR 1.12) at univariate analysis. After adjustment, lower eGFR (OR 14.8) was found to be the independent predictor for angiographic no-reflow. In-hospital mortality was more common in patients with either no-reflow condition separately.

CONCLUSIONS

Longer ischemic time and lower initial eGFR values were associated with no-reflow phenomenon. Irrespective of poor reperfusion criteria, no-reflow phenomenon is associated with in-hospital outcome. Future efforts should be made to reduce the incidence of no-reflow especially in patients with lower initial eGFR values.

KEY WORDS

Acute myocardial infarction • Glomerular filtration rate • No-reflow phenomenon • Primary percutaneous coronary intervention.

Facing Time in Ischemic Stroke: An Alternative Hypothesis for Collateral Failure

Several randomized-controlled trials could recently demonstrate that ischemic stroke which is caused by large-cerebral-artery-occlusion can be treated effectively by endovascular recanalization. Among these studies, particularly the data from the ESCAPE study further corroborated the strong association between macrovascular pial collateral flow (before recanalization) and clinical outcome after recanalization. This review briefly gives an overview on these data and on the clinical key observations demonstrating this association in practice. Since the ischemic penumbra can only be sustained by collateral flow, the collapse of collateral blood flow or poor collateral filling, observed for example by DSA or CTA before recanalization, seems to be a primary cause of rapidly progressive infarction and futile therapeutic recanalization. However, it needs to be emphasized that the true cause-effect relationship between collateral failure and rapidly progressive infarction of the penumbra, i.e. the high probability of unfavorable clinical outcome despite recanalization, remains unclear. Along this line, an alternative hypothesis is offered viewing the collapse of collateral flow not as a cause but possibly as an inevitable secondary consequence of increasing peripheral/microvascular resistance during progressive infarction.

Amelioration of persistent left ventricular function impairment through increased plasma ascorbate levels following myocardial infarction

PURPOSE

Percutaneous coronary angioplasty (PCA) has been demonstrated to reduce mortality and morbidity and thereby improve the prognosis of patients undergoing acute myocardial infarctions (AMIs). However, this procedure paradoxically increases the initial damage as the result of a condition known as 'myocardial reperfusion injury'. Oxidative stress may contribute to the mechanism of this injury. The goal of the present study was to ascertain whether high plasma ascorbate levels could ameliorate the reperfusion injuries that occur after the successful restoration of blood flow.

METHODS

Patients from three clinical centers of the public health system were included in the study. The groups were formed by either-sex patients with a diagnosis of ST-segment elevation myocardial infarction with an indication for primary PCA. Only the patients who presented with their first myocardial infarction were enrolled. Ascorbate was administered through an infusion given prior to the restoration of the coronary flow, which was then followed by oral treatment with vitamin C (500 mg/12 hours) plus vitamin E (400 IU/day) for 84 days. The left ventricular ejection fraction (LVEF) was determined by using cardiac magnetic resonance on days 6 and 84 following the onset of the reperfusion. In addition, the microvascular function was assessed by an angiographic evaluation using the Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG). The results were grouped according to the plasma ascorbate concentration achieved immediately following the onset of reperfusion into either the HA group (high ascorbate, >1 mmol/l) or the LA group (low ascorbate, <1 mmol/l). The biochemical parameters were analyzed throughout the protocol.

RESULTS

The LVEF of the HA group was significantly higher than that of the LA group, values on day 84 in the HA group were 33% higher than those of the LA group. The amelioration of the LVEF was accompanied by an improvement in the microvascular dysfunction, after PCA, 95% of the patients in the HA group achieved a TMPG of 2-3, in the LA group only 79% of patients showed a TMPG of 2-3.

CONCLUSIONS

These data are consistent with the protective effect of high plasma levels of ascorbate against the oxidative challenge caused by reperfusion injury in patients subjected to PCA following an AMI. Further studies are needed to elucidate the mechanism accounting for this beneficial antioxidant effect.