Infarct size reduction: a review of the clinical trials

Early Elevation of Systemic Plasma Clusterin after Reperfused Acute Myocardial Infarction in a Preclinical Porcine Model of Ischemic Heart Disease

Clusterin exerts anti-inflammatory, cytoprotective and anti-apoptotic effects. Both an increase and decrease of clusterin in acute myocardial infarction (AMI) has been reported. We aimed to clarify the role of clusterin as a systemic biomarker in AMI. AMI was induced by percutaneous left anterior artery (LAD) occlusion for 90 min followed by reperfusion in 24 pigs. Contrast ventriculography was performed after reperfusion to assess left ventricular ejection fraction (LVEF), left ventricular end diastolic volume (LVEDV) and left ventricular end systolic volume (LVESV) and additional cMRI + late enhancement to measure infarct size and LV functions at day 3 and week 6 post-MI. Blood samples were collected at prespecified timepoints. Plasma clusterin and other biomarkers (cTnT, NT-proBNP, neprilysin, NGAL, ET-1, osteopontin, miR21, miR29) were measured by ELISA and qPCR. Gene expression profiles of infarcted and remote region 3 h (n = 5) and 3 days (n = 5) after AMI onset were analysed by RNA-sequencing. AMI led to an increase in LVEDV and LVESV during 6-week, with concomitant elevation of NT-proBNP 3-weeks after AMI. Plasma clusterin levels were increased immediately after AMI and returned to normal levels until 3-weeks. Plasma NGAL, ET-1 and miR29 was significantly elevated at 3 weeks follow-up, miR21 increased after reperfusion and at 3 weeks post-AMI, while circulating neprilysin levels did not change. Elevated plasma clusterin levels 120 min after AMI onset suggest that clusterin might be an additional early biomarker of myocardial ischemia.

Serum Fatty Acids, Traditional Risk Factors, and Comorbidity as Related to Myocardial Injury in an Elderly Population with Acute Myocardial Infarction

Background. Epidemiological and randomized clinical trials indicate that marine polyunsaturated n-3 fatty acids (n-3 PUFAs) may have cardioprotective effects. Aim. Evaluate the associations between serum fatty acid profile, traditional risk factors, the presence of cardiovascular diseases (CVD), and peak Troponin T (TnT) levels in elderly patients with an acute myocardial infarction (AMI). Materials and Methods. Patients (n = 299) consecutively included in the ongoing Omega-3 fatty acids in elderly patients with myocardial infarction (OMEMI) trial were investigated. Peak TnT was registered during the hospital stay. Serum fatty acid analysis was performed 2–8 weeks later. Results. No significant correlations between peak TnT levels and any of the n-3 PUFAs were observed. However, patients with a history of atrial fibrillation had significantly lower docosahexaenoic acid levels than patients without. Significantly lower peak TnT levels were observed in patients with a history of hyperlipidemia, angina, MI, atrial fibrillation, intermittent claudication, and previous revascularization (all p < 0.02). Conclusions. In an elderly population with AMI, no association between individual serum fatty acids and estimated myocardial infarct size could be demonstrated. However, a history of hyperlipidemia and the presence of CVD were associated with lower peak TnT levels, possibly because of treatment with cardioprotective medications.

Phosphorylation of mammalian cytochrome c and cytochrome c oxidase in the regulation of cell destiny: respiration, apoptosis, and human disease

The mitochondrial oxidative phosphorylation (OxPhos) system not only generates the vast majority of cellular energy, but is also involved in the generation of reactive oxygen species (ROS), and apoptosis. Cytochrome c (Cytc) and cytochrome c oxidase (COX) represent the terminal step of the electron transport chain (ETC), the proposed rate-limiting reaction in mammals. Cytc and COX show unique regulatory features including allosteric regulation, isoform expression, and regulation through cell signaling pathways. This chapter focuses on the latter and discusses all mapped phosphorylation sites based on the crystal structures of COX and Cytc. Several signaling pathways have been identified that target COX including protein kinase A and C, receptor tyrosine kinase, and inflammatory signaling. In addition, four phosphorylation sites have been mapped on Cytc with potentially large implications due to its multiple functions including apoptosis, a pathway that is overactive in stressed cells but inactive in cancer. The role of COX and Cytc phosphorylation is reviewed in a human disease context, including cancer, inflammation, sepsis, asthma, and ischemia/reperfusion injury as seen in myocardial infarction and ischemic stroke.

Mitochondria, the calcium uniporter, and reperfusion-induced ventricular fibrillation

The role of the mitochondria, and in particular the calcium (Ca) uniporter, in mediating reperfusion-induced arrhythmias is a novel investigative area. This commentary assesses the importance of a new article on this topic, published in this issue of the journal. Ventricular arrhythmogenesis remains an important area of research in the search of novel targets. The article by García-Rivas et al in this issue represents a possible novel focus for investigation.

Hyaluronidase in the prevention of sclerotherapy-induced extravasation necrosis. A dose-response study

BACKGROUND

A previous study found hyaluronidase to be effective in the prevention of necrosis following intradermal sodium tetradecyl sulfate and 23.4% sodium chloride. There are no published dose-response studies of hyaluronidase used in this manner.

OBJECTIVE

To conduct a dose-response study using hyaluronidase in the prevention of necrosis following intradermal 23.4% sodium chloride.

METHODS

Study I evaluated control vs hyaluronidase groups (150, 300, 450 units; all in volume of 3 mL) in the prevention of necrosis following intradermal 0.25 mL 23.4% sodium chloride. Incidence and size of necrosis were compared between groups. In study II, hyaluronidase was administered in doses ranging from 18.75 to 900 units (all in volume of 3 mL) immediately following the intradermal instillation of 0.25 mL of 23.4% sodium chloride. A control group had no therapy. The incidence of necrosis was compared between groups. A dose-response curve was constructed. Both studies were randomized and blinded and used Sprague-Dawley rats.

RESULTS

A statistically significant protective effect was found in the treated vs the untreated groups in both studies. Maximal protection was achieved by 75 units of hyaluronidase and was not improved upon by higher doses.

CONCLUSION

In the event of extravasation with 23.4% sodium chloride, in the model studied, one can expect maximal protection with a dose of 75 units of hyaluronidase.

Cutaneous necrosis, telangiectatic matting, and hyperpigmentation following sclerotherapy. Etiology, prevention, and treatment

BACKGROUND

Telangiectatic matting and hyperpigmentation are some of the most commonly observed side effects of sclerotherapy. Cutaneous necrosis is relatively rare and often of limited sequelae but most commonly related to extravasation of sclerosant. Physicians treating varicosities and telangiectasia by sclerotherapy must be familiar with causes and means for minimization of all three side effects.

OBJECTIVE

This review article discusses the proposed etiology, risk factors, approach for minimizing, and suggested treatment for the three side effects of cutaneous necrosis, telangiectatic matting, and hyperpigmentation.

RESULTS

Cutaneous necrosis may occur with the injection of any sclerosing agent even under ideal circumstances and does not necessarily represent physician error. When sclerosant extravasation occurs, dilution must occur immediately. Telangiectatic matting is a recognized complication occurring in approximately 15-20% of patients treated by sclerotherapy. Although the exact mechanism of the phenomena remains unknown, reactive inflammatory and/or angiogenic mechanisms are felt to play a role. Patients are advised that telangiectatic matting is usually not permanent and usually resolves spontaneously in 3-12 months. Postsclerosis pigmentation is defined as the appearance of persistent, increased pigmentation running the course of an ectatic blood vessel treated by sclerotherapy. The general incidence of hyperpigmentation ranges from 10 to 30%. Although hyperpigmentation may persist for months, its presence rarely deters patients from continuing treatment. Spontaneous resolution occurs in 70% at 6 months with 99% resolution occurring within 1 year.

CONCLUSIONS

With understanding the etiology, risk factors, and ways to minimize these side effects our goal is to reduce their incidence. Attempting prevention may ultimately be the most effective means of treatment. Dermatol Surg 1995;21:19-29.

LEARNING OBJECTIVES

After studying the following article, participant should be able to: 1. Understand the definition and potential causes of cutaneous necrosis, telangiectatic matting, and hyperpigmentation following sclerotherapy. 2. Advise patients prior to treatment on the common risks involved in sclerotherapy and to advise them on the relative incidence. 3. Understand the concept of minimal sclerosant concentration and how it can help the physician to choose sclerosing solution concentrations to minimize risks.

The prevention of cutaneous necrosis following extravasation of hypertonic saline and sodium tetradecyl sulfate

BACKGROUND

Most authors have recommended treating extravasation during sclerotherapy by infiltrating the area with 0.9% sodium chloride and/or procaine.

OBJECTIVE

To evaluate interventions in the prevention of necrosis following intradermal injection of 23.4% sodium chloride and 3% sodium tetradecyl sulfate.

METHODS

Following intradermal 23.4% sodium chloride (Study I) or 3% sodium tetradecyl sulfate (Study II), subjects (Sprague-Dawley rats) received either no treatment or injections of 0.9% sodium chloride, sterile water, 1% procaine, or hyaluronidase. Groups were compared regarding incidence and size of necrosis.

RESULTS

In study I, hyaluronidase treated groups had significantly fewer and smaller areas of necrosis than other groups. In study II, the hyaluronidase group developed significantly fewer ulcers than the 0.9% sodium chloride group. The 0.9% sodium chloride group had significantly larger ulcers than other groups.

CONCLUSION

In the model studied, hyaluronidase was the only effective treatment in the prevention of necrosis. Following 3% sodium tetradecyl sulfate, 0.9% sodium chloride was associated with larger ulcers than other groups.

Early intervention with angiotensin-converting enzyme inhibitors during thrombolytic therapy in acute myocardial infarction: rationale and design of captopril and thrombolysis study. CATS investigators group

The adjunctive use of angiotensin-converting enzyme (ACE) inhibitors with thrombolytic therapy early during acute myocardial infarction offers theoretic advantages. In the acute phase, captopril may scavenge free radicals, blunt the catecholamine response, elicit coronary vasodilation, and increase prostacyclin and bradykinin levels. In the chronic phase, ventricular remodeling may be attenuated. At present, a large number of controlled clinical trials mainly focusing on the effects of ACE inhibition in the chronic phase are underway. Only a few studies concentrate on the effect of acute intervention with ACE inhibitors in ischemia-reperfusion, i.e., thrombolysis in myocardial infarction. In April 1990 under auspices of the Interuniversity Cardiology Institute of the Netherlands, a large nationwide acute intervention trial with captopril in 280 patients receiving thrombolytic therapy was started, the Captopril and Thrombolysis Study (CATS). The primary hypothesis of CATS supposes a very early effect of ACE inhibition on evolving myocardial damage due to ischemia and the consequences of early reperfusion. This will be evaluated by serial echocardiography, Holter monitoring and neurohumoral measurements immediately on thrombolysis and during the first year after myocardial infarction.

Effect of the ultrashort-acting beta-blocker Brevibloc on free-radical-mediated injuries during the early reperfusion state

The left descending coronary artery (LAD) was ligated for 45 min or 90 min followed by 1-h reperfusion. During experiments the animals in Group I (15 dogs) received saline infusion, in Group II (20 dogs) they received the ultrashort-acting beta-blocker Brevibloc (esmolol HCl). The marker of lipid peroxidation the malondialdehyde (MDH) as well as endogen scavengers, the glutathione (GSH), and superoxide dismutase (SOD) were measured in the heart tissue homogenates. In blood and heart tissue samples the 6-keto-prostaglandin F1 alpha (PGF1 alpha) and thromboxane B2 (TXB2) were determined. Biochemical measurements revealed that esmolol HCl has beneficial effect on the free-radical-meduated-damage reducing the MDA content in the ischemic area. In Group I the value of MDA after 90 min of LAD ligature was 138 +/- 5.6%, in Group II the elevation was only 107.4 +/- 3.2%. After treatment with Brevibloc the GSH content of ischemic-reperfused areas decreased slightly (81.75 +/- 3.5% of the normal value), moreover, in Group I the depletion of GSH was considerable (64.5 +/- 4.2%). Coronary reperfusion caused the release of eicosanoids in both groups, mainly in the first 10 min. The highest value of thromboxane in blood samples could be measured in Group I after 90 min of LAD ligature (24.8 +/- 3.6 pmol/ml; the normal value 8-12 pmol/ml). In Group II during the same period of experiments the TXB2 in the blood was 14 +/- 3.7 pmol/ml. In heart tissue samples the amount of endoperoxides increased in ischemic and non-ischemic areas of Group I and II. Nevertheless, the calculated ratio of PGF1 alpha and TXB2 was near to the normal after Brevibloc treatment (0.85-0.9; the normal values were 1-1.2). These results indicate that esmolol HCl can modulate both the free-radical-mediated reaction and arachidonic acid metabolism.

Is aeromedical transport of patients during acute myocardial infarction safe?

The emergence of coronary artery thrombolysis and angioplasty have raised new questions about the transfer of patients with acute myocardial infarction (AMI). Since these modalities are generally limited in their availability, and since the success of thrombolysis is strongly time-dependent, the interfacility transfer of patients during AMI has become more common. Study of a relatively small number of patients indicates that aeromedical helicopter transport can be conducted in a safe manner, and that the outcome of management is of benefit to the patients. Reperfusion events, however, must be anticipated during transport of patients in whom thrombolysis is initiated preflight. Furthermore, initiation of thrombolytic therapy may be problematic if begun in patients with events mimicking AMI, particularly aortic dissection or Prinzmetal's angina.

Thrombolytic therapy and acute myocardial infarction

Coronary thrombosis and subsequent time-dependent wavefront cardiac muscle necrosis are the pathophysiological hallmarks of an acute myocardial infarction. Early treatment of the thrombus by intravenous thrombolytic therapy results in a major reduction of mortality by salvage of myocardial muscle and preservation of left ventricular function. Although the benefit of streptokinase has been best documented, second generation thrombolytics (APSAC and rt-PA) are probably superior thrombolytic agents. The data on the additive effect of inhibition of platelet aggregation with low dose acetylsalicylic acid on degree of thrombolysis and mortality after a myocardial infarction are convincing. The reduction in mortality brought about by intravenous thrombolytic therapy is highly time-dependent, so that its application in a patient presenting with an acute myocardial infarction must be considered as a race against time.

Myocardial infarction: is bepridil, a new calcium antagonist, able to improve the course of the acute phase?

Several calcium antagonists are useful in the treatment of ischemic heart disease. This open randomized study was designed to determine the effects of bepridil, a new long-acting calcium antagonist with antiarrhythmic properties, on the course of acute myocardial infarction (AMI). Two hundred patients with AMI of less than 48 hours duration (average 10.9 hours) were randomly assigned to two treatment groups: The first one was treated with bepridil (BEP, n = 100), and the second one was considered as a control group, using isosorbide dinitrate at a low dosage (ISDN, n = 100). BEP was administered intravenously for 48 hours at a dosage of 4 mg/kg/day; at the same time, an oral dose of 200 mg t.i.d. was started and continued for 21 days. In the control group, ISDN was given orally at the low dosage of 5 mg every 4 hours for 21 days. An uneventful course was seen in 28 BEP patients versus 15 in the control group (p less than 0.05). Mortality and recurrence of angina were lower in the BEP group than in the control group, but the difference is not significant. On the other hand, moderate and severe hemodynamic complications did not occur in 80 BEP patients versus 65 in the control group (p less than 0.05). Ventricular arrhythmias occurred in 36 BEP patients versus 50 in the control group (p less than 0.05). Antiarrhythmic therapy was required in 14 BEP patients versus 61 in the control group (p less than 0.001). These results show that bepridil seems capable of improving the hemodynamics and arrhythmologic course of AMI.

Effect of some non-steroidal anti-inflammatory drugs on ouabain-induced arrhythmias in guinea-pigs

1. Effects of some non-steroidal anti-inflammatory drugs on ouabain-induced arrhythmias in guinea-pigs were studied. 2. Ventricular premature beats, ventricular fibrillation and cardiac arrest were induced in pentobarbitone-anaesthetized guinea-pigs by a slow intravenous infusion of ouabain. 3. Aspirin and indomethacin were found to accord a significant protection to the guinea-pigs against arrhythmias whereas ketoprofen was found to be ineffective. 4. It is concluded that the protective effect of aspirin and indomethacin may be due to inhibition of synthesis and release of thromboxane A2 from the myocardium.

Effects of calcium channel blocker on responses of blood flow, function, arrhythmias, and extent of infarction following reperfusion in conscious baboons

Two groups of chronically instrumented, conscious baboons were studied. The effects of coronary artery occlusion for 3 hours and reperfusion for 1 week were examined on measurements of left ventricular function, ischemic-zone wall thickness, regional myocardial blood flow, arrhythmias, and extent of necrosis. The experimental group of animals (n = 7) was treated with the calcium channel blocker nisoldipine (0.1 microgram/kg/min) from 1 hour after coronary occlusion to 3 hours after coronary reperfusion. The control group (n = 6) received the vehicle (n = 4) or saline (n = 2). The effects of coronary artery occlusion and reperfusion on arterial pressure, left ventricular systolic pressure, heart rate, and left ventricular dP/dt were similar in both groups. Systolic wall thickening was reversed to paradoxical wall thinning during occlusion in both groups, and there was no recovery to systolic wall thickening over the 1-week period in either group. There were differences in regional blood flow; during coronary artery occlusion, nisoldipine increased blood flow significantly in the endocardium and epicardium of nonischemic and ischemic zones. There was a major difference in the number of arrhythmic beats per minute on reperfusion; during reperfusion, the number of arrhythmias rose markedly in the vehicle-treated group but actually fell in the nisoldipine-treated group. The size of areas at risk, infarcts, infarcts related to the area at risk, and amount of total creatine kinase (CK) and MB-CK appearing in blood were not significantly different in the two groups. Thus, in the conscious baboon, nisoldipine administered 1 hour after coronary artery occlusion exerted a marked effect in diminishing reperfusion-induced arrhythmias and improved blood flow to the ischemic zone during occlusion but did not salvage ischemic tissue.

Newer emergency reperfusion techniques in acute myocardial infarction

We have given an overview of the management of the acute myocardial infarction patient utilizing the aggressive reperfusion techniques available today. Anatomic reperfusion rates have been over 95% with the combined methods described. The remaining problems technically are those of earlier reperfusion, methods to enhance myocardial recovery after ischemia, and prevention of restenosis or reocclusion. The use of laser methodology, coronary sinus retroperfusion, partial left heart bypass, and other innovative strategies may improve these results. The introduction of tissue plasminogen activator will affect our approach and will profoundly alter society's expectations of therapeutic success. Still, patients will die from acute myocardial infarction and its complications. The search for a prevention must, therefore, not be overshadowed by our current enthusiasm for reperfusion techniques. Hopefully, our current approach will become a historical footnote as breakthroughs in preventive strategies occur.