Effect of therapy with methylprednisolone on the size of myocardial infarcts in man

The role of inflammation in the pathogenesis and treatment of arrhythmias

The pathogenesis of arrhythmias is complex and multifactorial. The role of inflammation in the pathogenesis of both atrial and ventricular arrhythmias (VA) has been explored. However, developing successful pharmacotherapy regimens based on those pathways has proven more of a challenge. This narrative review provides an overview of five common arrhythmias impacted by inflammation, including atrial fibrillation (AF), myocardial infarction, arrhythmogenic cardiomyopathy, cardiac sarcoidosis, and QT prolongation, and the potential role for anti-inflammatory therapy in their management. We identified arrhythmias and arrhythmogenic disease states with the most evidence linking pathogenesis to inflammation and conducted comprehensive searches of United States National Library of Medicine MEDLINE^® and PubMed databases. Although a variety of agents have been studied for the management of AF, primarily in an effort to reduce postoperative AF following cardiac surgery, no standard anti-inflammatory agents are used in clinical practice at this time. Although inflammation following myocardial infarction may contribute to the development of VA, there is no clear benefit with the use of anti-inflammatory agents at this time. Similarly, although inflammation is clearly linked to the development of arrhythmias in arrhythmogenic cardiomyopathy, data demonstrating a benefit with anti-inflammatory agents are limited. Cardiac sarcoidosis, an infiltrative disease eliciting an immune response, is primarily treated by immunosuppressive therapy and steroids, despite a lack of primary literature to support such regimens. In this case, anti-inflammatory agents are frequently used in clinical practice. The pathophysiology of arrhythmias is complex, and inflammation likely plays a role in both onset and duration, however, for most arrhythmias the role of pharmacotherapy targeting inflammation remains unclear.

A sequential interferon gamma directed chemotactic cellular immune response determines survival and cardiac function post-myocardial infarction

AIMS

Myelomonocytic cells are critical in injury and healing post-myocardial infarction (MI). Mechanisms of regulation, however, are incompletely understood. The aim of the study was to elucidate the role of interferon gamma (IFN-γ) in the orchestrated inflammatory response in a murine model of MI.

METHODS AND RESULTS

MI was induced in 8- to 12-week-old male mice (C57BL/6 background) by permanent ligation of the left anterior descending (LAD) coronary artery. Lysozyme M (LysM)+ cell-depleted LysMiDTR transgenic mice displayed a reduced influx of CD45.2+/CD3-/CD11b+/Gr-1high neutrophils into infarcted myocardium 1 day post-MI compared with infarcted controls, paralleled by decreased cardiac mRNA levels of IFN-γ and tumour necrosis factor alpha (TNF-α). Mortality after MI was significantly increased in LysM+ cell-depleted mice within 28 days post-MI. To more specifically address the role of neutrophils, we depleted C57BL/6 mice with a monoclonal anti-Gr-1 antibody and found increased mortality, deteriorated cardiac function as well as decreased cardiac IFN-γ mRNA expression early after MI. Ccl2, Cxcl1, Cx3cl1, and Il12b mRNA were reduced 3 days after MI, as was the amount of CD11b+/Ly-6G-/Ly-6Chigh inflammatory monocytes. LAD-ligated Cramp-/- mice lacking cathelicidin important in neutrophil-dependent monocyte chemotaxis as well as IFNγ-/- and TNFα-/- mice phenocopied Gr-1+ cell-depleted mice, supporting a regulatory role of IFN-γ impacting on both the sequence of inflammatory cell invasion and cardiac outcome early after MI. The use of conditional IFN-γ receptor deficient mice indicated a direct effect of IFN-γ on LysM+ cells in cardiac injury post-MI. Using IFN-γ reporter mice and flow cytometry, we identified cardiac lymphoid cells (CD4+ and CD8+ T cells and natural killer cells) as primary source of this cytokine in the cardiac inflammatory response post-MI.

CONCLUSION

IFN-γ directs a sequential chemotactic cellular immune response and determines survival and cardiac function post-MI.

Anti-inflammatory therapies in myocardial infarction: failures, hopes and challenges

In the infarcted heart, the damage-associated molecular pattern proteins released by necrotic cells trigger both myocardial and systemic inflammatory responses. Induction of chemokines and cytokines and up-regulation of endothelial adhesion molecules mediate leukocyte recruitment in the infarcted myocardium. Inflammatory cells clear the infarct of dead cells and matrix debris and activate repair by myofibroblasts and vascular cells, but may also contribute to adverse fibrotic remodelling of viable segments, accentuate cardiomyocyte apoptosis and exert arrhythmogenic actions. Excessive, prolonged and dysregulated inflammation has been implicated in the pathogenesis of complications and may be involved in the development of heart failure following infarction. Studies in animal models of myocardial infarction (MI) have suggested the effectiveness of pharmacological interventions targeting the inflammatory response. This article provides a brief overview of the cell biology of the post-infarction inflammatory response and discusses the use of pharmacological interventions targeting inflammation following infarction. Therapy with broad anti-inflammatory and immunomodulatory agents may also inhibit important repair pathways, thus exerting detrimental actions in patients with MI. Extensive experimental evidence suggests that targeting specific inflammatory signals, such as the complement cascade, chemokines, cytokines, proteases, selectins and leukocyte integrins, may hold promise. However, clinical translation has proved challenging. Targeting IL-1 may benefit patients with exaggerated post-MI inflammatory responses following infarction, not only by attenuating adverse remodelling but also by stabilizing the atherosclerotic plaque and by inhibiting arrhythmia generation. Identification of the therapeutic window for specific interventions and pathophysiological stratification of MI patients using inflammatory biomarkers and imaging strategies are critical for optimal therapeutic design.

Steroid use in kidney transplant recipients presented with acute myocardial infarction

Suppression of the hypothalamic-pituitary-adrenal axis due to chronic exogenous steroid use is the most common cause of secondary adrenal insufficiency. Most kidney transplant recipients receive steroid therapy for immunosuppression; they are also at high risk for acute coronary events which can increase their physiological stress. Use of steroids early in the course of acute myocardial infarction (MI) raises concerns about the possibility of an increased risk of aneurysm formation and myocardial rupture. We present six case reports of kidney transplant recipients. Two of these recipients developed adrenal insufficiency after acute anterior MI; the life-threatening situation was successfully managed with corticosteroid administration. Four of these kidney transplant recipients presented with acute anterior MI; in these patients prophylactic steroid therapy prevented adrenal insufficiency, without any complication of the MI. We recommend the use of prophylactic corticosteroids for kidney transplant recipients to prevent adrenal insufficiency in the early course of acute MI.

Monocytes in coronary artery disease and atherosclerosis: where are we now?

Despite improvements in interventional and pharmacological therapy of atherosclerotic disease, it is still the leading cause of death in the developed world. Hence, there is a need for further development of effective therapeutic approaches. This requires better understanding of the molecular mechanisms and pathophysiology of the disease. Atherosclerosis has long been identified as having an inflammatory component contributing to its pathogenesis, whereas the available therapy primarily targets hyperlipidemia and prevention of thrombosis. Notwithstanding a pleotropic anti-inflammatory effect to some therapies, such as acetyl salicylic acid and the statins, none of the currently approved medicines for management of either stable or complicated atherosclerosis has inflammation as a primary target. Monocytes, as representatives of the innate immune system, play a major role in the initiation, propagation, and progression of atherosclerosis from a stable to an unstable state. Experimental data support a role of monocytes in acute coronary syndromes and in outcome post-infarction; however, limited research has been done in humans. Analysis of expression of various cell surface receptors allows characterization of the different monocyte subsets phenotypically, whereas downstream assessment of inflammatory pathways provides an insight into their activity. In this review we discuss the functional role of monocytes and their different subpopulations in atherosclerosis, acute coronary syndromes, cardiac healing, and recovery with an aim of critical evaluation of potential future therapeutic targets in atherosclerosis and its complications. We will also discuss technical difficulties of delineating different monocyte subpopulations, understanding their differentiation potential and function.

Intravenous clusterin administration reduces myocardial infarct size in rats

BACKGROUND

Clusterin (Apolipoprotein J), a plasma protein with cytoprotective and complement-inhibiting activities, localizes in the infarcted heart during myocardial infarction (MI). Recently, we have shown a protective effect of exogenous clusterin in vitro on ischaemically challenged cardiomyocytes independent of complement. We therefore hypothesized that intravenous clusterin administration would reduce myocardial infarction damage.

METHODS

Wistar rats undergoing experimental MI, induced by 40 min ligation of a coronary vessel, were treated with either clusterin (n=15) or vehicle (n=13) intravenously, for 3 days post-MI. After 4 weeks, hearts were analysed. The putative role of megalin, a clusterin receptor, was also studied.

RESULTS

Administration of human clusterin significantly reduced both infarct size (with 75 ± 5%) and death of animals (23% vehicle group vs. 0% clusterin group). Importantly, histochemical analysis showed no signs of impaired wound healing in the clusterin group. In addition, significantly increased numbers of macrophages were found in the clusterin group. We also found that the clusterin receptor megalin was present on cardiomyocytes in vitro which, however, was not influenced by ischaemia. Human clusterin co-localized with this receptor in vitro, but not in the human heart. In addition, using a megalin inhibitor, we found that clusterin did not exert its protective effect on cardiomyocytes through megalin.

CONCLUSIONS

Our results thus show that clusterin has a protective effect on cardiomyocytes after acute myocardial infarction in vivo, independent of its receptor megalin. This indicates that clusterin, or a clusterin derivate, is a potential therapeutic agent in the treatment of MI.

Dexamethasone could improve myocardial infarction outcomes and provide new therapeutic options for non-interventional patients

BACKGROUND

Statins reduce death and morbidity of acute myocardial infarction in part through immunosuppressive mechanisms, suggesting glucocorticoids could produce similar benefits. Glucocorticoids inhibit proliferation of smooth muscle cells and activation of macrophages within atherosclerotic plaques and protect ischemic myocardium through inhibition of a heat shock protein. Dexamethasone-eluting coronary stents have a decreased rate of restenosis, and oral prednisone reduces restenosis of conventional stents. Some studies from the 1970's and 1980's showed that steroids improve survival in myocardial infarction, but no conclusive large-scale randomized well-powered trials have been conducted.

PRESENTATION OF THE HYPOTHESIS

Dexamethasone administered alongside statins in the setting of acute myocardial infarction could attenuate myocardial damage in patients with diffuse disease.

TESTING THE HYPOTHESIS

Patients with acute myocardial infarction who cannot undergo angioplasty or coronary artery bypass grafting could be given a statin and intravenous and oral dexamethasone. Dexamethasone minimizes fluid retention and avoids mineralocorticoid-induced cell proliferation in plaques. Blood glucose monitoring should be ordered for all patients, but diabetic patients need not be excluded. There should be measures to prevent steroid-induced homocystinuria or more common complications such as ulcers, osteoporosis, infections and psychosis.

IMPLICATIONS OF THE HYPOTHESIS

Showing that acute coronary syndrome is a steroid-responsive disorder would have immediate relevance for patients limited to medical management because of anatomy and comorbidities, and results would similarly have application for acute ischemic stroke.

Meta-analysis of corticosteroid treatment in acute myocardial infarction

Acute and chronic inflammation play a central role in the pathophysiology of atherosclerosis. Corticosteroids are the gold standard anti-inflammatory agent and may have a role in treating acute myocardial infarction. However, concern exists regarding the potential for impaired wound healing and wall thinning. The MEDLINE and PreMEDLINE databases were searched for articles from 1966 through May 2002. A total of 186 articles and 16 English-language publications were identified. A meta-analysis of mortality in controlled trials was performed. Sensitivity analyses and 2 tests for publication bias were used to test the robustness of the results. Sixteen studies involving 3,793 patients were reviewed. Most studies were small (<100 patients) and revealed conflicting efficacy using surrogate outcome measures, such as infarct size. No clear association with myocardial rupture was observed. Meta-analysis of 11 controlled trials (2,646 patients) revealed a 26% decrease in mortality with corticosteroids (odds ratio 0.74, 95% confidence interval [CI] 0.59 to 0.94; p = 0.015). Sensitivity analyses limited to large studies and randomized controlled trials revealed odds ratios of 0.76 (95% CI 0.53 to 1.09) and 0.95 (95% CI 0.72 to 1.26), respectively. Two tests revealed no evidence for publication bias. Thus, the review of available clinical studies demonstrated no harm and a possible mortality benefit of corticosteroids in acute myocardial infarction.

Corticosteroids and peptic ulcer: meta-analysis of adverse events during steroid therapy

OBJECTIVES

This meta-analysis was performed to determine whether corticosteroid therapy induces the development of peptic ulcer and other putative complications of steroid therapy.

DESIGN

A retrospective investigation in which we analysed all the randomized, double-blind, controlled trials (RDBCT) in which steroids had been administered that we were able to identify. The number of episodes of peptic ulcer, dermatological effects, sepsis, diabetes, hypertension, osteoporosis, psychosis and tuberculosis reported in both the placebo and steroid groups were compared.

SETTING

The international medical literature was analysed for any RDBCT in which any steroid or ACTH had been administered in any dosage for any duration, and any putative complication of steroid therapy was reported.

SUBJECTS

Of 1857 articles, 93 satisfied our requirements and were analysed by the meta-analytic techniques of Peto, DerSimonian and Laird. A total of 6602 patients were included.

MAIN OUTCOME MEASURES

The relative frequencies of each of these eight 'complications' were compared in the placebo and steroid groups using conventional statistics and meta-analysis. The relative frequencies of 'annualized' subgroups of patients who received treatment for 1 to 7 days, 1 week to 1 month, 1 to 3 months and more than 3 months, were similarly analysed.

RESULTS

Nine of 3267 patients in the placebo group (0.3%) and 13 of 3335 patients in the steroid group (0.4%) were reported to develop peptic ulcer (P > 0.05). The dermatological cosmetic effects of steroid therapy were observed more frequently in the steroid group (P < 0.001), as was diabetes (P < 0.001), hypertension (P < 0.01) and psychosis (P < 0.001). Sepsis, osteoporosis and tuberculosis all occurred more frequently in the steroid than in the placebo group, but the differences are not statistically significant.

CONCLUSIONS

Peptic ulcer is a rare complication of corticosteroid therapy that should not be considered a contraindication when steroid therapy is indicated.

Severe cardiovascular adverse effects in association with acute, high-dose corticosteroid administration

Severe cardiovascular adverse reactions including death have been associated with high-dose intravenous corticosteroid therapy. Some of the patients appeared to have acute hypersensitivity reactions to the corticosteroid, with rashes and bronchospasm; other problems included arrhythmias and myocardial infarctions. Most of the patients had underlying renal disease and/or were undergoing renal transplantation. All of the patients having the cardiovascular reactions associated with the corticosteroid received individual doses of at least 250 mg of methylprednisolone or its equivalent. The doses were usually administered over a 30-minute period or less. A cause-effect relationship between high-dose corticosteroid therapy and severe cardiovascular reactions has not been scientifically proved by a controlled trial, but caution is advised when high-dose corticosteroid therapy is administered.

Steroid-induced enhancement of functional recovery of postischemic, reperfused myocardium in conscious dogs

The effects of methylprednisolone sodium succinate (20 mg/kg, intravenously administered) on the time course of functional recovery of myocardium following a 15-minute coronary artery occlusion period and subsequent 5 hour reperfusion period were studied in chronically instrumented, conscious dogs. In comparison to a control group, animals receiving methylprednisolone 90 minutes prior to coronary occlusion demonstrated less depression of regional segment shortening following 15 minutes of reperfusion (52 +/- 13% vs control levels of 23 +/- 7% of preocclusion values) and improved recovery at 5 hours postreperfusion (106 +/- 6% vs control levels of 54 +/- 4% of preocclusion values). In animals receiving methylprednisolone immediately prior to reperfusion, there was also similar recovery of segment shortening at 5 hours (97 +/- 3%). In contrast, dogs receiving methylprednisolone 15 minutes after the onset of reperfusion or sodium succinate (5.5 mg/kg, intravenously administered) 90 minutes prior to occlusion demonstrated no improvement in recovery of function. Experiments in dogs not subjected to coronary occlusion documented that methylprednisolone sodium succinate lacked inotropic and vasodilator properties. The results suggest that methylprednisolone administered prior to or during coronary artery occlusion but not after reperfusion enhances the functional recovery of hypokinetic, postischemic, reperfused myocardium. These effects are unrelated to any direct hemodynamic action of steroids or to the sodium succinate salt.

Infarct size reduction: a review of the clinical trials

The most important finding to emerge from this review of experimental and clinical studies is that the earlier therapy is begun after the onset of symptoms of acute MI, the greater the potential for reduction of infarct size and possibly mortality. It is difficult to define a precise time after which therapy would not have an effect, since the clinical trials for each drug group vary significantly in respect to time of therapy initiation. In experimental studies, major salvage of ischemic myocardium occurs when the drug is given within two hours of coronary artery occlusion. If drug therapy is begun four to six hours postocclusion, then only minor or no reductions in infarct size will occur. The ability of any drug or intervention to reduce infarct size in humans would be optimized if therapy were begun less than four hours of onset of symptoms. With the realization of the wavefront phenomenon and the potential salvage of myocardium at risk with reperfusion, the introduction of reperfusion in the clinical setting with thrombolytic agents or other procedures becomes highly desirable. Clot-selective thrombolytic agents, such as tissue plasminogen activator, diminish the adverse effects and high costs of intracoronary thrombolytic therapy or PTCA. Consequently, it is probable that the initial procedure of choice would be the use of clot-selective thrombolytic therapy. Thrombolytic therapy only lyses thrombi and does not affect the underlying causes of the coronary artery occlusion. Therefore, therapy to reduce the chances of reinfarction and death must also be initiated. Percutaneous transluminal coronary angioplasty, in selected patients, should reduce the reocclusion rate. Beta-adrenoceptor blocking agents appear to be an excellent therapy for reducing mortality when administered chronically; these agents reduce myocardial oxygen consumption and reverse the imbalance between oxygen supply and oxygen demand caused by activation of the sympathetic nervous system and actions of catecholamines. Since thrombus formation has occurred at least once in patients who survive an MI, it is probable that the conditions for thrombus formation still exist. Therefore, institution of antiplatelet aggregating drugs, such as aspirin, would seem to be an appropriate prophylactic regimen. Beta blockers and possibly nitroglycerin have desirable effects when thrombolysis is unavailable. The efficacy of calcium-channel blocking agents on reduction of infarct size appears to be limited, although in the setting of stable and unstable angina postinfarction, these agents can play an important role.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of methylprednisolone on the ischemic damage in patients with acute myocardial infarction

In this double-blind randomized study, 19 patients with acute transmural myocardial infarction were treated with methylprednisolone administered 4.4 +/- 0.7 hours (+/- SEM) after the onset of chest pain, and were compared with 21 patients who received placebo 4.5 +/- 0.4 hours after the start of clinical symptoms. The two groups were comparable in reference to sex, prevalence of risk factors, clinical status on admission, location of myocardial infarction and magnitude of ischemic injury as assessed by standard ECGs and precordial ST-segment and QRS maps. The treated patients, however, were older than the patients who received placebo. Methylprednisolone in an i.v. dose of 2.0 g was administered on admission and a similar dose was infused 3 hours later. Placebo administration followed an identical schedule. Mortality, cardiac rupture, incidence of ventricular arrhythmias, blocks, extension of myocardial infarction, pericarditis, postinfarction chest pain, persistent ST-segment elevation at discharge, and change in Killip class during hospitalization were the same in both groups. Peak enzyme values, and changes in ECG variables pertaining to resolution of ST-segment elevation or development of QRS evolutionary alterations were similar in both groups. Follow-up for 6 months did not reveal any differences in the clinical course of the two groups. Methylprednisolone infused in a total dose of 4.0 g within 12 hours after the onset of chest pain in patients with acute transmural myocardial infarction does not result in any demonstrable beneficial or harmful effects.

Use of methylprednisolone in patients following acute myocardial infarction. Hemodynamic and metabolic effects

Hemodynamic and metabolic effects of methylprednisolone were investigated in a double-blind study of 28 patients with acute myocardial infarction (AMI), confirmed by unequivocal electrocardiographic and enzyme changes. Measurements were performed prior to and at 1.5, 3, 4, 4.5, 12 and 24 hours following infusion of methylprednisolone (13 patients) or placebo (15 patients). Although systemic vascular resistance decreased from 1,750 to 1,420 dynes . sec . cm-5 (p less than .001) and cardiac index increased from 2.77 to 3.10 L/min/m2 (p less than .02) between 0 and 4.5 hours, an abnormal increase in blood lactate was observed in 10 of the 13 patients following administration of methylprednisolone (3.0 vs 1.2 mM/L, p less than .001). Lactate elevation appeared one hour after infusion of methylprednisolone, was maximal at 12 hours, and persisted for more than 24 hours. There was no significant change in blood lactate in placebo treated patients. A transient but significant decrease in plasma volume was also observed following infusions of methylprednisolone. The elevation of blood lactate could not be explained by the reduction in plasma volume since the most striking increases in lactate were observed 12 hours following the initial infusion of methylprednisolone when the plasma volume was returning to the control value. No significant differences in other hemodynamic or metabolic parameters, infarct size or patient survival were observed between the two groups. We conclude that the hemodynamic benefits of glucocorticoids characterized by increased cardiac output and lowered systemic vascular resistance are counterbalanced by the potentially unfavorable conditions of lactate elevation and volume depletion.

Corticosteroids in acute myocardial infarction

Forty-two patients admitted to the Coronary Care Unit with a diagnosis of acute myocardial infarction were studied within 24 hours of the onset of symptoms. In addition to therapy determined by the attending physician, there was a double-blinded administration of either a placebo or methylprednisolone, 30 mg/kg intravenously every 6 hours for four doses. This drug had no beneficial effect on infarct size, dysrhythmias, complications, or left ventricular function 2 weeks after infarction.

Mechanism of the beneficial effect of dexamethasone on myocardial cell integrity in acure myocardial ischemia

Dexamethasone (6 mg/kg) given intravenously to anesthetized cats exerted no significant hemodynamic effect on control open-chest cats or in cats subjected to acute myocardial ischemia by coronary artery ligature. However, dexamethasone normalized elevated S-T segments toward preischemic values, and prevented much of the increase in plasma CPK activity following coronary artery ligation. Moreover, dexamethasone prevented loss of CK activity within ischemic myocardial tissue five hours after the onset of ischemia. Dexamethasone also reduced the extent of ischemic damage as assessed by a nitro-blue tetrazolium staining technique, providing anatomic verification of the reduced ischemic damage. Moreover, dexamethasone prvented the swelling and vacuolization of myocardial lysosomes in the ischemic region, indicating a stabilization of lysosomal membranes within the heart. These data indicate that lysosomal disruption is an important consequence of myocardial ischemia and that early treatment with dexamethasone prevents the loss of myocardial lysosomal and cellular enzymes as reflected in normalization of the ECG and plasma CK activity of ischemic cats. In this way, dexamethasone may act to retard the spread of the developing infarct within the ischemic myocardium.