Thrombolytic treatment of acute myocardial infarction after out-of-hospital cardiac arrest

Thrombolysis as a Therapeutic Modality in Cardiac Arrest

Introduction

In recent years, thrombolysis has emerged as a potentially promising treatment for cardiac arrest. Patients with cardiac arrests from myocardial infarction or pulmonary embolism, as well as out-of-hospital cardiac arrests, were reported to have improvement in both survival and neurologic outcome after being treated with thrombolysis. This paper aims to review the available literature on the use of thrombolysis in cardiac arrest.

Method

Study of papers from PubMed literature search for all articles with terms related to thrombolysis and cardiac arrest in title or abstract.

Results

Thrombolytics are thought to act by lysing both macroscopic clots and microthrombi, particularly in the cerebral microcirculation, thus alleviating or reversing post-arrest cerebral no-reflow. Their use in cardiac arrest has been restrained by concerns over their safety after cardiopulmonary resuscitation, in particular bleeding-related complications, although these concerns seem to have been misplaced.

Conclusions

Thrombolysis for cardiac arrest is likely to be most efficacious in a pre-hospital environment, and future research should be directed to this setting.

Improving neurological outcome after cardiac arrest: Therapeutic hypothermia the best treatment

Cardiac arrest, irrespective of its etiology, has a high mortality. This event is often associated with brain anoxia which frequently causes severe neurological damage and persistent vegetative state. Only one out of every six patients survives to discharge following in-hospital cardiac arrest, whereas only 2-9% of patients who experience out of hospital cardiac arrest survive to go home. Functional outcomes of survival are variable, but poor quality survival is common, with only 3-7% able to return to their previous level of functioning. Therapeutic hypothermia is an important tool for the treatment of post-anoxic coma after cardiopulmonary resuscitation. It has been shown to reduce mortality and has improved neurological outcomes after cardiac arrest. Nevertheless, hypothermia is underused in critical care units. This manuscript aims to review the mechanism of hypothermia in cardiac arrest survivors and to propose a simple protocol, feasible to be implemented in any critical care unit.

Post-resuscitation care for survivors of cardiac arrest

Cardiac arrest can occur following a myriad of clinical conditions. With advancement of medical science and improvements in Emergency Medical Services systems, the rate of return of spontaneous circulation for patients who suffer an out-of-hospital cardiac arrest (OHCA) continues to increase. Managing these patients is challenging and requires a structured approach including stabilization of cardiopulmonary status, early consideration of neuroprotective strategies, identifying and managing the etiology of arrest and initiating treatment to prevent recurrence. This requires a closely coordinated multidisciplinary team effort. In this article, we will review the initial management of survivors of OHCA, highlighting advances and ongoing controversies.

Clinical outcome of patients treated with an early invasive strategy after out-of-hospital cardiac arrest

Little is known about the impact of early invasive treatment in patients following out-of-hospital cardiac arrest (OHCA). The present study investigated the clinical characteristics and long-term prognosis of 1254 patients with suspected acute coronary syndrome, including 65 with OHCA who underwent successful cardiopulmonary resuscitation (CPR) and 1189 patients who did not require CRP. All patients underwent immediate coronary angiography even if clear signs of myocardial infarction (MI) were absent. The incidence of ST-elevation and non-ST-elevation MI did not differ between the two groups. Cardiac biomarkers were significantly higher in CPR patients despite a shorter period from symptom onset to admission. The 6-month mortality rate was 29% in the CPR group and 4% in the non-CPR group, with > 90% of fatalities occurring ≤ 3 weeks after admission. In summary, early invasive treatment leads to a considerably reduced mortality and improved prognosis in patients after OHCA.

[Managing the post-cardiac arrest syndrome. Directing Committee of the National Cardiopulmonary Resuscitation Plan (PNRCP) of the Spanish Society for Intensive Medicine, Critical Care and Coronary Units (SEMICYUC)]

Since the advent of cardiopulmonary resuscitation more than 40 years ago, we have achieved a return to spontaneous circulation in a growing proportion of patients with cardiac arrest. Nevertheless, most of these patients die in the first few days after admission to the intensive care unit (ICU), and this situation has not improved over the years. Mortality in these patients is mainly associated to brain damage. Perhaps recognizing that cardiopulmonary resuscitation does not end with the return of spontaneous circulation but rather with the return of normal brain function and total stabilization of the patient would help improve the therapeutic management of these patients in the ICU. In this sense, the term cardiocerebral resuscitation proposed by some authors might be more appropriate. The International Liaison Committee on Resuscitation recently published a consensus document on the "Post-Cardiac Arrest Syndrome" and diverse authors have proposed that post-arrest care be integrated as the fifth link in the survival chain, after early warning, early cardiopulmonary resuscitation by witnesses, early defibrillation, and early advanced life support. The therapeutic management of patients that recover spontaneous circulation after cardiopulmonary resuscitation maneuvers based on life support measures and a series of improvised actions based on "clinical judgment" might not be the best way to treat patients with post-cardiac arrest syndrome. Recent studies indicate that using goal-guided protocols to manage these patients including therapeutic measures of proven efficacy, such as inducing mild therapeutic hypothermia and early revascularization, when indicated, can improve the prognosis considerably in these patients. Given that there is no current protocol based on universally accepted evidence, the Steering Committee of the National Cardiopulmonary Resuscitation Plan of the Spanish Society of Intensive Medicine and Cardiac Units has elaborated this document after a thorough review of the literature and an online discussion involving all the members of the committee and a consensus meeting with the aim of providing a platform for the development of local protocols in different ICSs in our country to fit their own means and characteristics.

Thrombolytic therapy vs primary percutaneous intervention after ventricular fibrillation cardiac arrest due to acute ST-segment elevation myocardial infarction and its effect on outcome

The aim of this study was to evaluate the effect of thrombolytic therapy on neurologic outcome and mortality in patients after cardiac arrest due to acute ST-elevation myocardial infarction and to compare this with those in patients treated with primary percutaneous coronary intervention (PCI). We retrospectively examined patients after they had ventricular fibrillation cardiac arrests. To assess the effect of thrombolysis and PCI on outcome, we used odds ratios and their 95% confidence intervals and logistic regression modeling. Thrombolysis was applied in 101 patients (69%) and PCI in 46 patients (31%). More patients who received thrombolysis had favorable functional neurologic recovery (cerebral performance category 1 and 2) and survived to 6 months compared with patients with primary PCI (P = .38 and P = .13, respectively). In patients with cardiac arrest due to ST-elevation myocardial infarction, it may be acceptable to use thrombolysis as a reperfusion strategy. This applies especially in hospitals where immediate PCI is not available.

Adherence to resuscitation guidelines during prehospital care of cardiac arrest patients

OBJECTIVE

The impact of prehospital care after the return of spontaneous circulation in out-of-hospital cardiac arrest patients is not known. This study describes adherence to the resuscitation guidelines, factors associated with poor adherence and possible impact of prehospital postresuscitation care on the outcome of out-of-hospital cardiac arrest.

METHODS

One hundred and fifty-seven Finnish out-of-hospital cardiac arrest patients hospitalized during 1 year, were analyzed retrospectively. Patient and arrest characteristics, prehospital postresuscitation care and survival to hospital discharge were analyzed using multivariate logistic regression.

RESULTS

Forty percent of the patients received care accordant with the guidelines. Male sex (P=0.045), witnessed arrest (P=0.031), initial ventricular fibrillation/ventricular tachycardia rhythm (P=0.007) and the presence of an emergency physician (P=0.017) were associated with care in line with the current guidelines. In multivariate logistic regression analysis, age over median (odds ratio=3.6, 95% confidence interval 1.5-8.6), nonventricular fibrillation/ventricular tachycardia initial rhythm (odds ratio=4.0, 95% confidence interval 1.6-9.8), administration of adrenaline (odds ratio=7.0, 95% confidence interval 2.3-21.4) and unsatisfactory prehospital postresuscitation care (odds ratio=2.5, 95% confidence interval 1.1-6.3) were associated with a failure to survive up to hospital discharge.

CONCLUSIONS

Less than 50% of out-of-hospital cardiac arrest patients received prehospital postresuscitation care compatible with the current guidelines. Markers of poor prognosis were associated with unsatisfactory care, which in turn was more frequent among the patients who did not survive to hospital discharge. The importance of the guidelines should be highlighted in the future.

Role of thrombolytic agents in cardiac arrest

The prognosis of patients having a cardiac arrest is generally poor, with a few exceptions. Interventions that aim to improve outcome in cardiac arrest have proved to be disappointing. In particular, no drug has been reliably proved to increase survival to discharge after cardiac arrest. Given that coronary thrombosis in situ and pulmonary thromboembolism are implicated in a large proportion of patients with cardiac arrest, the use of thrombolytic agents has been suggested. Case reports and animal studies have shown favourable results, and have proposed plausible mechanisms to explain them. This is a review of the current literature focusing on the use of thrombolysis during cardiac arrest. A comprehensive literature search was carried out on Medline from 1966 to January 2006, Embase from 1988 to January 2006 and the Cochrane Library, using the Ovid interface. Six articles were selected for review. Although some results are encouraging, all the studies currently available are limited by size and flaws in design.

Influence of medical direction on the management of prehospital myocardial infarction

Prehospital management of myocardial infarction was evaluated in two differently structured Emergency Medical Service (EMS) systems in Southern Finland: a physician directed EMS with on-site physician involvement (physician EMS) and an EMS without operational physician involvement with paramedics only (non-physician EMS). The management of 641 consecutive acute ST-elevation myocardial infarction (STEMI) patients between 1997 and 1999 (263 patients in the physician EMS group and 378 patients in non-physician EMS group) were studied. Patients treated in the physician EMS received all necessary medical care including thrombolytic therapy at the scene whereas patients in the non-physician EMS were transported to hospital for definitive treatment after initial care. There were no differences in the demographics of the patients. The delays from onset of pain to initiation of thrombolysis were shorter in the physician EMS-group (124+/-101 min (25-723) versus 196+/-150 min (12-835), p<0.001). In 2% of the patients in the physician EMS group the pain to therapy-time was unknown compared to 27% in the non-physician EMS group (p<0.001). Fifty-two patients (20%) in the physician EMS received thrombolytic therapy after cardiopulmonary resuscitation compared to two patients in the non-physician EMS (p<0.001). Of the resuscitated patients in the physician directed EMS group 60% were discharged from the hospital, and 44% of these had a good neurological recovery. We conclude that a physician directed EMS is able to reduce the pain to therapy delays significantly in STEMI patients and may offer thrombolytic therapy to a wider patient group compared to an EMS without operational medical involvement.

Intensive care after resuscitation from cardiac arrest: a focus on heart and brain injury

Less than 3% of all patients who have out-of-hospital cardiac arrests have return of spontaneous circulation (ROSC), survive the hospitalization, and have a reasonable functional recovery. The fact that many patients who have ROSC ultimately die or fail to have favorable neurologic recovery suggests that processes that occur after hospitalization, especially in the ICU, have an impact on survival and neurologic recovery. This article addresses the acute care, with emphasis on the cardiac and neurologic aspects,that patients who have post cardiac arrest are provided in the cardiac ICU.

Post resuscitation care: what are the therapeutic alternatives and what do we know?

A large proportion of deaths in the Western World are caused by ischaemic heart disease. Among these patients a majority die outside hospital due to sudden cardiac death. The prognosis among these patients is in general, poor. However, a significant proportion are admitted to a hospital ward alive. The proportion of patients who survive the hospital phase of an out of hospital cardiac arrest varies considerably. Several treatment strategies are applicable during the post resuscitation care phase, but the level of evidence is weak for most of them. Four treatments are recommended for selected patients based on relatively good clinical evidence: therapeutic hypothermia, beta-blockers, coronary artery bypass grafting, and an implantable cardioverter defibrillator. The patient's cerebral function might influence implementation of the latter two alternatives. There is some evidence for revascularisation treatment in patients with suspected myocardial infarction. On pathophysiological grounds, an early coronary angiogram is a reasonable alternative. Further randomised clinical trials of other post resuscitation therapies are essential.

Thrombolysis with streptokinase during cardiopulmonary resuscitation: a single center experience and review of the literature

OBJECTIVE

To report our experience with use of thrombolysis with streptokinase during cardiopulmonary resuscitation of patients with cardiac arrest due to myocardial infarction.

DESIGN

A case series.

METHODS

Thrombolytic therapy (streptokinase) was administered during cardiopulmonary resuscitation of 4 patients with suspected myocardial infarction as the cause of cardiac arrest.

RESULTS

3 of the 4 patients survived and were discharged from the hospital without any major complications or neurological sequela.

CONCLUSION

Thrombolysis with streptokinase during cardiopulmonary resuscitation of patients with suspected acute myocardial infarction is associated with reduced mortality and favorable neurological outcome.

Long-term survival and neurological outcome of patients who received recombinant tissue plasminogen activator during out-of-hospital cardiac arrest

OBJECTIVE

The long-term outcome in patients who received recombinant tissue plasminogen activator during cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA) of non-traumatic aetiology was assessed.

METHODS

The neurological outcome in survivors and their level of performance, subjective well-being and quality of life were evaluated.

RESULTS

A follow-up study of 27 cardiac arrest survivors was conducted; four patients (15%) died during the first year, a total of seven patients (26%) within 5 years. Twenty-two patients (81%) were discharged from hospital without neurological deficit (cerebral performance category (CPC) score: 1), three patients scored CPC 2 and two patients CPC 3. Heart failure classification on discharge was, according to the New York Heart Association (NYHA) criteria 2.1 +/- 0.9. Fifteen patients (56%) managed to return to their previous level of activity. At the time of follow-up 18 patients (67%) were still alive, of whom 15 responded to a survey regarding life satisfaction. Thirteen patients (87%) judged their situation to be worth living and twelve (80%) considered their survival a second chance, while five (33%) feared they could suffer another cardiac arrest. Reactions from close relatives included fear/anxiety (n = 14; 78%), a sustained burden on family life (n = 12; 67%), and occasional depression (n = 7; 39%).

CONCLUSIONS

Thrombolytic therapy during cardiopulmonary resuscitation may produce a favourable neurological outcome. The majority of long-term survivors reported a good subjective quality of life. In one-third of close family members some negative factors had a lasting impact on the quality of daily living.

A multiple logistic regression analysis of in-hospital factors related to survival at six months in patients resuscitated from out-of-hospital ventricular fibrillation

INTRODUCTION

The impact of the immediate in-hospital post-resuscitation care after out-hospital cardiac arrest is not well known. Based on treatment variables and laboratory findings a multiple logistic regression model was created for the prediction of survival at 6 months from the event.

MATERIALS AND METHODS

A retrospective study of the hospital charts of patients successfully resuscitated and treated in one of three community hospitals from 1998 to 2000. In addition to several pre-hospital variables, the mean 72 h values of clinical features such as blood pressure, blood glucose concentration and initiated treatment used, were included in a forward multiple logistic regression model predicting survival at 6 months from the event.

RESULTS

The charts of 98 out of a total of 102 patients were sufficiently complete and included in the analysis. Variables independently associated with survival were age, delay before a return of spontaneous circulation, mean blood glucose and serum potassium, and the use of beta-blocking agents during post-resuscitation care. When those patients who were assigned a 'do not attempt to resuscitate' (DNAR) order during the first 72 h of treatment were excluded from the analysis blood glucose, blood potassium and the use beta-blocking agents remained independently associated with survival.

CONCLUSION

This study suggests that in-hospital factors are associated with survival from out-of-hospital cardiac arrest. The mean blood glucose and serum potassium during the first 72 h of treatment and the use of beta-blocking agents were significantly and independently associated with survival.

Safety of thrombolysis during cardiopulmonary resuscitation

The prognosis is generally poor for patients who experience a cardiac arrest. The most common causes of sudden cardiac arrest are massive pulmonary embolism (PE) and acute myocardial infarction (MI). While thrombolysis is a first-line treatment option in massive PE and acute MI, cardiopulmonary resuscitation (CPR) has been regarded as a relative contraindication for thrombolysis because of the anticipated bleeding risk caused by traumatic cardiocompressions. However, an increasing number of case reports and clinical studies on thrombolysis during and after CPR highlight an increased frequency of the return of spontaneous circulation and a better neurological outcome of surviving patients. These effects are mainly due to the thrombolysis of macroscopic blood clots and the amelioration of microcirculatory reperfusion. This article reviews case reports and clinical studies of thrombolysis during and shortly after CPR in order to estimate the risk of severe bleeding events caused by CPR in association with thrombolysis compared with CPR without thrombolysis. Although thrombolysis per se can cause severe and potentially fatal haemorrhage, there is no evidence that severe bleeding events occur more often when thrombolysis is combined with cardiocompressions. In addition, by far the majority of bleeding complications can be treated effectively. Thus, in many cases, the possible benefit of thrombolysis during CPR seems to outweigh the potential risks. However, there may be a publication bias in some case reports and studies towards reporting successful rather than unsuccessful CPRs. In addition, not enough controlled clinical trials have yet been conducted. Therefore, data from large randomised, multicentre studies are needed to definitely answer the question of the relationship between safety and efficacy of this promising treatment option. We conclude that the currently available data do not indicate that thrombolysis contributes to a significant increase in bleeding complications when administered during CPR.

Major bleeding complications in cardiopulmonary resuscitation: the place of thrombolytic therapy in cardiac arrest due to massive pulmonary embolism

OBJECTIVE

Thrombolytic therapy in patients with massive pulmonary embolism (MPE) and prolonged cardiopulmonary resuscitation (CPR) is subject to debate. This study was performed to determine whether (1) thrombolytic treatment increases the risk of bleeding complications, (2) if the risk of bleeding is influenced by the duration of CPR and if (3) thrombolytic therapy improves outcome.

DESIGN

Retrospective cohort study.

SETTING

Emergency department of a tertiary care university hospital.

PATIENTS AND METHODS

Sixty-six patients with cardiac arrest (CA) due to MPE admitted between July 1993 and December 2001. Thirty-six patients received thrombolysis (TL) and were compared with 30 patients without thrombolytic therapy. Bleeding complications were assessed by clinical evidence or autopsy.

RESULTS

Major bleeding complications appear to occur more frequently in patients treated with thrombolytics (9/36 (25%) vs. 3/30 (10%)) even though the difference was statistically not significant (P=0.15). It appears that CPR duration >10 min has no adverse impact on major bleeding complications. No difference in the rate of major bleeding complications between thrombolyzed patients who had a CPR duration of </=10 or >10 min could be observed (2/8 (25%) vs. 7/28 (25%), P=0.99). In thrombolyzed patients a return of spontaneous circulation could be achieved more frequently (24/36 (67%) vs.13/30 (43%) in controls, P=0.06) and survival after 24 h was higher (19/36 (53%) vs. 7/30 (23%), P=0.01). Survival to discharge was also higher in the TL group (7/36 (19%) vs. 2/30 (7%)), but not statistically significant (P=0.15).

CONCLUSION

Although severe bleeding complications tend to occur more frequently in patients undergoing TL, the benefit of this treatment might outweigh the risk of bleeding.

Major bleeding complications after cardiopulmonary resuscitation: impact of thrombolytic treatment

OBJECTIVE

The risk of bleeding complications caused by thrombolysis in patients with cardiac arrest and prolonged cardiopulmonary resuscitation is unclear. We evaluate the complication rate of systemic thrombolysis in patients with out-of-hospital cardiac arrest caused by acute myocardial infarction, especially in relation to duration of cardiopulmonary resuscitation.

DESIGN

The study was designed as retrospective cohort study, the risk factor being systemic thrombolysis and the end-point major haemorrhage, defined as life-threatening and/or need for transfusion. Over 10.5 years, emergency cardiac care data, therapy, major haemorrhage and outcome of 265 patients with acute myocardial infarction admitted to an emergency department after successful cardiopulmonary resuscitation were registered.

RESULTS

We observed major haemorrhage in 13 of 132 patients who received thrombolysis (10%, 95% confidence interval 5-15%), five of these survived to discharge, none died because of this complication. Major haemorrhage occurred in seven of 133 patients in whom no thrombolytic treatment had been given (5%, 95% confidence interval 1-9%), two of these survived to discharge. Taking into account baseline imbalances between the groups, the risk of bleeding was slightly increased if thrombolytics were used (odds ratio 2.5, 95% confidence interval 0.9-7.4) but this was not significant (P = 0.09). There was no clear association between duration of resuscitation and bleeding complications (z for trend = 1.52, P = 0.12). Survival was not significantly better in patients receiving thrombolysis (odds ratio 1.6, 0.9-3.0, P = 0.12).

CONCLUSIONS

Bleeding complications after cardiopulmonary resuscitation are frequent, particularly in patients with thrombolytic treatment, but do not appear to be related to the duration of resuscitation. In the light of possible benefits on outcome, thrombolytic treatment should not be withheld in carefully selected patients.

Plasminogen activators in inflammation and sepsis

Mortality of severe sepsis remains at 40% to 50%. Intensive efforts over the past two decades have only marginally improved outcome. Improving outcome in sepsis depends on understanding its pathophysiology, which involves triggers, responses of the organism, and dysfunction. Stress, injury, or infection trigger host responses, including local and systemic orchestrated mechanisms. Dysfunction and outcome depend on both trigger and response. Blood coagulation, inflammation, immunity, and fibrinolysis are critical components of the organism's responses. Understanding their role in sepsis pathophysiology is the key to effective treatment. Relevant studies were identified by a systematic literature search, complemented by manual search of individual citations. Using PubMed, 'sepsis' yields more than 62,000 references, 'plasminogen activators' more than 21,000. The selection of citations was guided by preference for reviews that expand important threads of argumentation. Single original studies were included when relevant to critical points. This analytical review describes the essential elements of pathophysiology and the current status of sepsis treatment. Based on this context, an emerging therapeutic option will be discussed: plasminogen activators.