Impact of fibrinolysis on immediate prognosis of patients with out-of-hospital cardiac arrest

Characteristics, diagnostic accuracy, and safety in patients receiving selective prehospital thrombolysis in out-of-hospital cardiac arrest: A retrospective cohort study

Objectives

Out-of-hospital cardiac arrest (OOHCA) carries a significant mortality implication despite optimal conventional therapies. To better understand the role of prehospital thrombolysis for OOHCA, we report the clinical outcomes, safety and enhanced care team diagnostic accuracy concerning selective thrombolysis by a physician-paramedic staffed air ambulance service.

Methods

A retrospective database review of electronic documentation was undertaken for all cases where thrombolysis was administered in OOHCA between January 2017 to April 2022 at Essex and Hertfordshire Air Ambulance Trust (EHAAT). Data collected included demographics, timings, pertinent clinical features, outcomes, and the treating team's suspected cause of arrest. For patients who died, cause of death was obtained from local coroners.

Results

100 patients were identified and five survived to hospital discharge. The median (IQR) time from first cardiac arrest to thrombolysis was 58.5 min (44-75). The cause of death was available for 60 patients, among these 43% had suffered either a pulmonary embolus (PE) or myocardial infarction (MI). In patients who died of MI the critical care team correctly diagnosed this in 76.9% of cases, and of those who died of PE 92.3% were correctly diagnosed. However, the positive predictive value (PPV) of clinician diagnosis overall was only 36.7%.

Conclusion

Despite a high proportion of patients having a cause of OOHCA theoretically amenable to thrombolysis, survival to hospital discharge remains poor. Further work is required to better understand the future role and timing of prehospital thrombolysis in refractory OOHCA. Clinicians detected both MI and PE with high sensitivity but low PPV.

Systemic thrombolysis for refractory cardiac arrest due to presumed myocardial infarction

The empiric usage of systemic thrombolysis for refractory out of hospital cardiac arrest (OHCA) is considered for pulmonary embolism (PE), but not for undifferentiated cardiac etiology [1, 2]. We report a case of successful resuscitation after protracted OHCA with suspected non-PE cardiac etiology, with favorable neurological outcome after empiric administration of systemic thrombolysis. A 47-year-old male presented to the emergency department (ED) after a witnessed OHCA with no bystander cardiopulmonary resuscitation (CPR). His initial rhythm was ventricular fibrillation (VF) which had degenerated into pulseless electrical activity (PEA) by ED arrival. Fifty-seven minutes into his arrest, we gave systemic thrombolysis which obtained return of spontaneous circulation (ROSC). He was transferred to the coronary care unit (CCU) and underwent therapeutic hypothermia. On hospital day (HD) 4 he began following commands and was extubated on HD 5. Subsequent percutaneous coronary intervention (PCI) revealed non-obstructive stenosis in distal LAD. He was discharged home directly from the hospital, with one-month cerebral performance category (CPC) score of one. He was back to work three months post-arrest. Emergency physicians (EP) should be aware of this topic since we are front-line health care professionals for OHCA. Thrombolytics have the advantage of being widely available in ED and therefore offer an option on a case-by-case basis when intra-arrest PCI and ECPR are not available. This case report adds to the existing literature on systemic thrombolysis as salvage therapy for cardiac arrest from an undifferentiated cardiac etiology. The time is now for this treatment to be reevaluated.

International Survey of Thrombolytic Use for Treatment of Cardiac Arrest Due to Massive Pulmonary Embolism

Objectives

This survey sought to characterize the national prescribing patterns and barriers to the use of thrombolytic agents in the treatment of pulmonary embolism, with a specific focus on treatment during actual or imminent cardiac arrest.

Design

A 19-question international, cross-sectional survey on thrombolytic use in pulmonary embolism was developed, validated, and administered. A multivariable logistic regression was conducted to determine factors predictive of utilization of thrombolytics in the setting of cardiac arrest secondary to pulmonary embolism.

Setting

International survey study.

Subjects

Physicians, pharmacists, nurses, and other healthcare professionals who were members of the Society of Critical Care Medicine.

Interventions

None.

Measurements and Main Results

Thrombolytic users were compared with nonusers. Respondents (n = 272) predominately were physicians (62.1%) or pharmacists (30.5%) practicing in an academic medical center (54.8%) or community teaching setting (24.6%). Thrombolytic users (n = 177; 66.8%) were compared with nonusers (n = 88; 33.2%) Thrombolytic users were more likely to work in pulmonary/critical care (80.2% thrombolytic use vs 59.8%; p < 0.01) and emergency medicine (6.8% vs 3.5%; p < 0.01). Users were more likely to have an institutional guideline or policy in place pertaining to the use of thrombolytics in cardiac arrest (27.8% vs 13.6%; p < 0.01) or have a pulmonary embolism response team (38.6% vs 19.3%; p < 0.01). Lack of evidence supporting use and the risk of adverse outcomes were barriers to thrombolytic use. Working in a pulmonary/critical care environment (odds ratio, 2.36; 95% CI, 1.24-4.52) and comfort level (odds ratio, 2.77; 95% CI, 1.7-4.53) were predictive of thrombolytic use in the multivariable analysis.

Conclusions

Most survey respondents used thrombolytics in the setting of cardiac arrest secondary to known or suspected pulmonary embolism. This survey study adds important data to the literature surrounding thrombolytics for pulmonary embolism as it describes thrombolytic user characteristic, barriers to use, and common prescribing practices internationally.

Can Systemic Thrombolysis Improve Prognosis of Cardiac Arrest Patients During Cardiopulmonary Resuscitation? A Systematic Review and Meta-Analysis

BACKGROUND

Cardiac arrests are caused in most cases by thromboembolic diseases, such as acute myocardial infarction (AMI) and pulmonary embolism (PE).

OBJECTIVE

We aimed to ascertain the associations of thrombolytic therapy with potential benefits among cardiac arrest patients during cardiopulmonary resuscitation (CPR).

METHODS

We searched PubMed, Embase, and Cochrane databases for studies that evaluated systemic thrombolysis in cardiac arrest patients. The primary outcome was survival to hospital discharge, and secondary outcomes included return of spontaneous circulation (ROSC), 24-h survival rate, hospital admission rate, and bleeding complications.

RESULTS

Nine studies with a total of 4384 cardiac arrest patients were pooled in the meta-analysis, including 1084 patients receiving systemic thrombolysis and 3300 patients receiving traditional treatments. Compared with conventional therapies, the use of systemic thrombolysis did not significantly improve survival to hospital discharge (13.5% vs. 10.8%; risk ratio [RR] 1.13; 95% confidence interval [CI] 0.92-1.39; p = 0.24, I² = 35%), ROSC (50.9% vs. 44.3%; RR 1.29; 95% CI 1.00-1.66; p = 0.05, I² = 73%), and 24-h survival (28.1% vs. 25.6%; RR 1.25; 95% CI 0.88-1.77; p = 0.22, I² = 63%). We observed higher hospital admission rates for patients receiving systemic thrombolysis (43.4% vs. 30.6%; RR 1.53; 95% CI 1.04-2.24; p = 0.03, I² = 87%). In addition, higher risk of bleeding was observed in the thrombolysis group (8.8% vs. 5.0%; RR 1.65; 95% CI 1.16-2.35; p = 0.005, I² = 7%).

CONCLUSIONS

Systemic thrombolysis during CPR did not improve hospital discharge rate, ROSC, and 24-h survival for cardiac arrest patients. Patients receiving thrombolytic therapy have a higher risk of bleeding. More high-quality studies are needed to confirm our results.

Coagulofibrinolytic Changes in Patients with Post-cardiac Arrest Syndrome

Whole-body ischemia and reperfusion due to cardiac arrest and subsequent return of spontaneous circulation constitute post-cardiac arrest syndrome (PCAS), which consists of four syndromes including systemic ischemia/reperfusion responses and post-cardiac arrest brain injury. The major pathophysiologies underlying systemic ischemia/reperfusion responses are systemic inflammatory response syndrome and increased coagulation, leading to disseminated intravascular coagulation (DIC), which clinically manifests as obstruction of microcirculation and multiple organ dysfunction. In particular, thrombotic occlusion in the brain due to DIC, referred to as the "no-reflow phenomenon," may be deeply involved in post-cardiac arrest brain injury, which is the leading cause of mortality in patients with PCAS. Coagulofibrinolytic changes in patients with PCAS are characterized by tissue factor-dependent coagulation, which is accelerated by impaired anticoagulant mechanisms, including antithrombin, protein C, thrombomodulin, and tissue factor pathway inhibitor. Damage-associated molecular patterns (DAMPs) accelerate not only tissue factor-dependent coagulation but also the factor XII- and factor XI-dependent activation of coagulation. Inflammatory cytokines are also involved in these changes via the expression of tissue factor on endothelial cells and monocytes, the inhibition of anticoagulant systems, and the release of neutrophil elastase from neutrophils activated by inflammatory cytokines. Hyperfibrinolysis in the early phase of PCAS is followed by inadequate endogenous fibrinolysis and fibrinolytic shutdown by plasminogen activator inhibitor-1. Moreover, cell-free DNA, which is also a DAMP, plays a pivotal role in the inhibition of fibrinolysis. DIC diagnosis criteria or fibrinolysis markers, including d-dimer and fibrin/fibrinogen degradation products, which are commonly tested in patients and easily accessible, can be used to predict the mortality or neurological outcome of PCAS patients with high accuracy. A number of studies have explored therapy for this unique pathophysiology since the first report on "no-reflow phenomenon" was published roughly 50 years ago. However, the optimum therapeutic strategy focusing on the coagulofibrinolytic changes in cardiac arrest or PCAS patients has not yet been established. The elucidation of more precise pathomechanisms of coagulofibrinolytic changes in PCAS may aid in the development of novel therapeutic targets, leading to an improvement in the outcomes of PCAS patients.