Clinical controversies in thrombolytic therapy for the management of acute pulmonary embolism

Characterization of alteplase therapy for presumed or confirmed pulmonary embolism during cardiac arrest

PURPOSE

The dosing and administration of alteplase in cardiac arrest due to suspected or confirmed pulmonary embolism (PE) are characterized.

METHODS

This multicenter, retrospective, cohort study evaluated adult patients who received alteplase during PE-induced cardiac arrest at 16 medical centers. Outcomes analyzed included alteplase dosing characteristics, cardiopulmonary resuscitation survival, time to return of spontaneous circulation (ROSC), documented occurrence of major or minor bleeding, intensive care unit and hospital length of stay, and survival to discharge.

RESULTS

A total of 35 patients were included in the analysis. Forty-six percent of patients received alteplase by a bolus-only dosing strategy. The most common bolus-only alteplase dose was 50 mg. Patients in the bolus-only group had a significantly shorter mean time from cardiac arrest onset to alteplase administration (15.1 minutes) compared with both the infusion-only group (46.4 minutes) and the bolus-with-infusion group (48.0 minutes) (p = 0.006). The mean cumulative alteplase dose was significantly higher in patients who had ROSC than those who did not (90.6 and 69.4 mg, respectively; p = 0.03). Although there was a significant difference in the cardiac arrest survival between groups, there was no difference between dosing strategies and the attainment of ROSC, and survival to hospital discharge.

CONCLUSION

Among patients receiving alteplase for presumed or confirmed PE during cardiac arrest, the most common treatment was administration of a single 50-mg bolus of the thrombolytic agent. This treatment was received by all survivors of cardiac arrest.

Practice patterns and complication rates of thrombolysis for pulmonary embolism

Practice patterns, bleeding complication rates, and outcomes of thrombolytic use for pulmonary embolism (PE) outside of clinical trials are not well characterized. Retrospective cohort study of patients with PE, using an enhanced administrative database of approximately 20 % of hospitalizations in the United States, 2008-2011. We used hierarchical logistic regression to identify patient- and hospital-level factors associated with thrombolytic use and quantified between-hospital variation in thrombolysis. We calculated rates of hemorrhagic complications and mortality in patients receiving thrombolytics stratified by vasopressor use. We identified 91,860 hospitalizations for PE; thrombolytics were utilized in 13.2 % (578/4363) who received vasopressors and 1.6 % (1320/82,997) who did not receive vasopressors. Patients who received thrombolytics were younger, more likely white, with private insurance, fewer comorbidities and more acute organ failures. Hospitals varied widely in thrombolysis rates for PE (0-100 % of patients on vasopressors, 0-12.5 % not on vasopressors) with 17 % of variation unexplained by patient or hospital characteristics. Bleeding complication rates for patients receiving thrombolytics versus no thrombolytics, respectively, were: ICH (0.8 vs. 0.08 %, p < 0.01), major bleeding (13 vs. 3 %, p < 0.01), and major bleeding with transfusion (2.5 vs. 0.05 %, p < 0.01). Among patients given vasopressors, thrombolytics were not associated with hospital mortality (thrombolysis 41 % vs. no thrombolysis 35 % mortality; adjusted OR 0.97, 95 % CI 0.93-1.01, p = 0.15). There is wide variation in thrombolytic use for PE in the US. Patient characteristics and complications associated with real-world thrombolytic use were similar to published randomized trials.

Bleeding risk with systemic thrombolytic therapy for pulmonary embolism: scope of the problem

Acute pulmonary embolism represents a major complication of venous thromboembolism that is associated with high morbidity and mortality. Guidelines recommend the rapid initiation of anticoagulation and consideration of thrombolytic therapy in select patients, including those with hypotension or at high risk of developing hypotension. Evaluation for thrombolytic therapy should only be considered after assessment of contraindications and risk for major bleeding. The objective of this perspective article is to evaluate the bleeding risk associated with systemic thrombolytic therapy in the management of acute pulmonary embolism and discuss strategies to minimize this risk. Risk stratification of acute pulmonary embolism will be discussed to identify patient populations that warrant specific consideration of risk for major bleeding with thrombolytic therapy. In addition, the incidence, patient-specific risk factors, and pharmacologic characteristics, including concurrent anticoagulation and thrombolytic therapy, will be evaluated in the context of risk for major hemorrhage. Finally, supporting evidence for strategies to minimize risk of hemorrhage, including evaluation of contraindications, weight adjusted dosing, infusion strategy and catheter-directed thrombolytic administration will be evaluated. Despite published guidelines and review articles, select aspects to thrombolytic therapy for the management of pulmonary embolism remain controversial and under recognized, including risk of major hemorrhage. When making decisions about the role of thrombolytic therapy in pulmonary embolism, clinicians must be knowledgeable about the associated risks of thrombolytic therapy and individually evaluate patient risk factors prior to determining appropriate candidacy for thrombolytic therapy. For patients considered to be at high risk of major bleeding, strategies to minimize risk should be considered, including weight-adjusted doses and catheter directed therapy. Additional research is needed specific to the acute pulmonary embolism setting to validate risk factors and strategies to minimize major hemorrhage.

Systemic thrombolysis for acute pulmonary embolism

Acute pulmonary embolism is a frequent cause of hospitalization and is associated with a wide range of symptom severity. Anticoagulants are the mainstay of treatment for acute pulmonary embolism; however, in patients with massive or submassive pulmonary embolism, advanced therapy with thrombolytics may be considered. The decision to use thrombolytic therapy for acute pulmonary embolism should be based on careful risk-benefit analysis for each patient, including risk of morbidity and mortality associated with the embolism and risk of bleeding associated with the thrombolytic. Alteplase is currently the thrombolytic agent most studied and with the most clinical experience for this indication, although the most appropriate dose remains controversial, especially in patients with low body weight. When considering thrombolysis, unfractionated heparin is the preferred initial anticoagulant due to its short duration of action and its reversibility should bleeding occur.

Thrombolytic therapy in the treatment of acute sub-massive pulmonary embolism: a prospective observational study

The use of thrombolytic therapy in haemodynamically stable patients with sub-massive pulmonary embolism is still controversial. We conducted this study to observe the safety and efficacy of thrombolytic therapy in acute pulmonary embolism patients with normal blood pressure in a tertiary cardiac centre. In this study, 130 patients with sub-massive pulmonary embolism who had right-ventricular dysfunction were included and treated with thrombolytic therapy. Forty-one percent of patients in our study were within 40 years of age. Eighty-three percent of patients had clinical improvement. Both right-ventricular dysfunction and pulmonary artery systolic pressure were improved significantly following thrombolytic therapy from baseline (49 vs. 28 mmHg; P = 0.01; 95% confidence interval -13 to -56). Only 9% patients had died and two patients had intra-cerebral haemorrhage during this study. Thrombolytic therapy may be helpful in improving clinical course following sub-massive acute pulmonary embolism, especially for those who had low risk of bleeding. Further randomized study with large sample size is needed for final conclusion.

Successful thrombolysis in postoperative patients with acute massive pulmonary embolism

PURPOSE

The standard medical management for patients with acute massive pulmonary embolism (MPE) is systemic thrombolysis. However, it is generally thought that recent surgeries are a contraindication to thrombolytic therapy. In this study, we evaluated the efficacy and safety of systemic thrombolysis for postoperative patients with acute MPE and assessed the risk of bleeding.

METHODS

A retrospective review was performed on 21 postoperative patients with MPE in a timeframe of five years (from 2005 to 2010). The criteria for study inclusion were postoperative patients who received systemic thrombolysis for confirmed acute MPE within three weeks after surgery.

RESULTS

Seventeen postoperative patients, including men (12) and women (five) aged 53±16 (range 23-71) years, were treated with systemic thrombolysis. Significant haemodynamic improvement (shock index<0.9) was observed in 16 of 17 cases (94%). The remaining patient (6%) died of cardiac arrest within 24h. No major bleeding complication was observed. Sixteen patients survived and remained stable for 34±16 (range 11-52) days until hospital discharge.

CONCLUSION

Recent surgery is not an absolute contraindication to systemic thrombolysis. Further, to obtain a successful outcome, it is crucial to exclude patients who have received neurosurgical operations or those with other contraindications to thrombolytic therapy.