Overview of Management of Intermediate- and High-Risk Pulmonary Embolism

Direct Oral Anticoagulants for Pulmonary Embolism

Venous thromboembolism (VTE) is the third most common cardiovascular disease. For most patients, the standard of treatment has long consisted on low-molecular-weight heparin followed by vitamin K antagonists, but a number of clinical trials and, subsequently, post-marketing studies have shown that direct oral anticoagulants (DOACs) with or without lead-in heparin therapy are effective alternatives with fewer adverse effects. This evidence has led to important changes in the guidelines on the treatment of VTE, including pulmonary embolism (PE), with the DOACs being now recommended as the first therapeutic choice. Additional research has contributed to identifying low-risk PE patients who can benefit from outpatient management or from early discharge from the emergency department with DOAC treatment. There is evidence to support the use of DOACs in intermediate-risk PE patients as well as in high-risk patients receiving thrombolytic treatment. The use of DOACs has also been proven to be safe and effective in special populations of PE patients, such as patients with renal impairment, liver impairment, and cancer.

Management of high-risk pulmonary embolism in the emergency department: A narrative review

BACKGROUND

High-risk pulmonary embolism (PE) is a complex, life-threatening condition, and emergency clinicians must be ready to resuscitate and rapidly pursue primary reperfusion therapy. The first-line reperfusion therapy for patients with high-risk PE is systemic thrombolytics (ST). Despite consensus guidelines, only a fraction of eligible patients receive ST for high-risk PE.

OBJECTIVE

This review provides emergency clinicians with a comprehensive overview of the current evidence regarding the management of high-risk PE with an emphasis on ST and other reperfusion therapies to address the gap between practice and guideline recommendations.

DISCUSSION

High-risk PE is defined as PE that causes hemodynamic instability. The high mortality rate and dynamic pathophysiology of high-risk PE make it challenging to manage. Initial stabilization of the decompensating patient includes vasopressor administration and supplemental oxygen or high-flow nasal cannula. Primary reperfusion therapy should be pursued for those with high-risk PE, and consensus guidelines recommend the use of ST for high-risk PE based on studies demonstrating benefit. Other options for reperfusion include surgical embolectomy and catheter directed interventions.

CONCLUSIONS

Emergency clinicians must possess an understanding of high-risk PE including the clinical assessment, pathophysiology, management of hemodynamic instability and respiratory failure, and primary reperfusion therapies.

Intermediate-Risk Pulmonary Embolism: A Review of Contemporary Diagnosis, Risk Stratification and Management

Pulmonary embolism (PE) can have a wide range of hemodynamic effects, from asymptomatic to a life-threatening medical emergency. Pulmonary embolism (PE) is associated with high mortality and requires careful risk stratification for individualized management. PE is divided into three risk categories: low risk, intermediate-risk, and high risk. In terms of initial therapeutic choice and long-term management, intermediate-risk (or submassive) PE remains the most challenging subtype. The definitions, classifications, risk stratification, and management options of intermediate-risk PE are discussed in this review.

Oxygen Therapy Lowers Right Ventricular Afterload in Experimental Acute Pulmonary Embolism

OBJECTIVES

To investigate if oxygen could unload the right ventricle and improve right ventricle function in a porcine model mimicking intermediate-high risk acute pulmonary embolism.

DESIGN

Controlled, blinded, animal study.

SETTING

Tertiary university hospital, animal research laboratory.

SUBJECTS

Female, Danish pigs (n = 16, approximately 60 kg).

INTERVENTIONS

Acute autologous pulmonary embolism was induced until doubling of baseline mean pulmonary arterial pressure. Group 1 animals (n = 8) received increasing Fio2 (40%, 60%, and 100%) for time intervals of 15 minutes returning to atmospheric air between each level of Fio2. In group 2 (n = 8), the effects of Fio2 40% maintained over 75 minutes were studied. In both groups, pulmonary vasodilatation from inhaled nitric oxide (40 parts per million) was used as a positive control.

MEASUREMENTS AND MAIN RESULTS

Effects were evaluated by biventricular pressure-volume loop recordings, right heart catheterization, and arterial and mixed venous blood gasses. Pulmonary embolism increased mean pulmonary arterial pressure from 15 ± 4 to 33 ± 6 mm Hg (p = 0.0002) and caused right ventricle dysfunction (p < 0.05) with troponin release (p < 0.0001). In group 1, increasing Fio2 lowered mean pulmonary arterial pressure (p < 0.0001) and pulmonary vascular resistance (p = 0.0056) and decreased right ventricle volumes (p = 0.0018) and right ventricle mechanical work (p = 0.034). Oxygenation was improved and pulmonary shunt was lowered (p < 0.0001). Maximal hemodynamic effects were seen at Fio2 40% with no additional benefit from higher fractions of oxygen. In group 2, the effects of Fio2 40% were persistent over 75 minutes. Supplemental oxygen showed the same pulmonary vasodilator efficacy as inhaled nitric oxide (40 parts per million). No adverse effects were observed.

CONCLUSIONS

In a porcine model mimicking intermediate-high risk pulmonary embolism, oxygen therapy reduced right ventricle afterload and lowered right ventricle mechanical work. The effects were immediately present and persistent and were similar to inhaled nitric oxide. The intervention is easy and safe. The study motivates extended clinical evaluation of supplemental oxygen in acute pulmonary embolism.

Renal dysfunction improves risk stratification and may call for a change in the management of intermediate- and high-risk acute pulmonary embolism: results from a multicenter cohort study with external validation

BACKGROUND

Renal dysfunction influences outcomes after pulmonary embolism (PE). We aimed to determine the incremental value of adding renal dysfunction, defined by estimated glomerular filtration rate (eGFR), on top of the European Society of Cardiology (ESC) prognostic model, for the prediction of 30-day mortality in acute PE patients, which in turn could lead to the optimization of acute PE management.

METHODS

We performed a multicenter, non-interventional retrospective post hoc analysis based on a prospectively collected cohort including consecutive confirmed acute PE stratified per ESC guidelines. We first identified which of three eGFR formulae most accurately predicted death. Changes in global model fit, discrimination, calibration and reclassification parameters were evaluated with the addition of eGFR to the prognostic model.

RESULTS

Among 1943 patients (mean age 67.3 (17.1), 50.4% women), 107 (5.5%) had died at 30 days. The 4-variable Modification of Diet in Renal Disease (eGFR_MDRD4) formula predicted death most accurately. In total, 477 patients (24.5%) had eGFR_MDRD4 < 60 ml/min. Observed mortality was higher for intermediate-low-risk and high-risk PE in patients with versus without renal dysfunction. The addition of eGFR_MDRD4 information improved model fit, discriminatory capacity, and calibration of the ESC model. Reclassification parameters were significantly increased, yielding 18% reclassification of predicted mortality (p < 0.001). Predicted mortality reclassifications across risk categories were as follows: 63.1% from intermediate-low risk to eGFR-defined intermediate-high risk, 15.8% from intermediate-high risk to eGFR-defined intermediate-low risk, and 21.0% from intermediate-high risk to eGFR-defined high risk. External validation in a cohort of 14,234 eligible patients from the RIETE registry confirmed our findings with a significant improvement of Harrell's C index and reclassification parameters.

CONCLUSION

The addition of eGFR_MDRD4-derived renal dysfunction on top of the prognostic algorithm led to risk reclassification within the intermediate- and high-risk PE categories. The impact of risk stratification integrating renal dysfunction on therapeutic management for acute PE requires further studies.