Prevalence and Predictors of Cardiogenic Shock in Intermediate-Risk Pulmonary Embolism: Insights From the FLASH Registry

Relationship between the mixed venous-to-arterial carbon dioxide gradient and the cardiac index in acute pulmonary embolism

AIMS

Among patients with acute pulmonary embolism (PE) undergoing mechanical thrombectomy, the cardiac index (CI) is frequently reduced even among those without a clinically apparent shock. The purpose of this study is to describe the mixed venous-to-arterial carbon dioxide gradient (CO2 gap), a surrogate of perfusion adequacy, among patients with acute PE undergoing mechanical thrombectomy.

METHODS AND RESULTS

This was a single-centre retrospective study of consecutive patients with PE undergoing mechanical thrombectomy and simultaneous pulmonary artery catheterization over a 3-year period. Of 107 patients, 97 had simultaneous mixed venous and arterial blood gas measurements available. The CO2 gap was elevated (>6 mmHg) in 51% of the cohort and in 49% of patients with intermediate-risk PE. A reduced CI (≤2.2 L/min/m2) was associated with an increased odds [odds ratio = 7.9; 95% confidence interval (CI) 3.49-18.1, P < 0.001] for an elevated CO2 gap. There was an inverse relationship between the CI and the CO2 gap. For every 1 L/min/m2 decrease in the CI, the CO2 gap increased by 1.3 mmHg (P = 0.001). Among patients with an elevated baseline CO2 gap >6 mmHg, thrombectomy improved the CO2 gap, CI, and mixed venous oxygen saturation. When the CO2 gap was dichotomized above and below 6, there was no difference in the in-hospital mortality rate (9 vs. 0%; P = 0.10; hazard ratio: 1.24; 95% CI 0.97-1.60; P = 0.085).

CONCLUSION

Among patients with acute PE undergoing mechanical thrombectomy, the CO2 gap is abnormal in nearly 50% of patients and inversely related to the CI. Further studies should examine the relationship between markers of perfusion and outcomes in this population to refine risk stratification.

McConnell's sign predicts normotensive shock in patients with acute pulmonary embolism

BACKGROUND

Patients with intermediate-risk pulmonary embolism (PE) and normotensive shock may have worse outcomes. However, diagnosis of normotensive shock requires invasive hemodynamics. Our objective was to assess the predictive value of McConnell's sign in identifying normotensive shock in patients with intermediate-risk PE.

METHODS

Patients with intermediate-risk PE who underwent percutaneous mechanical thrombectomy between August 2020 and April 2023 at a large academic public hospital were included in the study. Normotensive shock was defined as systolic blood pressure ≥ 90 mmHg without vasopressor support with pre-procedural invasive measures of cardiac index ≤2.2 L/min/m2 and clinical evidence of hypoperfusion (i.e. elevated lactate, oliguria). The primary outcome was the association between McConnell's sign and normotensive shock.

RESULTS

Those with McConnell's sign (29/40, 72.5 %) had higher heart rate (114 vs 99 beats/min, p = 0.008), higher rates of elevated lactate (86 % vs 55 %, p = 0.038), lower cardiac index (1.9 vs 3.1 L/min/m2, p = 0.003), and higher rates of normotensive shock (76 % vs 27 %, p = 0.005). McConnell's sign had a sensitivity of 88 % and specificity of 53 % for identifying intermediate-risk PE patients with normotensive shock. Patients with McConnell's sign had an increased odds (odds ratio 8.38, confidence interval: 1.73-40.53, p = 0.008; area under the curve 0.70, 95 % confidence interval: 0.56-0.85) of normotensive shock.

CONCLUSION

This is the first study to suggest that McConnell's sign may identify those in the intermediate-risk group who are at risk for normotensive shock. Larger cohorts are needed to validate our findings.

Low left ventricular outflow tract velocity time integral predicts normotensive shock in patients with acute pulmonary embolism

In this study, we found that a low LVOT VTI (<15 cm), a simple bedside point-of-care measurement, predicts normotensive shock in patients with acute intermediate-risk PE.

Optimal hemodynamic parameters for risk stratification in acute pulmonary embolism patients

Hemodynamic assessment of patients with pulmonary embolism (PE) remains a fundamental component of early risk stratification that in turn, influences subsequent monitoring and therapeutic strategies. The current body of literature and international evidence-based clinical practice guidelines focus mainly on the use of systolic blood pressure (SBP). The accuracy of this single hemodynamic parameter, however, and its optimal values for the identification of hemodynamic instability have been recently questioned by clinicians. For example, abnormal SBP or shock index may be a late indicator of adverse outcomes, signaling a patient in whom the cascade of hemodynamic compromise is already well underway. The aim of the present article is to review the current evidence supporting the use of SBP and analyze the potential integration of other parameters to assess the hemodynamic stability, impending clinical deterioration, and guide the reperfusion treatment in patients with PE, as well as to suggest potential strategies to further investigate this issue.

Catheter Interventions for Pulmonary Embolism: Mechanical Thrombectomy Versus Thrombolytics

Pulmonary embolism is a debilitating and potentially life-threatening disease characterized by high mortality and long-term adverse outcomes. Traditional treatment options are fraught with serious bleeding risks and incomplete thrombus removal, necessitating the development of innovative treatment strategies. While new interventional approaches offer promising potential for improved outcomes with fewer serious complications, their rapid development and need for more comparative clinical evidence makes it challenging for physicians to select the optimal treatment for each patient among the many options. This review summarizes the current published clinical data for both traditional treatments and more recent interventional approaches indicated for pulmonary embolism. While published studies thus far suggest that these newer interventional devices offer safe and effective options, more data is needed to understand their impact relative to the standard of care. The studies in progress that are anticipated to provide needed evidence are reviewed here since they will be critical for helping physicians make informed treatment choices and potentially driving necessary guideline changes.

From Trendelenburg to PERTs: Evolution in the Management of Massive Pulmonary Embolism

Massive pulmonary embolism (MPE) is a serious condition affecting the pulmonary arteries and is difficult to diagnose, triage, and treat. The American College of Chest Physicians (AHA) and the European Society of Cardiology (ESC) have different classification approaches for PE, with the AHA defining three subtypes and the ESC four. Misdiagnosis is common, leading to delayed or inadequate treatment. The incidence of PE-related death rates has been increasing over the years, and mortality rates vary depending on the subtype of PE, with MPE having the highest mortality rate. The current definition of MPE originated from early surgical embolectomy cases and discussions among experts. However, this definition fails to capture patients at the point of maximal benefit because it is based on late findings of MPE. Pulmonary Embolism Response Teams (PERTs) have emerged as a fundamental shift in the management of MPE, with a focus on high-risk and MPE cases and a goal of rapidly connecting patients with appropriate therapies based on up-to-date evidence. This review highlights the challenges in diagnosing and managing MPE and emphasizes the importance of PERTs and risk stratification scores in improving outcomes for patients with PE.

Intermediate-Risk and High-Risk Pulmonary Embolism: Recognition and Management: Cardiology Clinics: Cardiac Emergencies

Pulmonary embolism (PE) is the third most common cause of cardiovascular death. Every specialty of medical practitioner will encounter PE in their patients, and should be prepared to employ contemporary strategies for diagnosis and initial risk-stratification. Treatment of PE is based on risk-stratification, with anticoagulation for all patients, and advanced modalities including systemic thrombolysis, catheter-directed therapies, and mechanical circulatory supports utilized in a manner paralleling PE severity and clinical context.

Percutaneous mechanical thrombectomy in acute pulmonary embolism: Outcomes from a safety-net hospital

BACKGROUND

Our study aims to present clinical outcomes of mechanical thrombectomy (MT) in a safety-net hospital.

METHODS

This is a retrospective study of intermediate or high-risk pulmonary embolism (PE) patients who underwent MT between October 2020 and May 2023. The primary outcome was 30-day mortality.

RESULTS

Among 61 patients (mean age 57.6 years, 47% women, 57% Black) analyzed, 12 (19.7%) were classified as high-risk PE, and 49 (80.3%) were intermediate-risk PE. Of these patients, 62.3% had Medicaid or were uninsured, 50.8% lived in a high poverty zip code. The prevalence of normotensive shock in intermediate-risk PE patients was 62%. Immediate hemodynamic improvements included 7.4 mmHg mean drop in mean pulmonary artery pressure (-21.7%, p < 0.001) and 93% had normalization of their cardiac index postprocedure. Thirty-day mortality for the entire cohort was 5% (3 patients) and 0% when restricted to the intermediate-risk group. All 3 patients who died at 30 days presented with cardiac arrest. There were no differences in short-term mortality based on race, insurance type, citizenship status, or socioeconomic status. All-cause mortality at most recent follow up was 13.1% (mean follow up time of 13.4 ± 8.5 months).

CONCLUSION

We extend the findings from prior studies that MT demonstrates a favorable safety profile with immediate improvement in hemodynamics and a low 30-day mortality in patients with acute PE, holding true even with relatively higher risk and more vulnerable population within a safety-net hospital.

Shock score for prediction of clinical outcomes among stable patients with acute symptomatic pulmonary embolism

BACKGROUND

The Composite Pulmonary Embolism Shock (CPES) score has been developed to identify normotensive patients with acute pulmonary embolism (PE) and a low cardiac index (referred to as normotensive shock). We aimed to externally assess the validity of this model for predicting a complicated course among hemodynamically stable patients with acute PE.

METHODS

Using prospectively collected data from the PROgnosTic valuE of Computed Tomography scan (PROTECT) study, we calculated the CPES score for each patient and the proportion of patients with a score > 3. We calculated the test performance characteristics to predict a complicated course (i.e., death from any cause, hemodynamic collapse, or recurrent PE) and the discriminatory power using the area under the receiver operating characteristic curve.

RESULTS

Sixty-three of the 848 (7.4 %) patients had a complicated course during the 30-day follow-up period. Of the 848 enrolled patients, the CPES score was positive (i.e., score > 3) in 78 (9.2 %). The specificity was 92.1 % (723/785), the positive predictive value was 20.5 % (16/78), and the positive likelihood ratio was 3.22 for a complicated course. The areas under the receiver operating characteristic curve for a complicated course were 0.71 (95 % confidence interval [CI], 0.65-0.78). With the higher score risk classification threshold (cutoff score > 4), the proportion of patients designated as positive was 2.1 %, and the specificity was 98.1 %. When echocardiographic right ventricle (RV) dysfunction was replaced by computed tomographic RV enlargement, the specificity was 85.4 %, the positive predictive value was 14.2 %, and the positive likelihood ratio was 2.06 for a complicated course. When analyses were restricted to the subgroup of patients with intermediate-risk PE, the specificity and the positive predictive value for a complicated course were identical to the overall cohort.

CONCLUSIONS

The CPES score has acceptable C-statistic, excellent specificity, and low positive predictive value for identification of hemodynamic deterioration in normotensive patients with PE.

CLINICALTRIALS

gov number: NCT02238639.

MACHINE LEARNING FOR PREDICTING HEMODYNAMIC DETERIORATION OF PATIENTS WITH INTERMEDIATE-RISK PULMONARY EMBOLISM IN INTENSIVE CARE UNIT

ABSTRACT

Background: Intermediate-risk pulmonary embolism (PE) patients in the intensive care unit (ICU) are at a higher risk of hemodynamic deterioration than those in the general ward. This study aimed to construct a machine learning (ML) model to accurately identify the tendency for hemodynamic deterioration in the ICU patients with intermediate-risk PE. Method: A total of 704 intermediate-risk PE patients from the MIMIC-IV database were retrospectively collected. The primary outcome was defined as hemodynamic deterioration occurring within 30 days after admission to ICU. Four ML algorithms were used to construct models on the basis of all variables from MIMIC IV database with missing values less than 20%. The extreme gradient boosting (XGBoost) model was further simplified for clinical application. The performance of the ML models was evaluated by using the receiver operating characteristic curve, calibration plots, and decision curve analysis. Predictive performance of simplified XGBoost was compared with the simplified Pulmonary Embolism Severity Index score. SHapley Additive explanation (SHAP) was performed on a simplified XGBoost model to calculate the contribution and impact of each feature on the predicted outcome and presents it visually. Results: Among the 704 intermediate-risk PE patients included in this study, 120 patients experienced hemodynamic deterioration within 30 days after admission to the ICU. Simplified XGBoost model demonstrated the best predictive performance with an area under the curve of 0.866 (95% confidence interval, 0.800-0.925), and after recalibrated by isotonic regression, the area under the curve improved to 0.885 (95% confidence interval, 0.822-0.935). Based on the simplified XGBoost model, a web app was developed to identify the tendency for hemodynamic deterioration in ICU patients with intermediate-risk PE. Conclusion: A simplified XGBoost model can accurately predict the occurrence of hemodynamic deterioration for intermediate-risk PE patients in the ICU, assisting clinical workers in providing more personalized management for PE patients in the ICU.

Randomized controlled trial of mechanical thrombectomy vs catheter-directed thrombolysis for acute hemodynamically stable pulmonary embolism: Rationale and design of the PEERLESS study

BACKGROUND

The identification of hemodynamically stable pulmonary embolism (PE) patients who may benefit from advanced treatment beyond anticoagulation is unclear. However, when intervention is deemed necessary by the PE patient's care team, data to select the most advantageous interventional treatment option are lacking. Limiting factors include major bleeding risks with systemic and locally delivered thrombolytics and the overall lack of randomized controlled trial (RCT) data for interventional treatment strategies. Considering the expansion of the pulmonary embolism response team (PERT) model, corresponding rise in interventional treatment, and number of thrombolytic and nonthrombolytic catheter-directed devices coming to market, robust evidence is needed to identify the safest and most effective interventional option for patients.

METHODS

The PEERLESS study (ClinicalTrials.gov identifier: NCT05111613) is a currently enrolling multinational RCT comparing large-bore mechanical thrombectomy (MT) with the FlowTriever System (Inari Medical, Irvine, CA) vs catheter-directed thrombolysis (CDT). A total of 550 hemodynamically stable PE patients with right ventricular (RV) dysfunction and additional clinical risk factors will undergo 1:1 randomization. Up to 150 additional patients with absolute thrombolytic contraindications may be enrolled into a nonrandomized MT cohort for separate analysis. The primary end point will be assessed at hospital discharge or 7 days post procedure, whichever is sooner, and is a composite of the following clinical outcomes constructed as a hierarchal win ratio: (1) all-cause mortality, (2) intracranial hemorrhage, (3) major bleeding, (4) clinical deterioration and/or escalation to bailout, and (5) intensive care unit admission and length of stay. The first 4 components of the win ratio will be adjudicated by a Clinical Events Committee, and all components will be assessed individually as secondary end points. Other key secondary end points include all-cause mortality and readmission within 30 days of procedure and device- and drug-related serious adverse events through the 30-day visit.

IMPLICATIONS

PEERLESS is the first RCT to compare 2 different interventional treatment strategies for hemodynamically stable PE and results will inform strategy selection after the physician or PERT determines advanced therapy is warranted.

Large-bore suction thrombectomy for sub-massive pulmonary embolism during second trimester of pregnancy: a case report

Background

Pregnancy-associated pulmonary embolism (PAPE) remains a significant cause of maternal mortality. Anticoagulation remains the mainstay of therapy for most pulmonary embolism (PE)-related pregnancies. However, in patients with haemodynamic compromise or those refractory to anticoagulation, management is challenging. Systemic thrombolysis is associated with a substantial risk of maternal bleeding and fetal loss. In non-pregnant PE patients, large bore catheter-directed suction thrombectomy is a proven and important technique to manage intermediate or high-risk PE, allowing for normalization of pulmonary pressures, avoidance of haemodynamic deterioration, without the need for thrombolytics, major surgery, significant blood loss, or prolonged hospitalization.

Case summary

A primigravid patient in her second trimester of pregnancy, initially diagnosed with a deep vein thrombosis refractory to heparin, presents with near-syncope due to sub-massive pulmonary embolism. The various management options including thrombolysis and surgical embolectomy etc. were discussed in detail by a multi-disciplinary PE team. She underwent large bore suction thrombectomy with complete thrombi removal, normalization of right heart strain, without the need for thrombolytics or surgery, minimal blood loss and was discharged after a short length of stay. She gave birth at term to a healthy infant.

Conclusion

Suction thrombectomy is an important consideration for physicians managing high-risk PAPE and is likely to be associated with much a lower risk of maternal and fetal mortality compared to thrombolysis or surgery.