Cardiothoracic CT: one-stop-shop procedure? Impact on the management of acute pulmonary embolism

Cardiovascular collapse during mechanical thrombectomy for acute pulmonary embolism and the role of extracorporeal membrane oxygenation in patient rescue

BACKGROUND

Driven by the ability to avoid thrombolytics and provide a one stop procedure with immediate hemodynamic improvement, there has been a dramatic increase in the use of mechanical thrombectomy (MT) devices for the treatment of intermediate-to-high risk pulmonary embolism (PE). This study investigated the incidence and outcomes of cardiovascular collapse during MT procedures and demonstrates the role of extracorporeal membrane oxygenation (ECMO) in salvaging patients.

METHODS

This single-center retrospective review included patients with PE undergoing MT with the FlowTriever device between 2017 and 2022. Patients presenting periprocedural cardiac arrest were identified and their perioperative characteristics and postoperative outcomes were evaluated.

RESULTS

A total of 151 patients with a mean age of 64 ± 14 years who presented with intermediate-to-high risk PE received LBAT procedures during the study period. The simplified PE severity score was ≥1 in 83% of cases and the average RV/LV ratio was 1.6 ± 0.5, with and elevated troponin in 84%. Technical success was achieved in 98.7% and a significant decrease in pulmonary artery systolic pressure (PASP) was observed (37 mm Hg vs 56 mm Hg; P < .0001). Intraoperative cardiac arrest occurred in nine patients (6%). These patients were more likely to present PASP of ≥70 mm Hg (84% vs 14%; P < .001), were more hypotensive upon admission (systolic of 94 ± 14 mm Hg vs 119 ± 23 mm Hg; P = .004), presented lower oxygen saturation levels (87 ± 6% vs 92 ± 6%; P = .023) and were more likely to present with a history of recent surgery (67% vs 18%; P = .004). Four patients were rescued successfully with ECMO and their residual PE was subsequently removed before discharge by surgical embolectomy in two of the four cases and repeat MT in the other two. All five patients (3%) who did not receive ECMO support expired intraoperatively. The overall 30-day mortality was 8% with no death occurring in patients who were salvaged with ECMO.

CONCLUSIONS

Large-bore aspiration thrombectomy for acute PE is associated with favorable technical outcomes, but the concern for acute cardiac decompensation is non-negligible in patients presenting with high-risk features and a PASP of ≥70 mm Hg. ECMO can help to salvage some of these patients and should be considered in the treatment algorithms of patients deemed at high risk.

Classification and Stratification of Pulmonary Embolisms

Pulmonary embolism remains a leading cause of cardiovascular mortality. Presentation and outcomes are variable among patients and require rapid risk stratification for assessment and prognosis, as well as selection of appropriate treatment. Over the past several decades, several different models and parameters have become available to assess risk and classify pulmonary embolism into different risk categories. Some patients may be candidates for early discharge or complete outpatient treatment, while some may require invasive diagnostics and intensive monitoring. In this review, we summarize contemporary guidelines and methods for classification and risk stratification in an effort to provide tools for physicians to use in their management of patients with acute pulmonary embolisms.

Current interventional therapies in acute pulmonary embolism

Pulmonary embolism (PE) is the third leading cause of cardiovascular mortality. The management of PE is currently evolving given the development of new technologies and team-based approaches. This document will focus on risk stratification of PEs, review of the current interventional therapies, the role of clinical endpoints to assess the effectiveness of different interventional therapies, and the role for mechanical circulatory support in the complex management of this disease.

Endovascular therapies for pulmonary embolism

Purpose

The aim of this article is to define the place of new endovascular methods for the management of pulmonary embolisms (PE), on the basis of a multidisciplinary consensus.

Method and results

Briefly, from the recent literature, for high-risk PE presenting with shock or cardiac arrest, systemic thrombolysis or embolectomy is recommended, while for lowrisk PE, anticoagulation alone is proposed. Normo-tense patients with PE but with biological or imaging signs of right heart dysfunction constitute a group known as “at intermediate risk” for which the therapeutic strategy remains controversial. In fact, some patients may require more aggressive treatment in addition to the anticoagulant treatment, because approximately 10% will decompensate hemodynamically with a high risk of mortality. Systemic thrombolysis may be an option, but with hemorrhagic risks, particularly intra cranial. Various hybrid pharmacomechanical approaches are proposed to maintain the benefits of thrombolysis while reducing its risks, but the overall clinical experience of these different techniques remains limited. Patients with high intermediate and high risk pulmonary embolism should be managed by a multidisciplinary team combining the skills of cardiologists, resuscitators, pneumologists, interventional radiologists and cardiac surgeons. Such a team can determine which intervention – thrombolysis alone or assisted, percutaneous mechanical fragmentation of the thrombus or surgical embolectomy – is best suited to a particular patient.

Conclusions

This consensus document define the place of endovascular thrombectomy based on an appropriate risk stratification of PE.

Decreased pulmonary artery distensibility as a marker for severity in acute pulmonary embolism patients undergoing ECG-gated CTPA

To investigate the characteristics of pulmonary artery distensibility (PAD) in patients with acute pulmonary embolism (APE) and to assess whether a relationship exists between PAD and the disease severity. Clinical and radiological data of 30 APE patients who underwent retrospective electrocardiogram (ECG)-gated computed tomography pulmonary angiography (CTPA) with a definite diagnosis of APE were retrospectively reviewed in the present study, including 15 subjects in severe (SPE) group and 15 subjects in non-severe (NSPE) group. PAD and cardiac function parameters were compared between the two groups, their relationships were investigated, and receiver operating characteristic (ROC) curves were used to determine the sensitivity and specificity of the above parameters for the diagnosis of APE severity. The PAD decreased in the following order: NSPE group (6.065 ± 2.114) × 10^-3 (%/mmHg), and SPE group (4.334 ± 1.777) × 10^-3 (%/mmHg) (P < 0.05). All the cardiac function parameters except RA/LAdiameter showed statistically significant different values between the two groups (P < 0.05). As APE severity increased, the cardiac morphological measurements of RV/LVdiameter, RV/LVarea, RVEDV/LVEDV and RVESV/LVESV increased. There was a weak to moderate negative correlation between PAD and PAmax, PAmin, PA/AAmin, PA/AAmax, RV/LVdiameter, RV/LVarea (r = -0.393 to -0.625), that is, PAD was inversely correlated with cardiac function parameters. There was a moderate negative correlation between PAD and hemoptysis(r = -0.672). The area under the ROC curve (AUC) of PAD was 0.724, the critical value was 4.137 × 10^-3  mm/Hg, and the sensitivity and specificity were 60.0% and 93.3%, respectively. PAmin showed the strongest discriminatory power to identify high-risk patients (AUC = 0.827), with the highest sensitivity of 100%, which was also achieved by RA/LAarea. The PAD obtained by retrospective ECG-gated CTPA could be an indicator to be used in the evaluation of the presence and severity of APE.

CTPA pulmonary artery distensibility in assessment of severity of acute pulmonary embolism and right ventricular function

To investigate the characteristics of pulmonary artery distensibility (PAD) in patients with acute pulmonary embolism (APE) and to assess the correlation of PAD with APE severity and right ventricular function. A total of 33 patients who underwent retrospective electrocardiogram (ECG)-gated computed tomography pulmonary angiography (CTPA) with a definite diagnosis of APE were included in the study. According to APE severity, the patients were divided into severe (SPE) and non-severe (NSPE) groups. Data from a control group without APE matching the basic demographics of the APE patients were collected. Pulmonary artery distensibility (PAD) and right ventricular function parameters were compared among the 3 groups, their relationships were investigated, and receiver operating characteristic (ROC) curves were used to determine the sensitivity and specificity of the above parameters for the diagnosis of APE severity. The PAD values of the control, NSPE, and SPE groups were (7.877 ± 2.637) × 10-3 mm/Hg, (6.050 ± 2.011) × 10-3 mm/Hg, (4.321 ± 1.717) × 10-3 mm/Hg, respectively (P < .01). There were statistically significant differences in right ventricular function parameters among the 3 groups (P < .05). The correlation analysis between PAD and right ventricular function parameters showed a weak negative correlation (r = -0.281--0.392). The area under the ROC curve of PAD was 0.743, the critical value was 4.200, and the sensitivity and specificity were 62.5% and 94.1%, respectively. The PAD obtained by retrospective ECG-gated CTPA could accurately evaluate APE severity and right ventricular function. As the severity of APE increases, PAD decreases, which is helpful to identify patients at high risk of APE.

Interventional Therapies for Acute Pulmonary Embolism: Current Status and Principles for the Development of Novel Evidence: A Scientific Statement From the American Heart Association

Pulmonary embolism (PE) represents the third leading cause of cardiovascular mortality. The technological landscape for management of acute intermediate- and high-risk PE is rapidly evolving. Two interventional devices using pharmacomechanical means to recanalize the pulmonary arteries have recently been cleared by the US Food and Drug Administration for marketing, and several others are in various stages of development. The purpose of this document is to clarify the current state of endovascular interventional therapy for acute PE and to provide considerations for evidence development for new devices that will define which patients with PE would derive the greatest net benefit from their use in various clinical settings. First, definitions and limitations of commonly used risk stratification tools for PE are reviewed. An adjudication of risks and benefits of available interventional therapies for PE follows. Next, considerations for optimal future evidence development in this field are presented in the context of the current US regulatory framework. Finally, the document concludes with a discussion of the pros and cons of the rapidly expanding PE response team model of care delivery.

The feasibility of 1-stop examination of coronary CT angiography and abdominal enhanced CT

This study aims to evaluate the feasibility of performing coronary computed tomography angiography (CCTA) and abdominal enhanced computed tomography (CT) with 1-time injection of the agent.CCTA images (right coronary artery, left anterior descending coronary artery, and left circumflex coronary artery) were collected from 20 patients who completed a 1-stop combined examination of CCTA and abdominal enhanced CT (group A), 20 patients who only underwent abdominal enhanced CT (group B1), and 20 patients who only underwent CCTA (group B2). These images were interpreted using the 5-point Likert scale system by 2 experienced radiologists, and abdominal images were observed for breathing artifact. CT value, signal-to-noise ratio (SNR), and CTDI were recorded and compare among the 3 groups.The difference in image quality of the coronary and total volume of the contrast agent between group A and group B1 was not statistical significant (P > .05). The CT value and SNR in group B1 (CCTA) (CT: 394.65 ± 59.23, SNR: 17.38 ± 4.13) increased, compare with Group A (CT: 360.35 ± 34.16, SNR: 13.76 ± 1.84, P = .03, .01), while CTDI was undifferentiated between group A (17.14 ± 6.20) and group B1 (18.38 ± 9.79) (P = .64). The difference in CT value and SNR at the arterial phase and CT value at the venous phase between group A (abdomen) and group B2 were statistically significant, the CTDI in group A (9.09 ± 1.05) increased, compared with group B2 (8.23 ± 1.33) (P = .03), and SNR at the venous phase in group B2 (12.50 ± 2.43) increased, compared with group A (10.89 ± 2.03) (P = .03).Revolution CT can capture full images and very rapidly switch to the scan mode, enabling a 1-stop axial CCTA and enhanced helical abdominal scan. The 1-stop combined scan resulted in a satisfactory image quality, which reduced the contrast agent dose and simplified the workflow.The 1-stop combined scan allows for the high success rate of the examination, reduces the number of examinations, and decreases the dose and risk of injection of the contrast agent. This would be helpful for patients to obtain diagnostic images in time.

Interventional Treatment of Pulmonary Embolism

Pulmonary embolism (PE) is a serious and prevalent cause of vascular disease. Nevertheless, optimal treatment for many phenotypes of PE remains uncertain. Treating PE requires appropriate risk stratification as a first step. For the highest-risk PE, presenting as shock or arrest, emergent systemic thrombolysis or embolectomy is reasonable, while for low-risk PE, anticoagulation alone is often chosen. Normotensive patients with PE but with indicia of right heart dysfunction (by biomarkers or imaging) constitute an intermediate-risk group for whom there is controversy on therapeutic strategy. Some intermediate-risk patients with PE may require urgent stabilization, and ≈10% will decompensate hemodynamically and suffer high mortality, though identifying these specific patients remains challenging. Systemic thrombolysis is a consideration, but its risks of major and intracranial hemorrhages rival overall harms from intermediate PE. Multiple hybrid pharmacomechanical approaches have been devised to capture the benefits of thrombolysis while reducing its risks, but there is limited aggregate clinical experience with such novel interventional strategies. One method to counteract uncertainty and generate a consensus multidisciplinary prognostic and therapeutic plan is through a Pulmonary Embolism Response Team, which combines expertise from interventional cardiology, interventional radiology, cardiac surgery, cardiac imaging, and critical care. Such a team can help determine which intervention-catheter-directed fibrinolysis, ultrasound-assisted thrombolysis, percutaneous mechanical thrombus fragmentation, or percutaneous or surgical embolectomy-is best suited to a particular patient. This article reviews these various modalities and the background for each.

Assessment of Right Ventricular Strain by Computed Tomography Versus Echocardiography in Acute Pulmonary Embolism

BACKGROUND

Right ventricular strain (RVS) identifies patients at risk of hemodynamic deterioration from pulmonary embolism (PE). Our hypothesis was that chest computed tomography (CT) can provide information about RVS analogous to transthoracic echocardiography (TTE) and that RVS on CT is associated with adverse outcomes after PE.

METHODS

Consecutive emergency department patients with acute PE were prospectively enrolled and clinical, biomarker, and imaging data were recorded. CTs were overread by two radiologists. We compared diagnoses of RVS on CT (defined as right ventricle:left ventricle ratio ≥ 0.9 or interventricular septal bowing) to echocardiography (defined as right ventricular hypokinesis, right ventricular dilatation, or interventricular septal bowing). We calculated the test characteristics (with 95% confidence interval) of CT and TTE for a composite outcome of severe clinical deterioration, thrombolysis/thrombectomy, or death within 5 days.

RESULTS

A total of 298 patients were enrolled; 274 had CT and 118 had formal TTE. Of the 104 patients who had both CT and TTE, the mean (±SD) age was 58 (±17) years; 50 (48%) were female and 88 (85%) were Caucasian. Forty-two (40%) had RVS by TTE and 75 (72%) had RVS by CT. CT and TTE agreed on the presence or absence of RVS in 61 (59%) cases (κ = 0.24). Using TTE as criterion standard, the test characteristics of CT for RVS were as follows: sensitivity = 88%, specificity = 39%, positive predictive value = 49%, and negative predictive value = 83%. Fourteen (13%) patients experienced severe clinical deterioration or required hospital-based intervention within 5 days. This occurred in 30% of patients with RVS on both TTE and CT, 20% of patients with RVS on TTE alone, 3% of patients with RVS on CT alone, and 4% of patients without RVS on either modality.

CONCLUSIONS

In acute PE, CT is highly sensitive but only moderately specific for RVS compared to TTE. RVS on both CT and TTE predicts more events than either modality alone. TTE confers additional positive prognostic value compared to CT in predicting post-PE clinical deterioration.

Computed tomography angiography with pulmonary artery thrombus burden and right-to-left ventricular diameter ratio after pulmonary embolism

Purpose

Computed tomography angiography is used for quantifying the significance of pulmonary embolism, but its reliability has not been well defined.

Methods

The study cohort comprised 10 patients randomly selected from a 150-patient prospective trial of ultrasound-facilitated fibrinolysis for acute pulmonary embolism. Four reviewers independently evaluated the right-to-left ventricular diameter ratios using the standard multiplanar reformatted technique and a simplified (axial) method, and thrombus burden with the standard modified Miller score and a new, refined Miller scoring system.

Results

The intraclass correlation coefficient for intra-observer variability was .949 and .970 for the multiplanar reformatted and axial methods for estimating right-to-left ventricular ratios, respectively. Inter-observer agreement was high and similar for the two methods, with intraclass correlation coefficient of .969 and .976. The modified Miller score had good intra-observer agreement (intraclass correlation coefficient .820) and was similar to the refined Miller method (intraclass correlation coefficient .883) for estimating thrombus burden. Inter-observer agreement was also comparable between the techniques, with intraclass correlation coefficient of .829 and .914 for the modified Miller and refined Miller methods.

Conclusions

The reliability of computed tomography angiography for pulmonary embolism was excellent for the axial and multiplanar reformatted methods for quantifying the right-to-left ventricular ratio and for the modified Miller and refined Miller scores for quantifying of pulmonary artery thrombus burden.