Computed tomographic pulmonary angiography and prognostic significance in patients with acute pulmonary embolism

CT signs of right ventricular dysfunction: prognostic role in acute pulmonary embolism

OBJECTIVES

The purpose of this study was to compare the prognostic role of various computed tomography (CT) signs of right ventricular (RV) dysfunction, including 3-dimensional ventricular volume measurements, to predict adverse outcomes in patients with acute pulmonary embolism (PE).

BACKGROUND

Three-dimensional ventricular volume measurements based on chest CT have become feasible for routine clinical application; however, their prognostic role in patients with acute PE has not been assessed.

METHODS

We evaluated 260 patients with acute PE for the following CT signs of RV dysfunction obtained on routine chest CT: abnormal position of the interventricular septum, inferior vena cava contrast reflux, right ventricle diameter (RVD) to left ventricle diameter (LVD) ratio on axial sections and 4-chamber (4-CH) views, and 3-dimensional right ventricle volume (RVV) to left ventricle volume (LVV) ratio. Comorbidities and fatal and nonfatal adverse outcomes according to the MAPPET-3 (Management Strategies and Prognosis in Pulmonary Embolism Trial-3) criteria within 30 days were recorded.

RESULTS

Fifty-seven patients (21.9%) had adverse outcomes, including 20 patients (7.7%) who died within 30 days. An RVD(axial)/LVD(axial) ratio >1.0 was not predictive for adverse outcomes. On multivariate analysis (adjusting for comorbidities), abnormal position of the interventricular septum (hazard ratio [HR]: 2.07; p = 0.007), inferior vena cava contrast reflux (HR: 2.57; p = 0.001), RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 2.51; p = 0.009), and RVV/LVV ratio >1.2 (HR: 4.04; p < 0.001) were predictive of adverse outcomes, whereas RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 3.68; p = 0.039) and RVV/LVV ratio >1.2 (HR: 6.49; p = 0.005) were predictive of 30-day death.

CONCLUSIONS

Three-dimensional ventricular volume measurement on chest CT is a predictor of early death in patients with acute PE, independent of clinical risk factors and comorbidities. Abnormal position of the interventricular septum, inferior vena cava contrast reflux, and RVD(4-CH)/LVD(4-CH) ratio are predictive of adverse outcomes, whereas RVD(axial)/LVD(axial) ratio >1.0 is not.

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

In the treatment of pulmonary embolism (PE) two groups of patients are traditionally identified, namely the hemodynamically stable and instable groups. However, in the large group of normotensive patients with PE, there seems to be a subgroup of patients with an increased risk of an adverse outcome, which might benefit from more aggressive therapy than the current standard therapy with anticoagulants. Risk stratification is a commonly used method to define subgroups of patients with either a high or low risk of an adverse outcome. In this review the clinical parameters and biomarkers of myocardial injury and right ventricular dysfunction (RVD) that have been suggested to play an important role in the risk stratification of PE are described first. Secondly, the use of more direct imaging techniques like echocardiography and CT in the assessment of RVD are discussed, followed by a brief outline of new imaging techniques. Finally, two risk stratification models are proposed, combining the markers of RVD with cardiac biomarkers of ischemia to define whether patients should be admitted to the intensive care unit (ICU) and/or be given thrombolysis, admitted to the medical ward, or be safely treated at home with anticoagulant therapy.

[Update on diagnosis and treatment of high-risk pulmonary embolism]

INTRODUCTION

High-risk pulmonary embolism (PE) is associated with a significant early mortality, approaching 25%, and is defined by the presence of cardiogenic shock.

STATE OF THE ART

The high early mortality rate for patients with shock requires a rapid diagnostic approach with bedside tests. Right ventricular dilatation assessed by echocardiography in patients with a high clinical probability for PE confirms the diagnosis without the need for additional testing. Spiral CT pulmonary angiography remains the first line investigation for patients without shock. Anticoagulant treatment should be started as soon as pulmonary embolism is suspected. Fibrinolytic therapy is recommended for patients with high-risk pulmonary embolism. The prognostic value of cardiac biomarkers, such as B natriuretic peptide, troponins and right ventricular dilatation for early mortality has been demonstrated. These markers permit the identification of an intermediate risk group of patients with normotensive pulmonary embolism and prognostic scores have been developed.

PERSPECTIVES

It remains to be established whether fibrinolysis can have a clinical benefit or reduce mortality in patients with intermediate risk pulmonary embolism. A large randomised placebo-controlled study is currently under way to answer this question. Further studies will more clearly define the role of various predictive rules to identify patients requiring hospital care or those who should be considered for outpatient management.

Subjective assessment of right ventricle enlargement from computed tomography pulmonary angiography images

To retrospectively evaluate prognostic accuracy of subjective assessment of right ventricle (RV) enlargement on CT pulmonary angiography (CTPA) images in comparison with objective measures of RV enlargement in patients with acute pulmonary embolism (PE). For 200 consecutive patients with acute PE, two readers blinded to patient outcomes subjectively determined whether the maximum RV diameter was greater than that of the left ventricle (LV) using axial CTPA images. For the objective measurements, RV/LV diameter ratios were calculated using axial images and 4-chamber reformatted images. For all assessments, sensitivities and specificities for predicting PE-related death within 30-days and a composite outcome including PE-related death or the need for intensive therapies were compared. The agreement between two readers was 91.5% (kappa = 0.83) and all other assessments had pair-wise agreement over 75% (kappa = 0.53-0.72). There was no significant difference in sensitivity between the subjective and objective methods for predicting both outcomes. The specificity for subjective RV enlargement (55.4-67.7%) was significantly higher than objective measures (45.8-53.1%), except for the 4-chamber views where, for one reader, the specificity of the subjective evaluation was higher but did not reach statistical significance. Complex measurements of RV/LV diameter ratios may not be needed to maximize the prognostic value from CTPA. The radiologist who interprets the CTPA images should report RV enlargement when the RV diameter subjectively appears larger than the LV.

Electrocardiogram score predicts severity of pulmonary embolism in hemodynamically stable patients

BACKGROUND

Risk stratification of patients with pulmonary embolism (PE) is essential to guide therapy. The presence of right ventricle dysfunction (RVD) and the anatomic extent of PE have been suggested to predict clinical course. The aim of this study was to assess the ability of an electrocardiogram (ECG) scoring system to predict RVD or the clot load score in normotensive patients with PE.

METHODS

Consecutive patients presenting to the emergency room with PE and hemodynamic stability were prospectively included. ECG, echocardiography and computed tomography pulmonary angiography (CTPA) were performed on all patients.

RESULTS

A total of 103 patients were studied. ECG score correlated significantly with the clot load score (r = 0.41, 95% confidence interval [CI]: 0.22-0.57, P < 0.001), systolic pulmonary artery pressure (r= 0.31, 95% CI: 0.09-0.49, P = 0.006), pulmonary artery diameter (r = 0.28, 95% CI: 0.07-0.47, P = 0.011) and right ventricle to left ventricle ratio, both measured with echocardiography (r = 0.42, 95% CI: 0.22-0.57, P < 0.001) and with CTPA (r= 0.36, 95% CI: 0.13-0.56, P = 0.004). Area under the receiver operating characteristic curve for detecting RVD was 0.82 (95% CI: 0.72-0.89). Interobserver agreement regarding ECG score was substantial (κ = 0.80).

CONCLUSIONS

ECG score correlates with the severity of PE in hemodynamically stable patients. It is potentially useful for risk-stratification strategies in this setting.

Accuracy and reproducibility of blood clot burden quantification with pulmonary CT angiography

OBJECTIVE

The purpose of our study was to assess the accuracy and reproducibility of clot burden quantification with pulmonary CT angiography (CTA).

MATERIALS AND METHODS

A semiautomated program was developed for segmentation and volumetric quantification of pulmonary embolus with pulmonary CTA. The accuracy of this measurement method was assessed using two pulmonary embolus phantoms. Reproducibility of the measurement method was assessed using clinical pulmonary CTA in 30 patients (16 women, 14 men; mean age, 62 years) with pulmonary embolism (PE). Two observers segmented and measured the volume of blood clot from pulmonary CTA images twice at two separate sessions. Accuracy was evaluated by the relative volume measurement error. Intra- and interobserver reliability were evaluated using intraclass correlation coefficient (ICC); agreement between measurements within and between the two observers was assessed using Bland-Altman analysis.

RESULTS

Mean relative measurement error from the two phantoms was less than 1% for both observers. A total of 60 emboli were measured from the 30 patients. The intraobserver ICC was 0.990 for observer 1 and 0.999 for observer 2; interobserver ICC was 0.994 for session 1 and 0.989 for session 2. ICC for all four clot measurements was 0.988. Mean volume measurement difference for intraobserver agreement was 0.9% for observer 1 and 0.3% for observer 2, and interobserver agreement was -5.1% for session 1 and -5.8% for session 2.

CONCLUSION

Blood clot burden can be quantified with a high degree of accuracy and reproducibility from pulmonary CTA images using a semiautomated segmentation method.

Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association

Venous thromboembolism (VTE) is responsible for the hospitalization of >250 000 Americans annually and represents a significant risk for morbidity and mortality. Despite the publication of evidence-based clinical practice guidelines to aid in the management of VTE in its acute and chronic forms, the clinician is frequently confronted with manifestations of VTE for which data are sparse and optimal management is unclear. In particular, the optimal use of advanced therapies for acute VTE, including thrombolysis and catheter-based therapies, remains uncertain. This report addresses the management of massive and submassive pulmonary embolism (PE), iliofemoral deep vein thrombosis (IFDVT),and chronic thromboembolic pulmonary hypertension (CTEPH). The goal is to provide practical advice to enable the busy clinician to optimize the management of patients with these severe manifestations of VTE. Although this document makes recommendations for management, optimal medical decisions must incorporate other factors, including patient wishes, quality of life, and life expectancy based on age and comorbidities. The appropriateness of these recommendations for a specific patient may vary depending on these factors and will be best judged by the bedside clinician.

Are biomarkers additive to pulmonary embolism severity index for severity assessment in normotensive patients with acute pulmonary embolism?

BACKGROUND

Biomarkers and clinical prediction rules have been proposed for severity assessment in acute pulmonary embolism (PE).

AIM

The aim of this study was to compare biomarkers with the PE Severity Index (PESI), a validated scoring system for predicting 30-day mortality and to determine if addition of biomarkers to PESI would improve its predictive accuracy.

STUDY DESIGN AND METHODS

We conducted a retrospective analysis of normotensive patients admitted with PE confirmed by CT pulmonary angiogram, to three teaching hospitals between January 2005 and July 2007. All patients had admission levels of D-dimer and Troponin I and calculation of PESI score on admission. The outcome of interest was 30-day mortality.

RESULTS

There were 411 patients included in the study. Patients who died had higher levels of D-dimer (median 2947 ng/ml vs. 1464 ng/ml; P=0.02), Troponin (57.1% positive vs. 13.8%; P<0.0001) and higher PESI scores [median 109 vs. 83; P<0.0001], compared to survivors. PESI had superior accuracy for predicting 30-day mortality than a combination of Troponin and D-dimer (AUC 0.80 vs. 0.75). Addition of Troponin to PESI further improved the predictive value of the score (AUC 0.85 for vs. AUC 0.80 for PESI alone).

CONCLUSION

Biomarkers and clinical prediction rules predict outcome in acute PE. Addition of troponin to the PESI scoring system improves the predictive value for 30-day mortality and may be useful for guiding initial management of patients presenting with PE.

Association between the Pulmonary Embolism Severity Index (PESI) and short-term clinical deterioration

The Pulmonary Embolism Severity Index (PESI) has been shown to predict 30 and 90 day mortality after PE. However, whether the PESI predicts patients who will be free of clinically adverse outcomes during a typical hospitalisation is not known. Retrospective analysis of Emergency Department patients with PE from May 2006 to April 2008. We compiled demographics, data to calculate the PESI and a composite outcome. Patients were considered to have a negative PESI if they were in category I or II (≤85 points). Patients were considered to have the composite outcome if, within five days of diagnosis, they: A) had recurrent PE; B) developed a new cardiac dysrhythmia; C) required advanced cardiac life support; D) required respiratory support; E) required vasopressors; F) received thrombolysis; G) had major bleeding; H) returned to the ED; I) died. We enrolled 245 patients with PE. Of these, 115 (47%) were male, 204 (83%) were white. The mean age was 57 ± 17 years. The PESI identified 109 (44%) as low risk and 136 (56%) as high risk. Sixty-one (26%) patients had the outcome, of whom nine (14%) were characterised as low risk by the PESI. Test characteristics were: sensitivity 86% (95% confidence interval [CI]: 75%-93%), specificity 55% (95% CI: 47%-62%), NPV 63% (95% CI: 55%-70%), PPV 40% (95% CI: 31%-49%), LR(+) 1.9 (95% CI: 1.57-2.30) and LR(-) 0.26 (95% CI: 0.14-0.48). Of the patients who had an adverse clinical event or required a hospital-based intervention within the first five days after PE diagnosis, 14% were categorised by the PESI as safe for discharge [corrected] .

Predictors of clinical outcome in acute pulmonary embolism: Correlation of CT pulmonary angiography with clinical, echocardiography and laboratory findings

RATIONALE AND OBJECTIVES

The aims of this study were to retrospectively evaluate whether computed tomographic (CT) parameters were predictors of in-hospital mortality within 30 days of CT imaging and to compare CT parameters with clinical, echocardiographic, and laboratory findings in patients with acute pulmonary embolism (PE).

MATERIALS AND METHODS

A total of 122 patients (61 women, 61 men; mean age, 64 ± 15 years) with CT scans positive for acute PE were reviewed. Two independent readers who were blinded to clinical outcomes scored pulmonary artery obstructions, evaluated cardiovascular measurements, and assessed qualitative findings. Reports of echocardiographic, clinical, and laboratory findings and clinical outcome were reviewed. Results were correlated with patient outcomes using Wilcoxon's rank-sum, χ², and Student's t tests. Logistic regression analyses were performed to determine predictors of patient outcomes.

RESULTS

Thirteen patients (11%) died related to PE within 30 days in the hospital. There were significant differences in the ratio of arterial partial pressure of oxygen to inspired fraction of oxygen and in heart rate between survivors and nonsurvivors (P < .05). No CT or echocardiographic predictor was associated with mortality.

CONCLUSIONS

The ratio of arterial partial pressure of oxygen to inspired fraction of oxygen and heart rate strongly predicted mortality due to PE. Neither CT pulmonary angiographic variables nor echocardiography could successfully predict in-hospital mortality in patients with acute PE.

Application of a new pulmonary artery obstruction score in the prognostic evaluation of acute pulmonary embolism: comparison with clinical and haemodynamic parameters

PURPOSE

Evaluation of computed tomography (CT) pulmonary angiography parameters revealing pulmonary embolism (PE) severity with particular attention to pulmonary obstruction indexes. Comparison with clinical and hemodynamic data and determination of predictive role in the development of chronic pulmonary heart disease.

MATERIALS AND METHODS

This retrospective study analyzes 45 not consecutive patients from November 2007 to December 2008 with CT angiography diagnosis of acute PE. Included in the study are patients at the first documented episode of acute PE, with 6 month follow-up. Patients with severe pre-existent cardiopulmonary pathology or neoplastic diseases were excluded from the study. CT angiography evaluated right ventricular (RV)/left ventricular (LV) ratio, obstruction index according to Qanadli and Total Clot Burden (Ghanima score). PE indexes were compared with Troponin I measurement and echocardiography result; at last hospitalization and intensive care time were reported.

RESULTS

A significant association was found between Ghanima and Qanadli score: the two indexes are equivalent in quantification of pulmonary arterial obstruction (p<0.001). Among others CT parameters, the new Ghanima score evidenced the best accuracy to detect patients evolving to chronic pulmonary heart disease (76%). This value is higher than that of echocardiography (71%). Troponins showed highest accuracy (82%).

CONCLUSIONS

Ghanima score can be used in emergency CT angiography diagnosis as prognostic marker for a quickly risk stratification of pulmonary heart disease or death in patients with acute PE. This approach allows to obtain, with just one test, both the diagnosis and a rather accurate acute PE risk stratification.

Risk stratification of normotensive patients with acute symptomatic pulmonary embolism

Treatment guidelines recommend strong consideration of thrombolysis in patients with acute symptomatic pulmonary embolism (PE) that present with arterial hypotension or shock because of the high risk of death in this setting. For haemodynamically stable patients with PE, the categorization of risk for subgroups may assist with decision-making regarding PE therapy. Clinical models [e.g. Pulmonary Embolism Severity Index (PESI)] may accurately identify those at low risk of overall death in the first 3 months after the diagnosis of PE, and such patients might benefit from an abbreviated hospital stay or outpatient therapy. Though some evidence suggests that a subset of high-risk normotensive patients with PE may have a reasonable risk to benefit ratio for thrombolytic therapy, single markers of right ventricular dysfunction (e.g. echocardiography, spiral computed tomography, or brain natriuretic peptide testing) and myocardial injury (e.g. cardiac troponin T or I testing) have an insufficient positive predictive value for PE-specific mortality to drive decision-making toward such therapy. Recommendations for outpatient treatment or thrombolytic therapy for patients with PE necessitate further development of prognostic models and conduct of clinical trials that assess various treatment strategies.

Computed tomographic pulmonary angiography in the assessment of severity of chronic thromboembolic pulmonary hypertension and right ventricular dysfunction

PURPOSE

The aim was to investigate the role of computed tomographic pulmonary angiography (CTPA) in the assessment of severity and right ventricular function in chronic thromboembolic pulmonary hypertension (CTEPH).

MATERIALS AND METHODS

Clinical and radiological data of 56 patients with CTEPH January 2006-October 2009 were retrospectively reviewed in the present study. All patients received CTPA with a 64-row CT using the retrospective ECG-Gated mode before digital subtraction pulmonary angiography and right-heart catheterization. CTPA findings including Right Ventricular diameter (RVd) and left ventricular diameter (LVd) were measured at the end diastole. CT Pulmonary Artery Obstruction Indexes including Qanadli Index and Mastora Index were used in the assessment of severity of pulmonary arterial obstruction. Hemodynamic parameters and pulmonary hypertension classification were evaluated by right-heart catheterization in all patients. Right ventricular function was measured with echocardiography in 49 patients.

RESULTS

Qanadli Index and Mastora Index respectively were (37.93±14.74)% and (30.92±16.91)%, which showed a significant difference (Z=-5.983, P=0.000) and a good correlation (r=0.881, P=0.000). Neither Qanadli nor Mastora Index correlated with pulmonary hypertension classification (r=-0.009, P=0.920) or New York Heart Association heart function classification (r=-0.031, P=0.756). Neither Qanadli nor Mastora Index correlated with any echocardiographic right ventricular parameters (P>0.05), while RVd/LVd by CTPA correlated with echocardiographic right ventricular functional parameters (P<0.05). Both Qanadli (r=-0.288, P=0.006) and Mastora Index (r=-0.203, P=0.032) demonstrated a weakly negative correlation with SPO2. CTPA findings correlated with hemodynamic variables. Backward linear regression analysis revealed that the RVd/LVd, Right Ventricular Anterior Wall Thickness (RVAWT), Main Pulmonary Artery trunk diameter (MPAd) were shown to be independently associated with mean Pulmonary Artery Pressure (mPAP) levels (model: r2=0.351, P=0.025; RVd/LVd: beta=11.812, P=0.000; RVAWT: beta=2.426, P=0.000; MPAd: beta=0.677, P=0.003).

CONCLUSION

Computed tomographic pulmonary angiography is a valuable tool to evaluate hemodynamics, right ventricular function of CTEPH, but neither Qanadli Index nor Mastora Index can reflect pulmonary arterial obstruction in CTEPH accurately.

Right ventricular dilation on CT pulmonary angiogram independently predicts mortality in pulmonary embolism

BACKGROUND

The aim of this study was to determine the prognostic significance of right ventricular dilation on CT pulmonary angiogram in acute pulmonary embolism and to distinguish if this feature predicts mortality independently of the Pulmonary Embolism Severity Index, an established admission severity score.

METHODS

A retrospective study of patients admitted with pulmonary embolism confirmed by CT pulmonary angiogram to three teaching hospitals in East Scotland between January 2005 and July 2007. Two radiologists judged presence of right ventricular dilation on CT pulmonary angiogram independently. The outcome of interest was 30 day mortality. Multivariable logistic regression was used to compare this outcome in patients with right ventricular dilation compared to those without right ventricular dilation, adjusting for Pulmonary Embolism Severity Index score.

RESULTS

There were 585 patients included and 30.4% had right ventricular dilation on CT pulmonary angiogram. Patients with right ventricular dilation had increased 30 day mortality rates compared to patients without right ventricular dilation (12.4% vs. 5.4%; p=0.006). Survival analysis showed that a significantly greater proportion of deaths in the right ventricular dilation group occurred within the first 48h after admission compared to the group without right ventricular dilation (45.5% deaths vs. 9.1%; p=0.016). On multivariable analysis, adjusting for Pulmonary Embolism Severity Index score, right ventricular dilation was independently associated with increased 30 day mortality (OR 2.98; 95% CI 1.54-5.75; p=0.001).

CONCLUSION

Right ventricular dilation on CT pulmonary angiogram is an independent predictor of 30 day mortality in acute pulmonary embolism.

Volumetric analysis of pulmonary CTA for the assessment of right ventricular dysfunction in patients with acute pulmonary embolism

RATIONALE AND OBJECTIVES

To retrospectively determine the value of a volumetric ventricle analysis for the assessment of right ventricular dysfunction in patients with suspected pulmonary embolism (PE) by using image data from non-electrocardiographically (ECG)-gated multidetector computed tomography angiography (CTA).

MATERIALS AND METHODS

Hypothesizing that the presence of PE and the embolus location correlated with right ventricular dysfunction, we retrospectively analyzed 100 non-ECG-gated pulmonary CTA datasets of patients with central, peripheral, and without PE. Right ventricle/left ventricle (RV/LV) diameter ratio measured in transverse sections (RV/LV(trans)), four-chamber view (RV/LV(4ch)), and RV/LV volume ratio (RV/LV(vol)) were assessed on CT images. The results were correlated with the embolus location, the 30-day mortality rate, and the necessity of intensive care treatment.

RESULTS

All CT parameters showed statistically significant differences between all patients groups depended on embolus location. The receiver operating characteristic analysis RV/LV(vol) showed the strongest discriminatory power to differ between patients with central and without PE and between patients with central and peripheral PE (central PE vs. no PE: RV/LV(vol) = 0.932, RV/LV(trans) = 0.880, and RV/LV(4ch) = 0.811, central PE vs. peripheral PE: RV/LV(vol) = 0.950, RV/LV(trans) = 0.849, and RV/LV(4ch) = 0.881), indicating a correlation with embolus location predisposing for RVD. For the identification of high-risk patients with PE all three CT parameters showed statistically significant values (P < .0001), whereas in the receiver operating characteristic analysis, RV/LV(vol) had the strongest discriminatory power (RV/LV(vol) = 0.819, RV/LV(trans) = 0.799, and RV/LV(4ch) = 0.758).

CONCLUSION

Ventricle volumetry of non-ECG-gated CTA allows the assessment of right ventricular dysfunction in patients with acute PE. Compared to unidimensional measurements, a volumetric analysis seems to be slightly superior to identify high-risk patients with adverse clinical outcome. However, the method is more time consuming and requires dedicated software tools compared to unidimensional parameters, which is disadvantageous in an emergency setting.

The correlation between elevated cardiac troponin I and pulmonary artery obstruction index in ED patients with pulmonary embolism

OBJECTIVES

The aim of this study is to investigate the correlation between cardiac troponin I (cTnI) values and the pulmonary artery obstruction index assessed with spiral computed tomography (CT) scan in emergency department (ED) patients with pulmonary embolism (PE).

METHODS

This is a retrospective cohort study of all 179 ED patients diagnosed with PE between December 2004 and January 2007. Study population consisted of 104 (58.1%) of 179 patients with PE in whom both cTnI was measured and a contemporaneously performed CT scan was available for review. In these patients, the levels of cTnI measured in the ED were correlated with the degree of pulmonary vascular obstruction determined by applying the modified Computed Tomography Obstruction Index to the spiral CT scan performed in the ED.

RESULTS

Troponin values were elevated in 20 (19.2%) of 104 patients (95% confidence interval [CI], 11.6-26.8) with a mean cTnI concentration of 0.38 +/- 0.44 microg/L. Elevated cTnI value had a significant correlation with main pulmonary arteries involvement using the modified Computed Tomography Obstruction Index score (P = .0001). Elevated ED cTnI value had 53.8% (95% CI, 37.6-66) sensitivity and 92.3% (95% CI, 87-96.4) specificity, 70% (95% CI, 49-86) PPV, and 85.7% (95% CI, 80.7-90) NPV for predicting main pulmonary artery obstruction on CT. Increased cTnI values were highly correlated to intensive care unit admission of patients with PE (RR, 12.83; 95% CI, 3.87-42.4).

CONCLUSIONS

Measuring cTnI value might be considered in ED patients who are suspected of having PE. Elevated cTnI should raise the clinician's concern for the possibility of central pulmonary vascular obstruction.

Prognostic stratification of acute pulmonary embolism: focus on clinical aspects, imaging, and biomarkers

Pulmonary embolism (PE) represents a common disease in emergency medicine and guidelines for diagnosis and treatment have had wide diffusion. However, PE morbidity and mortality remain high, especially when associated to hemodynamic instability or right ventricular dysfunction. Prognostic stratification to identify high risk patients needing to receive more aggressive pharmacological and closer monitoring is of utmost importance. Modern guidelines for management of acute PE are based on risk stratification using either clinical, radiological, or laboratory findings. This article reviews the modern treatment of acute PE, which is customized upon patient prognosis. Accordingly the current risk stratification tools described in the literature such as clinical scores, echocardiography, helical computer tomography, and biomarkers will be reviewed.

Short-term prognosis of pulmonary embolism

Risk stratification tools that accurately quantify the prognosis of patients with pulmonary embolism (PE) may be useful in guiding medical decision making. Prospective studies demonstrated that clinical factors, echocardiographic right ventricular dysfunction, and cardiac biomarkers (troponins, brain natriuretic peptides) are independent predictors of short-term mortality in patients with PE. The presence of systemic hypotension or shock carries the highest risk of death, and thrombolysis is usually indicated. Among hemodynamically stable patients, clinical prognostic models, echocardiography, and biomarkers accurately identify low-risk patients with PE who are potential candidates for less costly outpatient care. However, the practical use of these prognostic measures is currently limited by the lack of studies demonstrating a positive impact on patient care. The benefit of risk stratification strategies based on clinical prognostic models, echocardiography, and cardiac biomarkers should be demonstrated in prospective studies before their implementation as decision aid to guide initial treatment can be recommended.

Guidelines on the diagnosis and management of acute pulmonary embolism: the Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC)

Non-thrombotic PE does not represent a distinct clinical syndrome. It may be due to a variety of embolic materials and result in a wide spectrum of clinical presentations, making the diagnosis difficult. With the exception of severe air and fat embolism, the haemodynamic consequences of non-thrombotic emboli are usually mild. Treatment is mostly supportive but may differ according to the type of embolic material and clinical severity.

Comparison of ECG-gated versus non-gated CT ventricular measurements in thirty patients with acute pulmonary embolism

OBJECTIVE

To prospectively compare cardiac ventricular measurements from non-gated CT and end-diastolic ECG-gated CT in patients with acute pulmonary embolism (PE).

MATERIALS AND METHODS

With institutional review board approval, 30 adult patients (16 female, mean age = 56 years, range = 26-77 years) underwent ECG-gated cardiac CT within 36 h of their CT diagnosis of acute PE to assess the right ventricle (RV). The axial and reformatted four-chamber ventricular diameters, areas and volumes were measured for both the non-gated CT and the ECG-gated CT in end-diastole and end-systole. Spearman's rank correlation coefficient (RCC) was calculated to compare measurements from the non-gated CT to the gated end-diastolic measurements. The median absolute differences between the gated and non-gated measurements relative to the gated measurements were provided to summarize the degree to which the two measurements differ. A statistical model was constructed to test for potential improvement in specificity for the prediction of 30-day mortality after acute PE using right ventricular measurements from ECG-gated CT versus non-gated CT.

RESULTS

The RCC (0.90 confidence interval) for non-gated and ECG-gated end-diastolic four-chamber and axial RV/LV diameter ratios were 0.83 (0.68-0.90) and 0.88 (0.74-0.95). The median absolute percent differences suggested a high degree of concordance between gated and non-gated measurements. The statistical model predicted that measuring the RV/LV diameter ratio from end-diastole using ECG-gated CT rather than non-gated CT would yield a potential improvement in specificity for death after PE of 0.035 (0.020-0.060) for axial diameter ratios and 0.035 (0.020-0.055) for four-chamber diameter ratios.

CONCLUSION

The benefit from a separate ECG-gated CT scan for the evaluation of RV ventricular diameter, area, and volume measurements is minimal and does not justify its routine clinical use.

ALTERATION OF RIGHT VENTRICULAR-PULMONARY VASCULAR COUPLING IN A PORCINE MODEL OF PROGRESSIVE PRESSURE OVERLOADING

In acute pulmonary embolism, right ventricular (RV) failure may result from exceeding myocardial contractile resources with respect to the state of vascular afterload. We investigated the adaptation of RV performance in a porcine model of progressive pulmonary embolism. Twelve anesthetized pigs were randomly divided into two groups: gradual pulmonary arterial pressure increases by three injections of autologous blood clot (n=6) or sham-operated controls (n=6). Right ventricular pressure-volume (PV) loops were recorded using a conductance catheter. Right ventricular contractility was estimated by the slope of the end-systolic PV relationship (Ees). After load was referred to as pulmonary arterial elastance (Ea) and assessed using a four-element Windkessel model. Right ventricular-arterial coupling (Ees/Ea) and efficiency of energy transfer (from PV area to external mechanical work [stroke work]) were assessed at baseline and every 30 min for 4 h. Ea increased progressively after embolization, from 0.26+/-0.04 to 2.2+/-0.7 mmHg mL(-1) (P<0.05). Ees increased from 1.01+/-0.07 to 2.35+/-0.27 mmHg mL(-1) (P<0.05) after the first two injections but failed to increase any further. As a result, Ees/Ea initially decreased to values associated with optimal SW, but the last injection was responsible for Ees/Ea values less than 1, decreased stroke volume, and RV dilation. Stroke work/PV area consistently decreased with each injection from 79%+/-3% to 39%+/-11% (P<0.05). In response to gradual increases in afterload, RV contractility reserve was recruited to a point of optimal coupling but submaximal efficiency. Further afterload increases led to RV-vascular uncoupling and failure.

Prognostic Models for Selecting Patients With Acute Pulmonary Embolism for Initial Outpatient Therapy

OBJECTIVE

To assess the performance of two prognostic models in predicting short-term mortality in patients with pulmonary embolism (PE).

SUBJECTS AND METHODS

We compared the test characteristics of two prognostic models for predicting 30-day outcomes (mortality, thromboembolic recurrences, and major bleeding) in a cohort of 599 patients with objectively confirmed PE. Patients were stratified into the PE severity index (PESI) risk classes I-V and the Geneva low-risk and high-risk strata. We compared the discriminatory power of both prognostic models.

RESULTS

The PESI classified fewer patients as low risk (strata I and II) [36%; 216 of 599 patients; 95% confidence interval (CI), 32 to 40%] compared to the Geneva prediction rule (84%; 502 of 599 patients; 95% CI, 81 to 87%) [p < 0.0001]. Using either prediction rule, the low-risk groups showed statistically relevant 30-day mortality difference (PESI, 0.9%; 95% CI, 0.3 to 2.2; vs Geneva, 5.6%; 95% CI, 3.6 to 7.6) [p < 0.0001], although nonfatal recurrent venous thromboembolism or major bleeding rates were statistically similar (PESI, 2.8%; 95% CI, 0.6 to 5.0%; vs Geneva, 4.2%; 95% CI, 2.4 to 5.9%). The area under the receiver operating characteristic curve was higher for the PESI (0.76; 95% CI, 0.69 to 0.83) than for the Geneva score (0.61; 95% CI, 0.51 to 0.71) [p = 0.002].

CONCLUSIONS

The PESI quantified the prognosis of patients with PE better than the Geneva score. This study demonstrated that PESI can select patients with very low adverse event rates during the initial days of acute PE therapy and assist in selecting patients for treatment in the outpatient setting.

Saddle pulmonary embolism diagnosed by CT angiography: frequency, clinical features and outcome

OBJECTIVE

To assess the frequency, clinical presentation and outcome associated with saddle pulmonary embolism (PE) diagnosed by computed tomographic angiography (CTA).

PATIENTS

Retrospective review of 546 consecutive patients diagnosed to have acute PE by CTA from 1 September 2002 to 31 December 2003.

RESULTS

Fourteen of 546 patients (2.6%) had saddle PE; 10 were men (71%). None of these patients had pre-existing cardiopulmonary disease. Most common presenting symptoms included dyspnea (72%) and syncope (43%). Hypotension was documented in 2 patients (14%). The most common risk factor for PE was obesity (64%). CTA revealed saddle PE and additional filling defects in the main pulmonary arteries in all patients. Echocardiography was performed within 48 h of the PE diagnosis in 10 patients and revealed right ventricular dysfunction in 8 (80%). All patients were initially managed in the hospital, median length of stay of 4 days (range, 1-45 days). Standard anticoagulant therapy with heparin and warfarin was administered to all patients. Five patients (36%) received additional therapy; thrombolytic therapy was administered to 1 patient (7%) and 4 patients (29%) received an inferior vena cava filter. None of the patients died during their hospitalization. Four patients (29%) died following their hospitalization after intervals of 1, 5, 6, and 12 months, respectively. Causes of death were known in 3 patients, all of whom died from progressive malignancy.

CONCLUSION

Saddle PE in patients without pre-existing cardiopulmonary disease is associated with a relatively low in-hospital mortality rate and may not necessitate aggressive medical management.

D-dimer level is associated with the extent of pulmonary embolism

OBJECTIVES

Our aim was to study the association between the level of D-dimer and the severity of pulmonary embolism (PE) as determined by various biochemical and radiological prognostic markers in order to investigate the potential value of D-dimer as a prognostic marker for the severity of PE.

PATIENTS AND METHODS

PE was diagnosed in 100 consecutive out-patients by multi-detector computerized tomography. One patient was excluded and the final cohort consisted of 99 patients. Pulmonary Artery Obstruction Index (PAOI) and Right Ventricular/Left Ventricular (RV/LV) ratio were assessed.

RESULTS

The median value for D-dimer was 5.0 mg/L (inter-quartile range: 1.8, 12.2). There was a significant association between log D-dimer, and between log RV/LV (r=0.45), log PAOI (r=0.5), and PaO(2) (r=0.40). The multivariate analysis showed an increased association between log D-dimer and between log RV/LV ratio (r=0.54) and log PAOI (r=0.52) after adjusting for age, gender and for the duration of symptoms. Significant association was found between the level of D-dimer and the most proximal level of PE (p<0.0005). There was a significant dose-response relationship between the level D-dimer and between Troponin-T and the frequency of thrombolysis (p<0.0005). In the subgroup of patients with D-Dimer over the upper quartile (>12.2), 12 (67%) patients had elevated Troponin-T and 8 (32%) patients received thrombolysis, compared to 1 (5%) patient with elevated Troponin-T and none treated with thrombolysis in the subgroup of patients with D-dimer<lower quartile.

CONCLUSIONS

We have shown that the level of D-dimer is related to the severity of PE assessed by various radiological, biochemical and clinical markers and might have a potential value as prognostic marker for the severity of PE.

The association between the proximal extension of the clot and the severity of pulmonary embolism (PE): a proposal for a new radiological score for PE

BACKGROUND

The aim of the study was to investigate the association between the proximal level of the clot and the severity of pulmonary embolism (PE).

METHODS

The cohort consisted of 99 consecutive patients with PE diagnosed by multi-detector computed tomography. A new score was constructed by calculating the mean value of the largest affected vessel [sub-segmental = 1, segmental = 2, lobar = 3, main pulmonary artery (MPA) = 4] in each lung.

RESULTS

A significant association was found between the most proximal level of PE and pulmonary artery obstruction index (PAOI) (P < 0.0001), right ventricular (RV)/left ventricular (LV) ratio (P < 0.0001), and PaO(2) (P = 0.004). No significant association was found between systolic blood pressure and the level of PE. Troponin-T was elevated in none of the sub-segmental, 5% of segmental, 20% of lobar, and in 56% of PEs in the MPA (P = 0.001). Significant association was found between the proposed score and PAOI (P < 0.0001), RV/LV ratio (P < 0.0001), PaO(2) (P < 0.008). Troponin-T was elevated in 10% of level 1, 0% of level 2, 43% level of 3, 66% of level 4 PE (P < 0.0001). Cut-off level score 4 yielded a sensitivity of 84% and a specificity of 74% for the detection of elevated troponin-T.

CONCLUSIONS

In conclusion, the study indicates that both the most proximal level of PE and the proposed score are related to the severity of PE as determined by blood oxygenation, biochemical and radiological parameters and could therefore be of value for rapid risk stratification of PE. However, the prognostic value of these classifications and their clinical significance needs to be evaluated in properly designed studies.

Right Ventricular Function in Patients with Acute Pulmonary Embolism: Analysis with Electrocardiography-synchronized Multi–Detector Row CT

PURPOSE

To prospectively assess electrocardiography (ECG)-synchronized multi-detector row computed tomography (CT) for the evaluation of right ventricular (RV) function in patients suspected of having pulmonary embolism (PE).

MATERIALS AND METHODS

All patients gave informed consent after the study details, including radiation exposure, were explained; institutional ethical committee approval was obtained. Nonsynchronized multi-detector row CT of the chest was performed in 66 consecutive patients (29 men, 37 women; mean age, 58 years+/-15 [standard deviation]) who were suspected of having PE. ECG-synchronized cardiac multi-detector row CT was performed to assess cardiac function. Dimension ratios for the RV and left ventricle (LV) were measured on nonsynchronized transverse and angulated four-chamber views. Furthermore, the RV end-diastolic and end-systolic volumes were measured on ECG-synchronized multi-detector row CT scans. An independent samples t test was performed to compare the mean value of different groups. An analysis of variance post hoc test was performed to investigate whether the values of the variables varied between groups.

RESULTS

PE was detected in 29 of 66 patients. The location of PE was categorized as central (n=17) or peripheral (n=12). The RV/LV dimension ratio was larger on the four-chamber view (P=.002), and RV end-systolic volume was larger (P=.01) and ejection fraction was lower (P=.01) in patients with PE. The RV end-systolic volumes and RV/LV volume ratios, as assessed by using ECG-synchronized multi-detector row CT, showed significant differences (P<.005) between patients with central PE and those with peripheral PE. However, the RV/LV dimensions on nonsynchronized images revealed no significant differences.

CONCLUSION

Retrospective ECG-synchronized multi-detector row CT facilitates detection of RV dysfunction, depending on pulmonary embolus location.

Multislice computed tomographic pulmonary angiography for diagnosing pulmonary embolism in the emergency department: has the 'one-stop shop' arrived?

Current diagnostic pathways for pulmonary embolism are complex and involve multiple tests. Clinicians await a single diagnostic modality that accurately rules in or out pulmonary embolism and also provides additional diagnostic and prognostic information. Multislice computed tomographic pulmonary angiography (msCTPA) might be that test. msCTPA has good outcomes using current reference standards and can be used as a stand alone test in low risk patients. Additional leg vein imaging should still be performed for higher-risk patients. CT venography performed immediately after msCTPA has sufficient sensitivity and specificity for proximal deep venous thrombosis to allow a single scan to rule out venous thromboembolism in most patients. Up to 40% of patients have important alternative diagnoses seen on msCTPA. Right ventricular measurements may be calculated from msCTPA data and provide prognostic information for patients with severe PE. This may replace the need for echocardiography in the future. msCTPA provides a safe single radiological investigation for diagnosing PE for most patients, after risk stratification and D-dimer testing. A pathway is provided for msCTPA use in the management of PE in the ED.