Respiratory review of 2013: pulmonary thromboembolism

Diagnostic and prognostic value of the D-dimer test in emergency department patients: secondary analysis of an observational study

Background D-dimer measurement improves the rule-out of thromboembolic disease. However, little is known about the risk of false positive results for the diagnosis of thromboembolic disease and its prognostic value. Herein, we investigated factors influencing the accuracy of D-dimer and its prognostic value in a large cohort of emergency department (ED) patients. Methods This is a secondary analysis of a prospective observational single center, cohort study. Consecutive patients, for whom a D-dimer test was requested by the treating physician, were included. Associations of clinical parameters on admission with false positive D-dimer results for the diagnosis of thromboembolic disease were investigated with logistic regression analysis. Results A total of 3301 patients were included, of which 203 (6.1%) had confirmed thromboembolic disease. The negative and positive predictive values of the D-dimer test at the 0.5 mg/L cut-off were 99.9% and 11.4%, respectively. Several factors were associated with positive D-dimer results potentially falsely indicating thromboembolic disease in multivariate analysis including advanced age (odds ratio [OR] 1.04, 95% confidence interval [CI] 1.04-1.05, p < 0.001), congestive heart failure (CHF) (OR 2.79, 95% CI 1.77-4.4, p < 0.01), renal failure (OR 2.00, 95% CI 1.23-3.24, p = 0.005), history of malignancy (OR 2.6, 95% CI 1.57-4.31, p < 0.001), C-reactive protein (CRP) (OR 1.02, 95% CI 1.01-1.02, p < 0.001) and glomerular filtration rate (GFR) (OR 0.99, 95% CI 0.99-1.00, p = 0.003). Regarding its prognostic value, D-dimer was associated with a 30-day mortality (adjusted OR 1.05, 95% CI 1.02-1.09, p = 0.003) with an area under the curve (AUC) of 0.79. Conclusions While D-dimer allows an accurate rule-out of thromboembolic disease, its positive predictive value in routine ED patients is limited and largely influenced by age, comorbidities and acute disease factors. The strong prognostic value of D-dimer in this population warrants further investigation.

Validation of STA-Liatest D-Di assay for exclusion of pulmonary embolism according to the latest Clinical and Laboratory Standard Institute/Food and Drug Administration guideline. Results of a multicenter management study

Combined clinical pretest probability (PTP) and D-dimer testing have great diagnostic value for pulmonary embolism exclusion. To harmonize performance levels of D-dimer assays available on the market, the Clinical and Laboratory Standard Institute (CLSI) has published a guideline, endorsed by the US Food and Drug Administration (FDA). Such guideline specifies the ideal D-dimer assay characteristic and target population. This study was conducted following the CLSI guideline to upgrade the assay-intended use and obtain FDA clearance of STA-Liatest D-Di assay for pulmonary embolism exclusion in patient with low/moderate PTP. This was an international, multicenter, prospective nonrandomized, noninterventional clinical outcome management study conducted in a standard of care setting. D-dimer assay was performed in consecutive, ambulatory outpatients suspected of pulmonary embolism, with low/moderate PTP, and without medical conditions or in clinical settings known to alter default D-dimer values regardless of the presence of thrombosis using a threshold of 0.5 μg/ml (fibrinogen equivalent units) for venous thromboembolism exclusion. Results were used to determine test performance. Of 1141 patients who underwent D-dimer testing, 1060 had valid results and completed study as planned. STA-Liatest D-Di assay performance has exceeded the CLSI/FDA guidance requirements, with a sensitivity of 97.6% (95% confidence interval: 91.7–99.7%) and a negative predictive value of 99.7% (95% confidence interval: 99.0–100%). STA-Liatest D-Di assay has an excellent performance when used in combination with a PTP score in relevant patients and has the potential to minimize the economic healthcare burden avoiding unnecessary and expensive imaging tests.

Rare etiological causes of iliofemoral deep venous thrombosis: Reports of 2 cases

Deep venous thrombosis is frequently seen in lower extremities. However, when seen in the iliac level, mass effect of an underlying pathology must be considered. In this report, we present two cases with upper region deep venous thrombosis, which had underlying pathologies of appendicitis and non-Hodgkin lymphoma.

[Evaluation of optimal parameters for non-contrast-enhanced non-breath-holding pulmonary artery MRA using 3D-FSE imaging with variable flip angle echo trains]

PURPOSE

The aim of this study was to find the optimal acquisition parameters of non-contrast-enhanced non-breath-holding pulmonary artery MRA using 3D-FSE imaging with variable flip angle echo trains.

MATERIALS AND METHODS

The 3D-FSE imaging method with variable flip angle echo trains (CUBE) was employed in this study. Pulmonary artery MRA was performed in five healthy volunteers using a 1.5 tesla (T) and a 3 T clinical scanner with multi-channel torso coils. The institutional review boards approved the study, and informed consent was obtained from all subjects. Prior to the CUBE studies, ECG-gated single-shot FSE scans were performed to determine the timing of systole and diastole. After that, CUBE scans with systolic timing and three adjusted (early, middle and delayed) diastolic timings using both ECG and respiratory gating were performed and subtracted images between systolic and diastolic images were calculated. Subtracted intensities of both lung parenchyma and pulmonary arteries were evaluated using the region of interest (ROI) function. Maximum intensity projection (MIP) images with six different scan parameters (three timings and two static magnetic fields) were processed for evaluation by the ranking method with visual assessment. Three observers each scored all six images and a statistical analysis based on the variation of ratings was performed.

RESULTS

The subtracted intensities of pulmonary arteries and lung parenchyma with middle diastolic timing were higher than that with both early and delayed systolic timing. The same tendency was shown in both 1.5 T and 3 T images. Though the subtracted intensity of 3 T was higher than that of 1.5 T, the contrast ratio between lung parenchyma and pulmonary artery of 1.5 T was higher than that of 3 T. The MIP image using the 1.5 T scanner with middle diastolic timing obtained the best score by the visual assessment using the ranking methods. The middle diastolic timing using the 1.5 T scanner provides the best non-contrast-enhanced non-breath-holding pulmonary artery MRA.

Medical and interventional options to treat pulmonary embolism

Venous thromboembolism remains one of the most common conditions. Pulmonary embolism carries a mortality rate of over 15 % in the first 3 months after diagnosis. Venous thromboembolism is the fourth leading cause of death in the Western world, and the third leading cause of cardiovascular death trailing myocardial infarction and stroke. This section highlights the medical and interventional options presently available to treat this potentially lethal disease.