Safety of ruling out acute pulmonary embolism by normal computed tomography pulmonary angiography in patients with an indication for computed tomography: systematic review and meta-analysis

Diagnosis and management of pulmonary embolism in the elderly

Elderly patients are a population not only at particularly high risk of venous thromboembolism including pulmonary embolism (PE), but also at high risk of adverse clinical outcomes and treatment-related complications. Major progresses have been achieved in the diagnosis and treatment of PE over the last two decades. Nevertheless, some of elderly patients' specificities still represent important challenges in the management of PE in this population, from its suspicion to its diagnosis and treatment, and are discussed in this review. Perspectives for the future are from a diagnostic point of view the potential implementation of age-adjusted d-dimer cut-offs that will allow ruling out PE in a greater proportion of elderly patients without the need for thoracic imaging. From a therapeutic point of view, acquisition of post-marketing clinical experience with the use of new oral anticoagulants is still necessary, and in the meantime, these drugs should be prescribed with great caution in thoroughly selected elderly patients.

How I diagnose acute pulmonary embolism

The clinical diagnosis of acute pulmonary embolism (PE) is frequently considered in patients presenting to the emergency department or when hospitalized. Since symptoms are a-specific and the consequences of anticoagulant treatment are considerable, objective tests to either establish or refute the diagnosis have become a standard of care. Computed tomographic pulmonary angiography (CTPA), which has replaced pulmonary angiography as first-line imaging test, is associated with radiation exposure, several complications resulting from contrast dye administration, and over diagnosis. Importantly, CTPA can be avoided in 20% to 30% of patients who present with a first or recurrent episode of clinically suspected acute PE by using a standardized algorithm. This algorithm should always include a clinical decision rule to assess the likelihood that PE is present, followed by a D-dimer blood test and/or CTPA. The aim of this review is to provide clinicians this practical diagnostic management approach using evidence from the literature.

Diagnostic management of acute deep vein thrombosis and pulmonary embolism

Acute deep vein thrombosis (DVT) and pulmonary embolism (PE) represent two expressions of a similar clinical pathological process, often referred to as venous thromboembolism (VTE). It has long been recognized that, as clinical signs and symptoms of PE and DVT are not specific for the diagnosis, objective diagnosis in both patients presenting with leg symptoms and those with chest symptoms is mandatory. Since the last review on this subject in this journal in 2009, several large trials have been performed that shed new light on all aspects of the diagnostic management of suspected VTE, especially in the field of simplified clinical decision rules, age-dependent D-dimer cut-offs and magnetic resonance imaging. A literature search covering the period 2007-2012 was performed using the Medline/PubMed database to identify all relevant papers regarding the diagnostic management of acute PE and DVT. Established concepts and the latest evidence on this subject will be the main focus of this review.

Diagnosis of pulmonary embolism: Advances and pitfalls

The signs and symptoms of patients with pulmonary embolism (PE) form a wide spectrum and considerably overlap with other cardiopulmonary diseases. Timely recognizing of this disease therefore remains challenging, but is of vital importance to avoid PE-related morbidity and mortality. To aid and standardize the initial diagnostic approach of patients with suspected PE, clinical probability rules have been developed and simplified for use in clinical practice. It has been demonstrated by clinical outcome studies that it is safe and of high clinical utility to exclude PE on the basis of an unlikely clinical probability and a normal D-dimer test result. For the remaining patients with suspected PE, imaging tests are required. The introduction of multi-detector computed tomographic pulmonary angiography (MD-CTA) has significantly improved the detection of PE, and this test is now regarded as the imaging test of first choice. This review will focus on recent advances and pitfalls that remain in the diagnostic work-up of patients with suspected acute PE.

Current approach to the diagnosis of acute nonmassive pulmonary embolism

Pulmonary embolism is a common and potentially lethal disease. Given the variable presentation and associated morbidity of this condition, an accurate and efficient diagnostic algorithm is required. Clinical pretest probability serves as the root of any diagnostic approach. We, thus, review several clinical decision rules that may help standardize this determination. Using a review of the literature, the accuracy, predictive values, and likelihood ratios for several diagnostic tests are described. The combination of these tests, based on the pretest probability of disease, can be used in a Bayesian fashion to make accurate treatment decisions. A completely noninvasive diagnostic algorithm for patients presenting with suspected acute pulmonary embolism is proposed.

[Diagnosis of pulmonary embolism]

Nowadays the diagnosis of pulmonary embolism (PE) is based on a "diagnostic strategy" rather than a single test. The first step, after identifying patients with suspicion of PE, is to establish the pre-test clinical probability. Several scores are available to make a standardised and reproducible assessment of the clinical probability and these, therefore, represent valuable diagnostic tools. Indeed, it is the clinical probability that guides further investigation. In patients with low or intermediate clinical probability, PE can be safely ruled out by a negative D-dimer in approximately one-third of patients without additional imaging. In the case of a positive D-dimer or high clinical probability, CT pulmonary angiography is now the recommended imaging technique. However, lower limb venous compression ultrasound and ventilation/perfusion scans remain useful in patients with contraindications to CT; mainly those with renal insufficiency. In the presence of readily available and strongly validated diagnostic strategies, the challenge for the future will probably be better identification of patients in whom PE should be suspected.

Magnetic resonance imaging and computed tomography developments in imaging of venous thromboembolism

Venous thromboembolism (VTE) is a disease that causes high morbidity and mortality in the population. At present the first-line imaging test for a suspected pulmonary embolism (PE) is computed tomography (CT) pulmonary angiography, and ultrasonography is widely used for the diagnosis of deep-vein thrombosis (DVT). Although these modalities are proven to be safe and accurate, unresolved issues remain, such as whether CT scanning in patients with a suspected PE should be extended to the legs. Another issue is the diagnosis of recurrent DVT. Magnetic resonance imaging (MRI) offers a number of advantages in the imaging of VTE. Recent developments of scanning protocols with shorter acquisition times, sometimes complemented by navigator gating or making use of endogenous contrast, offer new perspectives for the use of MRI. This review provides an overview of state of the art MRI techniques for the diagnosis of PE and DVT. Furthermore, the use of new contrast agents such as fibrin labeling to detect thrombi are addressed.

The value of 64-detector row computed tomography for the exclusion of pulmonary embolism

Recently, a diagnostic strategy using a clinical decision rule, D-dimer testing and spiral computed tomography (CT) was found to be effective in the evaluation of patients with clinically suspected pulmonary embolism (PE). However, the rate of venous thromboembolic complications in the three-month follow-up of patients with negative CT was still substantial and included fatal events. It was the objective to evaluate the safety of withholding anticoagulants after a normal 64-detector row CT (64-DCT) scan from a cohort of patients with suspected PE. A total of 545 consecutive patients with clinically suspected first episode of PE and either likely pre-test probability of PE (using the simplified Wells score) or unlikely pre-test probability in combination with a positive D-dimer underwent a 64-DCT. 64-DCT scanning was inconclusive in nine patients (1.6%), confirmed the presence of PE in 169 (31%), and ruled out the diagnosis in the remaining 367. During the three-month follow-up of the 367 patients one developed symptomatic distal deep-vein thrombosis (0.27%; 95%CI, 0.0 to 1.51%) and none developed PE (0 %; 95%CI, 0 to 1.0%). We conclude that 64-DCT scanning has the potential to safely exclude the presence of PE virtually in all patients presenting with clinical suspicion of this clinical disorder.

Update on techniques for the diagnosis of pulmonary embolism

IMPORTANCE OF THE FIELD

The clinical suspicion of acute pulmonary embolism (PE) is frequently raised. However, the diagnosis of PE is confirmed in only 20 - 30% of these patients. The high incidence in addition to the potential harm from false-positive or false-negative diagnostic decisions underline the importance of a standardised diagnostic algorithm with high sensitivity as well as specificity.

AREAS COVERED IN THIS REVIEW

This article reviews the diagnostic tests for the diagnosis of PE.

WHAT THE READER WILL GAIN

This review provides an overview of the different clinical decision rules (CDRs), D-dimer tests and imaging techniques in patients suspected of PE. Furthermore, the diagnostic process in patients with clinically suspected recurrent PE, suspicion during pregnancy and new research areas are discussed.

TAKE HOME MESSAGE

Various diagnostic tests are available to detect or exclude PE with good accuracy. CDRs and D-dimer tests play an important role in the exclusion of PE. Neither is sufficient as a single test, but the combination of an 'unlikely' clinical prediction and a normal D-dimer test result safely excludes PE. In case of a high CDR score and/or an elevated D-dimer concentration, extra imaging is necessary with multi-slice computed tomography pulmonary angiography as first choice modality.

[Diagnostic strategy and comparison of clinical scores for pulmonary embolism]

The diagnostic approach to pulmonary embolism can be divided in several consecutive steps. First of all, the clinician must identify the patients with potential pulmonary embolism based on clinical presentation and the presence or absence of personal risk factors. Further investigations can then be guided by the use of a clinical probability score. The revised Geneva score and the Wells score are the most validated tools. They are reliable in stratifying patients into low, intermediate, and high-risk categories. When clinical probability is low or intermediate, the dosage of d-dimers is helpful. A negative result excludes pulmonary embolism with a very high negative predictive value, close to 100%. When positive, a multidetector thoracic CT will confirm or exclude the diagnosis. The utility of a lower-limb venous ultrasound is very low, and its use is therefore no longer recommended.