Cardiothoracic CT: one-stop-shop procedure? Impact on the management of acute pulmonary embolism
posted on September 6, 2011

by: Pauline J. Abrahams-van Doorn and Ieneke J. C. Hartmann

Open Access

ABSTRACT: 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.

INTRODUCTION
Pulmonary embolism (PE) is a common and potentially fatal cardiovascular disorder. The clinical presentation of acute PE reveals a wide spectrum, ranging from mild dyspnea to cardiac arrest. The short-term mortality of PE also varies widely, ranging from less than 1% in hemodynamically stable patients with non-massive PE and no signs of right heart overload to over 90% in patients who present with cardiorespiratory arrest [1].

In the treatment of PE two groups of patients are traditionally identified. Given the high mortality risk in hemodynamically unstable patients, aggressive therapies such as thrombolytics, inotropic vasoactive drugs, embolectomy, or thrombus fragmentation are indicated [2–4]. In the large group of normotensive patients, anticoagulant treatment is started as the risk of an adverse event due to more aggressive treatment is considered higher than the relatively low risk of PE-related death.

Recent studies have demonstrated that up to 55% of normotensive patients with PE have asymptomatic right ventricular dysfunction (RVD). These normotensive patients with RVD have a higher risk of an adverse outcome with an estimated 30-day mortality directly related to PE between 3 and 10% [5], and an absolute increase in early PE-related mortality of 4–5% [6], or a doubling of the risk of all-cause death during 3-month follow-up [7]. This is significantly higher than the early PE-related mortality in the overall group of normotensive patients (1–7%) [8, 9]. It has been debated that normotensive PE patients with RVD might benefit from thrombolytic therapy [10, 11]. In contrast, there may also be a subgroup of hemodynamically stable patients without RVD that have a very low risk of adverse outcomes and in whom early hospital discharge or even home treatment may be considered.

Risk stratification is a frequently used method to identify subgroups of patients that may benefit from different diagnostic or treatment methods based on a different risk profile. In this review, we discuss the parameters that are currently proposed for prognostic stratification of patients with acute PE. These parameters can, from a practical point of view, be classified into three groups: the first group consists of clinical parameters that can be immediately obtained at bedside, mainly to assess hemodynamic status and distinguish high-risk from non-high-risk PE patients. The second group contains biomarkers of myocardial injury, and finally, markers of RVD make up the third group. Both cardiac biomarkers and markers of RVD can be used to further stratify non-high-risk PE patients into intermediate- and low-risk subgroups [3]. Based on the literature currently available, a potential risk stratification strategy is proposed. The benefit of this and other risk stratification strategies, however, is currently under investigation and has to be demonstrated in prognostic studies before implementation in clinical practice can be recommended. Before we discuss the parameters that are currently considered for clinical risk stratification of patients with PE, we will first expound the pathophysiology of PE to understand the broad clinical spectrum of PE.

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