**2.1.1 Echocardiographic RV/LV ratio**

170 Pulmonary Embolism

Jimenez et al., 2010; Lu et al., 2009; Qanadli et al., 2001; Sanchez et al., 2008; Schoepf & Costello,

This chapter will focus on recent studies comparing CT and echocardiographic findings of RV dysfunction. The data obtained in these trials provide the background for emerging risk stratification algorithms, which we hope will lead to the use of chest CT as an alternative to

Transthoracic echocardiography is a noninvasive tool that can be easily utilized at the bedside, even in hemodynamically compromised patients. It can help diagnose conditions that mimic acute PE but are treated differently, such as acute myocardial infarction, aortic dissection, and pericardial tamponade. Although echocardiography is not recommended for the diagnosis of PE, it can detect or exclude RV dysfunction. Moreover, echocardiography is an important tool for risk stratification in patients with PE because RV dysfunction on an echocardiogram is a powerful and independent predictor of mortality (Ribeiro et al., 1997; Torbicki et al., 2003). Echocardiographic findings suggesting RV dysfunction have been reported to occur in at least 25% of patients with PE (Kreit, 2004). A meta-analysis found that patients with echocardiographic signs of RV dysfunction were at greater than two-fold higher risk of PE-related mortality than patients without signs of RV dysfunction (ten Wolde et al., 2004). Importantly, patients with normal echocardiographic findings had excellent outcomes, with in-hospital PE-related mortality rates <1% in most of the reported series. A recent systemic review (Fremont et al., 2008) identified five studies that evaluated the prognostic role of echocardiography in diagnosing RV dysfunction. The unadjusted relative

Echocardiography, however, has limitations, including restricted availability and relatively high cost. Moreover, in some patients, including those with chronic obstructive pulmonary disease or morbid obesity, it is difficult to adequately image the RV free wall with a transthoracic approach. More importantly, the lack of a clear echocardiographic definition of RV dysfunction is problematic (ten Wolde et al., 2004). A meta-analysis of eight studies that compared the impact of RV dysfunction measured by echocardiography and CT found that the presence of echocardiographically determined RV dysfunction in patients with submassive PE was associated with increased short-term mortality (OR 2.36, 95% CI: 1.3-43), but that corresponding pooled negative and positive likelihood ratios independent of death rates were unsatisfactory for clinical usefulness in risk stratification (Coutance et al., 2011). Unfortunately, the echocardiographic criteria of RV dysfunction differ among published studies and have included RV dilatation, hypokinesis, increased RV/LV diameter ratio and increased velocity of the tricuspid regurgitation jet. Thus, since there is no universal echocardiographic definition of RV dysfunction, only a completely normal result should be considered as defining low-risk PE. This is particularly important because, in some of trials, echocardiographic signs of RV pressure overload alone (such as increased tricuspid insufficiency peak gradient and decreased acceleration time of RV ejection) were considered

RV dysfunction is diagnosed by the presence of RV dilatation, defined as a RV/LV enddiastolic dimension ratio >0.6 on a parasternal long-axis view or >0.9 on a four-chamber

2004; van der Meer et al., 2005; Wu et al., 2004).

echocardiography in the successful identification of RV dysfunction.

risk of RV dysfunction for predicting death was 2.5 (95% CI 1.2-5.5).

sufficient to classify a patient as having RV dysfunction.

**2.1 Echocardiographic findings of right ventricular dysfunction** 

**2. Echocardiographic assessment of right ventricular dysfunction** 

A retrospective study of 950 patients showed that the echocardiographic RV/LV ratio was prognostic in the evaluation of PE, with a critical cutoff for prediction of in-hospital mortality of 0.9 (Fremont et al., 2008). Echocardiograms were electrocardiogram (ECG) gated to allow end-diastolic diameter measurement on the R wave. The minor axes of the RV and LV were measured in apical 4-chamber views from the septum to the lateral wall endothelium at their widest point just above the mitral valve and tricuspid valve annulus. The prognostic value of this easily measurable echocardiographic parameter was independent of patient history and clinical data. Multivariate analysis showed that the independent predictors of in-hospital mortality included systolic BP < 90 mm Hg (odds ratio [OR], 10.73; p < 0.0001), history of left heart failure (OR, 8.99; p < 0.0001), and RV/LV ratio > 0.9 (OR, 2.66; p < 0.01).
