CT vs TTE for RV strain in PE

October 20, 2016

Short Attention Span Summary

RV:LV ratio > 0.9 = RV Strain
CT pulmonary angiogram (CTPA) can not only visualize the clot but can also detect evidence of RV strain.  This study found that compared with the gold standard, transthoracic echo (TTE), CT sensitivity for RV strain was 88%, specificity 39%, PPV 49% and NPV 83%.  If CT and TTE showed RV strain, 30% had the “composite outcome of severe clinical deterioration, thrombolysis/thrombectomy or death within 5 days”; if TTE showed RV strain, 20%; if CT alone only 3%; 4% had neither CT or TTE signs of RV strain but still had a bad outcome.

Spoon Feed
CTPA has good sensitivity for detecting RV strain but is not specific and is a poor sole predictor of bad outcome if TTE does not confirm RV strain.  Radiopaedia has some nice images if you haven’t seen this.

---

Abstract

Acad Emerg Med. 2016 Sep 24. doi: 10.1111/acem.13108. [Epub ahead of print]

Assessment of Right Ventricular Strain by Computed Tomography versus Echocardiography in Acute Pulmonary Embolism.

Dudzinski DM1,2, Hariharan P1,3, Parry BA1,3, Chang Y1,4, Kabrhel C5,6.

Author information: 

• 1Center for Vascular Emergencies, Massachusetts General Hospital, Boston, Massachusetts.
• 2Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts.
• 3Division of Emergency Medicine, Massachusetts General Hospital, Boston, Massachusetts.
• 4Division of General Internal Medicine, Massachusetts General Hospital, Boston, Massachusetts.
• 5Center for Vascular Emergencies, Massachusetts General Hospital, Boston, Massachusetts. ckabrhel@partners.org.
• 6Division of Emergency Medicine, Massachusetts General Hospital, Boston, Massachusetts. ckabrhel@partners.org.

ABSTRACT

BACKGROUND: 

Right ventricular strain (RVS) identifies patients at risk of hemodynamic deterioration from pulmonary embolism (PE). Our hypothesis was that chest computed tomography (CT) can provide information about RVS analogous to transthoracic echocardiography (TTE) and that RVS on CT is associated with adverse outcomes after PE.

METHODS: 

Consecutive emergency department (ED) patients with acute PE were prospectively enrolled and clinical, biomarker, and imaging data were recorded. CTs were over-read by two radiologists. We compared diagnoses of RVS on CT (defined as: RV:LV ratio ≥ 0.9 or interventricular septal bowing) to echocardiography (defined as: right ventricular hypokinesis, right ventricular dilatation, or interventricular septal bowing). We calculated the test characteristics (with 95% CI) of CT and TTE for a composite outcome of severe clinical deterioration, thrombolysis/thrombectomy or death within 5 days.

RESULTS: 

Two hundred and ninety-eight patients were enrolled; 274 had CT and 118 had formal TTE. Of the 104 patients who had both CT and TTE, the mean age was 58 (SD=17) years; 50 (48%) were female and 88 (85%) were Caucasian. Forty-two (40%) had RVS by TTE and 75 (72%) had RVS by CT. CT and TTE agreed on the presence or absence of RVS in 61 (59%) cases (kappa=0.24). Using TTE as criterion standard, the test characteristics of CT for RVS were: sensitivity = 88%, specificity = 39%, PPV = 49% and NPV = 83%. Fourteen (13%) patients experienced severe clinical deterioration or required hospital-based intervention within 5 days. This occurred in 30% of patients with RVS on both TTE and CT, 20% of patients with RVS on TTE alone, 3% of patients with RVS on CT alone, and 4% of patients without RVS on either modality.

CONCLUSIONS: 

In acute PE, CT is highly sensitive but only moderately specific for RVS compared to TTE. RVS on both CT and TTE predicts more events than either modality alone. TTE confers additional positive prognostic value compared to CT in predicting post-PE clinical deterioration. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.

PMID: 27664798 [PubMed – as supplied by publisher]