Prospective evaluation of two-dimensional transthoracic echocardiography in emergency department patients with suspected pulmonary embolism.

OBJECTIVE: To prospectively examine the diagnostic accuracy of two-dimensional transthoracic echocardiography (2-D echo) in emergency department (ED) patients being evaluated for acute pulmonary embolism (PE). METHODS: This was a 14-month prospective observational trial of a convenience sample of ED patients undergoing evaluation for suspected PE at a suburban teaching hospital. The 2-D echo was defined as positive if any two of the following were noted: right ventricular dilation, abnormal septal motion, loss of right ventricular contractility, elevated pulmonary artery or right ventricular pressures, moderate to severe tricuspid regurgitation, or visualization of a clot seen in the right ventricle or pulmonary artery. The patient was considered to have a PE if one of the following was positive: a pulmonary angiogram, contrast helical computed tomography, a magnetic resonance angiogram, a high-probability ventilation/perfusion (V/Q) scan without contradictory evidence, or an intermediate-probability V/Q scan with ultrasonic evidence of deep venous thrombosis. RESULTS: Of 225 cases identified, 39 met the defined criteria for PE (17%). A 2-D echo was performed on 124 patients (55%), of whom 27 (22%) had PE. In 20 patients the 2-D echo had at least two indicators of right ventricular strain; however, only 11 of these patients had confirmed pulmonary embolus. The 2-D echo had a sensitivity of 0.41 (95% CI = 0.32 to 0.49) and a specificity of 0.91 (95% CI = 0.86 to 0.96). The likelihood ratio positive was a moderately strong 4.4, with a weak likelihood ratio negative of 0.6. CONCLUSIONS: Bedside 2-D echo is not a sensitive test for the diagnosis of PE in ED patients. Positive findings moderately increase the suspicion for PE but are not diagnostic.

Use of two-dimensional echocardiography for the diagnosis of pulmonary embolus.

We investigated the diagnostic utility of transthoracic echocardiogram (2-D ECHO) in identifying acute right heart strain in patients with suspected pulmonary embolus (PE) undergoing a pulmonary angiogram during their hospitalization. A retrospective case control study was conducted over a 3-year period at a tertiary, community teaching hospital. Patients were eligible if they had a pulmonary angiogram and a transthoracic echocardiogram. Cases were defined as an angiogram positive for PE and controls were defined as an angiogram negative for PE. We excluded cases in which the time interval between 2-D ECHO and angiogram was greater than 2 days. The 2-D ECHO was considered positive for right heart strain if two of the following were present: enlarged right ventricle, moderate or severe tricuspid regurgitation, increased right ventricular pressures, or paradoxical septal wall motion. We were able to identify 71 patients, of whom 24 met our criteria for PE. Of these, 13 had an echocardiogram consistent with our definition of acute right heart strain, for a sensitivity of 0.54. Forty-six of the 47 patients without PE did not have findings of acute right heart strain. The echocardiogram was positive in 14 patients, for a positive predictive value of 0.93. In seven patients with systolic blood pressures of less than 100 mmHg, five had a PE, all of whom met our criteria for acute right heart strain. We conclude that 2-D ECHOs show promise in identifying PE and hemodynamic compromise as a result of PE, and that further studies are warranted.