Clinical study
Value of transthoracic echocardiography in the diagnosis of pulmonary embolism: results of a prospective study in unselected patients

https://doi.org/10.1016/S0002-9343(01)00693-3Get rights and content

Abstract

PURPOSE: Echocardiography is advocated by some as a useful diagnostic test for patients with suspected pulmonary embolism (PE), but its diagnostic accuracy is unknown. The present study was undertaken to determine prospectively the sensitivity and specificity of transthoracic echocardiography in the diagnosis of PE.

SUBJECTS AND METHODS: We examined 110 consecutive patients with suspected PE. The study protocol included assessment of clinical probability, echocardiography, and perfusion lung scanning. Pulmonary angiography was performed in all patients with abnormal scans. As echocardiographic criteria to diagnose acute PE, we used the presence of any two of the following: right ventricular (RV) hypokinesis, RV end-diastolic diameter >27 mm (without RV wall hypertrophy), or tricuspid regurgitation velocity >2.7 m/sec. Clinical estimates of PE served as pretest probabilities in calculating, after echocardiography, the posttest probabilities of PE.

RESULTS: Pulmonary angiography confirmed PE in 43 (39%) of 110 patients. Echocardiographic diagnostic criteria for PE yielded a sensitivity of 56% and a specificity of 90%. For pretest probabilities of 10%, 50%, and 90%, the posttest probabilities of PE conditioned by a positive echocardiogram were 38%, 85%, and 98%, respectively. The posttest probabilities of PE conditioned by a negative echocardiogram were 5%, 33%, and 81%, respectively.

CONCLUSIONS: In unselected patients with suspected PE, transthoracic echocardiography fails to identify some 50% of patients with angiographically proven PE. Although echocardiographic findings of RV strain, paired with a high clinical likelihood, support a diagnosis of PE, the transthoracic echocardiography has to have a better sensitivity to be used as a screening test to rule out PE.

Section snippets

Patient population

The study population consisted of 125 consecutive patients referred to our institute because of suspected PE from February 1 through December 31, 1997. In 15 (12%) of these 125 patients, the echocardiographic study could not be completed because of a poor acoustic window. The following is the report of the results obtained from the 110 patients in whom the echocardiographic study was completed. All patients were examined uniformly according to a standardized protocol described below.

Clinical evaluation

Upon study

Patient characteristics and prevalence of PE

The mean age of the 110 patients who had been referred for lung scanning with clinically suspected PE was 63.8 ± 17.2 years (range 15 to 91); 45 of them (41%) were male. Most—79 of 110, or 72%—were hospitalized at the time of study entry. The median time between onset of symptoms and study entry was 1 day (range 0 to 30).

Table 1shows the classification of patients according to clinical probability and perfusion lung scan results. Lung scans were normal or near-normal in 34 (31%) of the 110

Discussion

Over the last decade, there has been growing interest in using transthoracic echocardiography in the noninvasive diagnostic work-up of patients with suspected PE 12, 13, 14, 25. The contribution of echocardiography to the diagnosis of PE is most often indirect because visualization of right-sided heart emboli is a relatively rare occurrence. In fact, in the International Cooperative Pulmonary Embolism Registry (ICOPER), intracardiac thrombi were visualized in only 45 (4%) of 1,135 patients

Acknowledgements

The authors wish to thank Drs. Germana Allescia, Carolina Bauleo, Laura Carrozzi, Giosuè Catapano, Alba Dainelli, and Luigi Rizzello for their help in the clinical evaluation of patients; Giuseppe Maltinti, Claudio Mazzotti, Loredana Salis, Armando Perissinotto, Alberto Pollastri, and Nilo Faraoni for their excellent technical assistance; and Prof. Anthony L. Johnson for reviewing the manuscript.

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Supported in part by the Ministry of Health and the Ministry of University and Scientific and Technological Research of Italy.

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