[Transthoracic echocardiography and diagnosis of acute pulmonary embolism. Change in the diagnostic valve with respect to thresholds of classification].

The diagnostic value of transthoracic echocardiography in acute pulmonary embolism is not well established. Although many parameters are abnormal, the thresholds used vary according to the authors, limiting the contribution of the investigation to the diagnosis. In a prospective study of 70 patients with suspected acute pulmonary embolism without previous cardio-respiratory disease, the authors tried to determine the diagnostic thresholds using discriminating linear analysis and ROC curves. Parameters easily recorded in an emergency were analysed: end diastolic ventricular dimensions, ratio of these diameters and maximal velocity of tricuspid regurgitant flow. Thirty-one patients had pulmonary embolism quantified by the Miller index (average: 16 +/- 7, range 2 to 28). Measurements of left ventricular dimension were disappointing (sensitivity: 0.52, specificity: 0.73 for a threshold value of 45 mm). The right ventricular dimension was a better predictive parameter (sensitivity: 0.70, specificity: 0.86 for a threshold value of 25 mm). However, the ratio of right to left ventricular dimension had a better diagnostic value (sensitivity: 0.85, specificity: 0.78 for a threshold value of 0.5). The best diagnostic parameter was the maximal velocity of tricuspid regurgitation (sensitivity: 0.93, specificity: 0.82 for a threshold value of 2.5 m/s). The authors conclude that the maximal velocity of tricuspid regurgitation with a threshold of 2.5 m/s and the ratio of the ventricular dimensions with a threshold value of 0.5 are valuable diagnostic indicators for acute pulmonary embolism.