Lung scan evaluation of thrombolytic therapy for pulmonary embolism

Data from three trials of thrombolytic therapy for pulmonary embolism (PE) were combined to assess the utility of perfusion lung scan defect scoring in predicting the response to thrombolytic therapy.

Pre- and post-therapy lung scans and duration of symptoms were available for a total of 221 patients, 167 were treated with various thrombolytic regimes and 54 were treated with heparin alone.

Improvement in the lung scan defect score was correlated with larger initial defect score (r = 0.53), segmental appearance (r = 0.31) and shorter duration of symptoms (r = 0.20). There was no significant residual correlation between improvement and segmental appearance in a multiple regression analysis after accounting for initial defect score and duration of symptoms. Two lung scan scoring methods (segmental and anterior-posterior method) provided similar results with low interobserver variability (r = 0.90 for both methods).

This study indicates that the baseline perfusion lung scan defect severity helps to predict the response to thrombolytic therapy.