Combination of clinical and V/Q scan assessment for the diagnosis of pulmonary embolism: a 2-year outcome prospective study

With the aim of evaluating the efficiency of our diagnostic approach in patients with suspected acute pulmonary embolism (PE), we prospectively studied 143 patients investigated by means of a ventilation/perfusion (V/Q) lung scan. A pre-test clinical probability of PE (P-clin) was assigned to all patients by the clinicians and scans were interpreted blinded to clinical assessment. A 2-year follow-up of our patients was systematically performed and possible in 134 cases. Distribution of clinical probabilities was high P-clin in 22.5%, intermediate P-clin in 24% and low P-clin in 53.5%, whereas the distribution of scan categories was high P-scan in 14%, intermediate P-scan in 18%, low P-scan in 57% and normal P-scan in 11%. The final prevalence of PE was 24.5%. High P-scan and normal P-scan were always conclusive (19 and 15 cases respectively). Low P-scan associated with low P-clin could exclude PE in 43/45 cases (96%). None of the patients in whom the diagnosis of PE was discarded had a major event related to PE during the 2-year follow-up. Overall, the combined assessment of clinical and scintigraphic probabilities allowed confirmation or exclusion of PE in 80% of subjects (107/134) and proved to be a valuable tool for selecting patients who needed pulmonary angiography, which was required in 20% of our patients (27/134).