Review of 6-month mortality following low-probability lung scans

Ventilation perfusion lung scanning is widely used as a diagnostic method for evaluating patients suspected of having pulmonary embolism (PE). While lung scan interpretation is traditionally performed in terms of probability of PE (usually low, moderate or intermediate, and high), in recent years concern has been raised that the term low probability may be misleading because adverse and even fatal sequelae of PE occasionally occur in such patients. To assess these concerns, a review of mortality in a large series of patients following low-probability lung scans was performed.

To determine the 6-month mortality in a consecutive series of patients following low-probability ventilation perfusion (V/Q) lung scans.

Records of all patients who had low-probability V/Q scans during a 9-year period (1987-1995) were reviewed. Causes of mortality for those patients who died during the 6-month period after the index scan were established from patients' charts, autopsy reports, and computer record data.

Of the total 536 evaluable patients, 83 (15%) died within 6 months of the date of the lung scan; 73 (88%) died while inpatients at the Seattle Veterans Affairs Medical Center, Seattle, Wash, and the other 10 (12%) died at other facilities or at home. Pulmonary embolism was not reported as a suspected or probable contributing factor in any of the 83 deaths. Sixty-three patients (76%) who died had a diagnosis of either cancer (n = 32) or advanced cardiovascular disease (n = 31) at the time of their lung scans. Twenty-six patients (31%) underwent autopsies, and PE was not identified on examination of the lungs in any of them. Of the 27 patients who died within 1 month of the scan date, 17 (63%) underwent autopsies.

Review of data from all patients with low-probability V/Q scans and a follow-up of 6 months showed no documentation to attribute any deaths to PE.