Background: Pulmonary embolism (PE) is a common and potentially life-threatening condition. V/Q SPECT is one of the diagnostic procedures, but inconclusive results are causing problems in the clinical setting.

Aims:

Methods: A retrospective review of electronic medical records was made for all patients with suspected PE who underwent V/Q SPECT 2014-2019 at two teaching hospitals. The frequency of additional imaging with computed tomography pulmonary angiography (CTPA) and the resulting anticoagulation therapy (ACT) of patients was analyzed.

Results: A total of 865 patients with suspected PE were included, 574 acute and 291 chronic PE. 502 female and 363 male, age 19-99 years (mean 65, SD 19) for both groups. There were 131 (15%) positive and 568 (66%) negative cases for PE of V/Q SPECT. The remaining 166 cases (19%) had an inconclusive result. 20% (n=112) in the acute and 19% (n=54) in the chronic PE group.
In the group with suspected acute PE and inconclusive V/Q SPECT result, only 9% (n=10) underwent further diagnostics with CTPA, which were all negative.
Of the remaining 102 patients, 10% (n=10) were already on a longterm therapeutic dose of ACT. 14% (n=14) were started on ACT and 76% (n=78) did not receive any ACT.
See the figure for the chronic PE group.
V/Q SPECT flow chart

Conclusions: Our study shows that 20% of patients with suspected PE receive an inconclusive V/Q SPECT result. The clinical consequences for this group were that most (76%) were not treated with ACT. Considering the high mortality of pulmonary embolism, the need for a more accurate diagnostic method in patients with contraindication for CTPA is urgent.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/clinical-implications-of-v-q-spect-scans-being-inconclusive-in-20-of-patients-referred-on-suspicion-of-pulmonary-embolism/