Background: Many isolated subsegmental pulmonary emboli (ISSPE) are found incidentally. Whether the clinical outcomes of incidental ISSPE differ from symptomatic events is unclear.
Aims: To determine if demographics or clinical outcomes differ between incidentally noted versus symptomatic ISSPE.
Methods: Consecutive patients with ISSPE enrolled in the Mayo Clinic VTE registry (March 1, 2013, through December 31, 2020) were followed prospectively. ISSPE was defined based on radiologic criterion with clot isolated to subsegmental pulmonary vasculature without involvement of more proximal vasculature or evidence of right ventricular strain. The primary efficacy outcome was venous thromboembolism (VTE) recurrence with death as the secondary outcome. The primary safety outcome was major bleeding.
Results: There were 225 patients with ISSPE of which 60% were incidentally noted. Patients with incidental ISSPE were older with lower body weight than symptomatic patients. A higher percentage of malignancy was found in incidental ISSPE (72.6% v 36.7%, p < 0.0001, Table 1). Incidentally noted ISSPE had a delay of anticoagulation initiation by a mean of 0.6 days (p =0.0027). Outcomes, including death, were similar between the groups (Table 2). However, there were no major bleeding events in the incidental group.
| Variables | Symptomatic (n=90) | Incidental (n=135) | p-value |
| Age, years, mean (SD) | 57.8 (16.5) | 63.0 (12.6) | 0.040 |
| Weight, kilograms, mean (SD) | 90.8 (23.2) | 79.7 (20.6) | <0.001 |
| Female, n (%) | 39 (43.3) | 62 (45.9) | 0.702 |
| Provoked pulmonary emboli, n (%) | 67 (76.1) | 117 (86.7) | 0.043 |
| Active cancer, n (%) | 33 (36.7) | 98 (72.6) | <0.001 |
| Chemotherapy, n (%) | 22 (71.0) | 6 (66.0) | 0.607 |
| Immobility, n (%) | 18 (20.0) | 11 (8.1) | 0.009 |
| Other, n (%) | 17 (18.9) | 14 (10.4) | 0.062 |
| Time to anticoagulation start for diagnosis, days, mean (SD) | 0.4 (1.5) | 1.0 (2.2) | 0.003 |
Demographic and clinical variables of patients with symptomatic versus incidental, isolated subsegmental pulmonary embolism.
| Isolated Subsegmental Pulmonary Embolism | |||
| Outcomes | Symptomatic (n=79) | Incidental (n=119) | p-valuea |
| VTEb recurrence (n) Total follow up person-years VTEb recurrence rate 100 person-years |
1 48.79 2.05 |
2 91.82 2.18 |
0.89 |
| Major bleeding (n) Total follow up person-years Major bleeding rate 100 person-years |
2 45.87 4.36 |
0 95.07 N/A |
N/A |
| CRNMBc (n) Total follow up person-years CRNMBc rate 100 person-years |
6 44.12 13.60 |
8 90.66 8.82 |
0.68 |
| Death (n) Total follow up person-years Death rate per 100 person-years |
20 49.50 40.40 |
31 95.07 32.60 |
0.45 |
| a P-values result from analysis of variance for continuous variables and Chi square test for categorical variables; b VTE = venous thromboembolism; c CRNMB = clinically relevant non-major bleeding. | |||
Venous thromboembolism (VTE) recurrence, major bleeding, clinically relevant non-major bleeding, and death in patients anticoagulated for symptomatic versus incidental, isolated subsegmental pulmonary embolism without concurrent proximal DVT.
Conclusions: ISSPE is often found incidentally, particularly in cancer patients. Compared to those presenting with symptoms, VTE recurrence, major bleeding, CRNMB and death occur with similar frequency. Delayed anticoagulation initiation is a common feature of incidental ISSPE. These results suggest that incidentally noted ISSPE carries similar gravity as those identified in symptomatic patients.
To cite this abstract in AMA style:
T Vlazny D, Hirao-Try Y, O Hodge D, I Casanegra A, E Houghton D, A Meverden R, G Peterson L, D McBane R, E Wysokinski W. Symptomatic versus Incidentally Noted Isolated Subsegmental Pulmonary Embolus Outcomes [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/symptomatic-versus-incidentally-noted-isolated-subsegmental-pulmonary-embolus-outcomes/. Accessed November 29, 2023.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/symptomatic-versus-incidentally-noted-isolated-subsegmental-pulmonary-embolus-outcomes/