Management of single subsegmental pulmonary embolism: a prospective observational study at North Shore and Waitakere Hospitals, Auckland

Abstract

Background: Single subsegmental pulmonary embolism is increasingly diagnosed but the benefit to anticoagulate in the absence of concurrent deep vein thrombosis is not consistently established.Aims: To investigate the safety of an observational approach in patients with isolated subsegmental pulmonary embolism and the utility of the second lower limb ultrasound after 7 days.Methods: Prospective observational study of patients diagnosed with isolated subsegmental pulmonary embolism between July 2016 and July 2020 at North Shore and Waitakere Hospitals, Auckland. The primary outcome was the venous thromboembolism recurrence rate within 3 months of single subsegmental pulmonary embolism diagnosis. Secondary outcomes included all-cause mortality, bleeding complications and the percentage of deep vein thrombosis diagnosed at serial compressive ultrasounds (CUS) of lower limbs.Results: Among the 48 patients studied (two excluded due to revised diagnosis), no statistically significant differences were found in the baseline characteristics between the anticoagulated (n = 17) and observed (n = 31) groups. After patients with deep vein thrombosis were excluded, comparisons did not reveal significant differences in the primary outcome (0 vs 1 recurrent venous thromboembolism in the anticoagulated vs. observational groups respectively) and the secondary outcomes. In the observational cohort, 77.4% (n = 24) patients had repeat bilateral lower limb CUS after 7 days, and none had deep vein thrombosis diagnosed on the second CUS.Conclusions: Withholding anticoagulation was a feasible management option for this cohort of patients with single subsegmental pulmonary embolisms with an absence of deep vein thrombosis. The utility of a second lower limb ultrasound is questionable and would warrant further assessment in a prospective study.

Subsegmental pulmonary embolism and anticoagulant therapy: the impact of clinical context

“…Two previous retrospective studies described further Doppler ultrasound investigation for 27% to 97% of patients with SSPE, with positivity rates of 9% and 19% 24,27 . Our findings broadly align with these studies, with ultrasound rates of 32% and positivity rates of 21%.…”

“…In addition, rates of anticoagulation for SSPE vary from 52% to 100% 10,16,24,27 . Our study fits within this range, with an anticoagulation rate of 74%.…”

“…In addition, rates of anticoagulation for SSPE vary from 52% to 100%. 10,16,24,27 Our study fits within this range, with an anticoagulation rate of 74%. Two previous retrospective studies described further Doppler ultrasound investigation for 27% to 97% of patients with SSPE, with positivity rates of 9% and 19%.…”

“…Reported rates of Doppler ultrasound at diagnosis vary greatly among existing retrospective studies (0% to 68%) 15,18–20,22–24 . In two recent prospective studies, deep venous thrombosis was observed in 10 (21%) of 48 patients 27 and 28 (10%) of 292 patients 26 …”

Clinical Surveillance vs Anticoagulation Therapy for Isolated Subsegmental Pulmonary Embolism: A Systematic Review of Clinical Outcomes

“…After further screening by title and abstract and performing full-text reviews, 10 studies remained with a total of 1224 patients (Figure 1). This included 4 prospective studies 14,18,21,22 and 6 retrospective studies. 6,[15][16][17]19,20 Seven studies evaluated patients with both single and multiple ISSPE 6,14,16,17,[20][21][22] and 3 studies evaluated patients with single ISSPE only.…”