Routine use of ultrasound-assisted catheter-directed thrombolysis for the management of intermediate-high risk pulmonary embolism: a service evaluation project
Authors: Elguindy M , Hossain I , Shah J 
Published: October 2024

Abstract

Background
Intermediate-high risk Pulmonary Embolism (PE) has considerable morbidity. Conservative management could be sub-optimal. Ultrasound-Assisted Catheter-Directed Thrombolysis (UACDT) is used in our centre for the routine management of this presentation.

Purpose
We assessed the procedure safety and short-term outcomes by reviewing locally performed procedures.

Methods
This is an observational retrospective cohort study, with a historic control group. Our centre is a District General Hospital (DGH) in the United Kingdom, and we receive referrals from local acute hospitals. Since the introduction of this service in June 2018 until November 2023, 129 patients (2 patients/month) received routine management with UACDT for intermediate-high risk PE. The controls are 75 acute PE patients of comparable risk classes, managed from January to December 2016.
We assessed procedural and in-hospital outcomes including minor, major bleeding/complications and death. We also assessed Length of Stay (LoS) in hospital, recurrent Venous Thrombo-Embolism (VTE) and re-admission rates for recurrent PE at 30 days. Reduction of oxygen requirements and improved estimated systolic Pulmonary Artery Pressure (sPAP) post-procedure were assessed as surrogate measures. Continuous variables were analysed with a Mann-Whitney U test, and categorical variables with a Chi-square Test.

Results
Baseline demographics are listed in Table 1. Mean duration between CT Pulmonary Angiography (CTPA) and the UACDT procedure was 1.6 (±SD 1.4) days, including inter-hospital transfer. Only 6% (8/129) of UACDT cohort received ≤12 mg standard alteplase dose. In the control group, 4% (3/75) of patients received standard 100mg systemic thrombolysis.
There was no significant difference in the rates of minor (p= 0.9), major bleeding/complications (p= 0.8), or death (p= 1.0) between both groups. There was also no significant difference in rates of recurrent VTE (p= 1.0) or re-admission within 30 days for PE (p=0.1) (Table 2).
LoS in hospital data were ratified, to exclude inappropriate delays (e.g. physiotherapy requirements, etc). We used the date when the patient was declared medically fit for discharge, and no significant difference was noted (p= 0.2). This was confirmed with a regression analysis of UACDT treatment effect (p= 0.9, CI= -3.5 to 3.1). Nonetheless, there was a 25% reduction of median LoS in hospital from 8 days in the controls to 6 days with UACDT.
The proportion of patients requiring O2 was also reduced from 69% (89/129) to 41% (54/129) on day 1 post-procedure. A significant reduction of the estimated sPAP by TTE post-procedure was detected by a mean of 10.4 (±SD 13.9) mmHg (p= &lt;0.01).

Conclusion
UACDT is generally safe with low complications rate. Compared to the control group, there was a reduction in absolute deaths and median LoS in hospital. This can be secondary to the significant acute reduction of systolic pulmonary artery pressure identified.