General information
  • Disease category Arterial and venous diseases including deep venous thrombosis and lung embolism (BASEC)
  • Study Phase Phase 4 (ICTRP)
  • Recruitment status recruitment ongoing (BASEC/ICTRP)
  • Trial sites
    Aarau, Basel, Bern, Geneva, Lausanne, Neuchatel, St. Gallen, Winterthur, Zurich, Other
    (BASEC)
  • Contact Drahomir Aujesky drahomirantonin.aujesky@insel.ch (BASEC)
  • Data Source(s) BASEC: Import from 30.01.2026 ICTRP: Import from 13.09.2025
  • Last update 30.01.2026 15:36
HumRes49503 | SNCTP000003905 | BASEC2019-02297 | NCT04263038

Clinical observation compared to anticoagulation in low-risk patients with isolated subsegmental pulmonary embolisms: a multicenter randomized placebo-controlled study

  • Disease category Arterial and venous diseases including deep venous thrombosis and lung embolism (BASEC)
  • Study Phase Phase 4 (ICTRP)
  • Recruitment status recruitment ongoing (BASEC/ICTRP)
  • Trial sites
    Aarau, Basel, Bern, Geneva, Lausanne, Neuchatel, St. Gallen, Winterthur, Zurich, Other
    (BASEC)
  • Contact Drahomir Aujesky drahomirantonin.aujesky@insel.ch (BASEC)
  • Data Source(s) BASEC: Import from 30.01.2026 ICTRP: Import from 13.09.2025
  • Last update 30.01.2026 15:36

Summary description of the study

Pulmonary embolisms are blood clots in the pulmonary arteries and encompass a wide spectrum, ranging from large to very small (so-called subsegmental) embolisms. The vast majority of pulmonary embolisms, regardless of their size, are treated with anticoagulants, which are associated with a risk of bleeding. The risk-benefit ratio of anticoagulation in subsegmental pulmonary embolisms remains unclear to this day. This study aims to compare the prognosis of a management strategy with and without anticoagulation in patients with subsegmental pulmonary embolisms. Patients with isolated subsegmental pulmonary embolisms who have a low risk of complications are potential participants in this international study. After being informed about the study and providing appropriate consent, the presence of a thrombosis (blood clot) in the leg veins is first excluded using ultrasound. Patients with subsegmental pulmonary embolisms without simultaneous venous thrombosis are randomly assigned (randomization) to one of two groups: clinical observation plus placebo or clinical observation plus oral anticoagulant. The group allocation is double-blind, meaning that the allocation is unknown to both the patient and the physician. The two treatment groups are monitored for 90 days and compared regarding the risk of thrombosis/embolism, bleeding, mortality, quality of life, functional status, and consumption of medical resources. If it turns out that the group without anticoagulation is not inferior to the group with anticoagulation regarding these study endpoints, unnecessary treatments with anticoagulants could be avoided in the future for low-risk patients with isolated subsegmental pulmonary embolisms, thus reducing the risk of bleeding. For this study, a total of 276 patients will be randomized over a period of 4 years.

(BASEC)

Intervention under investigation

The vast majority of pulmonary embolisms are treated with anticoagulants regardless of their size, which is associated with an increased risk of bleeding. This study therefore investigates whether a treatment strategy without anticoagulation is not inferior to a treatment with anticoagulation concerning recurrent embolisms or thromboses in patients with very small (subsegmental) pulmonary embolisms.

(BASEC)

Disease under investigation

very small, so-called subsegmental pulmonary embolisms

(BASEC)

Criteria for participation in trial
- Age 18 years or older - Objective diagnosis of very small (so-called subsegmental) pulmonary embolisms (blood clots in the pulmonary arteries) (BASEC)

Exclusion criteria
- Presence of a blood clot (thrombosis) in the legs - Active cancer - Active bleeding or high risk of bleeding (BASEC)

Trial sites

Aarau, Basel, Bern, Geneva, Lausanne, Neuchatel, St. Gallen, Winterthur, Zurich, Other

(BASEC)

Aarau, Baden, Basel, Bern, Biel, Burgdorf, Frauenfeld, Genf, Lausanne, Liestal, Neuchatel, St. Gallen, Winterthur, Zürich Triemli.

(BASEC)

Belgium, Canada, France, Netherlands, Switzerland (ICTRP)

Sponsor

Insel Gruppe AG, Inselspital Bern

(BASEC)

Contact

Contact Person Switzerland

Drahomir Aujesky

+41 31 632 88 84

drahomirantonin.aujesky@insel.ch

Department of General Internal Medicine

(BASEC)

General Information

Inselspital, Bern University Hospital, University of Bern,

+41 31 632 88 84

SAFE-SSPE@insel.ch

(ICTRP)

General Information

Inselspital, Bern University Hospital, University of Bern

+41 31 632 88 84

SAFE-SSPE@insel.ch

(ICTRP)

Scientific Information

Inselspital, Bern University Hospital, University of Bern,

+41 31 632 88 84

SAFE-SSPE@insel.ch

(ICTRP)

Name of the authorising ethics committee (for multicentre studies, only the lead committee)

Ethics Committee Bern

(BASEC)

Date of authorisation

11.05.2020

(BASEC)


ICTRP Trial ID
NCT04263038 (ICTRP)

Official title (approved by ethics committee)
Clinical Surveillance vs. Anticoagulation for Low-risk Patients with Isolated Subsegmental Pulmonary Embolism: A Multicenter Randomized Placebo-Controlled Non-Inferiority Trial (BASEC)

Academic title
Clinical Surveillance vs. Anticoagulation for Low-risk Patients With Isolated Subsegmental Pulmonary Embolism: a Multicenter Randomized Placebo-controlled Non-inferiority Trial (ICTRP)

Public title
Clinical Surveillance vs. Anticoagulation for Low-risk Patients With Isolated Subsegmental Pulmonary Embolism (ICTRP)

Disease under investigation
Pulmonary EmbolismEmbolismEmbolism and ThrombosisLung DiseasesCardiovascular DiseasesRespiratory Tract DiseasesVenous ThromboembolismAnticoagulant-induced BleedingBleeding (ICTRP)

Intervention under investigation
Drug: RivaroxabanDrug: Placebo (ICTRP)

Type of trial
Interventional (ICTRP)

Trial design
Allocation: Randomized. Intervention model: Parallel Assignment. Primary purpose: Treatment. Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor). (ICTRP)

Inclusion/Exclusion criteria
Inclusion Criteria:

1. Informed Consent as documented by signature

2. Age =18 years

3. Objective diagnosis of symptomatic or asymptomatic isolated SSPE

Exclusion Criteria:

1. Presence of leg deep vein thrombosis (DVT) or upper extremity DVT (subclavian vein
or above)

2. Active cancer, defined as cancer treated with surgery, chemotherapy, radiotherapy,
or palliative care during the last 6 months

3. =1 prior episode of unprovoked VTE (absence of a transient or permanent risk factor)

4. Clinical instability (systolic blood pressure <100 mm Hg or arterial Oxygen
saturation <92% at ambient air) at the time of presentation

5. Active bleeding or at high risk of bleeding

6. Severe renal failure (creatinine clearance <30ml/min)

7. Severe liver insufficiency (Child-Pugh B or C)

8. Concomitant use of strong CYP3A4 inhibitors or strong CYP3A4 inducers

9. Known hypersensitivity to rivaroxaban

10. Need for therapeutic anticoagulation for another reason

11. Therapeutic anticoagulation for >72 hours for any reason at the time of screening

12. Hospitalized for >72 hours prior to the diagnosis of isolated SSP (hospital-acquired
VTE)

13. Known pregnancy or breast feeding (pregnancy test to be performed for women of
childbearing potential)

14. Lack of safe contraception in women of childbearing potential

15. Refusal or inability to provide informed consent

16. Prior enrolment in this trial (ICTRP)

not available

Primary and secondary end points
Recurrent venous thromboembolism (ICTRP)

Clinically significant bleeding;All-cause mortality (ICTRP)

Registration date
not available

Incorporation of the first participant
not available

Secondary sponsors
University of Bern;Schweizerischer Nationalfonds;Leiden University Medical Center;The Ottawa Hospital;Bayer (ICTRP)

Additional contacts
Drahomir Aujesky, Prof. MD MSc;Drahomir Aujesky, Prof. MD MSc, SAFE-SSPE@insel.ch, +41 31 632 88 84, Inselspital, Bern University Hospital, University of Bern, (ICTRP)

Secondary trial IDs
2019-02297 (ICTRP)

Results-Individual Participant Data (IPD)
not available

Further information on the trial
https://clinicaltrials.gov/study/NCT04263038 (ICTRP)

Results of the trial

Results summary

not available

Link to the results in the primary register

not available