The Gonda Vascular Center- Thrombophilia Clinic at Mayo Clinic in Rochester, Minnesota utilizes a standardized, guideline-directed, yet patient-oriented approach for treating patients diagnosed with venous thromboembolism (VTE).This study is the ongoing registry of clinical practice with standardized approach to patient assessment and therapy. As most of registries it does not have any definite number of recruited subjects or the date of study completion but provides anticipated number of recruited subjects and the time of anticipated enrolment which was provided only because of formal requirement related to structure of ClinicalTrials.gov website. This number will be updated and upgraded as we continue this registry.

The rates of VTE recurrence, major bleeding, clinically relevant non-major bleeding (CRNMB) and survival in patients treated with anticoagulation for acute VTE are assessed during prospective observation. VTE cases include an acute deep vein thrombosis (DVT) of lower or upper extremities, splanchnic veins, gonadal, renal, cerebral veins thrombosis and pulmonary embolism (PE). Therapy includes the whole spectrum of FDA approved anticoagulants such as "classic" agents: warfarin and heparinoids and the newer direct oral anticoagulants (DOACs) such as rivaroxaban, dabigatran, apixaban, and edoxaban.

When a patient has positive testing for acute VTE the radiologist interpreting the study contacts the Thrombophilia Center and the patient is immediately evaluated. Standardized information about guidelines endorsed anticoagulation therapy is provided in a uniform fashion with a standardized script for providers and a short summary table for the patient. This initial review also includes patient-specific cost information by contacting a pharmacy service phone-line. Patients with cancer-related VTE are counselled regarding the guideline endorsed use of low molecular heparin (LMWH) as the preferred option of anticoagulation and available data on DOACs. After the shared decision making is complete, the prescription is promptly filled at the pharmacy located within the same building, with the first dose administered within the ensuing hour. For patients with acute VTE diagnosed after hours, evaluation is accomplished in the Emergency Department; one dose of LMWH is administered and the patient is referred the next day to the Thrombophilia Clinic.

Patients with symptomatic PE or extensive symptomatic iliofemoral DVT are referred for prompt hospitalization. While in the hospital, they are consulted by a Vascular Medicine service and an appropriate follow up visit at the Thrombophilia Clinic is arranged. For patients with asymptomatic or minimally symptomatic pulmonary embolism (simplified Pulmonary Embolism Severity Index (PESI) score of 0), outpatient management is offered. All patients with cancer-associated PE are referred for lower extremity duplex ultrasound, and if symptomatic or if a central venous catheter is in place, also for upper extremity venous assessment.

Demographic and clinical data are entered into a REDCap. The registry is maintained on institutional servers, which are backed-up nightly and protected in controlled computer room with uninterrupted power supplies, data will never reside on a desktop computer system. Transfer of registry data will occur inside the Mayo Clinic firewall via our integrated high speed network. Analysis will be done using the most current version of SAS® software.

At the most recent update, over 2775 patients were enrolled. These data are used to analyze currently relevant clinical questions and are presented and published.

Inclusion Criteria:

• VTE seen at Thrombophilia Clinic and treatment with anti-coagulant is started within 14 days of VTE diagnosis date.

Exclusion Criteria:

• Patients already on anticoagulation for other reasons or enrolled into anticoagulation clinical trials.

Mayo Clinic patients prescribed anticoagulation for treatment of acute DVT or PE. Treatment with all FDA-approved anticoagulants are captured in the database