This is a phase 4 cohort prospective, open, national, multicentre study that collects data on history of patients treated chronically with anticoagulant drugs, including the novel direct oral anticoagulants (DOACs). The Registry is designed solely for observational purposes and is not intended to have any influence on the treatment of the single patients included.

Patients are included when they start the anticoagulant treatment, whatever the drug used, or when they shift from a vitamin K antagonist (VKA) drug to one of the novel direct oral anticoagulants, provided that the therapy is expected to last at least 3 months.

The general aims of the study are to provide a better evaluation of efficacy and safety of different treatment options, and to improve our understanding of the risks/benefits of the various anticoagulant drugs and the different therapy options.

The Registry is open to the participation of clinical centres or individual professionals (now called Participants) that are involved with management of anticoagulated patients.

Participants can include patients with 18 years or more who satisfy the following preset criteria:

• Participants should included patients consecutively to avoid selection bias; criteria to avoid selection bias are proposed to Participants, which should decide the one they want to adopt.
• Patients should have been receiving anticoagulation therapy for no more than 30 days at the time of inclusion, regardless of age, clinical indication for treatment, therapeutic range expected (in cases of treatment with VKAs) and expected duration of the treatment (providing a duration of at least 3 months is foreseen). Patients who have already been receiving chronic anticoagulation therapy for some time may be included if they are switched from VKAs to DOACs or to low molecular weight heparin or to fondaparinux
• Patients not prepared to undergo constant monitoring at their enrolling centres or who take part in phase II or III clinical studies should not be included. Patients who participate in other observational or phase IV studies can be included in the Register.
• All patients must give their informed written consent -- following procedures laid down by local Ethical Committees - for the compilation and conservation on the Register's central database of data regarding their personal clinical histories and anticoagulation treatment patterns and for use of said data.
• All the patients inserted must be followed for at least 1 year, even though an indefinite follow-up of all patients continuing anticoagulation therapy is highly recommended. If in single patients anticoagulation treatment is discontinued within 1 year of inclusion, active participating members should nonetheless keep on compiling (telephonically too) information regarding the possible onset of complications (thrombotic, bleeding clinical events of another nature) till 1 year -follow-up.
• The Participants of the Register must use a computer programme as database - for all the information to be collected. The computer programme must meet the features requested by the Executive Committee of the Registry and must be able to send the information to the centralised database via internet and connection to the web site. By way of alternative the Participants can use the "Simple-START" software provided free by the Registry.
• As criterion for safeguarding the privacy of patients, every patient inserted in the Registry is identified by a "Patient log" which includes the identification code of the enrolling Participant and the identification code of each single patient, using the computer database programme used by the Participant. The enrolling Participant is committed to keeping for the whole duration of the Register the whole demographic data of each patient associated with the Patient log".
• Are excluded patients who: have < 18 years age, are not willing to sign informed consent, are not ready to submit to constant monitoring, participate in phase II or III clinical studies
• Follow-Up All the patients inserted must be followed for at least 1 year even though an indefinite follow up of all patients continuing anticoagulation therapy is strongly recommended. If anticoagulation therapy is interrupted in single patients within 1 year of insertion the Participants must still continue to collect (even telephonically) data regarding the possible onset of complications (thrombotic, bleeding or other clinical events) for 1 year of follow-up.

Inclusion Criteria:

• age >= 18 years

Exclusion Criteria:

• < 18 years
• not willing to sign informed consent

Are included in the Registry patients who need chronic anticoagulation for atrial fibrillation, or venous thromboembolism, or heart valve diseases or prosthesis, or other clinical conditions requiring anticoagulation.

For the sampling method, participants are instructed to choose and declare one modality of inclusion for VKA treated patients: one week per month, or one day per week (always the same), etc. For patients treated with DOACs (low number in our country) it is recommended to include all patients progressively