The purpose of a caval filter is to prevent pulmonary embolism in patients with deep vein thrombosis in patients who have an absolute and temporary contraindication to anticoagulant therapy.
The long-term complications of a permanent filter are different: recurrence of DVT, fractures and migrations of the filter, penetration into the vena cava. Leaving a filter in place does not change the patient's long-term mortality; therefore, the current indications are to implant temporary caval filters, to be removed as soon as possible.
In clinical practice, however, some filters are difficult to recover for technical reasons and the filter is left in place because the patient is too old or too much time has passed since the implant. In these cases, the clinician is prompted to continue with anticoagulant therapy even if the thromboembolic event was secondary in nature.
This multi-center retrospective study evaluates the follow-up of patients with permanent vascular filters in which anticoagulation therapy was continued.
195 patients with permanent filters, over half of whom with cancer, were followed for about 5 years. Almost 90% of these patients were treated with oral anticoagulation. The control group, in which the vascular filter was removed, had a cancer prevalence of 38% and only 20% of these patients had been placed on anticoagulant therapy for an extended period. From the analyzes it emerges that the main cause of death was linked to the underlying neoplastic pathology.
Thromboembolic relapses in patients on anticoagulant therapy occurred in only 6 patients. Two patients had major thrombophilia (AT III deficiency and anti-phospholipid antibody syndrome); one patient had stopped anticoagulation due to a bleeding event; in four patients the INR was not in the therapeutic range or there was poor adherence to therapy.
The vena cava filter poses a risk for recurrent DVT and may be a reason to continue anticoagulation. From the data of this study it emerges that anticoagulation therapy effectively reduces the number of thromboembolic relapses compared to previous studies.
Interestingly, 37 patients with vena cava were being treated with DOAC and no complications related to thrombosis of the filter were reported. Indeed, the constant level of anticoagulation, greater adherence and lower risk of bleeding compared to warfarin would make them suitable drugs for extended therapy, even if the presence of a caval filter was an exclusion factor for DOACs registration studies.
We await the outcome of the ongoing trial that is comparing rivaroxaban and warfarin in patients with caval filter, even if the progressive reduction of the implants of these devices does not give us hope for results in the short term.