An overall amount of 638 patients was included.
Four hundred forty-nine patients were treated with permanent IVCFs and 189 with retrievable ones.
The number of filters placed over the years (Figure 1) showed a steady increase (p<0.0001).
The number of retrievable vena cava filters,
rather than the one of permanent,
significantly increased (p<0.0001).
During the interval 2010-2014 the application of these two types of device was balanced,
whereas just recently the retrievable filters became more prevalent.
Considering all risk factors and co-morbidities associated with VTE,
which may have influenced the selection of a retrievable or a permanent filter,
a significant association emerged only for patients’ age (Figure 2).
Indeed,
patients treated with retrievable filters were 10 years younger than those cured with a permanent filter (p<0.0001).
All other conditions such as the presence of tumor,
bleeding,
concomitant surgery,
or Ac failure,
didn’t show any significant statistical correlation.
A lack of knowledge about the most appropriate indications included in the reference guidelines regarding the management of VTE emerged.
For instance,
referring to the guidelines of the American College of Chest Physicians (ACCP) [7],
the use of IVCF proved to be off label in 25% of cases,
because there were no absolute contraindications concerning the anticoagulation or even there was a contemporary use of IVCF and anticoagulant therapy.
Moreover,
we found no benefit as a result of the association between IVCF and Ac therapy (Figure 3): the recurrence rate of VTE proved to be even lower in patients with an IVCF alone than the ones with associated Ac therapy (p=0.0492),
probably due to the use of inadequate therapeutic dose range.
The association of Ac therapy not only has not proved to be an efficient tool for preventing VTE recurrence,
but may even expose to an increased risk of bleeding (p=0.0835) (Figure 4).
Finally,
the safety of IVCF was investigated analyzing the device-related complications occurring during the in-situ period or associated with its placement and removal.
Complications during the positioning,
such as tilting,
tear of the vena cava or misplacement,
occurred in 6.25% of the cases when a permanent filters was used and in 11.97% of the patients when retrievable filters were applied.
Even if in our population the latter showed almost a twofold rate,
it can still be considered acceptable since all these complications were never followed by clinically relevant consequences.
During the in-situ period,
complications such as tilting (greater than 15 degrees),
migration (more than 2 cm),
perforation (greater than 3 mm),
loss of integrity of the filter,
fragment embolization or thrombosis,
occurred in 6.49% of the cases for permanent IVCF,
which is a significantly lower value than the ones recorded for retrievable filters (50.88%; p<0.0001) (Figures 5-6).
These complications,
albeit without any relevant clinical consequence,
lead to an increased difficulty in the removal procedure for retrievable filters,
sometimes requiring a double venous access (i.e.,
both femoral and jugular).
Relevant complications such as filter fracture (3 cases),
embolization of its fragments (2 cases) or filter closure with IVC thrombosis (1 case) (Figures 6-7) mainly occurred with old models of IVCF,
which are no longer in use.
Concerning the removal of the filters,
the retrievable IVCF showed a rate of complications similar to the positioning (12.73%).