Original clinical science
High Incidence of Thromboembolic Events in Left Ventricular Assist Device Patients Treated With Recombinant Activated Factor VII

https://doi.org/10.1016/j.healun.2009.04.028Get rights and content

Background

Dosing of recombinant activated factor VII (rFVIIa) is controversial and unstandardized, and there is growing concern about thromboembolic complications, especially in left ventricular assist device (LVAD)-supported patients. We reviewed our experience with rFVIIa administration in patients with LVADs and examined its effectiveness and adverse effects, including the incidence of thromboembolic events and its correlation with increasing doses.

Methods

We retrospectively reviewed the records of 62 patients who received an LVAD and rFVIIa at our center between January 2004 and November 2006. Patients who received a single dose of 10 to 20 μg/kg (n = 32; 52%) constituted the “low-dose” cohort, and patients who received 30 to 70 μg/kg (n = 30; 48%) constituted the “high-dose” cohort. Laboratory values obtained before and after rFVIIa administration, as well as patients' transfusion requirements, were compared to determine the effectiveness of rFVIIa in reversing coagulopathy and reducing blood loss. We also compared the incidence of thromboembolic events in the low- and high-dose groups.

Results

Administration of rFVIIa was associated with significant decreases in prothrombin time, activated partial thromboplastin time and transfusion requirements. This association was seen in both the low- and high-dose groups. In addition, the incidence of thromboembolic events was significantly higher in the high-dose group (36.7%) than in the low-dose group (9.4%) (p ≤ 0.001).

Conclusions

Although rFVIIa administration seemed helpful in controlling life-threatening hemorrhage, patients requiring higher doses (30 to 70 μg/kg) had a dramatically higher incidence of serious thromboembolic events.

Section snippets

Methods

We retrospectively reviewed the records of LVAD patients who received rFVIIa for off-label use indications at St. Luke's Episcopal Hospital between January 2004 and November 2006. During this period, 188 patients underwent procedures involving one of the following LVADs: the Levitronix (n = 46), the HeartMate II (n = 41), the HeartMate I (n = 38), the AB 5000 (n = 31), the Jarvik 2000 (n = 20), the Thoratec VAD (n = 7), the Novacor LVAS (n = 3), the BVS 5000 (n = 1) or the MicroMed DeBakey VAD (

Results

Of the LVAD-related procedures performed on the 62 patients (51 men, 11 women; mean age 51 years [range 15 to 78 years]) (Table 1), 45 (72.6%) were device placements, 8 (12.9%) were biventricular assist device (BiVAD) placements, 7 (11.3%) were pump exchanges, and 2 (3.2%) were pump-pocket revisions. Twenty-four of the 62 procedures (38.7%) were “redo” operations, signifying increased surgical risk. Of all 62 patients, 41 (66.1%) received rFVIIa while in the operating room, 11 (17.7%) while in

Discussion

The mechanism by which rFVIIa arrests hemorrhage is thought to involve generating thrombin by initially binding to tissue factor and subsequently activating factors IX and X, which leads to accelerated prothrombin activation and localized thrombin formation. The end result is a stabilized thrombin plug and tight fibrin structure that is resistant to lysis. Recombinant activated factor VII is hypothesized to have other mechanisms of action that we do not fully understand today. In addition to

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