Tissue factor pathway inhibitor antigen and activity in 96 patients receiving heparin for cardiopulmonary bypass.
OBJECTIVE
To identify patients with poor tissue factor pathway inhibitor (TFPI) response to heparin and observe any association with increased risk of excessive coagulation activation, morbidity, or mortality.


METHODS
Prospective, observational cohort study.


METHODS
University hospital.


METHODS
Patients (n = 96) undergoing cardiopulmonary bypass for various types of surgery.


METHODS
None.


RESULTS
TFPI antigen and activity were determined in patients before and after heparin administration, before cardiopulmonary bypass for cardiac surgery. The clinical progress of each patient was recorded. Median levels of TFPI activity were 0.98 U/mL (interquartile range, 0.83 to 1.14 U/mL) preheparin and 2.34 U/mL (2.18 to 2.54 U/mL) postheparin (p < 0.0001), representing a median 2.3-(2.1- to 2.8-) fold increase. Median TFPI antigen levels were 92.4 ng/mL (73.0 to 119.5 ng/mL) preheparin and 422.9 ng/mL (398.7 to 501.6 ng/mL) postheparin (p < 0.0001), representing a median 4.6-fold (3.6- to 6.2-fold) increase. Two patients had low (<300 ng/mL) postheparin levels of TFPI antigen that were not associated with low functional TFPI or adverse clinical outcome. Fourteen patients showed a low ratio of increased functional TFPI postheparin; all had a ratio of TFPI antigen increase of at least 3-fold.


CONCLUSIONS
The TFPI response to heparin is heterogenous. Two nonresponders were identified, with low postheparin levels of TFPI antigen, who did not suffer adverse clinical outcomes.
Adams
Murray J
MJ
Haematology Department, and Centre for Anaesthesia, University College London, London. United Kingdom.
Cardigan
Rebecca A
RA
Marchant
Warwick A
WA
Grocott
Michael P W
MP
Mythen
Monty G
MG
Mutch
Maj
M
Purdy
Gordon
G
Mackie
Ian J
IJ
Machin
Samuel J
SJ
D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000097:blood / Q000627:therapeutic use*; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D015331:Cohort Studies; D065427:Factor Xa Inhibitors; D005260:Female; D006493:Heparin / Q000097:blood / Q000627:therapeutic use*; D006801:Humans; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D008074:Lipoproteins; C051928:lipoprotein-associated coagulation inhibitor; D006493:Heparin