Plasma levels of microparticle-associated tissue factor activity in patients with clinically suspected pulmonary embolism.
BACKGROUND
Microparticles (MPs) carrying active tissue factor (TF) have been detected in the plasma of cancer patients in particular in those presenting with acute deep vein thrombosis (DVT) or pulmonary embolism (PE). Experimental studies in mice have revealed that circulating MPs carrying TF contribute to thrombus formation.


OBJECTIVE
To study whether unselected patients with an acute confirmed PE have elevated TF activity in the MP fraction (MP-TF activity).


METHODS
Plasma MP-TF activity was measured in 159 non-selected patients with clinically suspected PE and in 48 healthy controls as previously described. Blood was collected at time of inclusion. The diagnosis of acute PE was confirmed in 54 patients and excluded in 105 patients.


RESULTS
Median MP-TF activity in 159 patients with clinically suspected PE was 72 fM Xa/min [range 32-6657] fM Xa/min and higher than in healthy controls (66 [range 28-183] fM Xa/min; P<0.05). There was no significant difference (P=0.169) in MP-TF activity between patients with confirmed PE (median 84.5 fM Xa/min [range 36-2149]) and patients without PE (72 fM Xa/min [range 32-6657]) fM Xa/min). In the 159 patients with clinically suspected PE we observed in an exploratory analysis higher MP-TF activity levels in patients with active cancer (median 137 fM Xa/min [range 36-6657]) and cardiovascular disease (median 131.5 fM Xa/min [range 45-2149]) than in patients without these disorders (P=0.0004 and P=0.014, respectively).


CONCLUSIONS
In patients presenting with clinically suspected PE plasma MP-TF activity was not associated with confirmed PE.
Garcia Rodriguez
P
P
Department of Clinical Oncology, Leiden University Medical Center, Leiden, The Netherlands.
Eikenboom
H C J
HC
Tesselaar
M E T
ME
Huisman
M V
MV
Nijkeuter
M
M
Osanto
S
S
Bertina
R M
RM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000097:blood* / Q000175:diagnosis; D013925:Thromboplastin / Q000378:metabolism*; D055815:Young Adult
D013925:Thromboplastin