title: Thrombotic tendency in 75 symptomatic, unrelated patients with APC resistance.
abstract: Resistance to activated protein C (APC resistance) was measured in 284 individuals (169 females, 115 males) with a history of objectively confirmed venous thrombosis and/or pulmonary embolism. A decreased APC resistance ratio was found in 75 patients (26%), 47 were females, 28 males. Factor V Leiden was investigated in 60 of 75 patients with APC resistance, of whom 46 were heterozygous, 4 homozygous. In 10 APC resistant patients the Arg 506 Glu mutation was not identified. The median age of the first thromboembolic event in patients with APC resistance was 42 years (range 15-82 years). Most patients had a history of deep vein thrombosis (83%), 28% had experienced pulmonary embolism. More unusual sites of thrombosis were the deep arm veins (7%) and mesenteric veins (one patient, 1.3%). 53% of patients developed the first thromboembolic event spontaneously. Precipitating conditions for thromboembolism were surgery in 9.3% and trauma in 8%. In one third of female patients the first thromboembolic event occurred in conjunction with pregnancy and delivery (14.8%) or oral contraceptives (19%). At the time of investigation 40% of patients with APC resistance had experienced recurrent thromboembolic events. The family history was positive in 60% of patients. We conclude that the clinical feature of APC resistance is similar to the feature of a deficiency of antithrombin, protein C and protein S. Pregnancy, delivery and oral contraceptives seem to be a relevant additional risk factors for thrombosis in females with APC resistance.
authors.affiliation: First Department of Medicine, University of Vienna.
authors.forename: M
authors.initials: M
authors.lastname: Melichart
authors.forename: P A
authors.initials: PA
authors.lastname: Kyrle
authors.forename: S
authors.initials: S
authors.lastname: Eichinger
authors.forename: C
authors.initials: C
authors.lastname: Rintelen
authors.forename: C
authors.initials: C
authors.lastname: Mannhalter
authors.forename: I
authors.initials: I
authors.lastname: Pabinger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001779:Blood Coagulation Factors; D001780:Blood Coagulation Tests; D003276:Contraceptives, Oral / Q000008:administration & dosage / Q000009:adverse effects; D005165:Factor V / Q000235:genetics*; D005260:Female; D006580:Genetic Carrier Screening; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood / Q000175:diagnosis; D011486:Protein C / Q000235:genetics*; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D011956:Receptors, Cell Surface / Q000235:genetics*; D012307:Risk Factors; D013924:Thrombophlebitis / Q000097:blood / Q000175:diagnosis / Q000235:genetics*
chemical_list: D001779:Blood Coagulation Factors; D003276:Contraceptives, Oral; D011486:Protein C; D011956:Receptors, Cell Surface; C091963:activated protein C receptor; C095381:factor V Leiden; D005165:Factor V