Impaired plasma clot lysis and its determinants in patients with obstructive sleep apnea syndrome.

Evidence indicates that hypercoagulability and impaired fibrinolysis have been observed in patients with obstructive sleep apnea syndrome (OSAS). It is unclear which factors determine prolonged fibrin clot lysis in OSAS. One hundred and sixty-five consecutive patients suspected of OSAS underwent overnight polysomnography. Prior to polysomnography, we determined plasma clot lysis time (CLT), plasminogen activator inhibitor (PAI)-1 antigen, activated thrombin-activatable fibrinolysis inhibitor (TAFIa), plasmin, and antiplasmin. OSAS was diagnosed in 110 (66.7%) patients, including 35 (31.8%) with severe OSAS, 26 (23.6%) with moderate OSAS, and 49 (44.6%) mild OSAS. Compared with 55 (33.3%) individuals in whom OSAS was not confirmed, OSAS patients had prolonged CLT (+12.8%), associated with higher PAI-1 antigen (+18.1%) (after adjustment for age, diabetes, and body mass index; both P < 0.01) and similar levels of TAFIa, plasmin, or antiplasmin. PAI-1, TAFIa, and CLT correlated positively with apnea/hypopnea index, which reflects the severity of OSAS (R = 0.66, P < 0.001; R = 0.29, P = 0.002; R = 0.55, P = 0.001, respectively), and with other polysomnography parameters, with the most potent correlations observed for desaturation index. Regression analysis adjusted for potential confounders showed that in OSAS, CLT was independently predicted by apnea/hypopnea index (B = 0.29, P = 0.002), PAI-1 (B = 0.42, P < 0.001), and TAFIa (B = 0.81, P = 0.044), whereas both PAI-1 and TAFIa were predicted only by desaturation index (B = 0.24, P = 0.002; and B = 0.14, P = 0.001, respectively). The severity of OSAS is closely associated with hypofibrinolysis measured in a global plasma-based assay, driven largely by PAI-1. Attenuated fibrinolysis might contribute to high risk of thromboembolic events in this disease.

Exercise stress testing enhances blood coagulation and impairs fibrinolysis in asymptomatic aortic valve stenosis.

BACKGROUND: Increased thrombin formation and fibrin deposition on the valves were observed in patients with severe aortic valve stenosis (AS). Exercise enhances blood coagulation and fibrinolysis in healthy subjects, but its haemostatic effects in AS are unknown. We sought to investigate how stress echocardiography alters blood coagulation and fibrinolysis in AS patients free of significant atherosclerotic vascular disease. METHODS: We studied 32 consecutive asymptomatic moderate-to-severe AS patients and 32 age- and sex-matched controls. We measured peak thrombin generated using calibrated automated thrombogram, clot lysis time (CLT), and fibrinolytic markers at four time points, i.e. at rest, at peak exercise, and 1h and 24h after a symptom-limited exercise test. RESULTS: We observed that peak thrombin generated rose at peak exercise to 25% higher value in the patients than in controls (p<0.001) and reached its highest level 24h from exercise in AS patients while it decreased post-exercise in controls. Baseline CLT was 13% longer in AS patients (p=0.006) and associated with thrombin activatable fibrinolysis inhibitor (TAFI) activity (r=0.69, p<0.001), antiplasmin (r=0.47, p=0.007), and plasminogen (r=-0.55, p=0.001). In AS, CLT remained unaltered at peak exercise, while it decreased in controls, yielding the intergroup difference of 28% (p<0.001). Twenty-four hours after exercise CLT became 15% longer in AS patients (p<0.001). This hypofibrinolytic effect followed a similar pattern observed for TAFI activity. CONCLUSIONS: Asymptomatic moderate-to-severe AS patients respond to exercise with more pronounced and prolonged increase in thrombin generation, together with impaired fibrinolysis as compared to controls. Repeated episodes of exercise-induced prothrombotic state in AS might contribute to the progression of this disease.

Prolonged duration of type 2 diabetes is associated with increased thrombin generation, prothrombotic fibrin clot phenotype and impaired fibrinolysis.

It has been shown that type 2 diabetes (DM) is associated with enhanced thrombin generation and formation of denser fibrin clots of reduced lysability. We sought to investigate the impact of diabetes duration versus glycaemia control on fibrin clot phenotype and its determinants in type 2 diabetic patients. In 156 consecutive Caucasian patients with type 2 diabetes we investigated ex vivo thrombin generation, fibrinolytic proteins, along with plasma fibrin clot permeation (Ks), compaction, turbidity, and efficiency of tissue plasminogen activator (t-PA)-mediated fibrinolysis. Patients with longer diabetes duration (>5 years, median; n=68) had higher peak thrombin generation (+16.3%, p<0.001), plasminogen activator inhibitor-1 (PAI-1) antigen (+14.8%, p=0.001), t-PA antigen (+13.9%, p=0.002) compared with those with duration ≤5 years (n=88). No such differences were observed between patients with inadequate glycaemic control, defined as glycated haemoglobin (HbA1C) >6.5% (48 mmol/mol) (n=77), versus those with HbA1C≤6.5% (n=79). Fibrinogen, thrombin-activatable fibrinolysis inhibitor antigen, plasminogen and soluble thrombomodulin were unaffected by disease duration or glycaemia control. Lower clot permeability, longer clot lysis, and higher maximum D-dimer levels released from clots (all p<0.05 after adjustment for fibrinogen, age, body mass index, insulin, acetylsalicylic acid treatment, and HbA1c or diabetes duration) were also observed in patients with diabetes duration >5 years and those with HbA1C>6.5%. We conclude that prolonged duration of type 2 diabetes is associated with increased thrombin formation, hypofibrinolysis, and prothrombotic fibrin clot phenotype. The impact of disease duration on coagulation is different and stronger than that observed during inadequate glycaemia control.

Lipoprotein-associated phospholipase A2 is elevated in patients with severe aortic valve stenosis without clinically overt atherosclerosis.

BACKGROUND: Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory mediator involved in atherosclerosis. Since aortic valve stenosis (AVS) is regarded as an atherosclerosis-like inflammatory disease, we sought to investigate whether AVS is associated with elevated Lp-PLA2. METHODS: Plasma Lp-PLA2 levels were determined in 48 consecutive patients with severe AVS without atherosclerotic vascular disease and compared with the values obtained in 48 controls matched for age, sex and cardiovascular risk factors. RESULTS: Lp-PLA2 was higher in AVS than in controls (242.3±50.4 vs. 151.9±28.1 ng/mL, p<0.0001). Lp-PLA2 correlated inversely with aortic valve area (AVA) (r=-0.53; p=0.0001) and positively with mean pressure gradient (PG) (r=0.32; p=0.029). In multivariable analysis C-reactive protein (CRP) (OR=1.42; 95% CI 0.95-2.1; p=0.09) and AVA (OR=0.003; 95% CI 0.00004-0.23; p<0.01) were independently associated with Lp-PLA2 above a mean of 242 ng/mL. After adjustment for CRP, AVA was the only independent predictor of Lp-PLA2 in AVS patients (p<0.001). CONCLUSIONS: This study is the first to show that AVS is characterized by increased plasma Lp-PLA2 levels associated with the severity of AVS, which suggests active involvement of Lp-PLA2 in the pathogenesis of AVS.