Jan-Leendert P. Brouwer

Selective testing for thrombophilia in patients with first venous thrombosis: results from a retrospective family cohort study on absolute thrombotic risk for currently known thrombophilic defects in 2479 relatives

Thrombophilia screening is controversial. In a retrospective family cohort, where probands had thrombosis and a thrombophilic defect, 2479 relatives were tested for thrombophilia. In antithrombin-, protein C-, and protein S-deficient relatives, annual incidences of venous thrombosis were 1.77% (95% CI, 1.14-2.60), 1.52% (95% CI, 1.06-2.11), and 1.90% (95% CI, 1.32-2.64), respectively, at a median age of 29 years and a positive family history of more than 20% symptomatic relatives. In relatives with factor V (FV) Leiden, prothrombin 20210G>A, or high FVIII levels, these were 0.49% (95% CI, 0.39-0.60), 0.34% (95% CI, 0.22-0.49), and 0.49% (95% CI, 0.41-0.51), respectively. High FIX, FXI, and TAFI, and hyperhomocysteinemia were not independent risk factors. Annual incidence of major bleeding in antithrombin-, protein C-, or protein S-deficient relatives on anticoagulants was 0.29% (95% CI, 0.03-1.04). Cumulative recurrence rates in relatives with antithrombin, protein C, or protein S deficiency were 19% at 2 years, 40% at 5 years, and 55% at 10 years. In relatives with FV Leiden, prothrombin 20210G>A, or high levels FVIII, these were 7%, 11%, and 25%, respectively. Considering its clinical implications, thrombophilia testing should address hereditary deficiencies of antithrombin, protein C, and protein S in patients with first venous thrombosis at young age and/or a strong family history of venous thrombosis.

High Absolute Risks and Predictors of Venous and Arterial Thromboembolic Events in Patients With Nephrotic Syndrome Results From a Large Retrospective Cohort Study

Background— No data are available on the absolute risk of either venous thromboembolism (VTE) or arterial thromboembolism (ATE) in patients with nephrotic syndrome. Reported risks are based on multiple case reports and small studies with mostly short-term follow-up. We assessed the absolute risk of VTE and ATE in a large, single-center, retrospective cohort study and attempted to identify predictive factors in these patients. Methods and Results— A total of 298 consecutive patients with nephrotic syndrome (59% men; mean age, 42±18 years) were enrolled. Mean follow-up was 10±9 years. Nephrotic syndrome was defined by proteinuria ≥3.5 g/d, and patients were classified according to underlying histological lesions accounting for nephrotic syndrome. Objectively verified symptomatic thromboembolic events were the primary study outcome. Annual incidences of VTE and ATE were 1.02% (95% confidence interval, 0.68 to 1.46) and 1.48% (95% confidence interval, 1.07 to 1.99), respectively. Over the first 6 months of follow-up, these rates were 9.85% and 5.52%, respectively. Proteinuria and serum albumin levels tended to be related to VTE; however, only the predictive value of the ratio of proteinuria to serum albumin was significant (hazard ratio, 5.6; 95% confidence interval, 1.2 to 26.2; P=0.03). In contrast, neither the degree of proteinuria nor serum albumin levels were related to ATE. Sex, age, hypertension, diabetes, smoking, prior ATE, and estimated glomerular filtration rate predicted ATE (P≤0.02). Conclusions— This study verifies high absolute risks of symptomatic VTE and ATE that were remarkably elevated within the first 6 months. Whereas the ratio of proteinuria to serum albumin predicted VTE, estimated glomerular filtration rate and multiple classic risk factors for atherosclerosis were predictors of ATE.

High long-term absolute risk of recurrent venous thromboembolism in patients with hereditary deficiencies of protein S, protein C or antithrombin

Hereditary deficiencies of protein S, protein C and antithrombin are known risk factors for first venous thromboembolism. We assessed the absolute risk of recurrence, and the contribution of concomitant thrombophilic defects in a large cohort of families with these deficiencies. Annual incidence of recurrence was estimated in 130 deficient patients, with separate estimates for those with each of protein S, protein C, and antithrombin deficiency, and in eight non-deficient patients with prior venous thromboembolism. All patients were also tested for factor V Leiden, prothrombin G20210A, high levels of factors VIII, IX and XI, and hyperhomocysteinemia. There were 81 recurrent events among 130 deficient patients. Median follow-up was 4.6 years. Annual incidences (95% confidence interval) of recurrent venous thromboembolism were 8.4% (5.8-11.7) for protein S deficiency, 6.0% (3.9-8.7) for protein C deficiency, 10.0% (6.1-15.4) for antithrombin deficiency, and overall 7.7% (6.1-9.5). Relative risk of recurrence in patients with a spontaneous versus provoked first event was 1.5 (0.95-2.3). Cumulative recurrence rates at 1, 5 and 10 years were 15%, 38% and 53%. Relative risk of recurrence with concomitant defects was 1.4 (0.7-2.6) (1 defect) and 1.4 (0.8-2.7) (> or =2 defects). Annual incidence was 1.0% (0.03-5.5) in eight non-deficient patients. Annual incidence of major bleeding in deficient patients on oral anticoagulant treatment was 0.5% (0.2-1.0). We conclude that patients with a hereditary protein S, protein C or antithrombin deficiency appear to have a high absolute risk of recurrence. This risk is increased after a first spontaneous event, and by concomitance of other thrombophilic defects.

Hereditary Deficiency of Protein C or Protein S Confers Increased Risk of Arterial Thromboembolic Events at a Young Age Results From a Large Family Cohort Study

Background— Whether hereditary protein S, protein C, or antithrombin deficiency is associated with arterial thromboembolism (ATE) and whether history of venous thromboembolism in these subjects predisposes them to subsequent ATE have yet to be determined. Methods and Results— On the basis of pedigree analysis, we enrolled a total of 552 subjects (52% women; mean age, 46±17 years), belonging to 84 different kindreds, in this retrospective family cohort study. Detailed information on previous episodes of venous thromboembolism, ATE, anticoagulant use, and atherosclerosis risk factors was collected. Primary study outcome was objectively verified symptomatic ATE. Of 552 subjects, 308 had protein S (35%), protein C (39%), or antithrombin (26%) deficiency. Overall, annual incidences of ATE were 0.34% (95% confidence interval [CI], 0.23 to 0.49) in deficient versus 0.17% (95% CI, 0.09 to 0.28) in nondeficient subjects; the hazard ratio was 2.3 (95% CI, 1.2 to 4.5). Because the risk hazards varied over lifetime, we performed a time-dependent analysis. After adjusting for atherosclerosis risk factors and clustering within families, we found that deficient subjects had a 4.7-fold (95% CI, 1.5 to 14.2; P=0.007) higher risk for ATE before 55 years of age versus 1.1 (95% CI, 0.5 to 2.6) thereafter compared with nondeficient family members. For separate deficiencies, the risks were 4.6- (95% CI, 1.1 to 18.3), 6.9- (95% CI, 2.1 to 22.2), and 1.1- (95% CI, 0.1 to 10.9) fold higher in protein S–, protein C–, and antithrombin-deficient subjects, respectively, before 55 years of age. History of venous thromboembolism was not related to subsequent ATE (hazard ratio, 1.1; 95% CI, 0.5 to 2.2). Conclusions— Compared with nondeficient family members, subjects with protein S or protein C deficiency but not antithrombin deficiency have a higher risk for ATE before 55 years of age that is independent of prior venous thromboembolism.

The Pathogenesis of Venous Thromboembolism: Evidence for Multiple Interrelated Causes

Context Venous thromboembolism (VTE) is thought to arise from the interaction of environmental and genetic factors in persons predisposed to VTE. Contribution The authors studied persons with protein S, protein C, or antithrombin deficiency who were first-degree relatives of persons who had VTE. They assessed each relative for environmental exposures and additional thrombophilic defects. They found that risk for VTE increased with the number of defects and with exposure to environmental risk factors. Cautions The findings were not based on the total population of relatives. The authors could not quantify risk for interactions between specific defects and environmental risk factors. Implications The risk for VTE increases with the number of thrombophilic defects and environmental risk factors in persons with a hereditary predisposition to VTE. The study provides evidence that VTE arises from interactions between environmental and genetic risk factors and quantifies the risks. The Editors Venous thromboembolism (VTE) has an incidence of 0.1 to 0.2 per 100 person-years (1, 2). It has been speculated that the development of VTE results from interactions between multiple genetic and environmental risk factors (3). Several inherited or acquired coagulation defects have been identified as VTE risk factors over the past 30 years. Known thrombophilic defects include hereditary deficiencies of protein S, protein C, and antithrombin; factor V Leiden; the prothrombin G20210A mutation; high levels of coagulant factors VIII, IX, and XI; hyperhomocysteinemia; and antiphospholipid antibodies (4). Whether patients with VTE and their relatives should be tested for all of these defects is still debatable. Clinical implications mainly depend on the absolute risk for a first or recurrent episode of VTE in persons with a single defect or in those with a combination of defects. Most common defects are mild risk factors for VTE. In contrast, hereditary deficiencies of protein S, protein C, and antithrombin are strong risk factors but are rare. Although interactions between these deficiencies and 1 or more other thrombophilic defects might increase the risk for VTE, they cannot be studied easily because the prevalence of such combinations is low. Thus far, only a few studies have reported the risk for VTE associated with coinheritance of deficiencies of protein S, protein C, or antithrombin and factor V Leiden or the prothrombin G20210A mutation (510). The results were not consistent, possibly because of small numbers of cases. We performed a retrospective study to assess the contribution of currently known hereditary thrombophilic defects and exogenous risk factors to the absolute risk for VTE in a large series of protein S, protein C, or antithrombin-deficient families. Methods We aimed to assess interactions between known thrombophilic deficiencies and defects, including hereditary deficiencies of protein S, protein C, and antithrombin. Because these deficiencies are strong risk factors for VTE, the effects and clinical impact of interactions with more prevalent and mild thrombophilic defects may be more pronounced than interactions between mild defects. To enroll sufficient numbers of affected persons needed for accurate risk estimates, we identified families with these rare deficiencies. The family cohort study design enabled us to assess the clinical impact of interactions from absolute risk estimates. Participants The study comprised 3 cohorts of families with hereditary deficiencies of protein S, protein C, or antithrombin. Probands were consecutive patients with VTE who had 1 of these deficiencies. Primary care physicians referred patients with clinically suspected VTE to 1 of 2 hospitals in our region of the Netherlands; 50% were referred to the thrombosis outpatient clinic of our university hospital. Previous clinical trials did not show differences between patients who were referred to either hospital for this reason. Because it is common practice in the Netherlands to confirm suspected VTE, the proportion of patients who were not referred was probably small. All patients who had VTE confirmed at our outpatient clinic were tested for protein S, protein C, or antithrombin deficiencies, unless they had extensive malignant disease. After a deficiency was established by repeated measurement and after causative acquired conditions were excluded, the patients first-degree relatives who were older than age 15 years were identified by pedigree analysis and were contacted through the probands. Because the number of antithrombin-deficient probands was small, second-degree relatives with a deficient parent were also identified. Relatives were assessed for deficiency at the time of identification and then were followed for thromboembolic events from age 15 years to the time of testing. All participants provided informed consent. Physicians at our outpatient clinic collected detailed information about previous episodes of VTE, exposure to exogenous risk factors for VTE, and anticoagulant treatment using a validated questionnaire (11) and by reviewing medical records. The use of oral contraceptives and an obstetric history were documented for women. Blood samples were taken after clinical data had been collected. All relatives were tested for 10 thrombophilic deficiencies and defects in addition to their index deficiencies, including deficiencies of protein S, protein C, antithrombin, and plasminogen; factor V Leiden; prothrombin G20210A; high levels of factors VIII, IX, and XI; hyperhomocysteinemia; and lupus anticoagulant. Diagnosis of VTE Venous thromboembolism was considered established if deep venous thrombosis was confirmed by compression ultrasonography or venography, and pulmonary embolism was confirmed by ventilationperfusion lung scanning, spiral computed tomography scanning, or pulmonary angiography. When these techniques were not yet available, VTE was considered established when the patient had received full-dose unfractionated heparin and a vitamin K antagonist for at least 3 months. Venous thromboembolism was considered secondary if it had occurred at or within 3 months after exposure to exogenous risk factors, including major surgery, trauma, immobilization for more than 7 days, oral contraceptives, hormone replacement therapy, pregnancy, and malignant disease. In the absence of these risk factors, VTE was considered primary. Laboratory Studies Protein S and protein C antigen levels were measured by enzyme-linked immunosorbent assay (Dako, Glostrup, Denmark); activity of protein C (Berichrom Protein C, Dade Behring, Marburg, Germany), antithrombin (Coatest, Chromogenix AB, Mlndal, Sweden), and plasminogen (S2251, Chromogenix AB) was measured by chromogenic substrate assays. Levels of protein S, protein C, and antithrombin were expressed as a percentage of the levels measured in pooled plasma set at 100%. Normal ranges were determined in 393 healthy blood donors who had no family history of VTE, were not pregnant, and had not used oral contraceptives for at least 3 months. Protein S deficiency type I was defined by decreased free and total protein S levels, that is, below normal ranges, and protein S deficiency type III was defined by decreased free protein S levels and normal total protein S levels. After we had demonstrated that type III protein S deficiency was not a risk factor for thrombosis, families with this deficiency were excluded from the analysis (12). Protein C deficiency type I and type II were defined by decreased levels or activity of protein C antigen, and antithrombin deficiency was defined by decreased levels of antithrombin activity. Deficiencies were considered inherited if they were confirmed by measuring a second sample that was collected 3 months later and were found in at least 2 family members. Relatives with acquired conditions were excluded. If there was a discrepancy between the results of the 2 tests, a third sample was tested. A deficiency was considered acquired, through use of oral contraceptives or pregnancy, unless it was confirmed at least 3 months after withdrawal of oral contraceptives or delivery, respectively. Factor V Leiden and the prothrombin G20210A mutation were demonstrated by polymerase chain reaction (13, 14). Factors VIII:C, IX:C, and XI:C were measured by 1-stage clotting assays (Amelung GmbH, Lemgo, Germany) and were increased at levels above 150%. Lupus anticoagulant was defined by abnormal values of dilute Russell viper venom time, activated partial thromboplastin time, and tissue thromboplastin inhibition, which normalized by adding phospholipids to the participants plasma (15). Fasting and postmethionine-loading levels of homocysteine were measured by high-performance liquid chromatography (16). Hyperhomocysteinemia was defined as a fasting homocysteine level above 18.5 mol/L, a postloading level above 58.8 mol/L, or both, as described in a Dutch population (17). Blood samples were collected from probands and relatives at least 3 months after VTE. If probands or relatives were receiving long-term treatment with vitamin K antagonists, samples were taken after treatment had been interrupted for at least 2 weeks; in the meantime, nadroparin was given subcutaneously. Additional tests were performed on plasma stored at80C from relatives who had been enrolled at a time when 1 of more of these deficiencies or defects had not yet been recognized as risk factors for VTE. Statistical Analysis We compared the absolute risk for VTE in deficient and nondeficient relatives in each of the 3 cohorts and in the pooled cohorts. Probands were excluded from the analysis to avoid selection bias. Annual incidences were calculated by dividing the number of symptomatic relatives by the total number of observation-years. Ninety-five percent CIs were calculated around the incidence rates by using the Poisson distribution assumption. Observation time was defined as the period from age 15 yea

Heart rate variability in left ventricular dysfunction and heart failure: effects and implications of drug treatment.

OBJECTIVE--To review the importance of heart rate variability analysis in left ventricular dysfunction and heart failure and to assess the effects of drug treatment. In patients with left ventricular dysfunction or heart failure, a low heart rate variability is a strong predictor of a low probability of survival. Because drug treatment in these patients has rapidly changed over the past two decades, the effect of these drugs on heart rate variability needs special attention. DESIGN--A study of published reports to give an overview of heart rate variability in patients with left ventricular dysfunction or heart failure and how it is affected by drug treatment. RESULTS--Analysis of heart rate variability provides an easily obtained early marker for progression of disease. It seems to be more closely related to the degree of neurohumoral activation than to haemodynamic variables. Cardiovascular drugs may either stimulate or inhibit the degree of neurohumoral activation, and the effects of pharmacological intervention can be closely monitored with this method. CONCLUSIONS--The analysis of heart rate variability, including spectral analysis, is a novel non-invasive way to obtain potentially useful clinical information in patients with reduced left ventricular function. The effects of drug treatment on heart rate variability are in general consistent with their long-term effects in left ventricular dysfunction and heart failure.

Difference in absolute risk of venous and arterial thrombosis between familial protein S deficiency type I and type III. Results from a family cohort study to assess the clinical impact of a laboratory test‐based classification

Hereditary protein S (PS) deficiency type I is an established risk factor for venous thromboembolism. Contradictionary data on type III deficiency suggests a difference in risk between both types. We studied 156 first degree relatives (90% of eligible relatives) from type I deficient probands (cohort 1) and 268 (88%) from type III deficient probands (cohort 2) to determine the absolute risk of venous and arterial thromboembolism. Annual incidences of venous thromboembolism were 1·47 and 0·17 per 100 person‐years in deficient and non‐deficient relatives in cohort 1 [relative risk (RR) 8·9; 95% confidence interval (CI) 2·6–30·0], and 0·27 vs. 0·24 in cohort 2 (RR 0·9; 95% CI 0·4–2·2). Type III deficiency was demonstrated in 20% of non‐deficient relatives in cohort 1 and the annual incidence in this subgroup was 0·70 (RR 4·3;0·95–19·0). The cut‐off level of free PS to identify subjects at risk was 30%, the lower limit of its normal range (65%). PS deficiency was not a risk factor for arterial thromboembolism. In conclusion, type I deficiency was found to be a strong risk factor for venous thromboembolism, in contrast with type III deficiency. This was because of lower free PS levels in type I deficient subjects and a free PS cut‐off level far below the lower limit of its normal range.

The risk of venous and arterial thrombosis in hyperhomocysteinemic subjects may be a result of elevated factor VIII levels.

In a large retrospective study of thrombophilic families, we analyzed 405 relatives of patients, hypothesizing that hyperhomocysteinemia and elevated factor VIII levels are closely related. Median factor VIII levels in hyperhomocysteinemic relatives were 169 IU/dL, compared with 136 IU/dL in normohomocysteinemic relatives (p =0.007), and were more often elevated (>150 IU/dL; p =0.006). Hyperhomocysteinemia was associated with an increased risk of venous and arterial thrombosis; relative risk (RR) 2.6 (CI 1.3–4.8) and 3.7 (CI 1.5–8.4) respectively. Relatives with elevated FVIII were also at risk; RR 2.3 (CI 1.4–4.0) for venous thrombosis and 2.3 (CI 1.0–5.1) for arterial thrombosis. After excluding all relatives with elevated factor VIII, RR for hyperhomocysteinemia and venous thrombosis dropped to 1.3 (CI 0.2–9.8) and no relatives had arterial thrombosis. We conclude that it is likely that the increased risk of venous and arterial thrombosis in hyperhomocysteinemia is mainly related to elevated FVIII levels.

Interaction of Hereditary Thrombophilia and Traditional Cardiovascular Risk Factors on the Risk of Arterial Thromboembolism: Pooled Analysis of Four Family Cohort Studies

Background—Hereditary thrombophilia is associated with a slightly increased risk of arterial thromboembolism (ATE). Whether hereditary thrombophilia interacts with traditional cardiovascular risk factors on the risk of ATE has yet to be established. Methods and Results—A total of 1891 individuals belonging to 4 family cohorts from the Netherlands were included in the analyses. Five hereditary thrombophilic defects, including factor V Leiden, prothrombin G20210A defect, and deficiencies of the natural anticoagulants (ie, antithrombin, protein C, and protein S), were assessed, and data on risk factors and previous ATE were collected. Thrombophilia was associated with elevated risk of ATE (hazard ratio =1.74, 95% confidence interval, 1.18–2.58; P=0.005). Overall, the association of thrombophilia with ATE tended to be stronger in the presence of traditional cardiovascular risk factors, especially the synergistic effect of thrombophilia with diabetes mellitus was striking (hazard ratio of thrombophilia–ATE association was 1.41 in nondiabetics versus 8.11 in diabetics). Moreover, the association of thrombophilia with ATE tended to be stronger in females and before the age of 55 years as compared with males and individuals >55 years of age, respectively. Conclusions—Thrombophilia is associated with ATE. This association may be stronger in the presence of traditional cardiovascular risk factors in particular in individuals with diabetes mellitus. Future studies on thrombophilia–ATE risk should focus on high-risk populations with high prevalence of traditional cardiovascular risk factors.

Hemodynamic and autonomic effects of intravenous saterinone in patients with chronic heart failure

In this study, the hemodynamic and neurohumoral/autonomic effects of intravenous saterinone (a selective phosphodiesterase type III inhibitor, with additional alpha 1-blocking properties) were evaluated. In a double-blind, placebo-controlled design, 36 patients with moderate to severe heart failure were studied (saterinone, n = 24; placebo, n = 12). Invasive hemodynamic measurements, by using right-heart catheterization, were performed, as well as measurement of plasma neurohormones and analysis of heart rate variability (HRV), to study drug influences on neurohumoral activation and autonomic tone. Systemic vascular resistance significantly decreased during saterinone infusion, accompanied by a decrease in systemic blood pressure (both p values < 0.05) and an increase in heart rate (p = 0.05). Filling pressures also decreased during saterinone, but this was statistically significant only for pulmonary capillary wedge pressure, whereas the cardiac index remained unaffected. Plasma neurohormones (norepinephrine, epinephrine, and renin activity) were not significantly influenced by saterinone. HRV analysis revealed no significant effect of saterinone on autonomic tone. These results suggest that intravenous saterinone has a significant vasodilating effect in patients with moderate to severe chronic heart failure (CHF), without exerting an adverse effect on the autonomic nervous system, as demonstrated by assessment of plasma neurohormones and HRV analysis.