Monitoring antihypertensive drug concentrations to determine nonadherence in hypertensive patients with or without a kidney transplant.

BACKGROUND: Nonadherence to antihypertensive drugs (AHDs) is a major contributor to pseudo-resistant hypertension. The primary objective of this study was to determine the prevalence of nonadherence to AHDs among patients visiting the nephrology and vascular outpatient clinics. METHODS: Patients were eligible to participate in this prospective observational study if they used at least two AHDs that could be measured with a validated UHPLC-MS/MS method and had an office blood pressure at least 140 and/or at least 90 mmHg. For resistant hypertension, included patients had to use at least three AHDs including a diuretic or four AHDs. Adherence was assessed by measuring drug concentrations in blood. The complete absence of drug in blood was defined as nonadherence. A posthoc analysis was performed to determine the influence of a having a kidney transplant on the adherence rates. RESULTS: One hundred and forty-two patients were included of whom 66 patients fulfilled the definition of resistant hypertension. The overall adherence rate to AHDs was 78.2% ( n  = 111 patients), with the highest adherence rate for irbesartan (100%, n  = 9) and lowest adherence rate for bumetanide ( n  = 69%, n  = 13). In further analysis, only kidney transplantation could be identified as an important factor for adherence (adjusted odds ratio = 3.35; 95% confidence interval 1.23-9.09). A posthoc analysis showed that patients with a kidney transplant were more likely to be adherent to AHDs (non-KT cohort 64.0% vs. KT-cohort 85.7%, χ 2 (2) = 10.34, P  = 0.006). CONCLUSION: The adherence rate to AHDs in hypertensive patients was high (78.2%) and even higher after a kidney transplant (85.7%). Furthermore, patients after kidney transplant had a lower risk of being nonadherent to AHDs.

Von Willebrand Factor, ADAMTS13, and the Risk of Mortality: The Rotterdam Study.

OBJECTIVE: Von Willebrand Factor (VWF) is a plasma protein that plays a major role in platelet adhesion and aggregation. Large VWF multimers are cleaved into smaller, less coagulant forms by the metalloprotease ADAMTS13 (A Disintegrin And Metalloprotease with ThromboSpondin motif repeats 13). Previous studies have shown that high VWF and low ADAMTS13 levels are associated with cardiovascular disease, but whether these factors are associated with mortality is unclear. Our aim is to establish the association between VWF antigen (VWF:Ag) levels, ADAMTS13 activity, and mortality. APPROACH AND RESULTS: We included 6130 participants of the Rotterdam study, a population-based cohort study among individuals aged ≥55 years. We determined the association between ADAMTS13 activity, VWF:Ag levels, and all-cause and cardiovascular mortality by Cox proportional hazard regression analysis. During a median follow-up time of 11.3 years and a total of 90 635 person years, 1868 of the 6130 individuals died (30.5%), of whom 442 (23.7%) died because of cardiovascular disease. In individuals with low ADAMTS13 activity, the risk of cardiovascular mortality (hazard ratio, 1.46; 95% confidence interval, 1.09-1.96) was higher than that in individuals with high ADAMTS13 activity. The risk of cardiovascular mortality (hazard ratio, 1.29; 95% confidence interval 0.98-1.70) was higher in individuals with the highest VWF:Ag levels than in those with the lowest levels. In individuals with both low ADAMTS13 activity and high VWF:Ag levels, the risk of cardiovascular mortality was even higher (hazard ratio, 1.73 95% confidence interval, 1.28-2.35). CONCLUSIONS: In this large prospective cohort study, ADAMTS13 activity and VWF:Ag levels are both associated with an increased risk of all-cause and cardiovascular mortality.

von Willebrand Factor, ADAMTS13 Activity, and Decline in Kidney Function: A Population-Based Cohort Study.

BACKGROUND: Altered levels of von Willebrand factor (vWF) and ADAMTS13 can promote thrombosis and disturb blood flow in kidney microcirculations. We investigated the association of serum vWF:ADAMTS13 ratio in relation to decline in kidney function. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 2,479 individuals (mean age, 65.1±5.9 [SD] years; 43% men) from the population-based Rotterdam Study. PREDICTORS: vWF, ADAMTS13, and vWF:ADAMTS13 ratio. OUTCOMES & MEASUREMENTS: Annual decline in estimated glomerular filtration rate (eGFR), halving of eGFR, and new-onset eGFR<60mL/min/1.73m2 were assessed. RESULTS: During a median follow-up of 11 (range, 7.81-13.57) years, 500 cases of new-onset eGFR<60mL/min/1.73m2 occurred. The population had a mean eGFR decline of 0.96±0.92mL/min/1.73m2 per year. Higher vWF:ADAMTS13 ratio was associated with steeper annual decline in eGFR (difference, -0.06 [95% CI, -0.09 to -0.02] mL/min/1.73m2 per year) and higher risk for new-onset eGFR<60mL/min/1.73m2 (OR, 1.13; 95% CI, 1.01-1.27). Likewise, higher vWF:ADAMTS13 ratio was associated with higher risk for halving of eGFR (OR, 1.40; 95% CI, 1.02-1.93). After adjustment for cardiovascular risk factors and blood group, effect estimates remained the same. LIMITATIONS: No data available for albuminuria. Participants were classified based on a single measurement of vWF and ADAMTS13. CONCLUSIONS: In this population-based study, we showed that higher vWF:ADAMTS13 ratio is associated with decline in kidney function, suggesting a role of elevated prothrombotic factors in the development and progression of kidney disease.

Low ADAMTS13 activity is associated with an increased risk of ischemic stroke.

ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin motif repeats 13) has antithrombotic properties because it cleaves von Willebrand factor (VWF) in smaller, less active multimers. The aim of our study was to investigate prospectively the association between ADAMTS13 activity and ischemic stroke. We included 5941 individuals ≥55 years without a history of stroke or transient ischemic attack (TIA) of the Rotterdam Study, a population-based cohort study. ADAMTS13 activity was measured at inclusion with the FRETS-VWF73 assay and VWF antigen (VWF:Ag) levels by enzyme-linked immunosorbent assay. We assessed the association among ADAMTS13 activity, VWF:Ag levels, and ischemic stroke by Cox proportional hazard analysis. The added value of ADAMTS13 activity above the traditional risk factors for ischemic stroke risk prediction was examined by the C-statistic and the net reclassification improvement index (NRI). All individuals were followed for incident stroke or TIA. Over a median follow-up time of 10.7 years (56,403 total person-years), 461 participants had a stroke, 306 of which were ischemic. After adjustment for cardiovascular risk factors, individuals with ADAMTS13 activity in the lowest quartile had a higher risk of ischemic stroke (absolute risk, 7.3%) than did those in the reference highest quartile (absolute risk, 3.8%; hazard ratio, 1.65; 95% confidence interval [CI], 1.16-2.32). Adding ADAMTS13 to the model in prediction of ischemic stroke, increased the C-statistic by 0.013 (P = .003) and provided 0.058 (95% CI, -0.002 to 0.119) NRI. Low ADAMTS13 activity is associated with the risk of ischemic stroke and improves the accuracy of risk predictions for ischemic stroke beyond traditional risk factors.

Genetic variants in the ADAMTS13 and SUPT3H genes are associated with ADAMTS13 activity.

A disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13) cleaves von Willebrand factor, reducing its prothrombotic activity. The genetic determinants of ADAMTS13 activity remain unclear. We performed a genome-wide association study of ADAMTS13 activity in the Rotterdam Study, a population-based cohort study. We used imputed genotypes of common variants in a discovery sample of 3443 individuals and replication sample of 2025 individuals. We examined rare exonic variant associations in ADAMTS13 in 1609 individuals using an exome array. rs41314453 in ADAMTS13 was associated with ADAMTS13 activity in both our discovery (ß, -20.2%; P = 1.3 × 10(-33)) and replication sample (P = 3.3 × 10(-34)), and explained 3.6% to 6.5% of the variance. In the combined analysis of our discovery and replication samples, there were 2 further independent associations at the ADAMTS13 locus: rs3118667 (ß, 3.0; P = 9.6 × 10(-21)) and rs139911703 (ß, -11.6; P = 3.6 × 10(-8)). In addition, rs10456544 in SUPT3H was associated with a 4.2 increase in ADAMTS13 activity (P = 1.13.6 × 10(-8)). Finally, we found 3 independent associations with rare coding variants in ADAMTS13: rs148312697 (ß, -32.2%; P = 3.7 × 10(-6)), rs142572218 (ß, -46.0%; P = 3.9 × 10(-5)), and rs36222275 (ß, -13.9%; P = 2.9 × 10(-3)). In conclusion, we identified rs41314453 as the main genetic determinant of ADAMTS13 activity, and we present preliminary findings for further associations at the ADAMTS13 and SUPT3H loci.

Von Willebrand factor in relation to coronary plaque characteristics and cardiovascular outcome. Results of the ATHEROREMO-IVUS study.

High von Willebrand factor (VWF) plasma levels are associated with an increased risk of coronary artery disease. It has been suggested that the increase of VWF levels is partly due to endothelial dysfunction and atherosclerosis. Our aim was to investigate the association between coronary plaque burden, the presence of high-risk coronary lesions as measured by intravascular ultrasound virtual histology (IVUS-VH) and VWF levels. In addition, we studied the association between VWF levels and one-year cardiovascular outcome. Between 2008 and 2011, IVUS-VH imaging of a non-culprit coronary artery was performed in 581 patients undergoing coronary angiography for acute coronary syndrome (ACS) (n= 318) or stable angina pectoris (SAP) (n= 263). Arterial blood was sampled prior to the coronary angiography. VWF antigen (VWF:Ag) levels were measured using ELISA (n= 577). Patients with ACS had significantly higher VWF:Ag levels than SAP patients (median 1.73 IU/ml [IQR 1.27-2.31] vs 1.26 IU/ml [0.93-1.63], p< 0.001). High coronary plaque burden was associated with higher VWF:Ag levels (ß= 0.12, p=0.027) in SAP patients, but not in ACS patients. In ACS patients, VWF:Ag levels were associated with 1-year MACE (HR 4.14 per SD increase of lnVWF:Ag, 95 % CI 1.47-11.6), whereas in SAP patients VWF:Ag levels predicted 1-year all-cause death and hospitalisation for ACS (HR 7.07 95 % CI 1.40-35.6). In conclusion, coronary plaque burden was associated with VWF:Ag levels in SAP patients undergoing coronary angiography. In ACS and SAP patients, high VWF levels are predictive of adverse cardiovascular outcome and death during one-year follow-up.

Von Willebrand factor and ADAMTS13 in arterial thrombosis: a systematic review and meta-analysis.

Von Willebrand Factor (VWF) plays an important role in hemostasis by mediating platelet adhesion and aggregation. Ultralarge VWF multimers are cleaved by ADAMTS13 in smaller, less procoagulant forms. An association between high VWF levels and cardiovascular disease has frequently been reported, and more recently also an association has been observed between low ADAMTS13 levels and arterial thrombosis. We reviewed the current literature and performed meta-analyses on the relationship between both VWF and ADAMTS13 with arterial thrombosis. Most studies showed an association between high VWF levels and arterial thrombosis. It remains unclear whether ADAMTS13 is a causal independent risk factor because the association between low ADAMTS13 and arterial thrombosis is so far only shown in case-control studies. Prospective studies are awaited. A causal role for ADAMTS13 is supported by mice studies of cerebral infarction where the infusion of recombinant human ADAMTS13 reduced the infarct size.

Performance related factors are the main determinants of the von Willebrand factor response to exhaustive physical exercise.

BACKGROUND: Physical stress triggers the endothelium to release von Willebrand Factor (VWF) from the Weibel Palade bodies. Since VWF is a risk factor for arterial thrombosis, it is of great interest to discover determinants of VWF response to physical stress. We aimed to determine the main mediators of the VWF increase by exhaustive physical exercise. METHODS: 105 healthy individuals (18-35 years) were included in this study. Each participant performed an incremental exhaustive exercise test on a cycle ergometer. Respiratory gas exchange measurements were obtained while cardiac function was continuously monitored. Blood was collected at baseline and directly after exhaustion. VWF antigen (VWF:Ag) levels, VWF collagen binding (VWF:CB) levels, ADAMTS13 activity and common variations in Syntaxin Binding Protein-5 (STXBP5, rs1039084 and rs9399599), Syntaxin-2 (STX2, rs7978987) and VWF (promoter, rs7965413) were determined. RESULTS: The median VWF:Ag level at baseline was 0.94 IU/mL [IQR 0.8-1.1] and increased with 47% [IQR 25-73] after exhaustive exercise to a median maximum VWF:Ag of 1.38 IU/mL [IQR 1.1-1.8] (p<0.0001). VWF:CB levels and ADAMTS13 activity both also increased after exhaustive exercise (median increase 43% and 12%, both p<0.0001). The strongest determinants of the VWF:Ag level increase are performance related (p<0.0001). We observed a gender difference in VWF:Ag response to exercise (females 1.2 IU/mL; males 1.7 IU/mL, p = 0.001), which was associated by a difference in performance. Genetic variations in STXBP5, STX2 and the VWF promoter were not associated with VWF:Ag levels at baseline nor with the VWF:Ag increase. CONCLUSIONS: VWF:Ag levels strongly increase upon exhaustive exercise and this increase is strongly determined by physical fitness level and the intensity of the exercise, while there is no clear effect of genetic variation in STXBP5, STX2 and the VWF promoter.

Relationship of Von Willebrand Factor with carotid artery and aortic arch calcification in ischemic stroke patients.

BACKGROUND: Large population studies have revealed that increased von Willebrand Factor (VWF) levels are associated with an increased risk of ischemic stroke. In previous studies VWF was associated with atherosclerosis in healthy individuals. However, it is yet unknown what the association is between atherosclerosis and VWF levels in patients with ischemic stroke. OBJECTIVES: The aim of our study was to determine the association of atherosclerosis, measured with recent developed techniques, and VWF levels in a large, well characterized, cohort of ischemic stroke patients and to determine the prognostic value. METHODS: We included 925 consecutive patients with transient ischemic attack (TIA) or ischemic stroke. Calcification volumes (mm(3)) were scored in the aortic arch and both carotid arteries using multidetector computed tomography (CT) angiography. VWF antigen (VWF:Ag) levels were measured using ELISA. RESULTS: Mean VWF:Ag levels were significantly higher in the presence of calcification in either the aortic arch (1.47 vs. 1.37 IU/ml [P = 0.039]) or the carotid arteries (1.49 vs. 1.34 IU/ml [P = 0.001]). Patients with a large artery atherosclerosis ischemic stroke had significantly higher VWF:Ag levels then the other TOAST subtypes (P < 0.0001). High VWF:Ag levels were associated with an unfavorable outcome (modified Rankin Scale >2 vs. ≤2; 1.64 vs. 1.41 IU/ml, [P < 0.0001]). CONCLUSION: Our study showed a strong association between the extent of atherosclerosis in both the aortic arch and the carotid arteries and VWF levels in patients with TIA or ischemic stroke. Higher VWF levels are found in large artery atherosclerosis and are associated with a poor outcome.