Sebastian Göbel

Sirolimus-Induced Vascular Dysfunction: Increased Mitochondrial and Nicotinamide Adenosine Dinucleotide Phosphate Oxidase-Dependent Superoxide Production and Decreased Vascular Nitric Oxide Formation

OBJECTIVES This study sought to analyze mechanisms that mediate vascular dysfunction induced by sirolimus. BACKGROUND Despite excellent antirestenotic capacity, sirolimus-eluting stents have been found to trigger coronary endothelial dysfunction and impaired re-endothelialization. METHODS To mimic the continuous sirolimus exposure of a stented vessel, Wistar rats underwent drug infusion with an osmotic pump for 7 days. RESULTS Sirolimus treatment caused a marked degree of endothelial dysfunction as well as a desensitization of the vasculature to the endothelium-independent vasodilator nitroglycerin. Also, sirolimus stimulated intense transmural superoxide formation as detected by dihydroethidine fluorescence in aortae. Increased superoxide production was mediated in part by the vascular nicotinamide adenosine dinucleotide phosphate (NADPH) oxidase as indicated by a marked stimulation of p67(phox)/rac1 NADPH oxidase subunit expression and by increased rac1 membrane association. In addition, superoxide production in rat heart mitochondria was up-regulated by sirolimus, as measured by L012-enhanced chemiluminescence. As a consequence, electron spin resonance measurements showed a 40% reduction in vascular nitric oxide bioavailability, which was further supported by decreased serum nitrite levels. CONCLUSIONS Sirolimus causes marked vascular dysfunction and nitrate resistance after continuous treatment for 7 days. This impaired vasorelaxation may, in part, be induced by up-regulated mitochondrial superoxide release as well as by an up-regulation of NADPH oxidase-driven superoxide production. Both processes could contribute to endothelial dysfunction observed after coronary vascular interventions with sirolimus-coated stents.

Monitoring White Blood Cell Mitochondrial Aldehyde Dehydrogenase Activity: Implications for Nitrate Therapy in Humans

Recent animal data suggest that reduced lipoic acid (LA) prevents oxidative inhibition of the nitrate bioactivating enzyme, the mitochondrial aldehyde dehydrogenase (ALDH-2), and that pentaerythritol tetranitrate (PETN) does not induce nitrate tolerance because of its intrinsic antioxidative properties, thereby preserving ALDH-2 activity. We sought to determine whether ALDH-2 activity in circulating white blood cells (WBCs) can be used to monitor nitrate tolerance and whether LA can prevent nitroglycerin tachyphylaxis in humans. Eight healthy male volunteers received, in randomized order, a single dose of glyceryl trinitrate (GTN; 0.8 mg), PETN (80 mg), or GTN plus LA (600 mg) orally. GTN (30 min) and PETN (120 min) administration lead to a comparable dilation of the brachial artery (15 ± 1%). In contrast to PETN, acute GTN treatment resulted in a 60% decrease in WBC ALDH-2 activity (high-performance liquid chromatography), 30% reduction of nitrate bioactivation, and 25% decrease in serum antioxidant capacity (fluorescence assay), which all were prevented by pretreatment with LA. Mechanistic studies in rats identified oxidative stress, ALDH-2 inactivation, and vascular dysfunction as common features in acute and chronic nitrate tolerance. Treatment with GTN, but not PETN, acutely inhibits ALDH-2 activity and nitrate bioactivation in healthy volunteers. These effects were prevented by LA pretreatment, emphasizing the role of oxidative stress-triggered ALDH-2 dysfunction. Assessment of WBC ALDH-2 activity could be used as an easily accessible marker for the detection of nitroglycerin-induced tachyphylaxis in humans and may be of high clinical interest because recent data suggest that ALDH-2 activity correlates with protection from ischemic heart damage in infarct models.

Quality of oral anticoagulation with phenprocoumon in regular medical care and its potential for improvement in a telemedicine-based coagulation service – results from the prospective, multi-center, observational cohort study thrombEVAL

BackgroundThe majority of studies on quality of oral anticoagulation (OAC) therapy with vitamin K-antagonists are performed with short-acting warfarin. Data on long-acting phenprocoumon, which is frequently used in Europe for OAC therapy and is considered to enable more stable therapy adjustment, are scarce. In this study, we aimed to assess quality of OAC therapy with phenprocoumon in regular medical care and to evaluate its potential for optimization in a telemedicine-based coagulation service.MethodsIn the prospective observational cohort study program thrombEVAL we investigated 2,011 patients from regular medical care in a multi-center cohort study and 760 patients from a telemedicine-based coagulation service in a single-center cohort study. Data were obtained from self-reported data, computer-assisted personal interviews, and laboratory measurements according to standard operating procedures with detailed quality control. Time in therapeutic range (TTR) was calculated by linear interpolation method to assess quality of OAC therapy. Study monitoring was carried out by an independent institution.ResultsOverall, 15,377 treatment years and 48,955 international normalized ratio (INR) measurements were analyzed. Quality of anticoagulation, as measured by median TTR, was 66.3% (inte rquartile range (IQR) 47.8/81.9) in regular medical care and 75.5% (IQR 64.2/84.4) in the coagulation service (P <0.001). Stable anticoagulation control within therapeutic range was achieved in 63.8% of patients in regular medical care with TTR at 72.1% (IQR 58.3/84.7) as compared to 96.4% of patients in the coagulation service with TTR at 76.2% [(IQR 65.6/84.7); P = 0.001)]. Prospective follow-up of coagulation service patients with pretreatment in regular medical care showed an improvement of the TTR from 66.2% (IQR 49.0/83.6) to 74.5% (IQR 62.9/84.2; P <0.0001) in the coagulation service. Treatment in the coagulation service contributed to an optimization of the profile of time outside therapeutic range, a 2.2-fold increase of stabile INR adjustment and a significant decrease in TTR variability by 36% (P <0.001).ConclusionsQuality of anticoagulation with phenprocoumon was comparably high in this real-world sample of regular medical care. Treatment in a telemedicine-based coagulation service substantially improved quality of OAC therapy with regard to TTR level, frequency of stable anticoagulation control, and TTR variability.Trial registrationClinicalTrials.gov, unique identifier NCT01809015, March 8, 2013.

Evaluation of oral anticoagulation therapy: rationale and design of the thrombEVAL study programme.

Background Since decades, oral anticoagulation (OAC) with vitamin K antagonists (VKA) is an established therapy for both prevention and treatment of thromboembolism in daily clinical routine. Increasing life expectancy, demographic changes, and novel oral anticoagulants have led to an increasing complexity of medical therapy. However, data on quality and management of VKA therapy with phenprocoumon in current medical care are limited. Our aim is to investigate the quality of OAC with VKA in current health care and to evaluate the potential for improvements. Study design The investigator-initiated thrombEVAL study programme comprises two cohorts of patients treated with vitamin K antagonists for oral anticoagulation therapy in real-life settings: a multicentre cohort of patients in regular medical care and a multilocal, single-centre cohort of patients in a telemedicine-based coagulation service. The study programme is expected to enrol a total number of approximately 2000 to 2500 patients. Both cohorts will build on a detailed clinical assessment of participants and anticoagulation therapy at study enrolment. Subsequently active and passive follow-up investigations are carried out to document and validate complications of the treatment. The primary short-term outcome is the distribution of time in therapeutic range; the primary long-term outcome comprises the composite of stroke, systemic embolism, myocardial infarction, major and clinically relevant bleeding, and death. Conclusions The thrombEVAL project will provide a large prospective observational cohort of patients predominantly treated with phenprocoumon. It will evaluate the quality of oral anticoagulation in regular medical care and a telemedicine-based coagulation service.

Symptoms of depression and anxiety predict mortality in patients undergoing oral anticoagulation: Results from the thrombEVAL study program

BACKGROUND/OBJECTIVES Depression and anxiety are highly prevalent in cardiovascular patients. Therefore, we examined whether the 4-item Patient Health Questionnaire (PHQ-4, measuring symptoms of depression and anxiety) predicts all-cause mortality in outpatients with long-term oral anticoagulation (OAC). METHODS The sample comprised n=1384 outpatients from a regular medical care setting receiving long-term OAC with vitamin K antagonists. At baseline, symptoms of anxiety and depression were assessed with the PHQ-4 and the past medical history was taken. The outcome was all-cause mortality in the 24 month observation period. The median follow-up time was 13.3 months. RESULTS N=191 patients from n=1384 died (death rate 13.8%). Each point increase in the PHQ-4 score was associated with a 10% increase in mortality (hazard ratio [HR] 1.10, 95% confidence interval [95% CI] 1.05-1.16) after adjustment for age, sex, high school graduation, partnership, smoking, obesity, frailty according to the Barthel Index, Charlson Comorbidity Index and CHA2DS2-VASc score. The depression component (PHQ-2) increased mortality by 22% and anxiety (GAD-2) by 11% respectively. Neither medical history of any mental disorder, nor intake of antidepressants, anxiolytics or hypnotics predicted excess mortality. CONCLUSIONS Elevated symptoms of depression and, to a lesser degree, symptoms of anxiety are independently associated with all-cause mortality in OAC outpatients. The PHQ-4 questionnaire provides valuable prognostic information. These findings emphasize the need for implementing regular screening procedures and the development and evaluation of appropriate psychosocial treatment approaches for OAC patients.

Relevance of depression for anticoagulation management in a routine medical care setting: results from the ThrombEVAL study program

Depressive symptoms have detrimental effects on quality of life and mortality. Poor adherence to a treatment regimen is a potential mechanism for the increased risk of adverse medical events associated with depression. Regarding oral anticoagulation with vitamin K antagonists, adherence is crucial for the outcome. Little is known about the clinical relevance of current depressiveness for anticoagulation treatment.

History of deep vein thrombosis is a discriminator for concomitant atrial fibrillation in pulmonary embolism

BACKGROUND Pulmonary embolism (PE) is the consequence of deep vein thrombosis (DVT) in 70% of all cases. Although, PE and DVT are commonly related to risk factors of Virchows triad, both entities are linked to cardiovascular risk factors, but risk factors seem differently important in both entities. OBJECTIVES We aimed to investigate clinical profile and outcome of patients with PE history stratified by concomitant DVT. PATIENTS/METHODS Data from the observational multi-center thrombEVAL-study were analyzed. RESULTS The sample (N=2,318) comprised 295 PE patients, of whom 69.2% (N=204) had DVT. Individuals without DVT were older and had higher prevalence of concomitant atrial fibrillation (AF), chronic lung diseases, coronary artery disease, heart failure and hypertension. Multivariable regression revealed an independent association of AF (Odds Ratio (OR) 3.17, 95% CI 1.63-6.18, P<0.001) and coronary artery disease (OR 2.31, 95% CI 1.15-4.66, P=0.019) with PE without DVT. There was higher frequency of permanent AF in individuals without DVT, whereas paroxysmal AF was more prevalent in individuals with DVT. All AF subtypes were independently associated with PE without DVT with increasing ORs from paroxysmal to permanent AF. PE patients with and without DVT did not differ in survival (P=0.32) and cost-relevant clinical outcome (P=0.26) during follow-up. AF in PE patients was associated with cost-relevant clinical outcome (Hazard Ratio (HR) 1.78, 95% CI 1.03-3.09, P=0.040), but no significant difference in survival (HR 0.93, 95% CI 0.35-2.50, P=0.88) was observed. CONCLUSIONS History of DVT is a significant discriminator for clinical profile of PE patients. Individuals without DVT had more often cardiac and pulmonary disease with strongest association with AF. Data advocate a potential link between AF and PE. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov, Unique identifier NCT01809015.

e-Health based management of patients receiving oral anticoagulation therapy: results from the observational thrombEVAL study

Essentials e‐Health based health care by an expert centre may advance management of oral anticoagulation. Outcome of patients was compared between an e‐health based coagulation service and regular care. Patients in the coagulation service cohort experienced a significantly better clinical outcome. Lower risk for adverse events was related to anticoagulation‐specific and non‐specific outcome.

Age-related diagnostic value of D-dimer testing and the role of inflammation in patients with suspected deep vein thrombosis

Previous reports have investigated the impact of age on D-Dimer testing in elderly individuals with suspected deep vein thrombosis (DVT), but data on the age-related diagnostic value of D-dimer in a sample covering a broad age range are limited. The present study determined age-specifically the diagnostic accuracy of D-dimer and compared it to C-reactive protein (CRP), a marker of inflammation, in 500 patients with suspected DVT from the VTEval project (NCT02156401). Sensitivity of D-dimer was lower in patients < 60 years in comparison to patients ≥ 60 years (∆−16.8%), whereas specificity was 27.9% higher. Lowest levels of sensitivity were detected for female sex, unprovoked DVT, low thrombotic burden, and distal DVT. A fixed D-dimer threshold of 0.25 mg/L FEU resulted in elevated sensitivity for patients < 60 with a reduction of false negatives by 40.0% for proximal DVT and by 50.0% for distal DVT. In patients < 60 years, D-dimer and CRP demonstrated comparable diagnostic performance for both proximal and distal DVT (p > 0.05). In conclusion, these data outline a clinically-relevant limitation of D-dimer testing among younger patients with suspected DVT indicating a necessity for age-adapted cut-off values. Further research is required to decrypt the role of inflammation in the pathophysiology and diagnosis of venous thrombosis.

Management of Oral Anti-Coagulation in Patients with Heart Failure—Insights from the ThrombEVAL Study

Patients with heart failure (HF) are frequently anti-coagulated with vitamin K-antagonists (VKAs). The use of long-acting VKA may be preferable for HF patients due to higher stability of plasma concentrations. However, evidence on phenprocoumon-based oral anti-coagulation (OAC) therapy in HF is scarce. The aim of this study was to assess the impact of the presence of HF on quality of phenprocoumon-based OAC and the subsequent clinical outcome. Quality of OAC therapy and the incidence of adverse events were analysed in a cohort of regular care (n = 2,011) from the multi-centre thrombEVAL study program (NCT01809015) stratified by the presence of HF. To assess the modifiability of outcome, results were compared with data from individuals receiving specialized care for anti-coagulation (n = 760). Overall, the sample comprised of 813 individuals with HF and 1,160 subjects without HF in the regular care cohort. Quality of OAC assessed by time in therapeutic range (TTR) was 66.1% (47.8%/82.8%) for patients with HF and 70.6% (52.1%/85.9%) for those without HF (p = 0.0046). Stratification for New York Heart Classification (NYHA)-class demonstrated a lower TTR with higher NYHA classes: TTRNYHA-I 69.6% (49.4%/85.6%), TTRNYHA-II 66.5% (50.1%/82.9%) and TTRNYHA-≥III 61.8% (43.1%/79.9%). This translated into a worse net clinical benefit outcome for HF (hazard ratio [HR] 1.63 [1.31/2.02]; p < 0.0001) and an increased risk of bleeding (HR 1.40 [1.04/1.89]; p = 0.028). Management in a specialized coagulation service resulted in an improvement of all, TTR (∆+12.5% points), anti-coagulation-specific and non-specific outcome of HF individuals. In conclusion, HF is an independent risk factor for low quality of OAC therapy translating into an increased risk for adverse events, which can be mitigated by specialized care.