Anne Merrelaar

Dr. Anne Merrelaar

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 February 2024 in Thrombosis and Haemostasis
Verified
Journal Article
Closed access
JHJob Haenberg
Job Haenberg
RGRobert C. Gosselin
Robert C. Gosselin
ACAdam Cuker
Adam Cuker
CBCecilia Becattini
Cecilia Becattini
IPIngrid Pabinger
Ingrid Pabinger
CWChristel Weiss
Christel Weiss
With the widespread use of direct oral anticoagulants (DOACs), there is an urgent need for a rapid assay to exclude clinically relevant plasma levels. Accurate and rapid determination of DOAC levels would guide medical decision-making to (1) determine the potential contribution of the DOAC to spontaneous or trauma-induced hemorrhage; (2) identify appropriate candidates for reversal, or (3) optimize the timing of urgent surgery or intervention. The DOAC Dipstick test uses a disposable strip to identify factor Xa- or thrombin inhibitors in a urine sample. Based on the results of a systematic literature search followed by an analysis of a simple pooling of five retrieved clinical studies, the test strip has a high sensitivity and an acceptably high negative predictive value when compared with levels measured with liquid chromatography tandem mass spectrometry or calibrated chromogenic assays to reliably exclude plasma DOAC concentrations ≥30 ng/mL. Based on these data, a simple algorithm is proposed to enhance medical decision-making in acute care indications useful primarily in hospitals not having readily available quantitative tests and 24/7. This algorithm not only determines DOAC exposure but also differentiates between factor Xa and thrombin inhibitors to better guide clinical management.

4 July 2022 in Thrombosis and Haemostasis
Verified
Journal Article
Open access
PDF file
AMAnne Merrelaar
Anne Merrelaar
MBMagdalena S. Bögl
Magdalena S. Bögl
NBNina Buchtele
Nina Buchtele
MMMarieke Merrelaar
Marieke Merrelaar
HHHarald Herkner
Harald Herkner
MSMichael Schwameis
Michael Schwameis
An accurate point-of-care test for detecting effective anticoagulation by direct oral anticoagulants (DOACs) in emergencies is an unmet need. We investigated the accuracy of a urinary qualitative strip test (DOAC Dipstick) to detect relevant DOAC exposure in patients who presented to an emergency department. In this prospective single-center cohort-type cross-sectional study, adults on DOAC treatment were enrolled. We assessed clinical sensitivity and specificity of DOAC Dipstick factor Xa and thrombin inhibitor pads to detect DOAC plasma levels ≥30 ng/mL using urine samples as the testing matrix. Liquid chromatography coupled with tandem-mass spectrometry was used as the reference standard method for plasma and urine measurement of DOAC concentrations. Of 293 patients enrolled, 265 patients were included in the analysis, of whom 92 were treated with rivaroxaban, 65 with apixaban, 77 with edoxaban, and 31 with dabigatran. The clinical sensitivity and specificity of the dipstick on urine samples to detect ≥30 ng/mL dabigatran plasma levels were 100% (95% confidence interval [CI]: 87–100%) and 98% (95% CI: 95–99%), respectively. The sensitivity and specificity of the dipstick to detect ≥30 ng/mL factor Xa inhibitor plasma levels were 97% (95% CI: 94–99%) and 69% (95% CI: 56–79%), respectively. The DOAC Dipstick sensitively identified effective thrombin and factor Xa inhibition in a real-world cohort of patients presenting at an emergency department. Therefore, the dipstick might provide a valuable test to detect relevant DOAC exposure in emergencies, although further studies will be needed to confirm these findings.

1 October 2019 in Journal of Clinical Medicine
Verified
Journal Article
Open access
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LMLisa-Marie Mauracher
Lisa-Marie Mauracher
NBNina Buchtele
Nina Buchtele
CSChristian Schörgenhofer
Christian Schörgenhofer
CWChristoph Weiser
Christoph Weiser
HHHarald Herkner
Harald Herkner
MSMichael Schwameis
Michael Schwameis
The exact contribution of neutrophils to post-resuscitative brain damage is unknown. We aimed to investigate whether neutrophil extracellular trap (NET) formation in the early phase after return of spontaneous circulation (ROSC) may be associated with poor 30 day neurologic function in cardiac arrest survivors. This study prospectively included adult (≥18 years) out-of-hospital cardiac arrest (OHCA) survivors with cardiac origin, who were subjected to targeted temperature management. Plasma levels of specific (citrullinated histone H3, H3Cit) and putative (cell-free DNA (cfDNA) and nucleosomes) biomarkers of NET formation were assessed at 0 and 12 h after admission. The primary outcome was neurologic function on day 30 after admission, which was assessed using the five-point cerebral performance category (CPC) score, classifying patients into good (CPC 1–2) or poor (CPC 3–5) neurologic function. The main variable of interest was the effect of H3Cit level quintiles at 12 h on 30 day neurologic function, assessed by logistic regression. The first quintile was used as a baseline reference. Results are given as crude odds ratio (OR) with 95% confidence interval (95% CI). Sixty-two patients (79% male, median age: 57 years) were enrolled. The odds of poor neurologic function increased linearly, with 0 h levels of cfNDA (crude OR 1.8, 95% CI: 1.2–2.7, p = 0.007) and nucleosomes (crude OR 1.7, 95% CI: 1.0–2.2, p = 0.049), as well as with 12 h levels of cfDNA (crude OR 1.6, 95% CI: 1.1–2.4, p = 0.024), nucleosomes (crude OR 1.7, 95% CI: 1.1–2.5, p = 0.020), and H3Cit (crude OR 1.6, 95% CI: 1.1–2.3, p = 0.029). Patients in the fourth (7.9, 95% CI: 1.1–56, p = 0.039) and fifth (9.0, 95% CI: 1.3–63, p = 0.027) H3Cit quintile had significantly higher odds of poor 30 day neurologic function compared to patients in the first quintile. Increased plasma levels of H3Cit, 12 h after admission, are associated with poor 30 day neurologic function in adult OHCA survivors, which may suggest a contribution of NET formation to post-resuscitative brain damage and therefore provide a therapeutic target in the future.

21 February 2020 in Journal of Clinical Medicine
Verified
Journal Article
Open access
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NBNina Buchtele
Nina Buchtele
HHHarald Herkner
Harald Herkner
CSChristian Schörgenhofer
Christian Schörgenhofer
AMAnne Merrelaar
Anne Merrelaar
RLRoberta Laggner
Roberta Laggner
MSMichael Schwameis
Michael Schwameis
Transition from cangrelor to oral P2Y12 inhibitors after PCI carries the risk of platelet function recovery and acute stent thrombosis. Whether the recommended transition regimen is appropriate for hypothermic cardiac arrest survivors is unknown. We assessed the rate of high platelet reactivity (HPR) after transition from cangrelor to ticagrelor in hypothermic cardiac arrest survivors. Adult survivors of out-of-hospital cardiac arrest with ST-segment elevation myocardial infarction (STEMI), who were treated for hypothermia (33 °C ± 1) and received intravenous cangrelor during PCI and subsequent oral loading with 180mg ticagrelor were enrolled in this prospective observational cohort study. Platelet function was assessed using whole blood aggregometry. HPR was defined as AUC > 46U. The primary endpoint was the rate of HPR (%) at predefined time points during the first 24 h after cangrelor cessation. Poisson regression was used to estimate the relationship between the overlap time of cangrelor and ticagrelor co-administration and the number of subsequent HPR episodes, expressed as incidence rate ratio (IRR) with 95% confidence interval (95%CI). Between December 2017 and October 2019 16 patients (81% male, 58 years) were enrolled. On average, ticagrelor was administered 39 min (IQR 5–50) before the end of cangrelor infusion. The rate of HPR was highest 90 min after cangrelor cessation and was present in 44% (7/16) of patients. The number of HPR episodes increased significantly with decreasing overlap time of cangrelor and ticagrelor co-administration (IRR 1.03, 95%CI 1.01–1.05; p = 0.005). In this selected cohort of hypothermic cardiac arrest survivors who received cangrelor during PCI, ticagrelor loading within the recommended time frame before cangrelor cessation resulted in a substantial amount of patients with HPR.

Verified
Journal Article
Open access
PDF file
CSChristoph Schriefl
Christoph Schriefl
CSChristian Schörgenhofer
Christian Schörgenhofer
NBNina Buchtele
Nina Buchtele
MMMatthias Mueller
Matthias Mueller
MPMichael Poppe
Michael Poppe
MSMichael Schwameis
Michael Schwameis
Background: The clinical value of a prognostic score depends on its out-of-sample validity because inaccurate outcome prediction can be not only useless but potentially fatal. We aimed to evaluate the out-of-sample validity of a recently developed and highly accurate Korean prognostic score for predicting neurologic outcome after cardiac arrest in an independent, plausibly related sample of European cardiac arrest survivors. Methods: Analysis of data from a European cardiac arrest center, certified in compliance with the specifications of the German Council for Resuscitation. The study sample included adults with nontraumatic out-of-hospital cardiac arrest admitted between 2013 and 2018. Exposure was the PROgnostication using LOGistic regression model for Unselected adult cardiac arrest patients in the Early stages (PROLOGUE) score, including 12 clinical variables readily available at hospital admission. The outcome was poor 30-day neurologic function, as assessed using the cerebral performance category scale. The risk of a poor outcome was calculated using the PROLOGUE score regression equation. Predicted risk deciles were compared to observed outcome estimates in a complete-case analysis, a best-case analysis, and a multiple-data-imputation analysis using the Markov chain Monte Carlo method. Results: A total of 1051 patients (median 61 years, IQR 50–71; 29% female) were analyzed. A total of 808 patients (77%) were included in the complete-case analysis. The PROLOGUE score overestimated the risk of poor neurologic outcomes in the range of 40% to 100% predicted risk, involving 63% of patients. The model fit did not improve after missing data imputation. Conclusions: In a plausibly related sample of European cardiac arrest survivors, risk prediction by the PROLOGUE score was largely too pessimistic and failed to replicate the high accuracy found in the original study. Using the PROLOGUE score as an example, this study highlights the compelling need for independent validation of a proposed prognostic score to prevent potentially fatal mispredictions.

24 February 2025 in Thrombosis and Haemostasis
Verified
Journal Article
Open access
PDF file
KJKarin Janata
Karin Janata
ALAlexandra Julia Lipa
Alexandra Julia Lipa
AMAnne Merrelaar
Anne Merrelaar
MMMarieke Merrelaar
Marieke Merrelaar
UAUrsula Azizi-Semrad
Ursula Azizi-Semrad
JGJuergen Grafeneder
Juergen Grafeneder
Pulmonary embolism (PE) requires accurate risk assessment. We investigated the prognostic performance of the National Early Warning Score (NEWS) in emergency department patients with PE.We included patients ≥ 18 years from our PE registry (2017 to 2021), excluding patients after cardiac arrest or intubation before admission. The primary outcome was a composite of 30-day all-cause mortality or the need for advanced therapy (i.e., systemic or catheter-directed thrombolysis). We used logistic regression and the Cox proportional hazards models to estimate associations. The Pulmonary Embolism Severity Index (PESI) and the European Society of Cardiology (ESC) classification served as covariates. The overall score performances were quantified using receiver operating characteristic analysis.We included 524 patients. Each increase in NEWS points increased the odds of the primary outcome by 69% (odds ratio: 1.69, 95% confidence interval [CI]: 1.51–1.89, p < 0.001) and 30-day mortality by 44% (hazard ratio: 1.44, 95% CI: 1.30–1.60, p < 0.001). Within the ESC intermediate–high and high-risk group, the 30-day mortality rate was higher in patients with a NEWS ≥ 7 compared with NEWS < 7 (24 vs. 1%, p < 0.001). With a NEWS ≥ 7, 30-day mortality was lower in patients who received advanced therapy (18 vs. 39%) but not significantly. The NEWS predicted the primary outcome better than the PESI (area under the curve: 0.853 vs. 0.752, p < 0.001).The NEWS was associated with 30-day mortality and the need for advanced therapy. Incorporating the NEWS into the ESC classification could help to assess patient outcomes early and thus support timely treatment decisions.