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Kassar A, Macheret F, Kondamudi N, Chahine Y, Chamoun N, Al Yasiri H, Akoum N. Performance of Large Language Models as a Resource for Atrial Fibrillation Patients and Providers. Heart Rhythm 2024:S1547-5271(24)02550-5. [PMID: 38734229 DOI: 10.1016/j.hrthm.2024.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/13/2024]
Affiliation(s)
- Ahmad Kassar
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Fima Macheret
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Nitin Kondamudi
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Yaacoub Chahine
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Nadia Chamoun
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Hala Al Yasiri
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Nazem Akoum
- Electrophysiology Section, Division of Cardiology, University of Washington, Seattle, WA, USA; Department of Bioengineering, University of Washington, Seattle, WA, USA.
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Macheret F, Bifulco SF, Scott GD, Kwan KT, Chahine Y, Afroze T, McDonagh R, Akoum N, Boyle PM. Comparing Inducibility of Re-Entrant Arrhythmia in Patient-Specific Computational Models to Clinical Atrial Fibrillation Phenotypes. JACC Clin Electrophysiol 2023; 9:2149-2162. [PMID: 37656099 PMCID: PMC10909381 DOI: 10.1016/j.jacep.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/21/2023] [Accepted: 06/30/2023] [Indexed: 09/02/2023]
Abstract
BACKGROUND Computational models of fibrosis-mediated, re-entrant left atrial (LA) arrhythmia can identify possible substrate for persistent atrial fibrillation (AF) ablation. Contemporary models use a 1-size-fits-all approach to represent electrophysiological properties, limiting agreement between simulations and patient outcomes. OBJECTIVES The goal of this study was to test the hypothesis that conduction velocity (ϴ) modulation in persistent AF models can improve simulation agreement with clinical arrhythmias. METHODS Patients with persistent AF (n = 37) underwent ablation and were followed up for ≥2 years to determine post-ablation outcomes: AF, atrial flutter (AFL), or no recurrence. Patient-specific LA models (n = 74) were constructed using pre-ablation and ≥90 days' post-ablation magnetic resonance imaging data. Simulated pacing gauged in silico arrhythmia inducibility due to AF-like rotors or AFL-like macro re-entrant tachycardias. A physiologically plausible range of ϴ values (±10 or 20% vs. baseline) was tested, and model/clinical agreement was assessed. RESULTS Fifteen (41%) patients had a recurrence with AF and 6 (16%) with AFL. Arrhythmia was induced in 1,078 of 5,550 simulations. Using baseline ϴ, model/clinical agreement was 46% (34 of 74 models), improving to 65% (48 of 74) when any possible ϴ value was used (McNemar's test, P = 0.014). ϴ modulation improved model/clinical agreement in both pre-ablation and post-ablation models. Pre-ablation model/clinical agreement was significantly greater for patients with extensive LA fibrosis (>17.2%) and an elevated body mass index (>32.0 kg/m2). CONCLUSIONS Simulations in persistent AF models show a 41% relative improvement in model/clinical agreement when ϴ is modulated. Patient-specific calibration of ϴ values could improve model/clinical agreement and model usefulness, especially in patients with higher body mass index or LA fibrosis burden. This could ultimately facilitate better personalized modeling, with immediate clinical implications.
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Affiliation(s)
- Fima Macheret
- Division of Cardiology, University of Washington, Seattle, Washington, USA
| | - Savannah F Bifulco
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Griffin D Scott
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Kirsten T Kwan
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Yaacoub Chahine
- Division of Cardiology, University of Washington, Seattle, Washington, USA
| | - Tanzina Afroze
- Division of Cardiology, University of Washington, Seattle, Washington, USA
| | | | - Nazem Akoum
- Division of Cardiology, University of Washington, Seattle, Washington, USA; Department of Bioengineering, University of Washington, Seattle, Washington, USA.
| | - Patrick M Boyle
- Department of Bioengineering, University of Washington, Seattle, Washington, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA; Center for Cardiovascular Biology, University of Washington, Seattle, Washington, USA.
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Chahine Y, Afroze T, Bifulco SF, Macheret F, Abdulsalam N, Boyle PM, Akoum N. Cryoballoon temperature parameters during cryoballoon ablation predict pulmonary vein reconnection and atrial fibrillation recurrence. J Interv Card Electrophysiol 2023; 66:1367-1373. [PMID: 36418664 PMCID: PMC10205917 DOI: 10.1007/s10840-022-01429-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022]
Abstract
BACKGROUND Cryoballoon ablation (CBA) is an established approach for rhythm management of atrial fibrillation (AF). We sought to assess balloon temperature (BT) parameters as predictors of pulmonary vein (PV) reconnection within the index procedure and AF recurrence following CBA. METHODS BT was monitored in 119 AF patients undergoing CBA. PVs were assessed for reconnection during the procedure and patients were followed for arrhythmia recurrence. RESULTS PV reconnection was identified in 39 (8.3%) of 471 PVs. BT was significantly colder in the absence of PV reconnection (30 s: - 33.5 °C [- 36; - 30] vs - 29.5 °C [- 35; - 25.5], p = 0.001; 60 s: - 41 °C [- 44; - 37] vs - 36.5 °C [- 42; - 33.5], p < 0.001; nadir: - 47 °C [- 52; - 43] vs - 41.5 °C [- 47; - 38], p < 0.001). PV reconnection was associated with significantly longer time to reach - 15 °C and - 40 °C (14.5 s [11.5-18.5] vs 12 s [10-15.5], p = 0.023; and 75 s [40-95.5] vs 46 s [37-66.75], p = 0.005) and shorter rewarming time (5.75 s [4.75-8.5] vs 7 s [6-9], p = 0.012). ROC analysis of these procedural parameters had an AUC = 0.71 in predicting PV reconnection. AF recurrence occurred in 51 (42.8%) patients. Kaplan-Meier analysis showed better arrhythmia-free survival for patients in whom BT decreased below - 40 °C in all PVs and patients who had no early PV reconnections, compared to patients in whom BT below - 40 °C was not achieved in at least one PV (log rank = 6.3, p = 0.012) and patients who had PV reconnections (log rank = 4.1, p = 0.043). CONCLUSIONS Slower BT decline, warmer BT nadir, and faster rewarming time predict early PV reconnection. Absence of early PV reconnections and BT dropping below - 40 °C in all PVs during CBA are associated with lower rates of AF recurrence.
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Affiliation(s)
- Yaacoub Chahine
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Tanzina Afroze
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Savannah F Bifulco
- Department of Bioengineering, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Fima Macheret
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | | | - Patrick M Boyle
- Department of Bioengineering, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Nazem Akoum
- Division of Cardiology, University of Washington, Seattle, WA, USA.
- Department of Bioengineering, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA.
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Bifulco SF, Macheret F, Scott GD, Akoum N, Boyle PM. Explainable Machine Learning to Predict Anchored Reentry Substrate Created by Persistent Atrial Fibrillation Ablation in Computational Models. J Am Heart Assoc 2023; 12:e030500. [PMID: 37581387 PMCID: PMC10492949 DOI: 10.1161/jaha.123.030500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 07/21/2023] [Indexed: 08/16/2023]
Abstract
Background Postablation arrhythmia recurrence occurs in ~40% of patients with persistent atrial fibrillation. Fibrotic remodeling exacerbates arrhythmic activity in persistent atrial fibrillation and can play a key role in reentrant arrhythmia, but emergent interaction between nonconductive ablation-induced scar and native fibrosis (ie, residual fibrosis) is poorly understood. Methods and Results We conducted computational simulations in pre- and postablation left atrial models reconstructed from late gadolinium enhanced magnetic resonance imaging scans to test the hypothesis that ablation in patients with persistent atrial fibrillation creates new substrate conducive to recurrent arrhythmia mediated by anchored reentry. We trained a random forest machine learning classifier to accurately pinpoint specific nonconductive tissue regions (ie, areas of ablation-delivered scar or vein/valve boundaries) with the capacity to serve as substrate for anchored reentry-driven recurrent arrhythmia (area under the curve: 0.91±0.03). Our analysis suggests there is a distinctive nonconductive tissue pattern prone to serving as arrhythmogenic substrate in postablation models, defined by a specific size and proximity to residual fibrosis. Conclusions Overall, this suggests persistent atrial fibrillation ablation transforms substrate that favors functional reentry (ie, rotors meandering in excitable tissue) into an arrhythmogenic milieu more conducive to anchored reentry. Our work also indicates that explainable machine learning and computational simulations can be combined to effectively probe mechanisms of recurrent arrhythmia.
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Affiliation(s)
| | - Fima Macheret
- Division of CardiologyUniversity of WashingtonSeattleWAUSA
| | - Griffin D. Scott
- Department of BioengineeringUniversity of WashingtonSeattleWAUSA
| | - Nazem Akoum
- Department of BioengineeringUniversity of WashingtonSeattleWAUSA
- Division of CardiologyUniversity of WashingtonSeattleWAUSA
| | - Patrick M. Boyle
- Department of BioengineeringUniversity of WashingtonSeattleWAUSA
- Institute for Stem Cell and Regenerative MedicineUniversity of WashingtonSeattleWAUSA
- Center for Cardiovascular BiologyUniversity of WashingtonSeattleWAUSA
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Brandenberger L, Silva KW, Macheret F, Badulak J, Lebin JA. Woman With Syncopal Episode and Seizure-like Activity. Ann Emerg Med 2023; 82:216-218. [PMID: 37479398 DOI: 10.1016/j.annemergmed.2022.11.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 11/16/2022] [Accepted: 11/16/2022] [Indexed: 07/23/2023]
Affiliation(s)
| | | | - Fima Macheret
- Section of Electrophysiology, Division of Cardiology, University of Washington, Seattle, WA
| | - Jenelle Badulak
- Department of Emergency Medicine, University of Washington, Seattle, WA; Division of Pulmonary Critical Care and Sleep Medicine, University of Washington, Seattle, WA
| | - Jacob A Lebin
- Department of Emergency Medicine, University of Colorado, Aurora, CO; Washington Poison Center, Seattle, WA
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Bifulco S, Macheret F, Akoum N, Boyle PM. PO-690-02 ABLATION SCAR ARRHYTHMOGENICITY CAN BE PREDICTED BY AN EXPLAINABLE MACHINE LEARNING (ML) CLASSIFIER: PROOF-OF-CONCEPT FROM COMPUTATIONAL SIMULATIONS. Heart Rhythm 2022. [DOI: 10.1016/j.hrthm.2022.03.595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Afroze T, Chahine Y, Macheret F, Jafarvand M, Boyle P, Akoum N. CA-528-01 PATTERNS OF ESOPHAGEAL TEMPERATURE CHANGE PREDICT ESOPHAGEAL THERMAL INJURY IN CATHETER ABLATION FOR ATRIAL FIBRILLATION. Heart Rhythm 2022. [DOI: 10.1016/j.hrthm.2022.03.099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Chahine Y, Askari-Atapour B, Kwan KT, Anderson CA, Macheret F, Afroze T, Bifulco SF, Cham MD, Ordovas K, Boyle PM, Akoum N. Epicardial adipose tissue is associated with left atrial volume and fibrosis in patients with atrial fibrillation. Front Cardiovasc Med 2022; 9:1045730. [PMID: 36386377 PMCID: PMC9664066 DOI: 10.3389/fcvm.2022.1045730] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 10/17/2022] [Indexed: 11/07/2022] Open
Abstract
Background Obesity is a risk factor for atrial fibrillation (AF) and strongly influences the response to treatment. Atrial fibrosis shows similar associations. Epicardial adipose tissue (EAT) may be a link between these associations. We sought to assess whether EAT is associated with body mass index (BMI), left atrial (LA) fibrosis and volume. Methods LA fibrosis and EAT were assessed using late gadolinium enhancement, and Dixon MRI sequences, respectively. We derived 3D models incorporating fibrosis and EAT, then measured the distance of fibrotic and non-fibrotic areas to the nearest EAT to assess spatial colocalization. Results One hundred and three AF patients (64% paroxysmal, 27% female) were analyzed. LA volume index was 54.9 (41.2, 69.7) mL/m2, LA EAT index was 17.4 (12.7, 22.9) mL/m2, and LA fibrosis was 17.1 (12.4, 23.1)%. LA EAT was significantly correlated with BMI (R = 0.557, p < 0.001); as well as with LA volume and LA fibrosis after BSA adjustment (R = 0.579 and R = 0.432, respectively, p < 0.001 for both). Multivariable analysis showed LA EAT to be independently associated with LA volume and fibrosis. 3D registration of fat and fibrosis around the LA showed no clear spatial overlap between EAT and fibrotic LA regions. Conclusion LA EAT is associated with obesity (BMI) as well as LA volume and fibrosis. Regions of LA EAT did not colocalize with fibrotic areas, suggesting a systemic or paracrine mechanism rather than EAT infiltration of fibrotic areas.
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Affiliation(s)
- Yaacoub Chahine
- Division of Cardiology, University of Washington, Seattle, WA, United States
| | | | - Kirsten T Kwan
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Carter A Anderson
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Fima Macheret
- Division of Cardiology, University of Washington, Seattle, WA, United States
| | - Tanzina Afroze
- Division of Cardiology, University of Washington, Seattle, WA, United States
| | - Savannah F Bifulco
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Matthew D Cham
- Department of Radiology, University of Washington, Seattle, WA, United States
| | - Karen Ordovas
- Department of Radiology, University of Washington, Seattle, WA, United States
| | - Patrick M Boyle
- Department of Bioengineering, University of Washington, Seattle, WA, United States.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States.,Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States
| | - Nazem Akoum
- Division of Cardiology, University of Washington, Seattle, WA, United States.,Department of Bioengineering, University of Washington, Seattle, WA, United States
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Chahine Y, Macheret F, Ordovas K, Kim J, Boyle PM, Akoum N. MRI-quantified left atrial epicardial adipose tissue predicts atrial fibrillation recurrence following catheter ablation. Front Cardiovasc Med 2022; 9:1045742. [PMID: 36531696 PMCID: PMC9755198 DOI: 10.3389/fcvm.2022.1045742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/21/2022] [Indexed: 12/04/2022] Open
Abstract
Background Epicardial adipose tissue (EAT) plays a significant role in promoting atrial fibrillation (AF) due to its proinflammatory properties and anatomic proximity to the myocardium. We sought to assess whether left atrial (LA) EAT volume is associated with AF recurrence following catheter ablation. Methods EAT was assessed via the 3D MRI Dixon sequence in 101 patients undergoing AF ablation. Patients were followed for arrhythmia recurrence. Results During an average follow-up period of 1 year, post-ablation AF recurrence occurred in 31 (30.7%) patients. LA EAT index was higher in those with compared to without recurrence (20.7 [16.9, 30.4] vs. 13.7 [10.5, 20.1] mL/m2, p < 0.001), and so was LA volume index (66 [52.6, 77.5] vs. 49.9 [37.7, 61.8] mL/m2, p = 0.001). Cox regression analysis showed LA EAT (HR = 1.089; 95% CI: [1.049-1.131], p < 0.001) to be an independent predictor of post-ablation AF recurrence. The ROC curve for LA EAT index in the prediction of AF recurrence had an AUC of 0.77 (95% CI 0.68-0.86, p < 0.001) and showed an optimal cutoff value of 14.29 mL/m2 to identify patients at risk of post-ablation AF recurrence. Integrating LA EAT with clinical risk factors improved prediction of AF recurrence (AUC increased from 0.65 to 0.79, DeLong test p = 0.044). Kaplan-Meier analysis for recurrence-free survival showed a significant difference between two groups of patients identified by the optimal LA EAT index cutoff of 14.29 mL/m2 (log rank = 14.79; p < 0.001). Conclusion EAT quantified using cardiac MRI, a reproducible and widely accessible imaging parameter, is a strong and independent predictor of post-ablation AF recurrence.
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Affiliation(s)
- Yaacoub Chahine
- Division of Cardiology, University of Washington, Seattle, WA, United States
| | - Fima Macheret
- Division of Cardiology, University of Washington, Seattle, WA, United States
| | - Karen Ordovas
- Department of Radiology, University of Washington, Seattle, WA, United States
| | - Joonseok Kim
- Division of Cardiology, University of Washington, Seattle, WA, United States
| | - Patrick M Boyle
- Department of Bioengineering, University of Washington, Seattle, WA, United States.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States.,Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States
| | - Nazem Akoum
- Division of Cardiology, University of Washington, Seattle, WA, United States.,Department of Bioengineering, University of Washington, Seattle, WA, United States
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Huang Y, Li W, Macheret F, Gabriel RA, Ohno-Machado L. A tutorial on calibration measurements and calibration models for clinical prediction models. J Am Med Inform Assoc 2021; 27:621-633. [PMID: 32106284 PMCID: PMC7075534 DOI: 10.1093/jamia/ocz228] [Citation(s) in RCA: 138] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 12/18/2019] [Accepted: 01/02/2020] [Indexed: 12/23/2022] Open
Abstract
Our primary objective is to provide the clinical informatics community with an introductory tutorial on calibration measurements and calibration models for predictive models using existing R packages and custom implemented code in R on real and simulated data. Clinical predictive model performance is commonly published based on discrimination measures, but use of models for individualized predictions requires adequate model calibration. This tutorial is intended for clinical researchers who want to evaluate predictive models in terms of their applicability to a particular population. It is also for informaticians and for software engineers who want to understand the role that calibration plays in the evaluation of a clinical predictive model, and to provide them with a solid starting point to consider incorporating calibration evaluation and calibration models in their work. Covered topics include (1) an introduction to the importance of calibration in the clinical setting, (2) an illustration of the distinct roles that discrimination and calibration play in the assessment of clinical predictive models, (3) a tutorial and demonstration of selected calibration measurements, (4) a tutorial and demonstration of selected calibration models, and (5) a brief discussion of limitations of these methods and practical suggestions on how to use them in practice.
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Affiliation(s)
- Yingxiang Huang
- Department of Biomedical Informatics, UC San Diego Health, University of California, San Diego, La Jolla, California, USA
| | - Wentao Li
- Department of Biomedical Informatics, UC San Diego Health, University of California, San Diego, La Jolla, California, USA
| | - Fima Macheret
- Department of Biomedical Informatics, UC San Diego Health, University of California, San Diego, La Jolla, California, USA.,Division of Hospital Medicine, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Rodney A Gabriel
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA
| | - Lucila Ohno-Machado
- Department of Biomedical Informatics, UC San Diego Health, University of California, San Diego, La Jolla, California, USA.,Division of Health Services Research & Development, VA San Diego Healthcare System, San Diego, California, USA
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Adler ED, Voors AA, Klein L, Macheret F, Braun OO, Urey MA, Zhu W, Sama I, Tadel M, Campagnari C, Greenberg B, Yagil A. Improving risk prediction in heart failure using machine learning. Eur J Heart Fail 2019; 22:139-147. [PMID: 31721391 DOI: 10.1002/ejhf.1628] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/24/2019] [Accepted: 08/25/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Predicting mortality is important in patients with heart failure (HF). However, current strategies for predicting risk are only modestly successful, likely because they are derived from statistical analysis methods that fail to capture prognostic information in large data sets containing multi-dimensional interactions. METHODS AND RESULTS We used a machine learning algorithm to capture correlations between patient characteristics and mortality. A model was built by training a boosted decision tree algorithm to relate a subset of the patient data with a very high or very low mortality risk in a cohort of 5822 hospitalized and ambulatory patients with HF. From this model we derived a risk score that accurately discriminated between low and high-risk of death by identifying eight variables (diastolic blood pressure, creatinine, blood urea nitrogen, haemoglobin, white blood cell count, platelets, albumin, and red blood cell distribution width). This risk score had an area under the curve (AUC) of 0.88 and was predictive across the full spectrum of risk. External validation in two separate HF populations gave AUCs of 0.84 and 0.81, which were superior to those obtained with two available risk scores in these same populations. CONCLUSIONS Using machine learning and readily available variables, we generated and validated a mortality risk score in patients with HF that was more accurate than other risk scores to which it was compared. These results support the use of this machine learning approach for the evaluation of patients with HF and in other settings where predicting risk has been challenging.
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Affiliation(s)
- Eric D Adler
- Division of Cardiology, Department of Medicine, UC San Diego, La Jolla, CA, USA
| | - Adriaan A Voors
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Liviu Klein
- Division of Cardiology, Department of Medicine, UC San Francisco, San Francisco, CA, USA
| | - Fima Macheret
- Altman Clinical and Translational Research Institute (ACTRI), UC San Diego, La Jolla, CA, USA
| | - Oscar O Braun
- Cardiology, Department of Clinical Sciences, Lund University and Skåne University Hospital, Lund, Sweden
| | - Marcus A Urey
- Division of Cardiology, Department of Medicine, UC San Diego, La Jolla, CA, USA
| | - Wenhong Zhu
- Altman Clinical and Translational Research Institute (ACTRI), UC San Diego, La Jolla, CA, USA
| | - Iziah Sama
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Matevz Tadel
- Physics Department, UC San Diego, La Jolla, CA, USA
| | | | - Barry Greenberg
- Division of Cardiology, Department of Medicine, UC San Diego, La Jolla, CA, USA
| | - Avi Yagil
- Division of Cardiology, Department of Medicine, UC San Diego, La Jolla, CA, USA.,Physics Department, UC San Diego, La Jolla, CA, USA
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Adler E, Voors A, Klein L, Macheret F, Sama I, Braun O, Urey M, Zhu W, Tadel M, Campagnari C, Greenberg B, Yagil A. MACHINE LEARNING ALGORITHM USING 8 COMMONLY ACQUIRED CLINICAL VARIABLES ACCURATELY PREDICTS MORTALITY IN HEART FAILURE. J Am Coll Cardiol 2019. [DOI: 10.1016/s0735-1097(19)31297-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Adler E, Greenberg B, Braun O, Macheret F, Campagnari C. MARKER-HF (Machine Learning Assessment of RisK and EaRly mortality inHeart Failure): Development and Validation of a Novel Model MARKER-HF (Machine Learning Assessment of RisK and EaRly mortality inHeart Failure): Development and Validation of a Novel Model that AccuratelyIdentifies High Risk Heart Failure Patientsthat AccuratelyIdentifies High Risk Heart Failure Patients. J Card Fail 2018. [DOI: 10.1016/j.cardfail.2018.07.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Macheret F, Bartz TM, Djousse L, Ix JH, Mukamal KJ, Zieman SJ, Siscovick DS, Tracy RP, Heckbert SR, Psaty BM, Kizer JR. Higher circulating adiponectin levels are associated with increased risk of atrial fibrillation in older adults. Heart 2015; 101:1368-74. [PMID: 25855796 DOI: 10.1136/heartjnl-2014-307015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 03/13/2015] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Adiponectin has cardioprotective properties, suggesting that lower levels seen in obesity and diabetes could heighten risk of atrial fibrillation (AF). Among older adults, however, higher adiponectin has been linked to greater incidence of adverse outcomes associated with AF, although recent reports have shown this association to be U-shaped. We postulated that higher adiponectin would be linked to increased risk for AF in older adults in a U-shaped manner. METHODS We examined the associations of total and high-molecular-weight (HMW) adiponectin with incident AF among individuals free of prevalent cardiovascular disease (CVD) participating in a population-based cohort study of older adults (n=3190; age=74±5 years). RESULTS During median follow-up of 11.4 years, there were 886 incident AF events. Adjusted cubic splines showed a positive and linear association between adiponectin and incident AF. After adjusting for potential confounders, including amino-terminal pro-B-type natriuretic peptide 1-76, the HR (95% CI) for AF per SD increase in total adiponectin was 1.14 (1.05 to 1.24), while that for HMW adiponectin was 1.17 (1.08 to 1.27). Additional adjustment for putative mediators, including subclinical CVD, diabetes, lipids and inflammation, did not significantly affect these estimates. CONCLUSIONS The present findings demonstrate that higher, not lower, levels of adiponectin are independently associated with increased risk of AF in older adults despite its documented cardiometabolic benefits. Additional work is necessary to determine if adiponectin is a marker of failed counter-regulatory pathways or whether this hormone is directly harmful in the setting of or as a result of advanced age.
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Affiliation(s)
- Fima Macheret
- Department of Medicine, Penn Presbyterian Medical Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Traci M Bartz
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - Luc Djousse
- Division of Aging, Department of Medicine, Brigham and Women's Hospital and Boston VA Healthcare System, Boston, Massachusetts, USA
| | - Joachim H Ix
- Department of Medicine, and the Division of Preventive Medicine, Department of Family and Preventive Medicine, University of California San Diego, and Nephrology Section, Veteran Affairs San Diego Health Care System, San Diego, California, USA
| | - Kenneth J Mukamal
- Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Susan J Zieman
- Division of Geriatrics and Clinical Gerontology, National Institute on Aging, Bethesda, Maryland, USA
| | | | - Russell P Tracy
- Departments of Pathology and Biochemistry, University of Vermont, Burlington, Vermont, USA
| | - Susan R Heckbert
- Cardiovascular Health Research Unit, Departments of Medicine, Epidemiology, and Health Services, University of Washington, and Group Health Research Institute, Group Health Cooperative, Seattle, Washington, USA
| | - Bruce M Psaty
- Cardiovascular Health Research Unit, Departments of Medicine, Epidemiology, and Health Services, University of Washington, and Group Health Research Institute, Group Health Cooperative, Seattle, Washington, USA
| | - Jorge R Kizer
- Department of Medicine, and Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York, USA
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Suva D, Haller G, Lübbeke-Wolff A, Macheret F, Kindler V, Hoffmeyer P. [From aviation to surgery: the challenge of safety]. Rev Med Suisse 2014; 10:882-884. [PMID: 24834648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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16
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Costello-Boerrigter LC, Lapp H, Boerrigter G, Lerman A, Bufe A, Macheret F, Heublein DM, Larue C, Burnett JC. Secretion of prohormone of B-type natriuretic peptide, proBNP1-108, is increased in heart failure. JACC Heart Fail 2013; 1:207-12. [PMID: 24621871 DOI: 10.1016/j.jchf.2013.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Using a novel, specific assay for proBNP(1-108), this study tested the hypotheses that proBNP(1-108) is secreted by both nonfailing and failing human hearts and that proBNP(1-108) secretion is increased in failing hearts. BACKGROUND The prohormone of B-type natriuretic peptide (proBNP(1-108)) is a 108-amino acid peptide produced primarily by the heart and cleaved into biologically active BNP(1-32) and the biologically inactive NT-proBNP(1-76). It is unknown to what extent increased cardiac proBNP1-108 secretion compared to reduced peripheral processing is responsible for elevated proBNP(1-108) levels in patients with heart failure (HF) compared to subjects without HF. METHODS The transcardiac gradient of proBNP(1-108) was determined by collecting arterial blood and blood from the coronary sinus (CS). Samples from subjects without overt heart disease (n = 9) were collected during cardiac catheterization after coronary artery disease had been excluded. Samples from HF patients (n = 21) were collected during implantation of a biventricular pacemaker. ProBNP(1-108) was measured with a new assay. Values are medians (25th/75th percentiles). RESULTS The gradient of proBNP(1-108) across the nonfailing hearts was 8 (2/20) ng/l (aorta: 15 [1/25] ng/l; CS: 24 [8/41] ng/l; p = 0.018). The transcardiac gradient of proBNP(1-108) in the failing hearts was 326 (96/482) ng/l (arterial: 381 [201/586] ng/l; CS: 709 [408/1,087] ng/l; p<0.001). The transcardiac gradient was greater in failing than nonfailing hearts (p = 0.001). CONCLUSIONS ProBNP(1-108) is secreted by nonfailing and failing human hearts, but more so in the latter. It remains to be established where peripheral processing of proBNP(1-108) occurs and how this is affected by disease.
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Affiliation(s)
| | - Harald Lapp
- Helios Clinic, Erfurt, Germany; Witten/Herdecke University, Faculty of Health, School of Medicine, Witten, Germany
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Macheret F, Bartz T, Djousse L, Ix J, Mukamal K, Zieman S, Siscovick D, Tracy R, Heckbert S, Psaty B, Kizer J. HIGHER CIRCULATING TOTAL AND HIGH-MOLECULAR-WEIGHT ADIPONECTIN ARE ASSOCIATED WITH INCREASED RISK OF ATRIAL FIBRILLATION IN OLDER ADULTS. J Am Coll Cardiol 2013. [DOI: 10.1016/s0735-1097(13)60304-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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18
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Ichiki T, Mckie P, Macheret F, Burnett JC. B-type Natriuretic Peptide Molecular Forms and Their Convertases in Heart Failure. J Card Fail 2011. [DOI: 10.1016/j.cardfail.2011.06.403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Costello EC, Lapp H, Lerman A, Boerrigter G, Macheret F, Martin F, Bufe A, Larue C, Heublein DM, Burnett JC. The Prohormone of B-Type Natriuretic Peptide, proBNP1-108, Is Secreted by the Failing and Non-Failing Human Heart. J Card Fail 2011. [DOI: 10.1016/j.cardfail.2011.06.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Macheret F, Pundi KN, Broomall EM, Davis DM, Rodriguez V, Brands CK. Empiric treatment of protracted idiopathic purpura fulminans in an infant: a case report and review of the literature. J Med Case Rep 2011; 5:201. [PMID: 21605440 PMCID: PMC3126768 DOI: 10.1186/1752-1947-5-201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 05/23/2011] [Indexed: 12/02/2022] Open
Abstract
Introduction Idiopathic purpura fulminans is a cutaneous thrombotic disorder usually caused by autoimmune-mediated protein C or S deficiency. This disorder typically presents with purpura and petechiae that eventually slowly or rapidly coalesce into extensive, necrotic eschars on the extremities. We present the first known case of idiopathic purpura fulminans consistent with prior clinical presentations in the setting of a prothrombotic genetic mutation, but without hallmark biochemical evidence of protein C or protein S deficiency. Another novel feature of our patient's presentation is that discontinuation of anti-coagulation has invariably led to recurrence and formation of new lesions, which is unexpected in idiopathic purpura fulminans because clearance of autoimmune factors should be followed by restoration of anti-coagulant function. Although this disease is rare, infants with suspected idiopathic purpura fulminans should be rapidly diagnosed and immediately anti-coagulated to prevent adverse catastrophic outcomes such as amputation and significant developmental delay. Case presentation A six-month-old Caucasian boy was brought to our pediatric hospital service with a low-grade fever and subacute, symmetric, serpiginous, stellate, necrotic eschars on his forearms, legs and feet that eventually spread non-contiguously to his toes, thighs and buttocks. In contrast to his impressive clinical presentation, his serologic evaluation was normal, and he was not responsive to corticosteroids and antibiotics. Full-thickness skin biopsies revealed dermal vessel thrombosis, leading to a diagnosis of idiopathic purpura fulminans and successful treatment with low-molecular-weight heparin, which was transitioned to warfarin. Long-term management has included chronic anti-coagulation because of recurrence of lesions with discontinuation of treatment. Conclusion In infants with necrotic eschars, it is important to first consider infectious, inflammatory and hematologic etiologies. In the absence of etiology for protracted idiopathic purpura fulminans, management should include tissue biopsy, in which thrombotic findings warrant a trial of empiric anti-coagulation. Some infants, including our patient, may need long-term anti-coagulation, especially when the underlying etiology of coagulation remains unidentified and symptoms recur when treatment is halted. Given that our patient still requires anti-coagulation, he may have a yet to be identified autoimmune-mediated mechanism for his truly idiopathic case of protracted purpura fulminans.
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Affiliation(s)
- Fima Macheret
- Mayo Medical School, 200 First Street SW, Rochester, MN 55905, USA.
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Tonne JM, Campbell JM, Cataliotti A, Ohmine S, Thatava T, Sakuma T, Macheret F, Huntley BK, Burnett JC, Ikeda Y. Secretion of glycosylated pro-B-type natriuretic peptide from normal cardiomyocytes. Clin Chem 2011; 57:864-73. [PMID: 21482747 DOI: 10.1373/clinchem.2010.157438] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND B-type natriuretic peptide (BNP), a key cardiac hormone in cardiorenal homeostasis, is produced as a 108 amino acid prohormone, proBNP1-108, which is converted to a biologically active peptide BNP1-32 and an inactive N-terminal (NT)-proBNP1-76. The widely accepted model is that the normal heart releases a proteolytically processed BNP1-32 and NT-proBNP, whereas the diseased heart secretes high amounts of unprocessed/glycosylated proBNP1-108 or inappropriately processed BNPs. In contrast, circulating proBNP1-108 has recently been identified in healthy individuals, indicating that the normal heart also secretes unprocessed proBNP1-108. However, the mechanism of proBNP1-108 secretion from the normal heart remains elusive. Our goal was to determine the molecular mechanisms underlying proBNP1-108 intracellular trafficking and secretion from the normal heart. METHODS We expressed preproBNP in cardiomyocytes, and determined the subcellular localization and dominant intracellular and extracellular forms of BNP. RESULTS Intracellular immunoreactive BNPs were first accumulated in the Golgi apparatus, and then distributed throughout the cytoplasm as secretory vesicles. The predominant intracellular form of BNP was nonglycosylated proBNP1-108, rather than BNP1-32. Glycosylated proBNP1-108, but not nonglycosylated proBNP1-108, was detected as the major extracellular form in the culture supernatants of preproBNP-expressing cell lines and primary human cardiomyocytes. Ablation of O-glycosylation of proBNP1-108 at T71 residue, near the convertase recognition site, reduced the extracellular proBNP1-108 and increased extracellular BNP1-32. CONCLUSIONS Intracellular proBNP trafficking occurs through a conventional Golgi-endoplasmic reticulum pathway. Glycosylation of proBNP1-108 controls the stability and processing of extracellular proBNP1-108. Our data establish a new BNP secretion model in which the normal cardiac cells secrete glycosylated proBNP1-108.
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Affiliation(s)
- Jason M Tonne
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, Rochester, MN 55905, USA
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22
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Suva D, Haller G, Lübbeke-Wolff A, Macheret F, Kindler V, Hoffmeyer P. [From aviation to surgery: the challenge of safety]. Rev Med Suisse 2011; 7:670-673. [PMID: 21542383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Medical errors result in 44,000 to 98,000 deaths per year in the United States of America. Within the surgical specialties, half of these errors occur in the operating room. The origin of these errors is multifactorial, and is generally associated with problems in communication and teamwork. In order to improve safety in the operating room, many hospitals now propose to the medical staff "crew resource management" (CRM) training programs inspired by the aviation industry. This approach favors a better utilization of surgical checklists, improves efficiency during chirurgical interventions, and reduces patient mortality. In October 2009 we introduced a CRM course within the department of surgery at the Geneva University Hospitals. We are presenting this program as well as the first results following its application.
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Affiliation(s)
- D Suva
- Service de Chirurgie Orthopédique et Traumatologie de l'apparel Moteur Départment D'anesthémiologie Clinique.
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Macheret F, Boerrigter G, McKie P, Costello-Boerrigter L, Lahr B, Heublein D, Sandberg S, Ikeda Y, Cataliotti A, Bailey K, Rodeheffer R, Burnett JC. Pro-B-type natriuretic peptide(1-108) circulates in the general community: plasma determinants and detection of left ventricular dysfunction. J Am Coll Cardiol 2011; 57:1386-95. [PMID: 21414536 PMCID: PMC3927966 DOI: 10.1016/j.jacc.2011.01.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 12/27/2010] [Accepted: 01/03/2011] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The purpose of this study was to investigate circulating pro-B-type natriuretic peptide (proBNP(1-108)) in the general community and evaluate its ability to detect left ventricular (LV) dysfunction. BACKGROUND The current concept for cardiac endocrine function is that, in response to cardiac stress, the heart secretes B-type natriuretic peptide (BNP(1-32)) and amino-terminal pro-B-type natriuretic peptide (NT-proBNP(1-76)) after intracardiac cleavage of their molecular precursor, proBNP(1-108). We hypothesized that proBNP(1-108) circulates in normal human subjects and that it is a useful biomarker for LV dysfunction. METHODS Our population-based study included a cohort of 1,939 adults (age ≥45 years) from Olmsted County, Minnesota, with 672 participants defined as healthy. Subjects underwent in-depth clinical characterization, detailed echocardiography, and measurement of proBNP(1-108). Independent factors associated with proBNP(1-108) and test characteristics for the detection of LV dysfunction were determined. RESULTS ProBNP(1-108) in normal humans was strongly influenced by sex, age, heart rate, and body mass index. The median concentration was 20 ng/l with a mean proBNP(1-108) to NT-proBNP(1-76) ratio of 0.366, which decreased with heart failure stage. ProBNP(1-108) was a sensitive (78.8%) and specific (86.1%) biomarker for detecting LV systolic dysfunction, which was comparable to BNP(1-32), but less than NT-proBNP(1-76), in several subsets of the population. CONCLUSIONS ProBNP(1-108) circulates in the majority of healthy humans in the general population and is a sensitive and specific biomarker for the detection of systolic dysfunction. The proBNP(1-108) to NT-proBNP(1-76) ratio may provide insights into altered proBNP(1-108) processing during heart failure progression. Thus, this highly specific assay for proBNP(1-108) provides important new insights into the biology of the BNP system.
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Affiliation(s)
- Fima Macheret
- Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Department of Medicine and Physiology, Mayo Clinic, Rochester, Minnesota, USA.
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Macheret F, McKie P, Boerrigter G, Costello-Boerrigter L, Brian L, Heublein D, Sharon S, Cataliotti A, Rodeheffer R, Burnett JC. Pro-B-Type Natriuretic Peptide Predicts Mortality and Cardiovascular Events in the General Community: Comparison to Other BNP Biomarkers. J Card Fail 2010. [DOI: 10.1016/j.cardfail.2010.06.263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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25
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Macheret F, Heublein D, Lahr B, Costello-Boerrigter L, Boerrigter G, McKie P, Sandberg S, Rodeheffer R, Cataliotti A, Burnett JC. Pro-B-Type natriuretic peptide: a novel, specific biomarker for detection of left ventricular dysfunction in the general community. BMC Pharmacol 2009. [PMCID: PMC3313357 DOI: 10.1186/1471-2210-9-s1-p44] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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26
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Cataliotti A, Rodeheffer RJ, Lam CS, Boerrigter G, Redfield MM, Macheret F, Costello-Boerrigter LC, Chen HH, McKie PM, Cannone V, Burnett JC. Chronic Renal Insufficiency: Prevalence in the General Population and Improved Detection of Cardiac Disease in Combination with BNP Assays. J Card Fail 2009. [DOI: 10.1016/j.cardfail.2009.06.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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27
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Macheret F, Heublein D, Lahr B, Costello-Boerrigter L, McKie P, Boerrigter G, Sandberg S, Rodeheffer R, Cataliotti A, Burnett JC. Pro-B-Type Natriuretic Peptide: A Novel, Specific Biomarker for Detection of Left Ventricular Dysfunction in the General Community. J Card Fail 2009. [DOI: 10.1016/j.cardfail.2009.06.150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ichiki T, Huntley BK, Heublein DM, Sangaralingham SJ, Martin FL, Schirger JA, Macheret F, Jougasaki M, Burnett JC. Determinants of Circulating Corin in Healthy Subjects. J Card Fail 2009. [DOI: 10.1016/j.cardfail.2009.06.329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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El-Sayed I, Huang X, Macheret F, Humstoe JO, Kramer R, El-Sayed M. Effect of plasmonic gold nanoparticles on benign and malignant cellular autofluorescence: a novel probe for fluorescence based detection of cancer. Technol Cancer Res Treat 2008; 6:403-12. [PMID: 17877428 DOI: 10.1177/153303460700600505] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Due to the strong surface fields of noble metal nanoparticles, absorption and scattering of electromagnetic radiation is greatly enhanced. Noble metallic nanoparticles represent potential novel optical probes for simultaneous molecular imaging and photothermal cancer therapy using the enhanced scattering and absorption of light. Further, gold nanoparticles can affect molecular fluorescence via chemical, electronic, or photonic interactions. Live cells generate fluorescence due to intracellular and extracellular molecules. Differences in the biochemical composition between healthy and malignant cells can be exploited in vivo to help identify cancer spectroscopically. The interaction of gold nanoparticles with cellular autofluorescence has not yet been characterized. We hypothesized that gold nanoparticles delivered to live cells in vitro would alter cellular autofluorescence and may be useful as a novel class of contrast agent for fluorescence based detection of cancer. The fluorescence of two fluorophores that are responsible for tissue autofluorescence, NADH and collagen, and of two oral squamous carcinoma cell lines and one immortalized benign epithelial cell line were measured in vitro. Gold nanoparticles of different shapes, both spheres and rods, quenched the fluorescence of the soluble NADH and collagen. Reduction of NADH fluorescence was due to oxidation of NADH to NAD+ catalyzed by gold nanoparticles (results we previously published). Reduction of collagen fluorescence appears due to photonic absorption of light. Furthermore, a mean quenching of 12/8% (p<0.00050) of the tissue autofluorescence of cell suspensions was achieved in this model when nanospheres were incubated with the live cells. Gold nanospheres significantly decrease cellular autofluorescence of live cells under physiological conditions when excited at 280nm. This is the first report to our knowledge to suggest the potential of developing targeted gold nanoparticles optical probes as contrast agents for fluorescence based diagnoses of cancer.
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Affiliation(s)
- Ivan El-Sayed
- Department of Otolaryngology- A-730, Head and Neck Surgery, University of California at San Francisco Comprehensive Cancer Center, 400 Parnassus Ave, Box 0342, San Francisco, CA 94143, USA.
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Abstract
PURPOSE This study was conducted to determine whether newer infrared or laser welding technologies created joints superior to traditional furnace or torch soldering methods of joining metals. It was designed to assess the mechanical resistance, the characteristics of the fractured surfaces, and the elemental diffusion of joints obtained by four different techniques: (1) preceramic soldering with a propane-oxygen torch, (2) postceramic soldering with a porcelain furnace, (3) preceramic and (4) postceramic soldering with an infrared heat source, and (5) laser welding. MATERIAL AND METHODS Mechanical resistance was determined by measuring the ultimate tensile strength of the joint and by determining their resistance to fatigue loading. Elemental diffusion to and from the joint was assessed with microprobe tracings. Scanning electron microscopy micrographs of the fractured surface were also obtained and evaluated. RESULTS Under monotonic tensile stress, three groups emerged: The laser welds were the strongest, the preceramic joints ranged second, and the postceramic joints were the weakest. Under fatigue stress, the order was as follows: first, the preceramic joints, and second, a group that comprised both postceramic joints and the laser welds. Inspection of the fractographs revealed several fracture modes but no consistent pattern emerged. Microprobe analyses demonstrated minor diffusion processes in the preceramic joints, whereas significant diffusion was observed in the postceramic joints. CLINICAL IMPLICATIONS The mechanical resistance data conflicted as to the strength that could be expected of laser welded joints. On the basis of fatigue resistance of the joints, neither infrared solder joints nor laser welds were stronger than torch or furnace soldered joints.
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Affiliation(s)
- H W Wiskott
- Division of Fixed Prosthodontics, University of Geneva, Switzerland
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