Country differences in nocturnal sleep variability: Observations from a large-scale, long-term sleep wearable study.

Study Objectives: Country or regional differences in sleep duration are well-known, but few large-scale studies have specifically evaluated sleep variability, either across the work week, or in terms of differences in weekday and weekend sleep.

Methods: Sleep measures, obtained over 50 million night's sleep from ∼220,000 wearable device users in 35 countries, were analysed. Each person contributed an average of ∼242 nights of data.

Thicker polyethylene inserts (≥ 13 mm) increase the risk for early failure after primary cruciate-retaining total knee arthroplasty (TKA): a single-centre study of 7643 TKAs.

Purpose: This study investigates whether thicker (PE) inserts lead to a greater risk for revision after TKA. The differences between the TKA designs of three manufacturers (NexGen, PFC Sigma, Triathlon) are also compared.

Methods: A total of 7643 primary TKA surgeries were included.

Prediction model for an early revision for dislocation after primary total hip arthroplasty.

Dislocation is one of the most common complications after primary total hip arthroplasty (THA). Several patient-related risk factors for dislocation have been reported in the previous literature, but only few prediction models for dislocation have been made. Our aim was to build a prediction model for an early (within the first 2 years) revision for dislocation after primary THA using two different statistical methods.

Longitudinal profiling of metabolic ageing trends in two population cohorts of young adults.

Background: Quantification of metabolic changes over the human life course is essential to understanding ageing processes. Yet longitudinal metabolomics data are rare and long gaps between visits can introduce biases that mask true trends. We introduce new ways to process quantitative time-series population data and elucidate metabolic ageing trends in two large cohorts.

A longitudinal analysis of COVID-19 lockdown stringency on sleep and resting heart rate measures across 20 countries.

Lockdowns imposed to stem the spread of COVID-19 massively disrupted the daily routines of many worldwide, but studies to date have been mostly confined to observations within a limited number of countries, based on subjective reports and surveys from specific time periods during the pandemic. We investigated associations between lockdown stringency and objective sleep and resting-heart rate measures in ~ 113,000 users of a consumer sleep tracker across 20 countries from Jan to Jul 2020, compared to an equivalent period in 2019. With stricter lockdown measures, midsleep times were universally delayed, particularly on weekdays, while midsleep variability and resting heart rate declined.

Do cobalt or chromium accumulate in metal-on-metal hip arthroplasty patients who have mild, moderate, or severe renal insufficiency?

Aims: To find out if there is an inverse association between estimated glomerular filtration rate (eGFR) and whole blood cobalt (Co) and chromium (Cr) levels in patients with metal-on-metal (MoM) hip arthroplasties and renal insufficiency, suggesting that renal insufficiency could cause accumulation of Co and Cr in blood.

Methods: Out of 2,520 patients with 3,013 MoM hip arthroplasties, we identified 1,244 patients with whole blood Co, Cr, and creatinine measured within no more than a one-year interval. We analyzed the correlation of blood metal ion levels and eGFR to identify a potential trend of accumulating Co or Cr with decreasing eGFR.

Whole blood chromium concentration is very rarely elevated independently of whole blood cobalt.

Due to the risk of adverse reactions to metal debris resulting from increased wear of the arthroplasty more than one million metal-on-metal (MoM) hip replacements worldwide are in active follow-up. Follow-up usually includes measurement of both whole blood cobalt (Co) and chromium (Cr) concentrations. Our experience is that Cr is seldom independently elevated.

EpiMetal: an open-source graphical web browser tool for easy statistical analyses in epidemiology and metabolomics.

Motivation: An intuitive graphical interface that allows statistical analyses and visualizations of extensive data without any knowledge of dedicated statistical software or programming.

Implementation: EpiMetal is a single-page web application written in JavaScript, to be used via a modern desktop web browser.

General Features: Standard epidemiological analyses and self-organizing maps for data-driven metabolic profiling are included.

Direct Estimation of HDL-Mediated Cholesterol Efflux Capacity from Serum.

Background: HDL-mediated cholesterol efflux capacity (HDL-CEC) is a functional attribute that may have a protective role in atherogenesis. However, the estimation of HDL-CEC is based on in vitro cell assays that are laborious and hamper large-scale phenotyping.

Methods: Here, we present a cost-effective high-throughput nuclear magnetic resonance (NMR) spectroscopy method to estimate HDL-CEC directly from serum.

Postexercise recovery of the spatial QRS/T angle as a predictor of sudden cardiac death.

Background: Postexercise measurement of heart rate (HR) recovery and QT interval dynamics provides prognostic information in various patient populations.

Objective: The purpose of this study was to assess whether the measurement of the spatial relationship between the depolarization and repolarization wavefronts (total cosine R-to-T [TCRT]) during the postexercise recovery phase would yield prognostic information.

Methods: The population consisted of 1297 patients (56 ± 13 years; 67% men) who performed a clinically indicated bicycle stress test.

QRS-T morphology measured from exercise electrocardiogram as a predictor of cardiac mortality.

Aims: Total cosine R-to-T (TCRT) measured from the standard 12-lead electrocardiogram (ECG) reflects the spatial relationship between depolarization and repolarization wavefronts and a low TCRT value is a marker of poor prognosis. We tested the hypothesis that measurement of TCRT or QRS/T angle from exercise ECG would provide even more powerful prognostic information.

Methods And Results: The prognostic significances of TCRT and QRS/T angle were assessed from exercise ECG recordings in 1297 patients [age 56 ± 13 years (mean ± SD), 67% males] undergoing a clinically indicated bicycle stress-test and the subsequent follow-up.

Dynamics and rate-dependence of the spatial angle between ventricular depolarization and repolarization wave fronts during exercise ECG.

Background: QRS/T angle and the cosine of the angle between QRS and T-wave vectors (TCRT), measured from standard 12-lead electrocardiogram (ECG), have been used in risk stratification of patients. This study assessed the possible rate dependence of these variables during exercise ECG in healthy subjects.

Methods: Forty healthy volunteers, 20 men and 20 women, aged 34.

New Vectorcardiographic non-planarity measure of T-wave loop improves separation between healthy subjects and myocardial infarction patients.

Principal component analysis of vectorcardio-graphic T-wave loop has been shown to be a potential tool to describe the abnormality of the cardiac repolarization and to predict cardiac events in patients with cardiac disease. In this paper a new method for estimating the non-planarity of the T-wave loop is introduced and tested with healthy subjects and subjects with anterior or inferior myocardial infarction. The method is based on the resamping of T-wave data points with respect to the arc-length, the total least squares plane fitting, the identifying and reordering of the fitted axes, and decomposing the optimal rotation matrix.

T-Wave morphology in short QT syndrome.

Background: Short QT syndrome (SQTS) is an inherited disorder characterized by a short QT interval and vulnerability to ventricular tachyarrhythmias. The diagnostic criteria for this syndrome are not well defined, since there is uncertainty about the lowest normal limits for the corrected QT (QTc) interval.

Objective: The aim of this study was to determine whether T-wave morphology parameters are abnormal in short QT subjects and whether those parameters can help in the diagnosis of SQTS.

Electrocardiographic abnormalities and ventricular tachyarrhythmias after myocardial infarction.

Aims: To assess the association of electrocardiographic repolarization and depolarization patterns to vulnerability to ventricular tachyarrhythmias.

Methods: In the present case-control study, a 12-lead ECG, signal-averaged ECG (SAECG), T-wave and QRS morphology, and T-wave alternans (TWA) were analyzed in post-MI patients with and without documented sustained ventricular tachycardia (VT) or fibrillation (VF) (VT/VF group, n=40, Non-VT/VF group, n=37, respectively) and healthy subjects (n=41).

Results: The QRS complex duration, measured from standard ECG (128 +/- 32 ms vs.

Influence of size and location of myocardial infarction on TCRT parameter: a computer simulation study.

Electrocardiographic (ECG) parameter ;total cosine R-to-T' (TCRT) has been shown to have remarkable prognostic value as a predictor of the outcomes of the coronary artery disease and the postmyocardial infarction patients. In this study, equivalent double layer (EDL) model was used to find action potential based causes to explain the observed diminution of the TCRT after myocardial infarction (MI). The model parameters affected the characteristics of QRS complex, ST segment and T wave.

Influence of paper electrocardiogram digitizing on T wave and QRS complex morphology parameters.

Background: Many morphological parameters of the electrocardiogram (ECG) can be calculated from a digital ECG and paper prints of ECG after digitizing. However, the digitizing process, including printing, scanning, ECG contour extraction, and alignment, can produce changes to the signals, reducing the reliability of some sensitive parameters of QRS complex and T wave.

Methods: The influence of the digitizing process on the parameters of T wave and QRS complex morphology was studied by comparing systematically the values of the nine ECG morphology parameters, computed from the digital ECG and the corresponding paper ECG.

Functional significance of KCNH2 (HERG) K897T polymorphism for cardiac repolarization assessed by analysis of T-wave morphology.

Background: Although KCNH2 (HERG) K897T polymorphism has been shown to be associated with the QT interval measured from 12-lead electrocardiogram (ECG), the functional significance of K897T polymorphism has been debated. The aim of this study was to test whether the K897T polymorphism of the KCNH2 (HERG) gene coding for the rapidly activating delayed rectifier K+ channel influences cardiac repolarization assessed by principal component analysis (PCA) of T-wave morphology.

Methods: Twelve-lead ECGs were digitized and T-wave morphology was analyzed with a PCA method in a population consisting of 228 healthy middle-aged subjects (121 women and 107 men).

Usefulness of T-wave loop and QRS complex loop to predict mortality after acute myocardial infarction.

The aim of the study was to assess whether parameters based on the T-wave loop and QRS loop predict mortality, and cardiac mortality in particular, during follow-up of consecutive survivors of acute myocardial infarction (AMI). Patients with AMI (n = 437), treated according to contemporary guidelines, underwent digital high-resolution electrocardiography in orthogonal Frank leads (X, Y, Z) 5 to 14 days after AMI. Several T-wave and QRS loop parameters, such as the width and height of the loops and their ratio, T-wave loop dispersion (TWLD), QRS loop dispersion, and co-sine of the angle between the main vectors of the T-wave and QRS loops (TCRT), were calculated using a custom-made software package.