Effects of Atrial Fibrillation Screening According to N-Terminal Pro-B-Type Natriuretic Peptide: A Secondary Analysis of the Randomized LOOP Study.

BACKGROUND: Research suggests NT-proBNP (N-terminal pro-B-type natriuretic peptide) to be a strong predictor of incident atrial fibrillation (AF) and stroke. However, its utility in AF screening remains unknown. The aim of this study was to investigate NT-proBNP as a potential marker for screening efficacy with respect to AF yield and stroke prevention. METHODS: In the LOOP Study (Atrial Fibrillation Detected by Continuous ECG Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals), 6004 AF-naïve individuals at least 70 years old and with additional stroke risk factors were randomized 1:3 to either screening with an implantable loop recorder (ILR) and initiation of anticoagulation upon detection of AF episodes lasting ≥6 minutes or usual care (control). This post hoc analysis included study participants with available NT-proBNP measurement at baseline. RESULTS: A total of 5819 participants (96.9% of the trial population) were included. The mean age was 74.7 years (SD, 4.1 years) and 47.5% were female. The median NT-proBNP level was 15 pmol/L (interquartile range, 9-28 pmol/L) corresponding to 125 pg/mL (interquartile range, 76-233 pg/mL). NT-proBNP above median was associated with an increased risk of AF diagnosis both in the ILR group (hazard ratio, 1.84 [95% CI, 1.51-2.25]) and the control group (hazard ratio, 2.79 [95% CI, 2.30-3.40]). Participants with NT-proBNP above the median were also at higher risk of clinical events compared with those having lower levels (hazard ratio, 1.21 [95% CI, 0.96-1.54] for stroke or systemic embolism [SE], 1.60 [95% CI, 1.32-1.95] for stroke/SE/cardiovascular death, and 1.91 [95% CI, 1.61-2.26] for all-cause death). Compared with usual care, ILR screening was associated with significant reductions in stroke/SE and stroke/SE/cardiovascular death among participants with NT-proBNP above median (hazard ratio, 0.60 [95% CI, 0.40-0.90] and 0.70 [95% CI, 0.53-0.94], respectively) but not among those with lower levels (Pinteraction=0.029 for stroke/SE and 0.045 for stroke/SE/cardiovascular death). No risk reduction in all-cause death was observed in either NT-proBNP subgroup for ILR versus control (Pinteraction=0.68). Analyzing NT-proBNP as a continuous variable yielded similar findings. CONCLUSIONS: In an older population with additional stroke risk factors, ILR screening for AF was associated with a significant reduction in stroke risk among individuals with higher NT-proBNP levels but not among those with lower levels. These findings should be considered hypothesis generating and warrant further study before clinical implementation. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02036450.

Prevalence and prognostic relevance of electrocardiographic abnormalities among patients with ANCA-associated vasculitis.

OBJECTIVES: Current guidelines provide limited evidence for cardiovascular screening in ANCA-associated vasculitis (AAV). This study aimed to investigate the prevalence of electrocardiogram (ECG) abnormalities and associations between no, minor or major ECG abnormalities with cardiovascular mortality in AAV patients compared with matched controls. METHOD: Using a risk-set matched cohort design, patients diagnosed with granulomatosis with polyangiitis or microscopic polyangiitis with digital ECGs were identified from Danish registers from 2000-2021. Patients were matched 1:3 to controls without AAV on age, sex, and year of ECG measurement. Associated hazards of cardiovascular mortality according to ECG abnormalities were assessed in Cox regression models adjusted for age, sex, and comorbidities, with subsequent computation of 5-year risk of cardiovascular mortality standardized to the age- and sex-distribution of the sample. RESULTS: A total of 1431 AAV patients were included (median age: 69 years, 52.3% male). Median follow-up was 4.8 years. AAV was associated with higher prevalence of left ventricular hypertrophy (17.5% vs 12.5%), ST-T deviations (10.1% vs 7.1%), atrial fibrillation (9.6% vs 7.5%), and QTc prolongation (5.9% vs 3.6%). Only AAV patients with major ECG abnormalities demonstrated significantly elevated risk of cardiovascular mortality [HR 1.99 (1.49-2.65)] compared with controls. This corresponded to a 5-year risk of cardiovascular mortality of 19.14% (16-22%) vs 9.41% (8-11%). CONCLUSION: Patients with AAV demonstrated a higher prevalence of major ECG abnormalities than controls. Notably, major ECG abnormalities were associated with a significantly increased risk of cardiovascular mortality. These results advocate for the inclusion of ECG assessment into routine clinical care for AAV patients.

The Danish Nationwide Electrocardiogram (ECG) Cohort.

The electrocardiogram (ECG) is a non-invasive diagnostic tool holding significant clinical importance in the diagnosis and risk stratification of cardiac disease. However, access to large-scale, population-based digital ECG data for research purposes remains limited and challenging. Consequently, we established the Danish Nationwide ECG Cohort to provide data from standard 12-lead digital ECGs in both pre- and in-hospital settings, which can be linked to comprehensive Danish nationwide administrative registers on health and social data with long-term follow-up. The Danish Nationwide ECG Cohort is an open real-world cohort including all patients with at least one digital pre- or in-hospital ECG in Denmark from January 01, 2000, to December 31, 2021. The cohort includes data on standardized and uniform ECG diagnostic statements and ECG measurements including global parameters as well as lead-specific measures of waveform amplitudes, durations, and intervals. Currently, the cohort comprises 2,485,987 unique patients with a median age at the first ECG of 57 years (25th-75th percentiles, 40-71 years; males, 48%), resulting in a total of 11,952,430 ECGs. In conclusion, the Danish Nationwide ECG Cohort represents a novel and extensive population-based digital ECG dataset for cardiovascular research, encompassing both pre- and in-hospital settings. The cohort contains ECG diagnostic statements and ECG measurements that can be linked to various nationwide health and social registers without loss to follow-up.

Electrocardiographic markers in patients with type 2 diabetes and the role of diabetes duration.

BACKGROUND: The association between type 2 diabetes and electrocardiographic (ECG) markers are incompletely explored and the dependence on diabetes duration is largely unknown. We aimed to investigate the electrocardiographic (ECG) changes associated with type 2 diabetes over time. METHODS: In this cross-sectional study, we matched people with type 2 diabetes 1:1 on sex, age, and body mass index with people without diabetes from the general population. We regressed ECG markers with the presence of diabetes and the duration of clinical diabetes, respectively, adjusted for sex, age, body mass index, smoking, heart rate, diabetes medication, renal function, hypertension, and myocardial infarction. RESULTS: We matched 988 people with type 2 diabetes (332, 34% females) with as many controls. Heart rate was 8 bpm higher (p < 0.001) in people with vs. without type 2 diabetes, but the difference declined with increasing diabetes duration. For most depolarization markers, the difference between people with and without type 2 diabetes increased progressively with diabetes duration. On average, R-wave amplitude was 6 mm lower in lead V5 (p < 0.001), P-wave duration was 5 ms shorter (p < 0.001) and QRS duration was 3 ms (p = 0.03). Among repolarization markers, T-wave amplitude (measured in V5) was lower in patients with type 2 diabetes (1 mm lower, p < 0.001) and the QRS-T angle was 10 degrees wider (p = 0.002). We observed no association between diabetes duration and repolarization markers. CONCLUSIONS: Type 2 diabetes was independently associated with electrocardiographic depolarization and repolarization changes. Differences in depolarization markers, but not repolarization markers, increased with increasing diabetes duration.

Does targeted positioning of the left ventricular pacing lead towards the latest local electrical activation in cardiac resynchronization therapy reduce the incidence of death or hospitalization for heart failure?

BACKGROUND: Cardiac resynchronization therapy (CRT) improves symptoms, health-related quality of life and long-term survival in patients with systolic heart failure (HF) and shortens QRS duration. However, up to one third of patients attain no measurable clinical benefit from CRT. An important determinant of clinical response is optimal choice in left ventricular (LV) pacing site. Observational data have shown that achieving an LV lead position at a site of late electrical activation is associated with better clinical and echocardiographic outcomes compared to standard placement, but mapping-guided LV lead placement towards the site of latest electrical activation has never been investigated in a randomized controlled trial (RCT). The purpose of this study was to evaluate the effect of targeted positioning of the LV lead towards the latest electrically activated area. We hypothesize that this strategy is superior to standard LV lead placement. METHODS: The DANISH-CRT trial is a national, double-blinded RCT (ClinicalTrials.gov NCT03280862). A total of 1,000 patients referred for a de novo CRT implantation or an upgrade to CRT from right ventricular pacing will be randomized 1:1 to receive conventional LV lead positioning preferably in a nonapical posterolateral branch of the coronary sinus (CS) (control group) or targeted positioning of the LV lead to the CS branch with the latest local electrical LV activation (intervention group). In the intervention group, late activation will be determined using electrical mapping of the CS. The primary endpoint is a composite of death and nonplanned HF hospitalization. Patients are followed for a minimum of 2 years and until 264 primary endpoints occurred. Analyses will be conducted according to the intention-to-treat principle. Enrollment for this trial began in March 2018, and per April 2023, a total of 823 patients have been included. Enrollment is expected to be complete by mid-2024. CONCLUSIONS: The DANISH-CRT trial will clarify whether mapping-guided positioning of the LV lead according to the latest local electrical activation in the CS is beneficial for patients in terms of reducing the composite endpoint of death or nonplanned hospitalization for heart failure. Results from this trial are expected to impact future guidelines on CRT. GOV IDENTIFIER: NCT03280862.

Electrocardiographic markers of subclinical atrial fibrillation detected by implantable loop recorder: insights from the LOOP Study.

AIMS: Insights into subclinical atrial fibrillation (AF) development are warranted to inform the strategies of screening and subsequent clinical management upon AF detection. Hence, this study sought to characterize the onset and progression of subclinical AF with respect to 12-lead electrocardiogram (ECG) parameters. METHODS AND RESULTS: We included AF-naïve individuals aged 70-90 years with additional stroke risk factors who underwent implantable loop recorder (ILR) monitoring in the LOOP Study. Using data from daily ILR recordings and the computerized analysis of baseline ECG, we studied empirically selected ECG parameters for AF detection (≥6 min), cumulative AF burden, long-lasting AF (≥24 h), and AF progression. Of 1370 individuals included, 419 (30.6%) developed AF during follow-up, with a mean cumulative AF burden of 1.5% [95% CI: 1.2-1.8]. Several P-wave-related and ventricular ECG parameters were associated with new-onset AF and with cumulative AF burden in AF patients. P-wave duration (PWD), P-wave terminal force in Lead V1, and interatrial block (IAB) further demonstrated significant associations with long-lasting AF. Among AF patients, we observed an overall reduction in cumulative AF burden over time (IRR 0.70 [95% CI: 0.51-0.96]), whereas IAB was related to an increased risk of progression to AF ≥24 h (HR 1.86 [95% CI: 1.02-3.39]). Further spline analysis also revealed longer PWD to be associated with this progression in AF duration. CONCLUSION: We identified several ECG parameters associated with new-onset subclinical AF detected by ILR. Especially PWD and IAB were robustly related to the onset and the burden of AF as well as progression over time.

Ventricular rate in atrial fibrillation and the risk of heart failure and death.

AIMS: While clinical trials have suggested that a high ventricular rate is associated with increased risk of heart failure (HF) and mortality, all-comers studies are warranted. OBJECTIVE: To assess 1-year risk of new-onset diagnosed HF and all-cause mortality among rate-control treated patients presenting with atrial fibrillation (AF) on an electrocardiogram (ECG) according to ventricular rate. METHODS AND RESULTS: ECGs recorded at the Copenhagen General Practitioners Laboratory (2001-15) were used to identify patients with AF. Multivariate Cox proportional hazard regression models were used to compare risk of new-onset HF and all-cause mortality after first ECG presenting with AF according to ventricular rate on ECG [<60, 60-79, 80-99, and 100-110, > 110 beats per minute (bpm)]. We identified 7408 patients in treatment with rate control drugs at time of first ECG presenting with AF [median age 78 years (Q1,Q3 = 70-85 years)], 45.8% male, median ventricular rate 83 bpm, (Q1,Q3 = 71-101 bpm)]. During 1-year follow-up, 666 (9.0%) of all patients with AF developed HF and 858 (11.6%) died. Patients with AF ventricular rates 100-110 bpm and >110 bpm had a hazard ratio (HR) of 1.46 (CI: 1.10-1.95) and 2.41 (CI: 1.94-3.00) respectively for new-onset HF, compared with 60-79 bpm. Similarly, patients with AF ventricular rates 100-110 bpm and >110 bpm had a HR of 1.44 (CI: 1.13-1.82) and 1.34 (CI: 1.08-1.65) respectively for all-cause mortality, compared with 60-79 bpm. CONCLUSIONS: Ventricular rates ≥100 bpm among patients presenting with AF on ECG in treatment with rate control drugs were associated with greater risk of both new-onset HF and all-cause mortality.

The role of contractile dyssynchrony in pacing-induced cardiomyopathy: detailed assessment using index of contractile asymmetry.

AIMS: The pathophysiological effects of chronic right ventricular pacing and the role of right ventricular lead position are not well understood. Therefore, we investigated the association between left ventricular contractile dyssynchrony and pacing-induced cardiomyopathy (PICM) in patients with chronic right ventricular pacing. Furthermore, we assessed the association between right ventricular lead location and left ventricular contractile dyssynchrony. METHODS: This was a retrospective study using data from 153 pacemaker patients with normal (≥ 50%) pre-implant left ventricular ejection fraction (LVEF). Baseline and follow-up echocardiograms were analyzed, and PICM was defined as LVEF < 50% with ≥ 10% decrease in LVEF after pacemaker implantation. Relative index of contractile asymmetry (rICA), a novel strain rate-based method, was calculated to quantify left ventricular contractile dyssynchrony between opposing walls in the three apical views. Right ventricular lead position was categorized into anterior septum, posterior septum, free wall, and apex based on contrast-enhanced cardiac computed tomography. RESULTS: Forty-seven (31%) developed PICM. Overall contractile dyssynchrony, measured by mean rICA, was higher in the PICM group compared with the non-PICM group (1.19 ± 0.21 vs. 1.03 ± 0.19, p < 0.001). Left ventricular anterior-inferior dyssynchrony, assessed in the apical two-chamber view, was independently associated with PICM (p < 0.001). Thirty-seven (24%) leads were implanted anterior septal, 11 (7.2%) posterior septal, 74 (48.4%) apical, and 31 (20.3%) free wall. Left ventricular anterior-inferior dyssynchrony was significantly different between the four pacing lead locations (p < 0.01) with the highest rICA observed in the posterior septal group (1.30 ± 0.37). CONCLUSIONS: PICM is significantly associated increased contractile dyssynchrony assessed by rICA. This study suggests that especially left ventricular dyssynchrony in the anterior-inferior direction is associated with PICM, and pacing the right ventricular posterior septum resulted in the highest degree of anterior-inferior dyssynchrony. Quantification of left ventricular dyssynchrony by rICA provides important insights to the potential pathophysiology of PICM and the impact of right ventricular lead position.

Implantable loop recorder detection of atrial fibrillation to prevent stroke (The LOOP Study): a randomised controlled trial.

BACKGROUND: It is unknown whether screening for atrial fibrillation and subsequent treatment with anticoagulants if atrial fibrillation is detected can prevent stroke. Continuous electrocardiographic monitoring using an implantable loop recorder (ILR) can facilitate detection of asymptomatic atrial fibrillation episodes. We aimed to investigate whether atrial fibrillation screening and use of anticoagulants can prevent stroke in individuals at high risk. METHODS: We did a randomised controlled trial in four centres in Denmark. We included individuals without atrial fibrillation, aged 70-90 years, with at least one additional stroke risk factor (ie, hypertension, diabetes, previous stroke, or heart failure). Participants were randomly assigned in a 1:3 ratio to ILR monitoring or usual care (control) via an online system in permuted blocks with block sizes of four or eight participants stratified according to centre. In the ILR group, anticoagulation was recommended if atrial fibrillation episodes lasted 6 min or longer. The primary outcome was time to first stroke or systemic arterial embolism. This study is registered with ClinicalTrials.gov, NCT02036450. FINDINGS: From Jan 31, 2014, to May 17, 2016, 6205 individuals were screened for inclusion, of whom 6004 were included and randomly assigned: 1501 (25·0%) to ILR monitoring and 4503 (75·0%) to usual care. Mean age was 74·7 years (SD 4·1), 2837 (47·3%) were women, and 5444 (90·7%) had hypertension. No participants were lost to follow-up. During a median follow-up of 64·5 months (IQR 59·3-69·8), atrial fibrillation was diagnosed in 1027 participants: 477 (31·8%) of 1501 in the ILR group versus 550 (12·2%) of 4503 in the control group (hazard ratio [HR] 3·17 [95% CI 2·81-3·59]; p<0·0001). Oral anticoagulation was initiated in 1036 participants: 445 (29·7%) in the ILR group versus 591 (13·1%) in the control group (HR 2·72 [95% CI 2·41-3·08]; p<0·0001), and the primary outcome occurred in 318 participants (315 stroke, three systemic arterial embolism): 67 (4·5%) in the ILR group versus 251 (5·6%) in the control group (HR 0·80 [95% CI 0·61-1·05]; p=0·11). Major bleeding occurred in 221 participants: 65 (4·3%) in the ILR group versus 156 (3·5%) in the control group (HR 1·26 [95% CI 0·95-1·69]; p=0·11). INTERPRETATION: In individuals with stroke risk factors, ILR screening resulted in a three-times increase in atrial fibrillation detection and anticoagulation initiation but no significant reduction in the risk of stroke or systemic arterial embolism. These findings might imply that not all atrial fibrillation is worth screening for, and not all screen-detected atrial fibrillation merits anticoagulation. FUNDING: Innovation Fund Denmark, The Research Foundation for the Capital Region of Denmark, The Danish Heart Foundation, Aalborg University Talent Management Program, Arvid Nilssons Fond, Skibsreder Per Henriksen, R og Hustrus Fond, The AFFECT-EU Consortium (EU Horizon 2020), Læge Sophus Carl Emil Friis og hustru Olga Doris Friis' Legat, and Medtronic.

Effect of hydroxychloroquine on the cardiac ventricular repolarization: A randomized clinical trial.

AIMS: Hydroxychloroquine has been suggested as possible treatment for severe acute respiratory syndrome-coronavirus-2. Studies reported an increased risk of QTcF-prolongation after treatment with hydroxychloroquine. The aim of this study was to analyse the concentration-dependent effects of hydroxychloroquine on the ventricular repolarization, including QTcF-duration and T-wave morphology. METHODS: Twenty young (≤30 y) and 20 elderly (65-75 y) healthy male subjects were included. Subjects were randomized to receive either a total dose of 2400 mg hydroxychloroquine over 5 days, or placebo (ratio 1:1). Follow-up duration was 28 days. Electrocardiograms (ECGs) were recorded as triplicate at baseline and 4 postdose single recordings, followed by hydroxychloroquine concentration measurements. ECG intervals (RR, QRS, PR, QTcF, J-Tpc, Tp-Te) and T-wave morphology, measured with the morphology combination score, were analysed with a prespecified linear mixed effects concentration-effect model. RESULTS: There were no significant associations between hydroxychloroquine concentrations and ECG characteristics, including RR-, QRS- and QTcF-interval (P = .09, .34, .25). Mean ΔΔQTcF-interval prolongation did not exceed 5 ms and the upper limit of the 90% confidence interval did not exceed 10 ms at the highest measured concentrations (200 ng/mL). There were no associations between hydroxychloroquine concentration and the T-wave morphology (P = .34 for morphology combination score). There was no significant effect of age group on ECG characteristics. CONCLUSION: In this study, hydroxychloroquine did not affect ventricular repolarization, including the QTcF-interval and T-wave morphology, at plasma concentrations up to 200 ng/mL. Based on this analysis, hydroxychloroquine does not appear to increase the risk of QTcF-induced arrhythmias.

Left Atrial Remodeling and Cerebrovascular Disease Assessed by Magnetic Resonance Imaging in Continuously Monitored Patients.

BACKGROUND: Atrial remodeling is associated with future atrial fibrillation (AF) and stroke. AF has been associated with cognitive impairment and cerebral white matter lesions. We wished to investigate the possible direct association between atrial remodeling and cerebrovascular disease in patients with and without AF documented by implantable loop recorder (ILR). METHODS: Cardiac and cerebral magnetic resonance imaging were acquired in a cross-sectional study, including participants ≥70 years of age with stroke risk factors without known AF. Cerebrovascular disease was visually rated using the Fazekas scale and number of lacunar strokes. Left atrial (LA) and ventricular volumes and function were analyzed. Associations between atrial remodeling and cerebrovascular disease were assessed with logistic regression models. The analyses were stratified according to sinus rhythm or any AF during 3 months of continuous ILR monitoring to account for subclinical AF. RESULTS: Of 200 participants investigated, 87% had a Fazekas score ≥1 and 45% had ≥1 lacunar infarct. Within 3 months of ILR monitoring, AF was detected in 28 (14%) participants. For participants with sinus rhythm (n = 172), lower LA passive emptying fraction was associated with Fazekas score after multivariable adjustment (OR [95% CI]: 0.51 [0.27; 0.86] p = 0.02), and increased LA maximum (OR [95% CI]: 1.38 [1.07; 1.82] p = 0.01) and minimum volumes (OR [95% CI]: 1.48 [1.03; 2.17] p = 0.04) were associated with lacunar infarcts. There were no significant associations in patients with AF. CONCLUSION: In AF-free patients, as documented by ILR monitoring, we found an independent association between LA passive emptying fraction and Fazekas score and between atrial volumes and lacunar infarcts.

Prediction of postoperative atrial fibrillation with postoperative epicardial electrograms.

Objectives. New-onset postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery. The arrhythmia often entails a longer hospital stay, greater risk of other complications, and higher mortality both short- and long-term. An investigation of the use of early atrial electrograms in predicting POAF in cardiac surgery was performed. Design. In this prospective observational study, a total of 99 consecutive adult patients undergoing coronary artery bypass grafting, valve surgery or both were included. On the first postoperative morning, standard 12-lead electrograms (ECG), unipolar atrial electrograms (aEG), and vital values were recorded. The outcome was new-onset POAF within one month postoperatively. Results. Three multivariable prediction models for POAF were formed using measurements derived from the ECG, aEG, and patient characteristics. Age, body mass index, and two unipolar electrogram measurements quantifying local activation time and fractionation were strongly associated with the outcome POAF. The performance of the POAF prediction models was assessed through receiver operating curve characteristics with cross-validation, and discrimination using the leave-one-out-method to internally validate the models. The cross-validated area under the receiver operating characteristic curve (AUC) was improved in a prediction model using atrial-derived electrogram variables (AUC 0.796, 95% CI 0.698-0.894), compared with previous ECG and clinical models (AUC 0.716, 95% CI 0.606-0.826 and AUC 0.718, 95% CI 0.613-0.822, respectively). Conclusions. This study found that easily obtainable measurements from atrial electrograms may be helpful in identifying patients at risk of POAF in cardiac surgery.

Plasma potassium concentration and cardiac repolarisation markers, Tpeak-Tend and Tpeak-Tend/QT, during and after exercise in healthy participants and in end-stage renal disease.

PURPOSE: The cardiac T-wave peak-to-end interval (Tpe) is thought to reflect dispersion in ventricular repolarisation, with abnormalities in Tpe associated with increased risk of arrhythmia. Extracellular K+ modulates cardiac repolarisation, and since arterial plasma K+ concentration ([K+]) rapidly increases during and declines following exercise, we investigated the relationship between [K+] and Tpe with exercise. METHODS: Serial ECGs (Tpe, Tpe/QT ratio) and [K+] were obtained from 8 healthy, normokalaemic volunteers and 22 patients with end-stage renal disease (ESRD), at rest, during, and after exhaustive exercise. RESULTS: Post-exercise [K+] nadir was 3.1 ± 0.1, 5.0 ± 0.2 and 4.0 ± 0.1 mmol.L-1 (mean ± SEM) for healthy participants and ESRD patients before and after haemodialysis, respectively. In healthy participants, compared to pre-exercise, recovery-induced low [K+] was associated with a prolongation of Tpe (110 ± 8 vs. 87 ± 5 ms, respectively, p = 0.03) and an increase in Tpe/QT ratio (0.28 ± 0.01 vs. 0.23 ± 0.01, respectively, p = 0.01). Analyses of serial data revealed [K+] as a predictor of Tpe in healthy participants (ß = -0.54 ±0.05, p < 0.0001), in ESRD patients (ß = -0.75 ± 0.06, p < 0.0001) and for all data pooled (ß = -0.61 ± 0.04, p < 0.0001). The [K+] was also a predictor of Tpe/QT ratio in healthy participants and ESRD patients. CONCLUSIONS: Tpe and Tpe/QT ratio are predicted by [K+] during exercise. Low [K+] during recovery from exercise was associated with increased Tpe and Tpe/QT, indicating accentuated dispersion of ventricular repolarisation. The findings suggest that variations in [K+] with physical exertion may unmask electrophysiological vulnerabilities to arrhythmia.

Day-to-day measurement of physical activity and risk of atrial fibrillation.

AIMS: The aim of this study was to investigate the association between within-individual changes in physical activity and onset of atrial fibrillation (AF). METHODS AND RESULTS: A total of 1410 participants from the general population (46.2% women, mean age 74.7 ± 4.1 years) with risk factors but with no prior AF diagnosis underwent continuous monitoring for AF episodes along with daily accelerometric assessment of physical activity using an implantable loop recorder during ≈3.5 years. The combined duration of monitoring was ≈1.6 million days, where 10 851 AF episodes lasting ≥60 min were detected in 361 participants (25.6%) with a median of 5 episodes (2, 25) each. The median daily physical activity was 112 (66, 168) min/day. A dynamic parameter describing within-individual changes in daily physical activity, i.e. average daily activity in the last week compared to the previous 100 days, was computed and used to model the onset of AF. A 1-h decrease in average daily physical activity was associated with AF onset the next day [odds ratio 1.24 (1.18-1.31)]. This effect was modified by overall level of activity (P < 0.001 for interaction), and the signal was strongest in the tertile of participants with lowest activity overall [low: 1.62 (1.41-1.86), mid: 1.27 (1.16-1.39), and high: 1.10 (1.01-1.19)]. CONCLUSIONS: Within-individual changes in physical activity are associated with the onset of AF episodes as detected by continuous monitoring in a high-risk population. For each person, a 1-h decrease in daily physical activity during the last week increased the odds of AF onset the next day by ≈25%, while the strongest association was seen in the group with the lowest activity overall. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02036450.

Hepatic steatosis in patients with schizophrenia: a clinical cross-sectional study.

OBJECTIVE: With hepatic steatosis (HS) being an established risk factor for CVD in the general population, it may also be a predictor of CVD in patients with schizophrenia. The aim of the present study was to investigate if time since schizophrenia diagnosis, body mass index (BMI), sex, metabolic syndrome, alcohol use, smoking, alanine transaminase (ALT), and body fat percentage (as measured by bioelectrical impedance) were associated with HS, determined by computed tomography (CT), in a population of patients diagnosed with schizophrenia. METHODS: Moderate to severe HS (40 CT Hounsfield units as threshold) was determined utilizing non-contrast enhanced CT. The association between the explanatory variables and outcome of HS was assessed using multivariable logistic regression. RESULTS: In the present study, 145 patients diagnosed with schizophrenia (mean age 42.2 years (SD ± 13.8)) were included, with 88 (60.7%) being male. On average, patients had been diagnosed for 14.8 (SD ± 10.7) years. A total of 31 (21.4%) patients had HS as determined by CT. The presence of HS was associated with ALT (OR 1.06, 95% CI (1.02-1.10) per 1 U/L increase), and the presence of metabolic syndrome (OR 62.89, 95% CI (2.03-1949.55)). The presence of HS was not associated with BMI, body fat percentage or time since diagnosis in the multivariable analysis. CONCLUSION: Higher ALT and the presence of metabolic syndrome were associated with HS in patients with schizophrenia utilizing multivariable analysis. The findings suggest that risk factors for HS are similar in both the general population and in patients with schizophrenia.

Associations between primary care electrocardiography and non-Alzheimer dementia.

OBJECTIVES: To determine whether electrocardiogram (ECG) markers are associated with incident non-Alzheimer's dementia (non-AD) and whether these markers also improve risk prediction for non-AD. MATERIALS AND METHODS: We retrospectively included 170,605 primary care patients aged 60 years or older referred for an ECG by their general practitioner and followed them for a median of 7.6 years. Using Cox regression, we reported hazard ratios (HRs) for electrocardiogram markers. Subsequently, we evaluated if addition of these electrocardiogram markers to a clinical model improved risk prediction for non-AD using change in area under the receiver-operator characteristics curve (AUC). RESULTS: The 5-year cumulative incidence of non-AD was 3.4 %. Increased heart rate (HR=1.06 pr. 10 bpm [95% confidence interval: 1.04-1.08], p<0.001), shorter QRS duration (HR=1.07 pr. 10 ms [1.05-1.09], p<0.001), elevated J-amplitude (HR=1.16 pr. mm [1.08-1.24], p<0.001), decreased T-peak amplitude (HR=1.02 pr. mm [1.01-1.04], p=0.002), and increased QTc (HR=1.08 pr. 20 ms [1.05-1.10], p<0.001) were associated with an increased rate of non-AD. Atrial fibrillation on the ECG (HR=1.18 [1.08-1.28], p<0.001) Sokolow-Lyon index > 35 mm (HR=1.31 [1.18-1.46], p<0.001) and borderline (HR=1.18 [1.11-1.26], p<0.001) or abnormal (HR=1.40 [1.27-1.55], p<0.001) QRS-T angle were also associated with an increased rate of non-AD. Upon addition of ECG markers to the Cox model, 5-year and 10-year C-statistic (AUC) improved significantly (delta-AUC, 0.36 [0.18-0.50] and 0.20 [0.03-0.35] %-points, respectively). CONCLUSIONS: ECG markers typical of an elevated cardiovascular risk profile were associated with non-AD and improved both 5-year and 10-year risk predictions for non-AD.

Comprehensive Evaluation of Rhythm Monitoring Strategies in Screening for Atrial Fibrillation: Insights From Patients at Risk Monitored Long Term With an Implantable Loop Recorder.

BACKGROUND: Stroke is an increasing health problem worldwide. Atrial fibrillation (AF) is a major risk factor for stroke, and the attention given to AF screening is rising, as new monitoring technologies emerge. We aimed to evaluate the performance of a large panel of screening strategies and to assess population characteristics associated with diagnostic yield. METHODS: Individuals with stroke risk factors but without AF were recruited from the general population to undergo screening with an implantable loop recorder. New-onset AF lasting ≥6 minutes was adjudicated by senior cardiologists. After continuous monitoring for >3 years, complete day-to-day heart rhythm data sets were reconstructed for every participant, including exact time of onset and termination of all AF episodes. Random sampling was applied to assess the sensitivity and negative predictive value of screening with various simulated screening strategies compared with the implantable loop recorder. The diagnostic yield across strategies and population subgroups was compared by use of nonparametric tests. RESULTS: The rhythm data sets comprised 590 participants enduring a total of 659 758 days of continuous monitoring and 20 110 AF episodes. In these data, a single 10-second ECG yielded a sensitivity (and negative predictive value) of 1.5% (66%) for AF detection, increasing to 8.3% (67%) for twice-daily 30-second ECGs during 14 days and to 11% (68%), 13% (68%), 15% (69%), 21% (70%), and 34% (74%) for a single 24-hour, 48-hour, 72-hour, 7-day, or 30-day continuous monitoring, respectively. AF detection further improved when subsequent screenings were performed or when the same monitoring duration was spread over several periods compared with a single period (eg, three 24-hour monitorings versus one 72-hour monitoring; P<0.0001 for all comparisons). The sensitivity was consistently higher among participants with age ≥75 years, male sex, CHADS2 score >2, or NT-proBNP (N-terminal pro-B-type natriuretic peptide) ≥40 pmol/L and among participants with underlying ≥24-hour AF episodes compared with shorter AF (P<0.0001 for all screening strategies). CONCLUSIONS: In screening for AF among participants with stroke risk factors, the diagnostic yield increased with duration, dispersion, and number of screenings, although all strategies had low yield compared with the implantable loop recorder. The sensitivity was higher among participants who were older, were male, or had higher NT-proBNP. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02036450.

Atrial fibrillation burden and cognitive decline in elderly patients undergoing continuous monitoring.

AIMS: To study the relationship between subclinical atrial fibrillation (AF) and changes in cognitive function in a large cohort of individuals with stroke risk factors. METHODS: Individuals with no prior AF diagnosis but with risk factors for stroke were recruited to undergo annual cognitive assessment with the Montreal Cognitive Assessment (MoCA) along with implantable loop recorder (ILR) monitoring for AF for 3 years. If AF episodes lasting ≥6 minutes were detected, oral anticoagulation (OAC) treatment was initiated. RESULTS: A total of 1194 participants (55.2 % men, mean age 74.5 (±3.9)) had a combined duration of heart rhythm monitoring of ≈1.3 million days. Among these, 339 participants (28.3%) had adjudicated AF, with a median AF burden of 0.072% (0.02, 0.39), and 324 (96%) initiated OAC. When stratifying the participants into AF burden groups (No AF, AFlow (AF burden <0.25%), and AFhigh, (AF burden >0.25%)), only participants in the AFlow group had a decrease in MoCA score over time (P = .03), although this was not significant after adjustment for stroke risk factors. A subgroup analysis of 175 participants (14.6%) with a MoCA <26 at 3 years found no association to AF diagnosis or burden. CONCLUSIONS: In a high-risk population, subclinical AF detected by continuous monitoring and subsequently treated with OAC was not associated with a significant change in MoCA score over a 3-year period.

Comparing the consistency of electrocardiogram interval measurements by resting ECG versus 12-lead Holter.

In clinical trials, traditionally only a limited number of 12-lead resting electrocardiograms (ECGs) can be recorded and, thus, long intervals may elapse between assessment timepoints and valuable information may be missed during times when patients' cardiac electrical activity is not being monitored. These limitations have led to the increasing use of Holter recorders which provide continuous data registrations while reducing the burden on patients and freeing up time for clinical trial staff to perform other tasks. However, there is a shortage of data comparing the two approaches. In this study, data from a randomized, double-blind, four-period, crossover thorough QT study in 40 healthy subjects were used to compare continuous 12-lead Holter recordings to standard 12-lead resting ECGs which were recorded in parallel. Heart rate and QT interval data were estimated by averaging three consecutive heartbeats. Values exceeding the sample average by more than 5% were tagged as outliers and excluded from the analysis. Visual comparisons of the ECG waveforms of the Holter signal showed a good correlation with resting ECGs at matching timepoints. Resting ECG data revealed sex differences that Holter data did not show. Specifically, women were found to have a longer QTcF of 20 ms, while men had a lower heart rate. We found that continuous recordings provided a more accurate reflection of changes in cardiac electrical activity over 24 hr. However, manual adjudication is still required to ensure the quality and accuracy of ECG data, and that only artifacts are removed thereby avoiding loss of true signals.

Association between vectorcardiographic QRS area and incident heart failure diagnosis and mortality among patients with left bundle branch block: A register-based cohort study.

BACKGROUND: QRS duration and morphology including left bundle branch block (LBBB) are the most widely used electrocardiogram (ECG) markers for assessing ventricular dyssynchrony and predicting heart failure (HF). However, the vectorcardiographic QRS area may more accurately identify delayed left ventricular activation and HF development. OBJECTIVE: We investigated the association between QRS area and incident HF risk in patients with LBBB. METHODS: By crosslinking data from Danish nationwide registries, we identified patients with a first-time digital LBBB ECG between 2001 and 2015. The vectorcardiographic QRS area was derived from a 12­lead ECG using the Kors transformation method and grouped into quartiles. The endpoint was a composite of HF diagnosis, filled prescriptions for loop diuretics, or death from HF. Cause-specific multivariable Cox regression was used to compute hazard ratios(HR) with 95% confidence intervals(CI). RESULTS: We included 3316 patients with LBBB free from prior HF-related events (median age, 72 years; male, 40%). QRS area quartiles comprised Q1, 36-98 µVs; Q2, 99-119 µVs; Q3, 120-145 µVs; and Q4, 146-295 µVs. During a 5-year follow-up, 31% of patients reached the composite endpoint, with a rate of 39% in the highest quartile Q4. A QRS area in quartile Q4 was associated with increased hazard of the composite endpoint (HR:1.48, 95%CI:1.22-1.80) compared with Q1. CONCLUSIONS: Among primary care patients with newly discovered LBBB, a large vectorcardiographic QRS area (146-295 µVs) was associated with an increased risk of incident HF diagnosis, filling prescriptions for loop diuretics, or dying from HF within 5-years.