Standard Deviation Of Normal RR Intervals Research Articles

0613 Actigraphy-Based Sleep Disruption and Diurnal Biomarkers of Autonomic Function in Paroxysmal Atrial Fibrillation

Abstract Introduction Sleep architectural disruption is associated with atrial fibrillation (AF), however, associated autonomic influences remain unclear and it is unknown if this detriment persists during wakefulness. We hypothesize diurnal-patterned associations of sleep disruption and autonomic dysfunction in patients with paroxysmal AF Methods We analyzed data from the Sleep Apnea and Atrial Fibrillation Biomarkers and Electrophysiologic Atrial Triggers (SAFEBEAT) study designed to examine paroxysmal AF and sleep apnea involving simultaneous collection of continuous electrocardiogram monitoring (Heartrak Telemetry®) and actigraphy (Actiwatch GTX) for 7-21 days. Heart rate variability (HRV) measures in frequency and time domains were used as surrogates of autonomic function and averaged per sleep/wake per day. A linear mixed-effects model assuming compound symmetry correlation structure was used to assess the relationship of HRV with actigraphy-derived sleep data. Results The analytic sample (age 60.1±12 years, body mass index 32.6±6.7 kg/m², 36% female, 75% White) included 108 participants with paroxysmal AF. Significant associations were observed between sleep indices and HRV measures during wakefulness: a) Sleep latency with high-frequency power (HFP), b) total sleep time, wakefulness after sleep onset (WASO) and number of awakenings with low-frequency power (LFP), and c) Sleep efficiency with standard deviation of normal R-R intervals (SDNN) and coefficient of variation (CV). During sleep, a) total sleep time was associated with LFP/HFP ratio (LHR), and b) number of awakenings with LHR. Significant sleep-wake interactions were observed between a) Sleep latency and HFP, b) Sleep efficiency with SDNN and CV, c) WASO with SDNN, CV, and LFP, and d) number of awakenings with CV and LFP. Conclusion Our novel findings indicate actigraphy-based measures of sleep disruption were associated with autonomic function alterations and these relationships exhibited diurnal variability in patients with paroxysmal AF. Results provide unique insights into differential relationships of immediate (during sleep) versus sustained (during wakefulness) autonomic dysfunction related to sleep disruption which may contribute to atrial arrhythmogenesis Support (if any)  

Abstract P392: Association Between Blood Pressure Variability and Subclinical Measures of Cardiovascular Disease in Desk Workers

Introduction: Previous research has demonstrated that variability in resting blood pressure (BP) across arms, measurements, or days may be associated with an increased risk for cardiovascular disease (CVD) and mortality. Yet, the extent to which BP variability increases cardiovascular risk and the mechanisms explaining this association are unclear. This study evaluated associations between BP variability with subclinical pathways of CVD development (arterial stiffness (pulse wave velocity [PWV]) and cardiac autonomic function (heart rate variability [HRV]) in desk workers. Hypothesis: Higher BP variability will be associated with higher PWV and lower (worse) HRV Methods: This secondary analysis of baseline data from the Effect of Reducing Sedentary on Blood Pressure randomized controlled trial included 265 sedentary and inactive desk workers (mean age 44.9±11.6 years; 82.0% white; 57.9% female) with elevated-to-stage 2 hypertension and who were not using antihypertensive medication. Sequential BP measurements determined the arm with the higher systolic BP by using an oscillometric device (Omron HEM-907XL). BP was then measured at least twice from the arm with the higher systolic BP at the first (visit-1) and second (visit-2) visits, occurring ≤30 days apart. Systolic BP variability metrics included inter-arm (first measurements between arms at visit-1), intra-arm (first two measurements on the arm with higher systolic BP at visit-1), and inter-visit (average BP from repeated measurements on the same arm across visits-1 and -2). Subclinical measures of CVD included resting carotid- femoral(cfPWV) and carotid-radial(crPWV) PWV (Complier Analyse) and the log transformed standard deviation of normal R-R intervals (SDNN) and the root mean square of the successive differences (RMSSD) HRV measures (Polar Electro). Adjusted linear regression estimated the associations between subclinical measures of CVD and BP variability metrics; Metrics were operationalized into three categories: differences of 0-5 mmHg, 6-10 mmHg, and 11 or more mmHg. Results: The prevalence of having 6 mmHg or more difference for the inter-arm, intra-arm, and inter-visit systolic BP was 43%, 38%, and 53%, respectively. PWV and HRV were not different across categories of inter-arm systolic BP variability or inter-visit systolic BP variability (all p>0.05). However, a same-day intra-arm difference in systolic BP of 6-10 mmHg within visit-1 was associated with higher cfPWV (β=0.42 m/s, (95% CI: 0.07, 0.77) as compared to those with an intra-arm difference of 0-5 mmHg. Conclusion: These data suggest that higher systolic BP variability in the same arm within visit, but not variability across arms or between visits, may be associated with higher aortic stiffness in desk workers with untreated elevated-to-stage 2 hypertension.

Multimodal Assessment of Changes in Physiological Indicators when Presenting a Video Fragment on Screen (2D) versus a VR (3D) Environment.

The increasing role of virtual environments in society, especially in the context of the pandemic and evolving metaverse technologies, requires a closer study of the physiological state of humans using virtual reality (VR) for entertainment, work, or learning. Despite the fact that many physiological reactions to the content presented in various modalities under VR conditions have already been described, often these studies do not reflect the full range of changes in the physiological reactions that occur to a person during their immersion in the virtual world. This study was designed to find and compare the most sensitive physiological indicators that change when viewing an emotionally intense video fragment in standard format on screen and in virtual reality conditions (in a VR helmet). The research methodology involved randomly presenting a group of subjects with visual content-a short video clip-first on screen (2D) and then in a virtual reality helmet (3D). A special feature of this study is the use of multimodal physiological state assessment throughout the content presentation, in conjunction with psychological testing of the study participants before and after the start of the study. It has been discovered that the most informative physiological indicators reflecting the subjects' condition under virtual reality conditions were changes in theta rhythm amplitude, skin conductance, standard deviation of normal RR-intervals (SDRR), and changes in photoplethysmogram (PPG). The study results suggest that in the process of immersion in a virtual environment, the participants develop a complex functional state, different from the state when watching on screen, which is characterised by the restructuring of autonomic regulation and activation of emotion structures of the brain.

Impaired left ventricular deformation and ventricular-arterial coupling in post-COVID-19: association with autonomic dysregulation.

Coronavirus disease-19 (COVID-19) has extended implications namely the long COVID-19 syndrome. We assessed over-time changes in left ventricular (LV) function, aortic stiffness, autonomic function, and ventricular-arterial coupling (VAC) in post-COVID-19 patients. We followed 34 post-COVID-19 subjects, up to 6 months post-hospital discharge. Subjects without COVID-19 served as control. We evaluated LV global longitudinal strain (LV-GLS), arterial stiffness [carotid-femoral pulse wave velocity (cf-PWV)], and heart rate variability -standard deviation of normal RR intervals (SDNN). VAC was estimated as the ratio of cf-PWV to LV-GLS. Post-COVID-19 individuals (1-month post-hospital discharge) presented with impaired LV-GLS [−18.4%(3.1) vs. −22.0%(2.7), P < 0.001], cf-PWV [12.1 m/s (3.2) vs. 9.6 m/s (1.9), P < 0.001], SDNN [111.3 ms (22.6) vs. 147.2 ms (14.0), P < 0.001], and VAC [−0.68 (0.22) vs. −0.44 (0.10), P < 0.001] compared to control. LV-GLS, SDNN, and VAC improved at the 6-month follow-up however they did not reach control levels. In post-COVID-19 subjects, SDNN and VAC were correlated at the 1-month (R = 0.499, P = 0.003) and 6-month (R = 0.372, P = 0.04) follow-up. Long COVID-19 syndrome was associated with impaired LV-GLS, SDNN, and VAC. Post-COVID-19 subjects presented with autonomic dysregulation associated with aortic stiffness, ventricular-arterial impairment, and LV dysfunction, even 6-months post-hospital discharge. These abnormalities may be related to the presence of long COVID-19 syndrome.Graphical abstract

Heart rate variability and atrial fibrillation in the general population: a longitudinal and Mendelian randomization study

BackgroundSex differences and causality of the association between heart rate variability (HRV) and atrial fibrillation (AF) in the general population remain unclear.Methods12,334 participants free of AF from the population-based Rotterdam Study were included. Measures of HRV including the standard deviation of normal RR intervals (SDNN), SDNN corrected for heart rate (SDNNc), RR interval differences (RMSSD), RMSSD corrected for heart rate (RMSSDc), and heart rate were assessed at baseline and follow-up examinations. Joint models, adjusted for cardiovascular risk factors, were used to determine the association between longitudinal measures of HRV with new-onset AF. Genetic variants for HRV were used as instrumental variables in a Mendelian randomization (MR) analysis using genome-wide association studies (GWAS) summary-level data.ResultsDuring a median follow-up of 9.4 years, 1302 incident AF cases occurred among 12,334 participants (mean age 64.8 years, 58.3% women). In joint models, higher SDNN (fully-adjusted hazard ratio (HR), 95% confidence interval (CI) 1.24, 1.04–1.47, p = 0.0213), and higher RMSSD (fully-adjusted HR, 95% CI 1.33, 1.13–1.54, p = 0.0010) were significantly associated with new-onset AF. Sex-stratified analyses showed that the associations were mostly prominent among women. In MR analyses, a genetically determined increase in SDNN (odds ratio (OR), 95% CI 1.60, 1.27–2.02, p = 8.36 × 10–05), and RMSSD (OR, 95% CI 1.56, 1.31–1.86, p = 6.32 × 10–07) were significantly associated with an increased odds of AF.ConclusionLongitudinal measures of uncorrected HRV were significantly associated with new-onset AF, especially among women. MR analyses supported the causal relationship between uncorrected measures of HRV with AF. Our findings indicate that measures to modulate HRV might prevent AF in the general population, in particular in women.Graphical abstractAF; atrial fibrillation, GWAS; genome-wide association study, IVW; inverse variance weighted, MR; Mendelian randomization, MR-PRESSO; MR-egger and mendelian randomization pleiotropy residual sum and outlier, RMSSD; root mean square of successive RR interval differences, RMSSDc; root mean square of successive RR interval differences corrected for heart rate, SDNN; standard deviation of normal to normal RR intervals, SDNNc; standard deviation of normal to normal RR intervals corrected for heart rate, WME; weighted median estimator.aRotterdam Study n=12,334bHRV GWAS n=53,174cAF GWAS n=1,030,836

Association between Left Ventricular Wall Thickness and Heart Rate Variability with Complex Ventricular Arrhythmia in Hypertrophic Cardiomyopathy

Objective: To demonstrate the association between the maximal left ventricular (LV) wall thickness and the late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) and heart rate variability (HRV) with complex ventricular arrhythmia (VA) in patients with hypertrophic cardiomyopathy (HCM). Materials and Methods: The present study was a retrospective study. Fifty-seven HCM patients who underwent CMR and Holter monitoring at Siriraj Hospital, Bangkok, Thailand, were identified and included. Complex VA was defined as Lown grading system type 4a or 4b as couplet or non-sustained ventricular tachycardia. Standard deviation of normal RR-interval (SDNN) was used to assess HRV. Results: The authors studied 57 patients, 40 (70.2%) patients had LGE, and 13 (22.8%) patients had complex VA. Complex VA was demonstrated in 11 (27.5%) patients in the LGE group compared with two (11.8%) in those without (p=0.304), and four (57.1%), and nine (18.0%) in patients had a maximal LV wall thickness of 25 mm or more and less than 25 mm, respectively (p=0.041). SDNN was 100.98±29.82 ms versus 123.85±35.12 ms (p=0.015) in the LGE group compared with the no-LGE group, and 89.08±25.39 ms versus 113.34±33.06 ms (p=0.018) in patients with and without complex VA. Multivariate analysis showed significant associations of maximal LV wall thickness of 25 mm or more and SDNN of less than 105 ms with complex VA with odds ratios of 6.71 (95% confidence interval [CI] 1.09 to 41.14; p=0.040) and 5.15 (95% CI 1.14 to 23.30; p=0.033), respectively. Conclusion: In HCM patients, increased LV wall thickness and a reduction in SDNN are associated with complex VA. The present study supports the utility of CMR and HRV for risk stratification of patients with HCM. Keywords: Heart rate variability; Maximal left ventricular wall thickness; Complex ventricular arrhythmia; Hypertrophic cardiomyopathy

Wearable sensor device-based detection of decreased heart rate variability in Parkinson's disease.

The evidence that heart rate variability (HRV) decreases during early Parkinson's disease (PD) largely depends on electrocardiogram data. In this study, we examined HRV in PD using wearable sensors and assessed various evaluation methods for detecting disease-related alterations. We evaluated 27 patients with PD and 23 disease controls. The wearable sensors POLAR V800 HR and POLAR H10 were used for the HRV measurements. The participants wore the two sensors for approximately 24h, and long-term HRV data were acquired. We analyzed the standard deviation of normal R-R intervals (SDNN) and coefficient of variation of R-R intervals (CVRR) for every 100 consecutive beats. Focusing on the fluctuation of SDNN and CVRR, we extracted the minimum, first decile, first quartile, and median values of SDNN and CVRR. The area under the receiver operating characteristic curve (AUC) for each HRV parameter was calculated to differentiate PD from the disease controls. The minimum values of SDNN and CVRR had the highest AUC (SDNN: AUC 0.90, 95% confidence interval [CI] 0.78-0.96; CVRR: AUC 0.90, CI 0.76-0.96) among the evaluation methods tested. The minimum values of SDNN and CVRR were significantly decreased in PD (SDNN: 9.5 ± 4.0ms vs. 4.4 ± 2.0ms, p &lt; 0.0001; CVRR: 1.15 ± 0.33% vs. 0.65 ± 0.24%, p &lt; 0.0001). We detected decreased HRV in PD using wearable sensors. Analyzing the minimum values of the HRV parameter in long-term recordings appears to be appropriate for detecting the decrease in HRV in PD.

Effect of Transcranial Pulsed Current Stimulation on Fatigue Delay after Medium-Intensity Training.

The purpose of this study was to investigate the effect of transcranial pulsed current stimulation (tPCS) on fatigue delay after medium-intensity training. Materials and Methods: Ninety healthy college athletes were randomly divided into an experimental group (n = 45) and control group (n = 45). The experimental group received medium-intensity training for a week. After each training, the experimental group received true stimulation of tPCS (continuous 15 min 1.5 mA current intensity stimulation). The control group received sham stimulation. The physiological and biochemical indicators of participants were tested before and after the experiment, and finally 30 participants in each group were included for data analysis. Results: In the experimental group, creatine kinase (CK), cortisol (C), time-domain heart rate variability indices root mean square of the successive differences (RMSSD), standard deviation of normal R-R intervals (SDNN), and frequency domain indicator low frequency (LF) all increased slowly after the intervention. Among these, CK, C, and SDNN values were significantly lower than those in the control group (p < 0.05). Testosterone (T), T/C, and heart rate variability frequency domain indicator high frequency (HF) in the experimental group decreased slowly after the intervention, and the HF value was significantly lower than that in the control group (p < 0.05). The changes in all of the indicators in the experimental group were smaller than those in the control group. Conclusion: The application of tPCS after medium-intensity training enhanced the adaptability to training and had a significant effect on the maintenance of physiological state. The application of tPCS can significantly promote the recovery of autonomic nervous system function, enhance the regulation of parasympathetic nerves, and delay the occurrence of fatigue.

Reliability of the heart rate variability threshold during treadmill exercise.

The heart rate variability threshold (HRVT) is a clinical parameter used to gain insight into autonomic balance. Prior validation of the HRVT has been with cycle ergometry, with no studies examining the viability of treadmill exercise. The purpose of this study was to examine the reliability of the HRVT during treadmill exercise, and to compare the HRVT to the ventilatory threshold (VT). Ten healthy, college‐aged males completed two maximal graded exercise tests on a treadmill. A Polar RS800CX watch was used for heart rate and HRVT data. The HRVT was determined from three HRV variables including the root mean square of successive differences of continuous R−R intervals (RMSSD), the standard deviation of normal R−R intervals (SDNN) and the standard deviation of instantaneous beat intervals (SD1). A metabolic cart was utilized to determine the VT. Results showed no difference between the HRVT (2.4 ± 0.6 and 2.2 ± 0.3 for RMSSD, 2.8 ± 0.5 and 2.7 ± 0.5 for SDNN and 2.4 ± 0.6 and 2.3 ± 0.6 for SD1) or the VT (3.0 ± 0.3 and 3.1 ± 0.3) between trials. When compared to the VT, averaged HRVT values for RMSSD (2.3 ± 0.3) and SD1 (2.3 ± 0.5) were lower than averaged VT (2.8 ± 0.4, p < 0.05). The averaged HRVT from SDNN (2.8 ± 0.5) did not differ from the VT. These results suggest that treadmill is a viable mode for HRVT determination, and that HRVT determined by SDNN may be a better comparison to the VT.

Heart rate variability and atrial fibrillation in the general population: a longitudinal and mendelian randomization study

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): The Rotterdam Study is funded by Erasmus Medical Center and Erasmus University, Rotterdam, Netherlands Organization for the Health Research and Development (ZonMw), the Research Institute for Diseases in the Elderly (RIDE), the Ministry of Education, Culture and Science, the Ministry for Health, Welfare and Sports, the European Commission (DG XII), and the Municipality of Rotterdam. This study is further supported by the Gender and prevention grant (555003017) from ZonMw. Background Sex-differences and the causality of the association between heart rate variability (HRV) and atrial fibrillation (AF) remain unclear. Purpose To investigate the sex-differences and the causality of the association between heart rate variability and atrial fibrillation. Methods 12,334 participants free of AF from a large population-based cohort study were included. Measures of HRV including the standard deviation of normal RR-intervals (SDNN), SDNN corrected for heart rate (SDNNc), RR-interval differences (RMSSD), RMSSD corrected for heart rate (RMSSDc), and heart rate were assessed at baseline and follow-up examinations. Joint models, adjusted for cardiovascular risk factors, were used to determine the association between longitudinal measures of HRV with new-onset AF. Additionally, we evaluated sex-differences. Genetic variants for HRV were used as instrumental variables in a Mendelian randomization (MR) analysis using GWAS summary-level data. Results During a median follow-up of 9.4 years, 1,302 incident AF cases occurred. In joint models, higher SDNN (hazard ratio (HR), 95% confidence interval (CI), 1.24, 1.04-1.47, p=0.0213), and higher RMSSD (HR, 95% CI, 1.33, 1.13-1.54, p=0.0010) were significantly associated with new-onset AF. Sex-stratified analyses showed that the associations were mostly prominent among women. In MR analyses, genetically determined decreases in SDNN (odds ratio (OR), 95% CI, 1.60, 1.27-2.02, p=8.36x10-05), and RMSSD (OR, 95% CI, 1.56, 1.31-1.86, p= 6.32x10-07) were significantly associated with increased AF risk. Conclusions Longitudinal measures of uncorrected HRV were significantly associated with new-onset AF, in particular among women. MR analyses supported the causal relationship between uncorrected measures of HRV with AF. Our findings indicate that measures to modulate HRV might prevent AF in the general population, especially among women.

Ambulatory electrocardiography, heart rate variability, and pharmacologic stress testing in cats with subclinical hypertrophic cardiomyopathy

The utility of ambulatory electrocardiography (AECG) to evaluate cats with subclinical hypertrophic cardiomyopathy (HCM) for arrhythmias and heart rate variability (HRV) is not well defined but may provide information regarding risk stratification. This prospective study used AECG to evaluate ectopy and HRV in subclinical HCM cats compared to healthy controls and is the first to implement a pharmacologic cardiac stress test. Twenty-three purpose-bred, Maine coon cross cats (16 HCM, 7 control) underwent 48-h of continuous AECG. Terbutaline (0.2–0.3 mg/kg) was administered orally at 24 and 36 h. Heart rate, ectopy frequency and complexity and HRV parameters, including standard deviation of normal R-R intervals (SDNN), were compared pre-terbutaline and post-terbutaline and across phenotype, genotype and sex. Genotype for an HCM-causative mutation was significantly associated with the frequency of supraventricular (P = 0.033) and ventricular (P = 0.026) ectopy across all cats. Seven HCM cats and zero healthy cats had a sinus arrhythmia. Mean heart rate was significantly higher post-terbutaline (p < 0.0001). HCM cats had significantly greater HRV compared to controls (SDNN: p = 0.0006). Male cats had significantly higher HRV (SDNN: p = 0.0001) and lower mean heart rates (p = 0.0001). HRV decreased post-terbutaline (SDNN: p = 0.0008) and changes in HRV observed between sexes were attenuated by terbutaline.

Heart Rate Variability on 10-Second Electrocardiogram and Risk of Acute Exacerbation of COPD: A Secondary Analysis of the BLOCK COPD Trial.

Autonomic dysfunction is common in chronic obstructive pulmonary disease (COPD), and worse autonomic function may be a marker of risk for acute exacerbations of COPD (AECOPD). Heart rate variability (HRV) is a measure of autonomic function. Our objective was to test whether lower (worse) HRV is a risk factor for AECOPD. We measured standard deviation of normal RR intervals (SDNN) and root mean square of successive RR interval differences (RMSSD) on 10-second electrocardiograms (ECGs) performed at screening and day 42 in participants in the Beta Blockers for the Prevention of Acute Exacerbations of COPD trial ( BLOCK-COPD), a placebo-controlled trial of metoprolol for prevention of AECOPD. We used Cox-proportional hazards models to test if these HRV measures were associated with risk of any AECOPD, and separately, hospitalized AECOPD. We tested associations using baseline HRV measures and incorporating HRV measures from day 42 as a time-varying covariate. We also tested for interactions with metoprolol assignment. Of 532 trial participants, 529 (forced expiratory volume in 1 second [FEV1 ]41 ± 16.3 % predicted) were included in this analysis. We did not find a significant association between HRV measures and risk of AECOPD when all participants were analyzed together. There was a significant interaction between RMSSD and assignment to metoprolol on time to first hospitalized AECOPD; in the placebo group greater RMSSD was associated with a lower risk of hospitalized AECOPD (adjusted hazard ratio0.71, 95% confidence interval: 0.52 to 0.96, per 10 ms increase) but there was no association in the metoprolol group. Autonomic dysfunction as measured by HRV may be a risk factor for AECOPD. Future studies should analyze longer HRV recordings and their performance in broader samples of people with COPD, including those on beta-blockers.

Acute Effects of Foam Rolling Exercises on Arterial Stiffness, Flexibility and Autonomic Nervous System Function in Young and Middle-Aged Women

PURPOSE: Arterial stiffness is an independent risk factor for cardiovascular disease and inversely associated with flexibility. Self-myofascial release (SMR) using a foam roller is a popular intervention to improve flexibility, restore the muscles, fascia, tendons, and ligaments, and regain soft-tissue extensibility. This study aimed to investigate whether a single bout of SMR has a beneficial effect on arterial stiffness and the function of the autonomic nervous system and the relationships among these variables in young and middle-aged women by age.METHODS: Ten healthy young (23.20±0.59 years) and 10 middle-aged women (44.50±0.91 years) completed an instructed SMR using a foam roller. Brachial-ankle pulse wave velocity (baPWV), augmentation index (AIx), trunk flexibility, shoulder flexibility, heart rate variability, including standard deviation of normal R-R intervals (SDNN), and the root mean square of the standard deviation of the time between heartbeats (RMSSD) were measured before and after one 30-minutes bout of SMR.RESULTS: After one bout of SMR, trunk and shoulder flexibility increased in both groups of women, while AIx decreased significantly (from 6.9±2.9 to -1.9±4.6%, p=.0072, young women group; from 22.1±3.4 to 14.7±1.7%, p=.0049, middle-aged women group). However, the baPWV, RMSSD, and SDNN did not change. In the analysis of correlations between all measured variables, changes in AIx showed negative correlations with flexibility and SDNN.CONCLUSIONS: This study suggests that one bout of SMR using a foam roller positively affected arterial stiffness in women by reducing AIx and improving flexibility.

HEART RATE VARIABILITY ON 10-SECOND ECG AND RISK OF ACUTE EXACERBATIONS OF COPD: A SECONDARY ANALYSIS OF BLOCK COPD

TOPIC: Obstructive Lung Diseases TYPE: Original Investigations PURPOSE: Autonomic dysfunction is common in COPD, and worse autonomic function may be a marker of risk for acute exacerbations of COPD (AECOPD). Heart rate variability (HRV) is a measure of autonomic function which reflects sympathetic/parasympathetic balance, and incorporates vagal input from the lung. HRV measures typically require longer recording times, but 10-second electrocardiograms (ECG) have been shown to have moderate to strong correlation with HRV measures on longer recordings. We assessed whether HRV measures on 10-second ECG are associated with risk of AECOPD. METHODS: Secondary analysis of the BLOCK COPD trial (NEJM 2019). We measured the standard deviation of normal RR intervals (SDNN) and root mean square of successive RR interval differences (RMSSD) on baseline ECGs and day 42 ECGs (when dose titration was finalized). We used Cox-proportional hazards models to test if SDNN and RMSSD were associated with risk of any AECOPD, and separately for hospitalized AECOPD. We tested associations using baseline HRV measures, and additionally incorporated day 42 HRV measures by treating HRV measures as time-dependent covariates. We also tested for interactions with metoprolol assignment. Adjusted analyses incorporated FEV1 percent predicted, age, sex, race, coronary artery disease, long-acting antimuscarinic antagonist (LAMA) use, and randomized assignment to metoprolol vs placebo. T-tests were used to compare differences in change in HRV measures from baseline to day 42 between treatment groups. RESULTS: Of 532 trial participants, 529 (mean FEV1 41% predicted) were included in this analysis. We found no significant association between baseline HRV measures and risk of any AECOPD for SDNN [aHR 1.00 (95% CI 0.99 to 1.00)] or RMSDD [1.00 (0.99 to 1.00) for RMSSD]. Findings were similar for hospitalized AECOPD, and in time-dependent analyses incorporating day 42 measures. We found no significant interactions between HRV measures and assignment to metoprolol on time to AECOPD. Metoprolol was not associated with changes in SDNN (95% CI for difference in change between groups -6.4 to 3.1) or RMSSD (95% CI -10.8 to 1.3). CONCLUSIONS: HRV measures from 10-second ECG are not associated with risk of AECOPD. Compared to placebo, metoprolol did not affect these HRV measures. CLINICAL IMPLICATIONS: HRV measured on 10-second ECG is not associated with AECOPD risk, possibly due to limitations of these brief recordings. Future studies should assess longer or ambulatory ECG recordings, and include frequency domain HRV metrics, allowing for a more comprehensive analysis of HRV and AECOPD risk. DISCLOSURES: No relevant relationships by Selcuk Adabag, source=Web Response Speaker/Speaker's Bureau relationship with Boehringer-Ingelheim Please note: $5001 - $20000 by Richard Casaburi, source=Web Response, value=Honoraria Grant Recipient relationship with Boehringer-Ingelheim Please note: $20001 - $100000 by Richard Casaburi, source=Web Response, value=Grant/Research Support Advisory Committee Member relationship with GSK Please note: $5001 - $20000 by Richard Casaburi, source=Web Response, value=Honoraria Grant Recipient relationship with GSK Please note: $20001 - $100000 by Richard Casaburi, source=Web Response, value=Grant/Research Support Speaker/Speaker's Bureau relationship with GSK Please note: $1001 - $5000 by Richard Casaburi, source=Web Response, value=Honoraria Advisory Committee Member relationship with Astra Zeneca Please note: $5001 - $20000 by Richard Casaburi, source=Web Response, value=Consulting fee Grant Recipient relationship with Astra Zeneca Please note: >$100000 by Richard Casaburi, source=Web Response, value=Grant/Research Support Consultant relationship with Regeneron Please note: $1001 - $5000 by Richard Casaburi, source=Web Response, value=Consulting fee Advisory Committee Member relationship with Genentech Please note: $1001 - $5000 by Richard Casaburi, source=Web Response, value=Honoraria No relevant relationships by John Connett, source=Web Response Consultant relationship with AstraZeneca Please note: $1001 - $5000 by Mark Dransfield, source=Web Response, value=Personal fees Removed 04/26/2021 by Mark Dransfield, source=Web Response Consultant relationship with GSK Please note: $5001 - $20000 by Mark Dransfield, source=Web Response, value=Personal fees Removed 04/26/2021 by Mark Dransfield, source=Web Response Consultant relationship with AstraZeneca Please note: 2019-present Added 04/26/2021 by Mark Dransfield, source=Web Response, value=Consulting fee Consultant relationship with GSK Please note: 2019-present Added 04/26/2021 by Mark Dransfield, source=Web Response, value=Consulting fee Consultant relationship with PneumRx/BTG Please note: $1001 - $5000 by Mark Dransfield, source=Web Response, value=Consulting fee Removed 04/26/2021 by Mark Dransfield, source=Web Response Consultant relationship with Quark Please note: $5001 - $20000 by Mark Dransfield, source=Web Response, value=Consulting fee Removed 04/26/2021 by Mark Dransfield, source=Web Response Consultant relationship with Pulmonx Please note: $1-$1000 by Mark Dransfield, source=Web Response, value=Travel Removed 04/26/2021 by Mark Dransfield, source=Web Response Consultant relationship with Teva Please note: 2020-current Added 04/26/2021 by Mark Dransfield, source=Web Response, value=Consulting fee No relevant relationships by Erika Helgeson, source=Web Response Consultant relationship with Nuvaira Please note: $1001 - $5000 by Ken Kunisaki, source=Web Response, value=Consulting fee Contracted clinical research support relationship with Sanofi Please note: $1001 - $5000 by Ken Kunisaki, source=Web Response, value=Grant/Research Support Contracted clinical research support relationship with AstraZeneca Please note: $1001 - $5000 by Ken Kunisaki, source=Web Response, value=Grant/Research Support Removed 03/23/2021 by Ken Kunisaki, source=Web Response No relevant relationships by Sharon Ling, source=Web Response No relevant relationships by David MacDonald, source=Web Response No relevant relationships by Takudzwa Mkorombindo, source=Web Response No relevant relationships by Janos Porszasz, source=Web Response No relevant relationships Added 03/23/2021 by Harry Rossiter, source=Web Response, value=Consulting fee Removed 03/23/2021 by Harry Rossiter, source=Web Response No relevant relationships Added 03/23/2021 by Harry Rossiter, source=Web Response, value=Grant/Research Support Removed 03/23/2021 by Harry Rossiter, source=Web Response No relevant relationships Added 03/23/2021 by Harry Rossiter, source=Web Response, value=Grant/Research Support Removed 03/23/2021 by Harry Rossiter, source=Web Response No relevant relationships Added 03/23/2021 by Harry Rossiter, source=Web Response, value=Grant/Research Support Removed 03/23/2021 by Harry Rossiter, source=Web Response Investigator relationship with Astrazeneca Please note: >$100000 by William Stringer, source=Web Response, value=Grant/Research Support Author relationship with Wolters Kluwer Please note: $1001 - 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Please note: $1001 - $5000 by William Stringer, source=Web Response, value=Consulting fee Reduced Fee Medical Equipment relationship with Medical Graphics Corporation Please note: $20001 - $100000 by William Stringer, source=Web Response, value=Equipment No relevant relationships by Donxing Zhao, source=Admin input

Effects of rehabilitation programs on heart rate variability after stroke: a systematic review.

It has been shown that the autonomic nervous system can be modulated by physical exercise after stroke, but there is a lack of evidence showing rehabilitation can be effective in increasing heart rate variability (HRV). To investigate the effectiveness and safety of rehabilitation programs in modulating HRV after stroke. The search strategy was based in the PICOT (patients: stroke; interventions: rehabilitation; comparisons: any control group; outcomes: HRV; time: acute, subacute and chronic phases of stroke). We searched MEDLINE, CENTRAL, CINAHL, LILACS, and SCIELO databases without language restrictions, and included randomized controlled trials (RCTs), quasi-randomized controlled trials (quasi-RCTs), and non-randomized controlled trials (non-RCTs). Two authors independently assessed the risk of bias and we used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology to rate the certainty of the evidence for each included study. Four studies (two RCTs with low certainty of the evidence and two non-RCTs with very low certainty of the evidence) were included. Three of them showed significant cardiac autonomic modulation during and after stroke rehabilitation: LF/HF ratio (low frequency/high frequency) is higher during early mobilization; better cardiac autonomic balance was observed after body-mind interaction in stroke patients; and resting SDNN (standard deviation of normal R-R intervals) was significantly lower among stroke patients indicating less adaptive cardiac autonomic control during different activities. There are no definitive conclusions about the main cardiac autonomic repercussions observed in post-stroke patients undergoing rehabilitation, although all interventions are safe for patients after stroke.

Level of agreement between sPRO and Kubios software in the analysis of R-R intervals obtained by a chest strap

Heart rate variability (HRV) is becoming one of the most commonly used tools for tracking the time course of training adaptation/maladaptation of athletes and setting optimal training loads, leading to improved performance. The aim of this study was to compare Realtrack Systems manufacturer software (sPRO) with the Kubios HRV Standard. R-R intervals were recorded from 48 athletes using a chest strap synchronized to WIMU PRO™ device for 10 min to analyze time-domain HRV indices, located between the scapulae. Time-domain HRV indices analyzed included the square root of the mean squared differences of successive R-R intervals (RMSSD), standard deviation of normal R-R intervals (SDNN), and percentage of adjacent R-R intervals that differ from each other by more than 50 ms (pNN50). The intraclass correlation test and Bland-Altman plot were used to verify the agreement between the sPRO and the Kubios HRV Standard software for examining time-domain HRV indices. The intraclass correlation coefficient showed high values of agreement of R-R intervals and time-domain HRV indices between the two software options (RMSSD, SDNN, and pNN50; ICC &gt; 0.951). The Bland-Altman plot showed low bias for all the HRV indices analyzed (bias = −0.11 to −1.08). In addition, no systematic bias was found between the residual of the mean difference and the average values of the two software packages ( p &gt; 0.05). Therefore, both software options can be used interchangeably for analyzing time-domain HRV records.

Potassium excretion and blood pressure are associated with heart rate variability in healthy black adults: The African-PREDICT study

Background and aimsHeart rate variability (HRV) is a main determinant of autonomic function and related to the development of hypertension and cardiovascular (CV) disease. Hypertension develops in black populations at an earlier age, which could be due to differences in the autonomic nervous system activity and sodium/potassium handling in black and white populations. We investigated whether HRV is associated with 24 h urinary sodium and potassium excretion and blood pressure (BP) in a young bi-ethnic cohort. Methods and resultsWe examined 423 black and 483 white healthy adults (aged 24.5 ± 3.1 years) for 24 h HRV, including standard deviation of normal RR intervals (SDNN) reflecting autonomic variations over time, and root mean square of successive differences (RMSSD) reflecting parasympathetic activity. We measured 24 h urinary sodium and potassium concentration and BP. The black group had lower SDNN and potassium excretion as well as higher RMSSD, sodium and Na/k ratio compared to the white group (all p < 0.05). Only in black individuals, urinary potassium excretion was independently and negatively associated with SDNN (β[95% CI];-0.26[-0.50;-0.02]ms) and RMSSD (−0.14[-0.27;-0.01]ms, p < 0.05). One unit increase in sodium/potassium (Na/K) ratio was associated with higher SDNN (β[95% CI]; 3.04[0.89; 5.19]ms) and RMSSD (1.60[0.41; 2.78]ms) in the black cohort only (both p < 0.001). In both groups elevated 24 h diastolic BP was associated with lower RMSSD (p < 0.05). ConclusionLower potassium excretion and higher Na/K ratio related independently to higher HRV in young and healthy black adults. A better ethnic-specific understanding of sodium and potassium handling is required as part of preventive cardiology, especially in black individuals. Clinical trial registrationClinicalTrials.gov Identifier: NCT03292094; URL: https://clinicaltrials.gov/ct2/show/NCT03292094.

Heart rate variability changes during task shifting testing in pre‐symptomatic Alzheimer’s disease

AbstractBackgroundEarly detection of Alzheimer’s disease (AD) is vital to begin and monitor treatments. However, as AD pathology begins long before the onset of symptoms, early detection is difficult. Previous studies have suggested differences in the cardiac and autonomic nervous systems (ANS) in AD patients, providing a possible non‐invasive marker of disease onset. The goal of this study is to compare heart rate variability (HRV) measures, representative of cardiac and ANS function, at rest as well as during cognitive testing to assess the use of HRV as a possible marker of pre‐symptomatic AD.MethodAll participants are cognitively healthy (CH) separated into two subgroups based on ratios of amyloid/tau proteins in cerebrospinal fluid (CSF): normal (CH‐NAT, n=22) and pathological (CH‐PAT, n=36), which represents pre‐symptomatic AD. Heart rate variability (HRV) was assessed during 5‐minute intervals at rest and during Task Shifting testing. Participants were required to name the color or word of a colored word for each stimulus by pressing a button, with two sequential stimuli per trial. The trial could be switching (color‐word or word‐color) or repeat (color‐color or word‐word). ECG traces from subgroups of CH‐NATs (n=8) and CH‐PATs (n=13) were initially screened to remove ectopic beats, followed by identification of normal RR‐intervals (NN). HRV was analyzed as standard deviation of NN (SDNN), root mean squared of successive differences (RMSSD) in the time domain as well as high (HF) and low frequency (LF) in the frequency domain to assess changes to autonomic, and particularly parasympathetic, input to the heart.ResultComparing HRV changes assessed during rest and the task shifting testing in each individual, differences became apparent between CH‐NAT and CH‐PAT groups. In the CH‐NAT group, little to no change in SDNN and RMSSD occurred during cognitive testing from rest. The CH‐PAT group however showed a 20 percent drop in both SDNN and RMSSD during testing, indicating an imbalance of the ANS.ConclusionThis study provides a new approach and technique using HRV to non‐invasively differentiate between normal and pre‐symptomatic AD in cognitively healthy people.

Concurrent training and Eri silkworm pupae ingestion improve resting and exercise fat oxidation and energy expenditure in obese adults.

A randomized control trial was conducted to investigate the effects of combined concurrent training and Eri silkworm pupae ingestion on resting and exercise fat oxidation (FAO), as well as energy expenditure, and cardiometabolic risk markers in obese adults. Thirty-six sedentary, obese participants were divided into three groups: (1) placebo control group (CON, n=12), (2) Eri silkworm pupae ingestion group (ERI, n=12), and (3) combined concurrent training and Eri silkworm pupae ingestion group (CBT-ERI, n=12). Participants in the ERI and the CBT-ERI con-sumed 5-g Eri silkworm pupae/day (approximately 2.5-g linolenic acid). The concurrent training program comprised of supervised aerobic and resistance training: three 1-hr sessions/wk for 8 weeks. Body composi-tion, energy expenditure, and FAO at rest and during exercise, heart rate variability, and blood chemistry were measured before and after the 8-week interventions. Following the interventions, resting FAO, the natural logarithm of very low-frequency power (lnVLF), and high-sensi-tive C-reactive protein concentration significantly improved in both the ERI and the CBT-ERI. Only the CBT-ERI improved resting energy expen-diture, FAO during exercise, trunk and gynoid fat mass, total cholesterol concentration, the standard deviation of normal R-R intervals (SDNN), and the percentage difference between adjacent normal R-R intervals >50 ms. Furthermore, there were significant correlations between rest-ing energy expenditure and FAO, lnVLF and SDNN in the CBT-ERI. In conclusion, this study demonstrates that concurrent training together with dietary Eri silkworm pupae leads to increased energy expenditure through a significant increase in FAO at rest and during exercise, as well as reduced fat mass.

Acute Effects of Self-Selected Music Intervention on Golf Performance and Anxiety Level in Collegiate Golfers: A Crossover Study.

Music has been reported as a positive intervention for improving psychophysiological conditions and exercise performance. However, the effects of music intervention on golf performance in association with psychophysiological responses have not been well examined in the literature. The purpose of the study was to investigate the acute effects of self-selected music intervention on golf swing and putting performance, heart rate (HR), HR variability (HRV), and anxiety. Twenty collegiate golfers voluntarily participated in this study (age = 20.2 ± 1.4 years, height = 171.7 ± 8.0 cm, body weight = 69.5 ± 14.6 kg, golf experience = 7.5 ± 2.1 years). A cross-over and within-subject design was used in this study. Participants performed a non-music trial (T1), pre-exercise music trial (T2), and simultaneous music trial (T3) in a randomized order with 48–72 h apart. The participants were attached to a HR monitor to record the HR and HRV during the measurement. The golf swing and putting performance was assessed by using the Golfzon golf simulator system. The state-trait anxiety inventory-state questionnaire (STAI-S) was used to evaluate anxiety state. All measurements were taken during baseline (phase one) and after resting or music intervention (phase two). Repeated measurement of analysis of variance (ANOVA) and Cohen’s effect size (ES) were used for statistical analyses. The results show no significant differences in golf swing and putting performance (p > 0.05). However, significant decrease in STAI-S score was found in T2 (p = 0.047, ES = 0.32). A significant increase in the standard deviation of normal R-R interval (SDNN), low-frequency power spectrum (LF), standard deviation of along the line-of-identity (SD2) in T2 and T3 were observed (p < 0.05). In conclusion, a single pre-exercise or simultaneous self-selected music intervention contributes minor effects to golf performance in collegiate golfers. The positive benefits of self-selected music intervention on the psychological condition and cardia-related modulation while practicing golf is warranted.