Short- and medium-term cumulative effects of traffic-related air pollution on resting heart rate in the elderly: A wearable device study.

BACKGROUND: Epidemiological evidence regarding the association between air pollution and resting heart rate (RHR), a predictor of cardiovascular disease and mortality, is limited and inconsistent. OBJECTIVES: We used wearable devices and time-series analysis to assess the exposure-response relationship over an extended lag period. METHODS: Ninety-seven elderly individuals (>65 years) from the Taipei Basin participated from May to November 2020 and wore Garmin® smartwatches continuously until the end of 2021 for heart rate monitoring. RHR was defined as the daily average of the lowest 30-min heart rate. Air pollution exposure data, covering lag periods from 0 to 60 days, were obtained from nearby monitoring stations. We used distributed lag non-linear models and linear mixed-effect models to assess cumulative effects of air pollution. Principal component analysis was utilized to explore underlying patterns in air pollution exposure, and subgroup analyses with interaction terms were conducted to explore the modification effects of individual factors. RESULTS: After adjusting for co-pollutants in the models, an interquartile range increase of 0.18 ppm in carbon monoxide (CO) was consistently associated with increased RHR across lag periods of 0-1 day (0.31, 95 % confidence interval [CI]: 0.24-0.38), 0-7 days (0.68, 95 % CI: 0.57-0.79), and 0-50 days (1.02, 95 % CI: 0.82-1.21). Principal component analysis identified two factors, one primarily influenced by CO and nitrogen dioxide (NO2), indicative of traffic sources. Increases in the varimax-rotated traffic-related score were correlated with higher RHR over 0-1 day (0.36, 95 % CI: 0.25-0.47), 0-7 days (0.62, 95 % CI: 0.46-0.77), and 0-50 days (1.27, 95 % CI: 0.87-1.67) lag periods. Over a 0-7 day lag, RHR responses to traffic pollution were intensified by higher temperatures (ß = 0.80 vs. 0.29; interaction p-value [P_int] = 0.011). Males (ß = 0.66 vs. 0.60; P_int < 0.0001), hypertensive individuals (ß = 0.85 vs. 0.45; P_int = 0.028), diabetics (ß = 0.96 vs. 0.52; P_int = 0.042), and those with lower physical activity (ß = 0.70 vs. 0.54; P_int < 0.0001) also exhibited stronger responses. Over a 0-50 day lag, males (ß = 0.99 vs. 0.96; P_int < 0.0001), diabetics (ß = 1.66 vs. 0.69; P_int < 0.0001), individuals with lower physical activity (ß = 1.49 vs. 0.47; P_int = 0.0006), and those with fewer steps on lag day 1 (ß = 1.17 vs. 0.71; P_int = 0.029) showed amplified responses. CONCLUSIONS: Prolonged exposure to traffic-related air pollution results in cumulative cardiovascular risks, persisting for up to 50 days. These effects are more pronounced on warmer days and in individuals with chronic conditions or inactive lifestyles.

Associations of Personal Hourly Exposures to Air Temperature and Pollution with Resting Heart Rate in Chronic Obstructive Pulmonary Disease.

Previous studies linked higher daily ambient air temperature and pollution with increased cardiorespiratory morbidity, but immediate effects of personal, hourly exposures on resting heart rate remained unclear. We followed 30 older former smokers with chronic obstructive pulmonary disease (COPD) in Massachusetts for four nonconsecutive 30-day periods over 12 months, collecting 54,487 hourly observations of personal air temperature, fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone (O3), and resting heart rate. We explored the single lag effects (0-71 h) and cumulative effects (0-5 h, the significant lag windows) of air temperature and pollution on resting heart rate using generalized additive mixed models with distributed lag nonlinear models. Single lag effects of higher air temperature and pollutants on higher resting heart rate were most pronounced at lag 0 to 5 h. Cumulative effects of higher air temperature, PM2.5, O3, and NO2 (each interquartile range increment) on higher resting heart rate at lag 0-5 h, show differences of (beats per minute [bpm], 95% CI) 1.46 (1.31-1.62), 0.35 (0.32-0.39), 2.32 (2.19-2.45), and 1.79 (1.66-1.92), respectively. In conclusion, higher personal hourly air temperature, PM2.5, O3, and NO2 exposures at lag 0-5 h are associated with higher resting heart rate in COPD patients.

Association between resting heart rate and low natural killer cell activity: a cross-sectional study.

Resting heart rate (RHR), a simple physiological indicator, has been demonstrated to be associated with inflammation and even metabolic disorders. This study aimed to investigate whether RHR is associated with natural killer cell activity (NKA) in a large population of healthy adults using a novel assay to measure NKA. This cross-sectional study included 7,500 subjects in the final analysis. NKA was estimated by measuring the amount of interferon-gamma (IFN-γ) released by activated natural killer cells; low NKA was defined as IFN-γ level <500 pg/mL. Subjects were categorized into four groups according to RHR as follows: C1 (≤ 60 bpm), C2 (60-70 bpm), C3 (70-80 bpm), and C4 (≥ 80 bpm). Individuals with higher RHR exhibited poorer metabolic and inflammatory profiles, with the prevalence of low NKA being highest in the highest RHR category. Compared with C1 as reference, the fully adjusted odd ratios (ORs) [95% confidence intervals (CIs)] for low NKA were significantly higher in C3 (OR: 1.37, 95% CI: 1.08-1.75) and C4 (OR: 1.55, 95% CI: 1.20-2.00). In addition, RHR was shown to exert indirect effects on NKA upon consideration of the mediation effect of serum cortisol in path analysis. Our findings confirm a significant link between elevated RHR and low NKA, and suggest the usefulness of RHR, a simple indicator reflecting increased sympathetic nervous system activity and stress, in predicting reduced immune function.

Longitudinal Association Between Resting Heart Rate and Mortality in Atrial Fibrillation.

Rate control plays a fundamental role in the management of atrial fibrillation (AF), but the optimal target of resting heart rate (RHR) for reducing mortality remains uncertain. This study used longitudinal follow-up RHR data to evaluate the relationship between RHR and all-cause mortality. Data from the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) study were retrospectively analyzed. The association between RHR and mortality was longitudinally analyzed using mean RHR (mRHR) and individual trajectory patterns, where the Cox proportional hazards model and group-based trajectory model were used. A total of 3,921 patients (mean age, 69.47 ± 8.09 years) with AF were included in our study. A total of 578 deaths were recorded during a median follow-up of 3.4 years. Cox regression analyses showed an mRHR ≥80 bpm was associated with an increased risk of mortality (adjusted hazard ratio: 2.01, 95% CI: 1.59-2.55). Consistent association was found in the subgroup analyses. The Kaplan-Meier analysis showed notably reduced survival probabilities for patients with mRHR ≥80 bpm. Patients were classified into four stable trajectories based on RHR during follow-up, with the classes >70 bpm associated with an elevated risk of mortality. In conclusion, longitudinally measured RHR ≥80 bpm was associated with an increased risk of mortality in patients with AF.

Autocorrelation of daily resting heart rate: A novel metric of postoperative recovery.

PURPOSE: Resting heart rate (RHR) is a sensitive indicator of an individual's physiologic condition. However, its use in clinical practice has been limited due to the wide variation in baseline RHR based on multiple factors, including age, sex, cardiovascular fitness, and comorbidities. The study aims to develop a novel, clinically meaningful metric that is applicable across these conditions, based on day-by-day changes in RHR-the difference in autocorrelation of daily RHR (ACΔ-RHR). We present ACΔ-RHR in the context of monitoring post-discharge recovery for pediatric appendectomy patients. METHODS: Children 3-17 years old who underwent laparoscopic appendectomy for complicated appendicitis from 2019 to 2022 at a tertiary children's hospital wore a Fitbit for twenty-one postoperative days (POD). Patients without complications were included to describe normative recovery. Using RHR on POD 1-3 as the baseline, autocorrelation of daily RHR was calculated (fixed lag = 1) for POD 3-21. Then, daily ACΔ-RHR was determined by subtracting autocorrelation values between the current and previous day. Means and standard deviations were calculated for daily RHR to estimate on which POD ACΔ-RHR stabilized at 0, representing general RHR stability and recovery from surgery for all patients. Subgroup analyses were performed by age (3-10 years old vs 11-17 years old) and sex. RESULTS: Thirty-one patients were included (58.1 % 3-10 years old, 41.9 % female, 67.7 % Hispanic). Whereas the mean daily RHR did not demonstrate clear trends, the mean ACΔ-RHR for the cohort first reached 0 on POD 12 and stabilized on POD 14 (95 % confidence interval: POD [11,17]). Subgroup analysis showed that ACΔ-RHR stabilized on POD 9 for age of 3-10 years, POD 12 for age of 11-17 years, POD 12 for females and POD 10 for males. CONCLUSIONS: The ACΔ-RHR is a promising clinical metric that could enhance post-surgical patient monitoring, such as for children following laparoscopic appendectomy for complicated appendicitis.

Association of resting heart rate and physical activity with cardiovascular mortality: A population-based cohort study of Korean adults.

To examine the independent and combined association of resting heart rate (RHR) and physical activity (PA) with risk of cardiovascular disease (CVD) mortality. RHR was categorized as < 60, 60-69, 70-79, and ≥ 80 bpm. Meeting PA guidelines was defined as ≥ 150 min/week of moderate to vigorous physical activity (MVPA). Cox proportional hazard models were used to calculate hazard ratios (HRs) for CVD mortality associated with RHR and PA. Among 31,697 participants, 311 CVD deaths occurred during 9.2 years of follow-up. Compared to RHR of 60-69 bpm, the risk of CVD mortality was higher in RHR of < 60 bpm (HR, 1.48; 95% CI, 1.05-2.10) and ≥ 80 bpm (HR, 1.42; 95% CI, 1.06-1.91). Participants who met PA guidelines had a lower risk of CVD mortality (HR, 0.59; 95% CI, 0.44-0.78). Among physically inactive adults compared to participants in RHR of 60-69 bpm with meeting PA guidelines, the adjusted HR for CVD mortality was 2.41 (95% CI, 1.42-4.08) for RHR of < 60 bpm, 1.59 (95% CI, 1.01-2.49) for RHR of 60-69 bpm, 1.98 (95% CI, 1.23-3.20) for RHR of 70-79 bpm and 2.41 (95% CI, 1.50-3.89) for RHR of ≥ 80 bpm Exceeding the minimum level of PA guidelines may attenuate the risk of CVD mortality associated with RHR.

Association between Resting Heart Rate and Machine Learning-Based Brain Age in Middle- and Older-Age.

BACKGROUND: Resting heart rate (RHR), has been related to increased risk of dementia, but the relationship between RHR and brain age is unclear. OBJECTIVE: We aimed to investigate the association of RHR with brain age and brain age gap (BAG, the difference between predicted brain age and chronological age) assessed by multimodal Magnetic Resonance Imaging (MRI) in mid- and old-aged adults. DESIGN: A longitudinal study from the UK Biobank neuroimaging project where participants underwent brain MRI scans 9+ years after baseline. SETTING: A population-based study. PARTICIPANTS: A total of 33,381 individuals (mean age 54.74 ± 7.49 years; 53.44% female). MEASUREMENTS: Baseline RHR was assessed by blood pressure monitor and categorized as <60, 60-69 (reference), 70-79, or ≥80 beats per minute (bpm). Brain age was predicted using LASSO through 1,079 phenotypes in six MRI modalities (including T1-weighted MRI, T2-FLAIR, T2*, diffusion-MRI, task fMRI, and resting-state fMRI). Data were analyzed using linear regression models. RESULTS: As a continuous variable, higher RHR was associated with older brain age (ß for per 1-SD increase: 0.331, 95% [95% confidence interval, CI]: 0.265, 0.398) and larger BAG (ß: 0.263, 95% CI: 0.202, 0.324). As a categorical variable, RHR 70-79 bpm and RHR ≥80 bpm were associated with older brain age (ß [95% CI]: 0.361 [0.196, 0.526] / 0.737 [0.517, 0.957]) and larger BAG (0.256 [0.105, 0.407] / 0.638 [0.436, 0.839]), but RHR< 60 bpm with younger brain age (-0.324 [-0.500, -0.147]) and smaller BAG (-0.230 [-0.392, -0.067]), compared to the reference group. These associations between elevated RHR and brain age were similar in both middle-aged (<60) and older (≥60) adults, whereas the association of RHR< 60 bpm with younger brain age and larger BAG was only significant among middle-aged adults. In stratification analysis, the association between RHR ≥80 bpm and older brain age was present in people with and without CVDs, while the relation of RHR 70-79 bpm to brain age present only in people with CVD. CONCLUSION: Higher RHR (>80 bpm) is associated with older brain age, even among middle-aged adults, but RHR< 60 bpm is associated with younger brain age. Greater RHR could be an indicator for accelerated brain aging.

Effects of temporal changes in resting heart rate on future diabetes-related outcomes.

Background and aims: Most studies have analyzed the relationship between resting heart rate (RHR) measured at only one time point and future clinical events. The current study aims to investigate the impact of long-term RHR changes on future clinical outcomes in a decade-long cohort with type 2 diabetes mellitus (T2DM). Methods: The two-staged follow-up involved 2,513 T2DM participants. The first stage (2008-2014) intended to identify levels and trends in RHR changes, while the second stage (2014-2018) attempted to collect new occurrence records of clinical results. Cox proportional hazards models were applied to predict hazard ratios (HRs), along with 95% confidence interval (CI) for the correlation between RHR changes and future events. Results: There is no significant correlation between baseline RHR levels and long-term clinical events. According to the range of RHR change, compared with the stable RHR group, the adjusted HRs for cardiovascular events and all-cause death in the large increase group were 3.40 (95% CI: 1.33-8.71, p=0.010) and 3.22 (95% CI: 1.07-9.64, p=0.037), respectively. While the adjusted HRs for all-cause death and major adverse cardiac and cerebrovascular events (MACCE) in the moderate decrease group were 0.55 (95% CI: 0.31-0.96, p=0.037) and 0.51 (95% CI: 0.26-0.98, p=0.046). According to the trend of RHR, compared with the normal-normal group, the adjusted HRs for composite endpoint events and cerebrovascular events in the normal-high group were 1.64 (95% CI: 1.00-2.68, p=0.047) and 2.82 (95% CI: 1.03-7.76, p=0.043), respectively. Conclusion: Changes in RHR had predictive value for long-term clinical events in diabetic populations. Individuals with significantly elevated RHR over a particular period of time showed an increased risk of adverse events.

Effects of high-intensity interval exercise on arterial stiffness in individuals at risk for cardiovascular disease: a meta-analysis.

Objective: The purpose of this meta-analysis was to investigate the effect of high-intensity interval training (HIIT) on arterial stiffness (AS) and vascular function in persons at high risk of cardiovascular disease (CVD). Methods: We conducted a comprehensive search of randomized controlled trials (RCTs) published in electronic databases (PubMed, Web of Science, Cochrane, Embase, and Ebsco) since their inception through October 2023 to evaluate the effect of HIIT on AS and vascular function in persons at high risk for CVD. The weighted mean difference (WMD) and 95% confidence intervals (95% CI) were calculated, and heterogeneity was assessed using the I2 test. Results: This study included 661 participants from 16 studies. HIIT significantly reduced pulse wave velocity (PWV) in persons at high risk for CVD [weighted mean difference (WMD), -0.62; 95% CI, -0.86--0.38; P < 0.00001]. Subgroup analysis showed that the PWV improvement effect was better when the HIIT program was performed 2-3 times per week and the duration was controlled within 40 min [2-3 times, -0.67; 95% CI, -0.93--0.41; P < 0.00001; time of duration, ≤40 min, -0.66; 95% CI, -0.91--0.41; P < 0.00001]. HIIT significantly reduced systolic blood pressure (SBP, -5.43; 95% CI, -8.82--2.04; P = 0.002), diastolic blood pressure (DPB, -2.96; 95% CI, -4.88--1.04; P = 0.002), and resting heart rate (RHR, -4.35; 95% CI, -7.04--1.66; P = 0.002), but had no significant effect on augmentation index (AIX, -2.14; 95% CI, -6.77-2.50; P = 0.37). Conclusion: HIIT can improve PWV in high-risk individuals with CVD and reduce SBP, DBP, and RHR, but has no significant effect on AIX. HIIT can effectively improve AS and vascular function and can be recommended as an effective method to improve AS in high-risk persons with CVD. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42023471593.

HEXACO personality factors as predictors of physical activity, resting heart rate, body mass index, and healthy lifestyle behaviors.

BACKGROUND: Personality traits are known factors that may influence levels of physical activity and other healthy lifestyle measures and behaviors that ultimately lead to health problems later in life. Participants And Procedure: The aim of this study was to examine the association between personality traits (HEXACO) and levels of physical activity and resting heart rate (RHR) - measured using Fitbits, BMI, and a self-reported whole-person healthy lifestyle score for N = 2580 college students. Data were collected and analyzed for students enrolled in a University Success type course from August 2017 to May 2021. The relationships between HEXACO personality traits and various physical activity and healthy lifestyle behaviors were analyzed by building several multiple regression models using R version 4.0.2. Results: In general, students who are extraverted were more physically active and students who are more open to experience had a higher RHR, even when controlling for gender. Females and males however had different profiles as to how personality influenced physical activity and other health-related measures. Male extraverts with high negative emotionality scores tend to be more physically active, whereas females tend to be more physically active when they were high in extroversion and conscientiousness, and low in openness to experience. BMI values were higher for female participants with high honesty-humility and low agreeableness and conscientiousness scores. Females also had a lower RHR for high honesty-humility and emotionality and low conscientiousness scores. CONCLUSIONS: Personality can influence levels of physical activity, RHR, and BMI. This is especially true of women. Being aware of one's personality and the relationship of personality traits to levels of physical activity and other measures of leading a healthy lifestyle can be beneficial in determining strategies to improve long-term health outcomes.

Resting heart rate and risk of dementia: a Mendelian randomization study in the international genomics of Alzheimer's Project and UK Biobank.

Background: Observational studies have demonstrated that a higher resting heart rate (RHR) is associated with an increased risk of dementia. However, it is not clear whether the association is causal. This study aimed to determine the causal effects of higher genetically predicted RHR on the risk of dementia. Methods: We performed a two-sample Mendelian randomization analysis to investigate the causal effect of higher genetically predicted RHR on Alzheimer's disease (AD) using summary statistics from genome-wide association studies. The generalized summary Mendelian randomization (GSMR) analysis was used to analyze the corresponding effects of RHR on following different outcomes: 1) diagnosis of AD (International Genomics of Alzheimer's Project), 2) family history (maternal and paternal) of AD from UK Biobank, 3) combined meta-analysis including these three GWAS results. Further analyses were conducted to determine the possibility of reverse causal association by adjusting for RHR modifying medication. Results: The results of GSMR showed no significant causal effect of higher genetically predicted RHR on the risk of AD (ßGSMR = 0.12, P = 0.30). GSMR applied to the maternal family history of AD (ßGSMR = -0.18, P = 0.13) and to the paternal family history of AD (ßGSMR = -0.14, P = 0.39) showed the same results. Furthermore, the results were robust after adjusting for RHR modifying drugs (ßGSMR = -0.03, P = 0.72). Conclusion: Our study did not find any evidence that supports a causal effect of RHR on dementia. Previous observational associations between RHR and dementia are likely attributed to the correlation between RHR and other cardiovascular diseases.

Heart Rate at Rest and Incident Atrial Fibrillation in Patients With Diastolic Dysfunction.

Diastolic dysfunction (DD) is associated with incident atrial fibrillation (AF). The influence of heart rate at rest (RHR) on incident AF in patients with DD has not been investigated. The goal of this study is to assess the influence of RHR on incident AF in patients with DD. Patients from a large health system with no previous history of AF, a left ventricular ejection fraction ≥50%, and documented DD on echocardiography were divided into quartiles (<66, 66 to 76, 77 to 91, >91 beats per minute) based on RHR. Incident AF was estimated using AF hospitalization during follow-up. Hazard ratios (HR) for AF hospitalization and all-cause death were calculated with a Cox proportional hazards model. A total of 19,046 patients were analyzed. Over a median follow-up of 42.2 months, 742 (3.9%) patients were hospitalized for AF. Both slower and faster RHR were associated with increased risk of AF hospitalization (HR 1.40, confidence interval [CI] 1.14 to 1.71, p = 0.001, HR 1.23, CI 0.99 to 1.53, p = 0.06 and HR 1.72, CI 1.38 to 2.14, p <0.001, for quartiles 1, 2, and 4, respectively), suggesting a J-shaped relation. Progressive increase in all-cause death was noted with faster RHR (HR1.19 per quartile increase, CI 1.16 to 1.22, p <0.001). These results persisted after adjustment for age, cardiovascular co-morbidities, grade of DD, and ß-blocker use. In conclusion, this large, real-world analysis indicates increased risk of incident AF with slower and faster RHR in patients with DD. Randomized trials are needed to evaluate the potential of RHR modification to mitigate the risk of incident AF.

Resting heart rate is associated with the prevalence of chronic kidney disease in Korean adult: the Korean National Health and Nutrition Survey.

BACKGROUND: Chronic kidney disease (CKD) poses a significant health challenge, yet early detection remains difficult. Resting heart rate (RHR) has been shown to be a reliable indicator of type 2 diabetes, prompting interest in its potential as an independent predictor of CKD. This study aimed to investigate the association between RHR and CKD prevalence, as well as explore potential interactions between RHR and other risk factors for CKD in a sample of 25,246 adults. METHODS: Data from the Korean National Health and Nutrition Examination Survey (2011-2014) were utilized for this study, with 19,210 participants included after screening. Logistic regression analysis was employed to examine the relationship between RHR and CKD prevalence. Stratified analyses were conducted based on known risk factors for CKD. RESULTS: Participants with an RHR ≥ 90 bpm exhibited a 2.07-fold [95% confidence interval (CI): 1.28-3.34] and 2.22-fold (95% CI: 1.42-3.48) higher prevalence of CKD in men and women, respectively, compared to those with an RHR < 60 bpm. The association between RHR and CKD prevalence was particularly pronounced in younger participants (40-59 years vs. ≥ 60 years), individuals with diabetes (yes vs. no), and those with a longer duration of diabetes (≥ 7 years vs. < 7 years). CONCLUSION: Elevated RHR was found to be significantly associated with a higher prevalence of CKD in both men and women, independent of demographic, lifestyle, and medical factors. These findings suggest that RHR could serve as a valuable predictor for undiagnosed CKD.

Predictors of Cardiac Autonomic Dysfunction in Obesity-Related Hypertension.

INTRODUCTION: Cardiac Autonomic Dysfunction (CAD) is an overlooked cardiovascular risk factor in individuals with obesity-related hypertension. Despite its clinical significance, there is a notable lack of clarity regarding the pathophysiological correlates involved in its onset and progression. AIM: The present study aimed to identify potential predictors of CAD in obesity-related hypertension. METHODS: A total of 72 participants (34 men and 38 women) were enrolled. Comprehensive evaluations were conducted, including cardiac autonomic function assessments, body composition estimation and biochemical analysis. Participants were categorized as CAD-positive or CAD-negative based on Ewing's criteria for autonomic dysfunction. Univariate logistic regression analysis was performed to identify potential predictors for CAD. Multivariate logistic regression models were further constructed by adjusting clinically relevant covariates to identify independent predictors of CAD. RESULTS: Multivariate logistic regression analysis revealed that resting heart rate (HRrest), (odds ratio, confidence interval: 0.85, 0.78-0.93; p = 0.001) and percentage body fat (BF%), (odds ratio, confidence interval: 0.78, 0.64-0.96; p = 0.018) were significant independent predictors of CAD. Receiver Operating Characteristic curve analysis depicted optimal cut-off values for HRrest and BF% as > 74.1 bpm and > 33.6%, respectively. Multicolinearity analysis showed variance inflation factors (VIF) below the cautionary threshold of 3. CONCLUSIONS: The HRrest and BF% emerged as significant independent predictors of CAD in obesity-related hypertension. Therapeutic strategies should target HRrest < 74.1 bpm and BF% < 33.6% to mitigate CAD risk in this population. Future trials are required to establish causal relationships and may consider additional confounding variables in obesity-related hypertension.

Resting heart rate causally affects the brain cortical structure: Mendelian randomization study.

Resting heart rate (RHR) has been linked to impaired cortical structure in observational studies. However, the extent to which this association is potentially causal has not been determined. Using genetic data, this study aimed to reveal the causal effect of RHR on brain cortical structure. A Two-Sample Mendelian randomization (MR) analysis was conducted. Sensitivity analyses, weighted median, MR Pleiotropy residual sum and outlier, and MR-Egger regression were conducted to evaluate heterogeneity and pleiotropy. A causal relationship between RHR and cortical structures was identified by MR analysis. On the global scale, elevated RHR was found to decrease global surface area (SA; P < 0.0125). On a regional scale, the elevated RHR significantly decreased the SA of pars triangularis without global weighted (P = 1.58 × 10-4) and the thickness (TH) of the paracentral with global weighted (P = 3.56 × 10-5), whereas it increased the TH of banks of the superior temporal sulcus in the presence of global weighted (P = 1.04 × 10-4). MR study provided evidence that RHR might be causally linked to brain cortical structure, which offers a different way to understand the heart-brain axis theory.

New Insights into Rate Control: Time in Target Range of Resting Heart Rate and Major Adverse Outcomes in Atrial Fibrillation.

Background: Few studies have examined the relationship between the fluctuation of heart rate control over time and cardiovascular outcomes in patients with atrial fibrillation. Our study sought to evaluate the independent association between time in target range (TIR) of resting heart rate and cardiovascular outcomes in the AFFIRM (Atrial Fibrillation Follow-Up Investigation of Rhythm Management) study. Methods: Target range of resting heart was defined as less than 80 beats per minute (bpm) for both rate and rhythm control groups. Time in target range was estimated over the first 8 months of follow-up using Rosendaal interpolation method. The association between TIR of resting heart rate and cardiovascular outcomes was estimated using adjusted Cox proportional hazards regression models. Results: Time in target range of resting heart rate (months 0 through 8) was 71 ± 34% in the rate control group and 83 ± 27% in the rhythm control group. Each 1-SD increase in TIR of resting heart rate was significantly associated with lower risk of major adverse cardiovascular events after full adjustment for demographics, medical history and history of prior heart surgery, as well as all-cause mortality. Conclusions: Time in target range of resting heart rate independently predicts the risk of cardiovascular outcomes in patients with atrial fibrillation. Long-term maintenance of heart rate on target is of great importance for patients with atrial fibrillation.

Relationship between resting heart rate and long-term outcomes in stabilized patients with myocardial infarction: A prospective community-based cohort study.

BACKGROUND: Resting heart rate (RHR) during hospitalization has been shown to be associated with adverse outcomes in patients with myocardial infarction (MI). This study aimed to evaluate the long-term prognostic effect of RHR during the stable phase after MI in post-MI patients. METHODS: Patients who had prior or new-onset MI and RHR measurements during the stable period after MI between 2006 and 2018 in the community-based Kailuan Study were enrolled. RHR was divided into four groups based on quartiles. Cox regression analysis was used to analyze the association of RHR with primary composite outcome of all-cause death, hospitalization for heart failure (HF), stroke, and recurrent MI and its components. RESULTS: A total of 4447 post-MI patients were included. During a median follow-up of 7.5 years, 1813 patients (40.8%) developed primary outcomes. Compared to RHR ≤67 bpm, patients with 72 < RHR ≤80 bpm and RHR >80 bpm had increased risks of primary outcome, with adjusted hazard ratios (95% confidence intervals) of 1.23 (1.08-1.40) and 1.35 (1.18-1.55), respectively. The risk of primary outcome increased by 12% (1.07-1.17) for each 10-bpm increase in RHR. Similar results were observed in all-cause death and hospitalization for HF. Restricted cubic splines revealed a linear relationship between RHR and primary outcome, all-cause death, and hospitalization for HF (P for nonlinearity >0.05). CONCLUSIONS: RHR during the stable phase after MI was an independent predictor for primary outcome and all-cause death in post-MI patients, and RHR >72 bpm was associated with increased risk for primary outcome and all-cause death.

Interplay of heart rate variability and resting heart rate on mortality in type 2 diabetes.

AIMS: Heart rate variability (HRV) and resting heart rate (RHR) are usually analyzed and interpreted separately. We aimed to assess the interplay of HRV and RHR on mortality in type 2 diabetes. METHODS: The study included 7,529 participants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. HRV metrics included standard deviation of all normal-to-normal intervals (SDNN) and root mean square of successive differences between normal-to-normal intervals (rMSSD). Abnormal values were defined based on <25th percentile for HRV and >75th percentile for RHR. Interactions of HRV status and RHR status were tested on multiplicative and additive scales. Results were validated in a subset of patients with type 2 diabetes (n = 745) from the Multi-Ethnic Study of Atherosclerosis. RESULTS: Low SDNN was associated with increased all-cause mortality in the high RHR group (HR 1.60; 95% CI 1.29-1.97), but not in the normal RHR group. Compared with those who had neither low SDNN nor high RHR, the presence of either low SDNN or high RHR was not significantly associated with an increased risk of all-cause mortality. In contrast, the combination of low SDNN and high RHR was associated with a significantly increased risk of all-cause mortality (HR 1.68; 95% CI 1.43-1.97). Significant multiplicative and additive interactions were found between HRV status and RHR status on risk of all-cause mortality (all Pinteraction < 0.05). Similar findings were observed for cardiovascular mortality, in analyses using rMSSD, and in the Multi-Ethnic Study of Atherosclerosis. CONCLUSIONS: The association between HRV and mortality risk is modified by RHR levels. Furthermore, low HRV and high RHR have interdependent and synergistic associations with mortality risk.