Background Although physical activity (PA) is associated with a reduced risk of stroke and mortality, its impact among individuals with atrial fibrillation (AF) remains insufficiently explored. Therefore, the aim of this study was to examine the impact of PA on stroke and mortality, both overall and with respect to AF diagnosis. Methods We included 87 340 participants, of which 6539 had AF, from 2 Norwegian population‐based studies, the Tromsø Study and the HUNT (Trøndelag Health Study). Information about AF, stroke, and death were obtained from national health registries. Participants were classified as inactive (reference) or performing low, moderate, or high PA on the basis of a questionnaire. The data were analyzed using multivariable adjusted flexible parametric survival models. Results During a median follow‐up of 13.5 years, 3415 strokes and 7833 deaths occurred. The respective stroke risk reduction associated with low, moderate, and high PA was 9% (95% CI, 1%–16%), 19% (95% CI, 11%–27%) and 18% (95% CI, 8%–26%). Mortality was reduced by 11% (95% CI, 7%–14%), 18% (95% CI, 14%–22%), and 22% (95% CI, 18%–27%). Similar benefits were observed for both stroke and mortality when stratifying by presence or absence of AF. Among individuals with AF, an increased life expectancy was observed, with gains of 0.50 (95% CI, 0.22–0.78), 0.66 (95% CI, 0.31–1.01) and 1.15 (95% CI, 0.77–1.53) years, respectively. Conclusions PA was associated with a reduced risk of stroke and mortality, and similar benefits were observed irrespective of AF diagnosis. Our findings suggest that PA may complement current medical treatment strategies in individuals with AF.

BACKGROUND AND AIMS:Sleep disturbances can induce alterations in functional and electrical properties of the heart, thereby increasing susceptibility to atrial fibrillation (AF). We aimed to test the causal role of different sleep traits and their joint effects on the risk of AF. METHODS:We used an observational cohort study design along with one-sample and factorial Mendelian randomization (MR) approaches to test for individual and joint associations of sleep traits (i.e., insomnia symptoms, sleep duration and chronotype) on the risk of AF using UK Biobank and the second survey of the Trøndelag Health Study (HUNT2). RESULTS:One-sample MR analysis showed that genetic predisposition to insomnia symptoms (hazard ratio (HR) 1.14; 95% confidence interval (CI) 1.07, 1.21) and short (≤6 h vs. 7-8 h) sleep duration (HR 1.14; 95% CI 1.04, 1.26) increased the risk of AF in UK Biobank. However these findings (HR 0.95; 95% CI 0.81, 1.11 for insomnia symptoms and HR 1.41; 95% CI 0.57, 3.46 for short sleep duration) were not consistent in HUNT2. Factorial MR analysis showed participants with genetic predisposition to both insomnia symptoms and short sleep duration (HR 1.08; 95% CI 1.03, 1.12) had the highest risk of AF, although there was no evidence of interaction (relative excess risk due to interaction (RERI 0.03; 95% CI -0.03, 0.09). However, this finding (HR 0.96; 95% CI 0.89, 1.04) was not consistent in HUNT2. Participants with genetic predisposition to both a morning chronotype and insomnia symptoms (HR 1.08; 95% CI 1.04, 1.13) and a morning chronotype and short sleep (HR 1.06; 95% CI 1.02, 1.10) had the highest risk of AF in UK Biobank, although there was no evidence of interaction (RERI -0.01; 95% CI -0.07, 0.04 and RERI 0.06; 95% CI -0.01, 0.12, respectively). CONCLUSIONS:Our study indicates that insomnia symptoms and short sleep duration are causal risk factors for AF. However, having two sleep traits in combination does not increase risk beyond the additive risk of each individual trait. This reinforces clinical and public health efforts to effectively manage insomnia symptoms and short sleep, in order to mitigate the risk of AF and improve overall cardiovascular health.

Background:Evidence of the association between serum vitamin D levels and atrial fibrillation (AF) is inconclusive. Thus, this study investigated the relationship between long-term average serum 25-hydroxyvitamin D [25(OH)D] levels and AF incidence in the Norwegian Trøndelag Health (HUNT) Study using a prospective cohort design and a Mendelian randomization (MR) approach. Methods:A total of 3394 adults with 2 measurements of serum 25(OH)D at HUNT2 (1995-1997) and HUNT3 (2006-2008) and without AF at HUNT3 were followed up to 2021. Average serum 25(OH)D levels over 10 years were categorized into <50 and ≥50 nmol/L. AF diagnoses were retrieved from hospital registers and validated by doctors. Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). Furthermore, a 1-sample MR was conducted among 36 554 adults who participated in both HUNT2 and HUNT3 using the Wald ratio method. Results:During a median 12-year follow-up, 304 AF cases were diagnosed. Serum 25(OH)D levels <50.0 nmol/L were associated with a 27% reduced incidence of AF (HR 0.73, 95% CI 0.57-0.93) compared with ≥50 nmol/L after adjustment for confounders. A genetically determined 10 nmol/L decrease in the serum 25(OH)D levels was associated with a 7% reduced incidence of AF (HR 0.93, 95% CI 0.86-1.00) in the 1-sample MR. Sensitivity analyses supported this association. Conclusion:Using both traditional observational and 1-sample MR approaches, the study suggested a consistently positive association between long-term average serum 25(OH)D levels and incidence of AF in the Norwegian HUNT population.

AIMS:Despite well-studied associations between hypertensive disorders of pregnancy (HDP) and atrial fibrillation (AF), the mechanisms of the excess risk of AF in women with history of HDP are not fully understood. Furthermore, little is known about associations between other adverse pregnancy outcomes (APOs) and AF, including preterm birth, small/large-for-gestational-age (SGA/LGA) offspring. METHODS AND RESULTS:By linking the population-based HUNT study with the Medical Birth Registry of Norway (MBRN) and electronic patient administrative systems, 15 104 women ≥45 years with 34 674 births were followed and assessed for validated AF for a median of 12.9 years. Information on APOs was retrieved from the MBRN. We used Cox proportional hazards models to calculate hazard ratios (HRs) for associations of APOs with the risk of AF. By inverse odds ratio weighting, we assessed modifiable AF risk factors that could explain the associations. Among women aged 45-65, those with HDP had a higher risk of AF [HR 2.03, 95% confidence interval (CI) 1.27-3.24] as women without HDP, but not among women >65 years (HR 0.95, 95% CI 0.57-1.60). A history of LGA was associated with increased risk of AF (HR 1.38, 95% CI 1.03-1.84), but histories of preterm birth or SGA were not (HR 0.94, 95% CI 0.63-1.41, HR 0.90, 95% CI 0.66-1.23). Post-pregnancy body mass index might possibly explain ∼45% of the associations between HDP or LGA and AF. CONCLUSION:Women with history of HDP or LGA offspring are at higher risk of AF.

Background Self-rated health (SRH) is easy to obtain and is known to be a good predictor for mortality and several comorbidities, including cardiovascular disease, but its relation to atrial fibrillation (AF) is largely unknown. We determined the association of SRH with risk of developing AF. Methods We conducted a pooled cohort analysis of participants in the Atherosclerosis Risk in Communities Study (ARIC) (n= 10,255; mean age, 63 years), the Trøndelag Health Study (HUNT-3 Study) (n=43,668, mean age, 53 years), and the Multi-Ethnic Study of Atherosclerosis Study (MESA) (n=5,037, mean age, 66 years) cohorts to examine the association of SRH with risk of atrial fibrillation (AF). We categorized SRH as “poor or fair”, “good”, or “very good or excellent”. Incident AF was identified via visit electrocardiograms, hospital discharge codes, or Medicare claims. We used Cox regression to quantify the association of baseline SRH category and AF risk in each cohort. Models were adjusted for demographics, body mass index, tobacco use, alcohol, diabetes, hypertension, cholesterol, cardiovascular disease, and physical activity. We pooled the hazard ratios (HR) and 95% CIs using a fixed-effects model. Results Over a mean of 16±6, 9±2, and 10±4 years of follow-up, 2340 (22.8%), 1525 (3.5%), and 879 (17.4%) incident AF events occurred in ARIC, HUNT-3, and MESA respectively. Lower SRH categories were associated with higher AF risk in each cohort and in the pooled analysis: HR 1.11 (95% CI 1.02 to 1.20) for good SRH; and 1.40 (95% CI, 1.26 to1.55) for fair or poor SRH compared to very good or excellent SRH. Conclusions Worse SRH was independently associated with a higher risk of developing AF. SRH is an easily obtainable metric and may help to additionally identify individuals at higher risk for AF.

Background and Aims: Evidence of the association between serum vitamin D levels and atrial fibrillation (AF) is inconclusive. Thus, this study investigated the relationship between long-term average serum 25-hydroxyvitamin D (25(OH)D) levels and AF incidence in the Norwegian Trøndelag Health (HUNT) Study using a prospective cohort design and a Mendelian randomization (MR) approach. Methods: A total of 3394 adults with two measurements of serum 25(OH)D at HUNT2 (1995-1997) and HUNT3 (2006-2008) and without AF at HUNT3 were followed up to 2021. Average serum 25(OH)D levels over ten years were categorized into <50 and ?50 nmol/L. AF diagnoses were retrieved from hospital registers and validated by doctors. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI). Furthermore, a one-sample MR was conducted among 36,554 adults who participated in both HUNT2 and HUNT3 using the Wald ratio method. Results: During a median 12-year follow-up, 304 AF cases were diagnosed. Serum 25(OH)D levels <50.0 nmol/L were associated with a 27% reduced incidence of AF (HR 0.73, 95% CI 0.57 to 0.93) compared with ?50 nmol/L after adjustment for confounders. A genetically determined 10 nmol/L decrease in the serum 25(OH)D levels was associated with a 7% reduced incidence of AF (HR 0.93, 95% CI 0.86 to 1.00) in the one-sample MR. Sensitivity analyses supported this association. Conclusions: Using both traditional observational and one-sample MR approaches, the study suggested a consistently positive association between long-term average serum 25(OH)D levels and incidence of AF in the Norwegian HUNT population. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement LJ was supported by funding from the collaboration partner between the Liaison Committee for Education, Research and Innovation in Central Norway and Central Norway Regional Health Authority (project ID: 30320). YQS was supported by a researcher grant from The Liaison Committee for Education, Research and Innovation in Central Norway (project ID: 2018/42794). None of the funding sources was involved in any aspect of the study design, conduct, analyses, interpretation of data, or writing the report. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Regional Committee for Medical and Health Research Ethics of central Norway (application number:434217). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data from the HUNT Study that is used in research projects will, when reasonably requested by others, be made available on request to the HUNT Data Access Committee (hunt{at}medisin.ntnu.no).

Studies on the effect of insomnia on atrial fibrillation risk in the general population are limited, therefore we investigated the association between insomnia and the risk of atrial fibrillation in a large-scale population-based study with valid atrial fibrillation measure. A total of 33,983 participants (55% women) reported their insomnia symptoms in the third wave of the HUNT study (between 2006 and 2008) in Norway, and they were followed for their first atrial fibrillation diagnosis until 2020 using hospital registers. Atrial fibrillation diagnoses were validated by physicians based on medical records and electrocardiograms. Insomnia symptoms were assessed by four questions, and analysed both individually and as cumulative symptoms. Cox regression, adjusted for age, sex, social and marital status, working in shiftwork, alcohol consumption, smoking, physical activity, body mass index, systolic blood pressure, and symptoms of anxiety and depression, was conducted. Overall, 1592 atrial fibrillation cases were identified during the follow-up and 31.6% of individuals reported at least one insomnia symptom. In our analysis, we did not detect meaningful associations between insomnia symptoms and the risk of atrial fibrillation. In conclusion, in this population there was no evidence for an association between insomnia symptoms and the risk of subsequent atrial fibrillation.

AIMS:Gastroesophageal reflux disease (GERD) may influence the risk of atrial fibrillation (AF). We investigated the association between symptoms of GERD and AF in the Trøndelag Health Study (HUNT).METHODS:The study cohort comprised 34,120 adult men and women initially free of AF with information on GERD symptoms. Participants were followed from the baseline clinical examination (1 October 2006 to 30 June 2008) to March 31, 2018.RESULTS:During a median follow-up of 8.9 years, 1,221 cases of AF were diagnosed. When looking at the whole population, participants with much GERD symptoms did not have an increased risk of AF (HR: 1.01; CI: 95%, 0.82 to 1.24) while participants with little GERD symptoms had a 14% lower risk of AF compared those with no GERD symptoms (HR: 0.86; CI: 95%, 0.76 to 0.97). Among younger participants (<40 years of age), the risk of AF had a trend towards increased risk with increasing symptom load of GERD (little GERD symptoms, HR: 3.09; CI: 95%, 0.74 to 12.94 and much GERD symptoms, HR: 5.40; 95% CI: 0.82 to 35.58). Among older participants (≥65 years of age), we saw a slightly reduced risk of AF in participants with little symptoms (HR: 0.84; CI: 0.72 to 0.97) and no association among those with much GERD symptoms (HR: 1.06; 95% CI: 0.82 to 1.36).CONCLUSION:We did not find support for a clinically important association between symptoms of GERD and AF across all age groups but for some younger people, GERD might play a role in the development of AF. However, our estimates for this age group were very imprecise and larger studies including younger individuals are warranted.

Abstract Background Evidence on the association between serum vitamin D levels and incidence of atrial fibrillation (AF) was inconclusive. To elucidate the nature of the association, we studied the relationship between serum 25-hydroxyvitamin D (25(OH)D) levels and AF incidence in the Norwegian Trøndelag Health (HUNT) Study using both conventional observational and Mendelian Randomization (MR) approaches. Methods 3394 adult participants without AF diagnoses were followed up from HUNT3 (2006-2008) to 2021 in a prospective cohort. Average serum 25(OH)D levels over ten years between HUNT2 (1995-1997) and HUNT3 were calculated and categorized into <50 and ≥50 nmol/L as exposure. AF diagnoses were retrieved from hospital registers and validated by medical doctors. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI). Furthermore, a one-sample MR was conducted among 36,554 adults who participated in both HUNT2 and HUNT3. An externally weighted genetic risk score based on 19 vitamin D-related genetic variants, chosen for their clear biological functions in serum vitamin D transport, synthesis and metabolism, was used as instrument. We applied the Wald ratio method to assess the causal effect. Results During a median 13-year follow-up, 303 AF cases were diagnosed in the prospective cohort. Serum 25(OH)D level <50.0 nmol/L was associated with a 26% reduced incidence of AF (HR 0.74, 95% CI 0.58 to 0.95), compared to serum 25(OH)D ≥50 nmol/L after adjustment for confounders. Genetically determined 10 nmol/L decrease in serum 25(OH)D level was associated with a 7% reduced incidence of AF (HR 0.93, 95% CI 0.86 to 1.00) in the MR analysis. Sensitivity analyses supported this positive association. Conclusions We found a consistent positive association between serum 25(OH)D level and AF incidence in the Norwegian HUNT population using both observational and MR approaches. Key messages • Serum vitamin D levels appeared to be positively associated with the incidence of AF. • Vitamin D supplementation should be prescribed with caution, especially for people at high risk for AF.

Background: Age at menarche, reproductive lifespan, and age at menopause are associated with several cardiovascular diseases, but their relationship with atrial fibrillation (AF) is uncertain. Methods: We linked information on all women who participated in the third survey of the population-based, longitudinal HUNT study in Norway with medical records from all local hospitals. A total of 14,632 women aged 60 or more were followed for validated incident AF. We retrieved age at menarche and age at menopause from the HUNT questionnaires. Reproductive lifespan was defined as the difference between age at menarche and age at menopause. We used Cox proportional hazards regression models to assess associations between AF and age at menarche, reproductive lifespan, and age at menopause. Results: During a median follow-up of 8.17 years (136,494 person-years), 1217 (8.3 %) participants developed AF. In multivariable-adjusted analyses, we observed no associations between early or late age at menarche and AF (hazard ratios (HRs): <12 years: 0.85 [95 % confidence interval (CI), 0.65-1.12]; >= 16 years: 0.99 [95 % CI, 0.80-1.24] compared to those who attained menarche at 13-14 years). The HR for a reproductive lifespan shorter than 30 years was 0.91 [95 % CI, 0.72-1.15] compared to 34-37 years. Likewise, there was no clear association between premature or early age at menopause and AF (HRs: <40 years: 1.21 [95 % CI, 0.83-1.75]; 40-44 years: 0.97 [95 % CI, 0.77-1.22] compared to 50-54 years). Conclusions: In this population of women aged 60 years and over, the risk of AF was not associated with age at menarche, reproductive lifespan, or age at menopause.

Background Limited studies have triangulated the relationship between serum vitamin D [25(OH)D] levels and systolic blood pressure (SBP), diastolic blood pressure (DBP) or hypertension risk using traditional observational and Mendelian randomization (MR) approaches. Methods and results Data were obtained from the Norwegian Trøndelag Health Study (HUNT). A cross-sectional study was performed among 5854 participants from HUNT2. Among them, 3592 participants were followed over 11 years for a prospective analysis. Furthermore, a one-sample MR was conducted with 86,324 participants from HUNT. An externally weighted genetic risk score based on 19 genetic variants for 25(OH)D was used as instrument and the Wald ratio method was applied to evaluate causal associations. Additionally, two-sample MR were performed using updated publicly available data. Our cross-sectional analyses showed a 25 nmol/L increase in 25(OH)D was associated with a 1.73 mmHg decrease in SBP (95 % CI -2.46 to -1.01), a 0.91 mmHg decrease in DBP (95% CI - 1.35 to -0.47) and 19% lower prevalence of hypertension (OR 0.81, 95% CI 0.74 to 0.90) after adjusting for important confounders. However, these associations disappeared in prospective analyses. Both one-sample and two-sample MR results suggested no causal associations. Conclusions Cross-sectional findings of inverse associations between serum 25(OH)D levels and blood pressure or hypertension were not supported by results from the prospective and MR analyses, suggesting no causal links. Clinical Perspective What Is New? What Are the Clinical Implications? ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement LJ was supported by funding from the collaboration partner between the Liaison Committee for Education, Research and Innovation in Central Norway and Central Norway Regional Health Authority (project ID: 30320). YQS was supported by a researcher grant from The Liaison Committee for Education, Research and Innovation in Central Norway (project ID: 2018/42794). MD was supported by research funding from the Norwegian Women?s Public Health Association (N.K.S.: 40014) and top-up funding from the collaboration partner between St Olav hospital and NTNU, Norwegian University of Science and Technology. BMB works in a research unit funded by Stiftelsen Kristian Gerhard Jebsen; Faculty of Medicine and Health Sciences, NTNU; The Liaison Committee for Education, Research and Innovation in Central Norway. None of the funding sources was involved in any aspect of the study design, conduct, analyses, interpretation of data, or writing the report. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Regional Committee for Medical and Health Research Ethics of central Norway (application number:434217). All participants signed informed written consent on participation in HUNT. The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data from the HUNT Study is available on request to the HUNT Data Access Committee (hunt@ medisin.ntnu.no) when is used in research projects. The HUNT data access information describes the policy regarding data availability (). * ### Abbreviations and symbols BMI : Body mass index CI : Confidence interval DBP : Diastolic blood pressure GRS : genetic risk score GWAS : Genome-wide association study HUNT : The Trøndelag Health Study MR : Mendelian randomization MR-PRESSO : MR-Pleiotropy Residual Sum and Outlier OR : Odds ratio RCTs : Randomized Controlled Trials PCs : Principal components SBP : Systolic blood pressure SNP : Single Nucleotide Polymorphisms SUNLIGHT : Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits 25(OH)D : 25-hydroxyvitamin D

Abstract Limited studies have triangulated the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and systolic blood pressure (SBP), diastolic blood pressure (DBP) or hypertension risk utilizing both observational and Mendelian randomization (MR) approaches. We employed data from the Norwegian Trøndelag Health Study (HUNT) to conduct cross-sectional (n = 5854) and prospective (n = 3592) analyses, as well as one-sample MR (n = 86,324). We also used largest publicly available data for two-sample MR. Our cross-sectional analyses showed a 25 nmol/L increase in 25(OH)D was associated with a 1.73 mmHg decrease in SBP (95% CI − 2.46 to − 1.01), a 0.91 mmHg decrease in DBP (95% CI − 1.35 to − 0.47) and 19% lower prevalence of hypertension (OR 0.81, 95% CI 0.74 to 0.90) after adjusting for important confounders. However, these associations disappeared in prospective analyses. One-sample and two-sample MR results further suggested no causal relationship between serum vitamin D levels and blood pressure or hypertension risk in the general population.

AIMS:Although parity, infertility, and age at first birth are important for later development of cardiovascular disease, research on their association with atrial fibrillation (AF) is limited. METHODS AND RESULTS:We linked data from the population-based HUNT study and the Medical Birth Registry of Norway (MBRN) and validated medical records from local hospitals. A total of 24 015 women aged 45 years or older were followed for verified incident AF. Parity and age at first birth were retrieved from the MBRN or from self-reported questionnaires in the HUNT study. A history of infertility was self-reported on the HUNT questionnaire. Cox proportional hazards models were used to calculate hazard ratios (HRs) for the multivariable-adjusted associations of parity, infertility, and age at first birth with risk of AF. During a median follow-up of 12.8 years, 1448 (6.0%) participants developed AF. Women with higher parity (four or more births vs. two births) were at 21% higher risk of AF [HR 1.21, 95% confidence interval (CI) 1.05-1.39]. A history of infertility was also associated with the risk of AF (HR 1.20, 95% CI 1.02-1.42). Among parous women, younger age at first birth (<20 vs. 20-29 years) was associated with a 20% higher risk of AF (HR 1.20, 95% CI 1.03-1.40). CONCLUSION:Women with four or more births, or a history of infertility, or younger age at first birth have approximately a 20% higher risk of AF among women over 45 years old.

This study evaluated acute cardiac stress after a high-intensity interval training session in patients with type 2 diabetes (T2D) versus healthy controls. High intensity aerobic exercise was performed by 4 × 4-min intervals (90–95% of maximal heart rate), followed by a ramp protocol to peak oxygen uptake. Echocardiography was performed before and 30 min after exercise. Holter electrocardiography monitored heart rhythms 24 h before, during, and 24 h after the exercise. Left atrial end-systolic volume, peak early diastolic mitral annular velocity, and the ratio of peak early to late diastolic mitral inflow velocity were reduced by approximately 18%, 15%, and 31%, respectively, after exercise across groups. Left ventricular end-diastolic wall thickness was the only echo parameter that significantly differed between groups in response to exercise. The T2D group had a rate of supraventricular extrasystoles per hour that was 265% greater than that of the controls before exercise, which remained higher after exercise. A single exhaustive exercise session impaired left ventricular diastolic function in both groups. The findings also indicated impaired right ventricular function in patients with T2D after exercise. ClinicalTrials.gov Identifier: NCT02998008.

Abstract Aims Atrial fibrillation (AF) confers higher risk of mortality and morbidity, but the long-term impact of physical activity (PA) and cardiorespiratory fitness (CRF) on outcomes in AF patients is unknown. We, therefore, examined the prospective associations of PA and estimated CRF (eCRF) with all-cause mortality, cardiovascular disease (CVD) mortality, morbidity and stroke in individuals with AF. Methods and results We followed 1117 AF patients from the HUNT3 study in 2006–08 until first occurrence of the outcomes or end of follow-up in November 2015. We used Cox proportional hazard regression to examine the prospective associations of self-reported PA and eCRF with the outcomes. Atrial fibrillation patients meeting PA guidelines had lower risk of all-cause [hazard ratio (HR) 0.55, 95% confidence interval (CI) 0.41–0.75] and CVD mortality (HR 0.54, 95% CI 0.34–0.86) compared with inactive patients. The respective HRs for CVD morbidity and stroke were 0.78 (95% CI 0.58–1.04) and 0.70 (95% CI 0.42–1.15). Each 1-metabolic equivalent task (MET) higher eCRF was associated with a lower risk of all-cause (HR 0.88, 95% CI 0.81–0.95), CVD mortality (HR 0.85, 95% CI 0.76–0.95), and morbidity (HR 0.88, 95% CI 0.82–0.95). Conclusion Higher PA and CRF are associated with lower long-term risk of CVD and all-cause mortality in individuals with AF. The findings support a role for regular PA and improved CRF in AF patients, in order to combat the elevated risk for mortality and morbidity.

Objective Atrial fibrillation (AF) is the most common arrhythmia and has been described as a global epidemic. Although AF is associated with both obesity and its metabolic consequences, little is known about the association between metabolically healthy obesity and AF. Methods In a population‐based study, 47,870 adults were followed for incident AF from 2006 to 2008 until 2015. Participants were classified according to BMI and metabolic status (using waist circumference, triglycerides, high‐density lipoprotein cholesterol, blood pressure, and glucose) at baseline. Results During a median follow‐up of 8.1 years, 1,758 participants developed AF. Compared with metabolically healthy individuals with BMI < 25 kg/m 2 , the multivariable‐adjusted hazard ratios for metabolically healthy and unhealthy obesity were 1.6 (95% CI: 1.2 to 2.1) and 1.6 (95% CI: 1.3 to 1.9), respectively. AF risk increased according to the severity of obesity. Conclusions Metabolically healthy and unhealthy obesity increased AF risk to a similar extent. Severity of obesity was positively associated with AF risk regardless of metabolic status.

ABSTRACT Purpose To investigate the association between estimated cardiorespiratory fitness (eCRF) and risk of atrial fibrillation (AF), and examine how long-term changes in eCRF affects the AF risk. Methods This prospective cohort study includes data of 39,844 men and women from the HUNT2 (August 15, 1995 to June 18, 1997) and the HUNT3 study (October 3, 2006 to June 25, 2008). The follow-up period was from HUNT3 until AF diagnosis or November 30, 2015. The AF diagnoses were retrieved from hospital registers and validated by medical doctors. A nonexercise test based on age, waist circumference, resting heart rate and self-reported physical activity was used to estimate CRF. Cox regression was performed to assess the association between eCRF and AF. Results The mean age was 50.6 ± 14.6 yr for men and 50.2 ± 15.2 yr for women. Mean follow-up time was 8.1 yr. One thousand fifty-seven cases of AF were documented. For men, the highest risk reduction of AF was 31% in the fourth quintile of eCRF when compared with the first quintile (hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.53–0.89). For women, the highest risk reduction was 47% in the fifth quintile when compared with the first quintile (HR, 0.53; 95% CI, 0.38–0.74). One metabolic equivalent increase in eCRF over a 10-yr period was associated with 7% lower risk of AF (HR, 0.93; 95% CI, 0.86–1.00). Participants with improved eCRF had 44% lower AF risk compared with those with decreased eCRF (HR, 0.56; 95% CI, 0.36–0.87). Conclusions The eCRF was inversely associated with AF, and participants with improved eCRF over a 10-yr period had less risk of AF. These findings support the hypothesis that fitness may prevent AF.

Aims Although obesity has been associated with risk of atrial fibrillation (AF), the associations of long-term obesity, recent obesity, and weight change with AF risk throughout adulthood are uncertain. Methods and results An ambispective cohort study was conducted which included 15 214 individuals. The cohort was created from 2006 to 2008 (the baseline) and was followed for incident AF until 2015. Weight and height were directly measured at baseline. Data on previous weight and height were retrieved retrospectively from measurements conducted 10, 20, and 40 years prior to baseline. Average body mass index (BMI) over time and weight change was calculated. During follow-up, 1149 participants developed AF. The multivariable-adjusted hazard ratios were 1.2 (95% confidence interval 1.0-1.4) for average BMI 25.0-29.9 kg/m(2) and 1.6 (1.2-2.0) for average BMI >= 30 kg/m(2) when compared with normal weight. The association of average BMI with AF risk was only slightly attenuated after adjustment for most recent BMI. In contrast, current BMI was not strongly associated with the risk of AF after adjustment for average BMI earlier in life. Compared with stable BMI, both loss and gain in BMI were associated with increased AF risk. After adjustment for most recent BMI, the association of BMI gain with AF risk was largely unchanged, while the association of BMI loss with AF risk was weakened. Conclusion Long-term obesity and BMI change are associated with AF risk. Obesity earlier in life and weight gain over time exert cumulative effects on AF development even after accounting for most recent BMI.

Background Atrial fibrillation is the most common heart rhythm disorder, and high body mass index is a well-established risk factor for atrial fibrillation. The objective of this study was to examine the associations of physical activity and body mass index and risk of atrial fibrillation, and the modifying role of physical activity on the association between body mass index and atrial fibrillation. Design The design was a prospective cohort study. Methods This study followed 43,602 men and women from the HUNT3 study in 2006–2008 until first atrial fibrillation diagnosis or end of follow-up in 2015. Atrial fibrillation diagnoses were collected from hospital registers and validated by medical doctors. Cox proportional hazard regression analysis was performed to assess the association between physical activity, body mass index and atrial fibrillation. Results During a mean follow-up of 8.1 years (352,770 person-years), 1459 cases of atrial fibrillation were detected (4.1 events per 1000 person-years). Increasing levels of physical activity were associated with gradually lower risk of atrial fibrillation (p trend 0.069). Overweight and obesity were associated with an 18% (hazard ratio 1.18, 95% confidence interval 1.03–1.35) and 59% (hazard ratio 1.59, 95% confidence interval 1.37–1.84) increased risk of atrial fibrillation, respectively. High levels of physical activity attenuated some of the higher atrial fibrillation risk in obese individuals (hazard ratio 1.53, 95% confidence interval 1.03–2.28 in active and 1.96, 95% confidence interval 1.44–2.67 in inactive) compared to normal weight active individuals. Conclusion Overweight and obesity were associated with increased risk of atrial fibrillation. Physical activity offsets some, but not all, atrial fibrillation risk associated with obesity.