Objectively Measured Physical Activity and the Risk of Atrial Fibrillation (from the REGARDS Study)

Step Count, Self-reported Physical Activity, and Predicted 5-Year Risk of Atrial Fibrillation: Cross-sectional Analysis

BACKGROUND

Physical inactivity is a known risk factor for atrial fibrillation (AF). Wearable devices, such as smartwatches, present an opportunity to investigate the relation between daily step count and AF risk.

OBJECTIVE

The objective of this study was to investigate the association between daily step count and the predicted 5-year risk of AF.

METHODS

Participants from the electronic Framingham Heart Study used an Apple smartwatch. Individuals with diagnosed AF were excluded. Daily step count, watch wear time (hours and days), and self-reported physical activity data were collected. Individuals' 5-year risk of AF was estimated, using the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE)-AF score. The relation between daily step count and predicted 5-year AF risk was examined via linear regression, adjusting for age, sex, and wear time. Secondary analyses examined effect modification by sex and obesity (BMI≥30 kg/m²), as well as the relation between self-reported physical activity and predicted 5-year AF risk.

RESULTS

We examined 923 electronic Framingham Heart Study participants (age: mean 53, SD 9 years; female: n=563, 61%) who had a median daily step count of 7227 (IQR 5699-8970). Most participants (n=823, 89.2%) had a <2.5% CHARGE-AF risk. Every 1000 steps were associated with a 0.08% lower CHARGE-AF risk (P<.001). A stronger association was observed in men and individuals with obesity. In contrast, self-reported physical activity was not associated with CHARGE-AF risk.

CONCLUSIONS

Higher daily step counts were associated with a lower predicted 5-year risk of AF, and this relation was stronger in men and participants with obesity. The utility of a wearable daily step counter for AF risk reduction merits further investigation.

Current Evidence on Prevention of Atrial Fibrillation: Modifiable Risk Factors and the Effects of Risk Factor Intervention

Atrial fibrillation (AF) is one of the most encountered arrhythmias in clinical practice. It is also estimated that the absolute AF burden may increase by greater than 60% by 2050. It is inevitable that AF will become one of the largest epidemics in the world and may pose a major health problem for countries. Although AF rarely causes mortality in the acute period, it causes a significant increase in mortality and morbidity, including a fivefold increase in the risk of stroke, a twofold increase in dementia, and a twofold increase in myocardial infarction in the chronic period. Despite all the advances in the treatment of AF, it is better understood day by day that preventing AF may play a key role in reducing AF and its related complications. Modification of the main modifiable factors such as quitting smoking, abstaining from alcohol, changing eating habits, and exercise seems to be the first step in preventing AF. The strict adherence to the treatment process of secondary causes predisposing to AF such as DM, hypertension, obesity, and sleep apnea is another step in the prevention of AF. Both an individual approach and global public health campaigns can be highly beneficial to reduce the risk of AF. In this review, we aimed to summarize the current evidence on the relationship between modifiable risk factors and AF, and the impact of possible interventions on these factors in preventing or reducing the AF burden in the light of recently published guidelines and studies.

Epidemiology and modifiable risk factors for atrial fibrillation

The global prevalence of atrial fibrillation (AF) has increased substantially over the past three decades and is currently approximately 60 million cases. Incident AF and its clinical consequences are largely the result of risk factors that can be modified by lifestyle changes. In this Review, we provide evidence that the lifetime risk of AF is modified not only by sex and race but also through the clinical risk factor and comorbidity burden of individual patients. We begin by summarizing the epidemiology of AF, focusing on non-modifiable and modifiable risk factors, as well as targets and strategies for the primary prevention of AF. Furthermore, we evaluate the role of modifiable risk factors in the secondary prevention of AF as well as the potential effects of risk factor interventions on the frequency and severity of subsequent AF episodes. We end the Review by proposing strategies that require evaluation as well as global policy changes that are needed for the prevention of incident AF and the management of recurrent episodes in patients already affected by AF.

Weekly physical activity and incident atrial fibrillation in females - A dose-response meta-analysis

BACKGROUND

For years, physical activity (PA) has been considered a mixed blessing in terms of the risk of incident atrial fibrillation (AF). Previous analyses have had equivocal results regarding the cut-off of PA level beyond which AF risk increases, if such a limit really does exist. Data regarding females in particular have been scarce.

METHODS

We performed a dose-response meta-analysis to investigate the relationship between weekly PA and the risk for AF in females. Major electronic databases were searched for studies assessing the association between leisure time PA and the risk for incident AF in females from the general population. The linearity of the dose-response curve was assessed using the restricted cubic spline model.

RESULTS

A total of 15 studies, which involved 1,821,422 females, were included in the final analysis. AF incidence was 3.7%. Dose-response analysis revealed an inverse nonlinear relationship between weekly PA and the risk for incident AF (p for linearity <0.0001). No significant heterogeneity was documented (I² = 37%). Cautious interpretation is needed for PA exceeding 50 metabolic equivalents of task- hours per week (METs- h/w), due to limited available data for these high levels of PA.

CONCLUSION

According to this analysis, physicians can safely advise females to perform up to 50METs- h/w of moderate or vigorous PA, to reduce the risk for future AF. Interestingly, significant benefit can be attained even at low levels of regular weekly PA.

Wearable accelerometer-derived physical activity and incident disease

Physical activity is regarded as favorable to health but effects across the spectrum of human disease are poorly quantified. In contrast to self-reported measures, wearable accelerometers can provide more precise and reproducible activity quantification. Using wrist-worn accelerometry data from the UK Biobank prospective cohort study, we test associations between moderate-to-vigorous physical activity (MVPA) – both total MVPA minutes and whether MVPA is above a guideline-based threshold of ≥150 min/week—and incidence of 697 diseases using Cox proportional hazards models adjusted for age, sex, body mass index, smoking, Townsend Deprivation Index, educational attainment, diet quality, alcohol use, blood pressure, anti-hypertensive use. We correct for multiplicity at a false discovery rate of 1%. We perform analogous testing using self-reported MVPA. Among 96,244 adults wearing accelerometers for one week (age 62 ± 8 years), MVPA is associated with 373 (54%) tested diseases over a median 6.3 years of follow-up. Greater MVPA is overwhelmingly associated with lower disease risk (98% of associations) with hazard ratios (HRs) ranging 0.70–0.98 per 150 min increase in weekly MVPA, and associations spanning all 16 disease categories tested. Overall, associations with lower disease risk are enriched for cardiac (16%), digestive (14%), endocrine/metabolic (10%), and respiratory conditions (8%) (chi-square p < 0.01). Similar patterns are observed using the guideline-based threshold of ≥150 MVPA min/week. Some of the strongest associations with guideline-adherent activity include lower risks of incident heart failure (HR 0.65, 95% CI 0.55–0.77), type 2 diabetes (HR 0.64, 95% CI 0.58–0.71), cholelithiasis (HR 0.61, 95% CI 0.54–0.70), and chronic bronchitis (HR 0.42, 95% CI 0.33–0.54). When assessed within 456,374 individuals providing self-reported MVPA, effect sizes for guideline-adherent activity are substantially smaller (e.g., heart failure HR 0.84, 95% CI 0.80–0.88). Greater wearable device-based physical activity is robustly associated with lower disease incidence. Future studies are warranted to identify potential mechanisms linking physical activity and disease, and assess whether optimization of measured activity can reduce disease risk.

Sex-Specific Exposure-Effect Relationship Between Physical Activity and Incident Atrial Fibrillation in the General Population: A Dose-Response Meta-Analysis of 16 Prospective Studies

Background: Since evidence regarding the relationship between physical activity (PA) and atrial fibrillation (AF) incidence is inconsistent among studies, we performed a dose-response meta-analysis to comprehensively evaluate the exposure-effect association between PA and incident AF and the potential sex difference in the general population. Methods: The PubMed and Embase databases were searched for eligible studies published up to July 2020 (PROSPERO: CRD42018091692). The non-linear or linear exposure-effect relationship between PA and AF was examined using the robust error meta-regression method. Results: A total of 16 prospective studies involving 1,449,017 individuals and 39,884 AF cases were included. We observed an inverse non-linear association between PA level and incident AF (I ² = 0%, p _{non-linearity} < 0.001). In the linear model, a 5 metabolic equivalent of task (MET)-h/week increase in PA was associated with a decreased risk of AF [risk ratio (RR) = 0.992, 95% confidence interval (CI): 0.988-0.996, I ² = 0%]. In the sex-stratified analysis, we observed an inverse non-linear relationship between PA level and AF risk in females (I ² = 90%, p _{non-linearity} < 0.0001) but not in males (I ² = 0%, p _{non-linearity} = 0.40). In the linear model, a 5 MET-h/week increase in PA was associated with a reduced risk of AF in females (RR = 0.982, 95% CI: 0.975-0.989, I ² = 71%) but not in males (RR = 0.998, 95% CI: 0.994-1.002, I ² = 0%), with a significant interaction observed between the two groups (p _interaction < 0.0001). Conclusion: There was an inverse non-linear relationship between PA level and incident AF in the general population. The beneficial effect of PA in reducing AF risk might be predominantly observed in females.

Television viewing, physical activity and venous thromboembolism risk: The Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

INTRODUCTION

Television (TV) viewing may be associated with increased venous thromboembolism (VTE) risk independent of VTE risk factors including physical activity. This association was assessed in a large biracial US cohort of Black and White adults.

METHODS

Between 2003 and 2007 The Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study recruited 30,239 participants aged ≥45 years, who were surveyed for baseline TV viewing and followed for VTE events. TV viewing was categorized as <2 hours (light), 2 to 4 hours (moderate), and ≥4 hours (heavy) per day. Physical activity was classified as poor, intermediate, or ideal based on reported weekly activity. Hazard ratios of TV viewing and physical activity were calculated adjusting for VTE risk factors. Multiple imputation for missingness was used as a sensitivity analysis.

RESULTS

Over 96,813 person-years (median: 5.06 years) of follow-up there were 214 VTE events. Heavy TV viewing was not associated with VTE risk in the unadjusted and fully adjusted model (adjusted hazard ratio [aHR]: 0.92 [95% confidence interval (CI): 0.62, 1.36]). Ideal physical activity trended toward a reduced VTE risk (HR: 0.71 [95%CI: 0.51, 1.01]). There was no evidence of an interaction between TV viewing, physical activity, and risk of VTE.

CONCLUSIONS

In this contemporary racially and geographically diverse US cohort, there was no association between TV viewing and VTE risk, before and after accounting for physical activity. The high burden of traditional VTE risk factors in REGARDS may mask any association of TV viewing with VTE, or TV viewing may have only a modest association with VTE risk.

Accelerometer-derived physical activity and risk of atrial fibrillation

AIMS

Physical activity may be an important modifiable risk factor for atrial fibrillation (AF), but associations have been variable and generally based on self-reported activity.

METHODS AND RESULTS

We analysed 93 669 participants of the UK Biobank prospective cohort study without prevalent AF who wore a wrist-based accelerometer for 1 week. We categorized whether measured activity met the standard recommendations of the European Society of Cardiology, American Heart Association, and World Health Organization [moderate-to-vigorous physical activity (MVPA) ≥150 min/week]. We tested associations between guideline-adherent activity and incident AF (primary) and stroke (secondary) using Cox proportional hazards models adjusted for age, sex, and each component of the Cohorts for Heart and Aging Research in Genomic Epidemiology AF (CHARGE-AF) risk score. We also assessed correlation between accelerometer-derived and self-reported activity. The mean age was 62 ± 8 years and 57% were women. Over a median of 5.2 years, 2338 incident AF events occurred. In multivariable adjusted models, guideline-adherent activity was associated with lower risks of AF [hazard ratio (HR) 0.82, 95% confidence interval (CI) 0.75-0.89; incidence 3.5/1000 person-years, 95% CI 3.3-3.8 vs. 6.5/1000 person-years, 95% CI 6.1-6.8] and stroke (HR 0.76, 95% CI 0.64-0.90; incidence 1.0/1000 person-years, 95% CI 0.9-1.1 vs. 1.8/1000 person-years, 95% CI 1.6-2.0). Correlation between accelerometer-derived and self-reported MVPA was weak (Spearman r = 0.16, 95% CI 0.16-0.17). Self-reported activity was not associated with incident AF or stroke.

CONCLUSIONS

Greater accelerometer-derived physical activity is associated with lower risks of AF and stroke. Future preventive efforts to reduce AF risk may be most effective when targeting adherence to objective activity thresholds.

Self-reported physical activity and atrial fibrillation risk: A systematic review and meta-analysis

BACKGROUND

Although physical activity (PA) is an important component of cardiovascular disease prevention and treatment, its role in atrial fibrillation (AF) risk is less well established.

OBJECTIVE

The purpose of this study was to systematically summarize the evidence pertaining to the relationship of PA and risk of AF.

METHODS

We searched the PubMed and Embase databases for prospective cohort studies reporting the risk of AF associated with a specific PA volume through March 2020. From each study, we extracted the risk associated with a given PA level, in comparison with insufficiently active ("inactive") individuals. The reported risk was normalized to metabolic equivalent of task (MET)-minutes per week. A random-effects meta-analysis was used to compare AF risk between those who met and those who did not meet PA recommendations (450 MET-minutes per week), and a dose-response analysis between the level of PA and the risk of AF was performed.

RESULTS

Fifteen studies reporting data from 1,464,539 individuals (median age 55.3 years; 51.7% female) were included. Individuals achieving guideline-recommended level of PA had a significantly lower risk of AF (hazard ratio 0.94; 95% confidence interval 0.90-0.97; P = .001). Dose-response analysis showed that PA levels up to 1900 MET-minutes per week were associated with a lower risk of AF, with less certainty beyond that level.

CONCLUSION

PA at guideline-recommended levels and above are associated with a significantly lower AF risk. However, at 2000 MET-minutes per week and beyond, the benefit is less clear.

The counterintuitive role of exercise in the prevention and cause of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia, characterized by irregular atrial activity. AF is related to increased risk of thromboembolic events, heart failure, and premature mortality. Recent advances in our understanding of its pathophysiology include a potentially central role for inflammation and presence of cardiovascular risk factors. The role of physical activity and exercise in the development and progression of AF, however, are not yet fully understood. Physical activity is protective for modifiable cardiovascular risk factors, including those associated with AF. Indeed, emerging research has demonstrated beneficial effects of exercise on AF-specific outcomes, including AF recurrence postablation. Counterintuitively, the prevalence of AF in veteran endurance athletes seems higher compared with the general population. In this review, we discuss the novel evidence and underlying mechanisms underpinning the role of exercise as medicine in the development and management of AF but also the counterintuitive detrimental role of excessive endurance exercise. Finally, we advocate regular (but not long-term high-intensity endurance) exercise training as a safe and effective strategy to reduce the risk of incident AF and to minimize the associated risk of secondary cardiovascular events.