Aerobic Interval Training Prevents Age-Dependent Vulnerability to Atrial Fibrillation in Rodents

Aims: Increasing age is the most important risk factor for atrial fibrillation (AF). Very high doses of exercise training might increase AF risk, while moderate levels seem to be protective. This study aimed to examine the effects of age on vulnerability to AF and whether long-term aerobic interval training (AIT) could modify these effects.Methods: Nine months old, male Sprague-Dawley rats were randomized to AIT for 16 weeks (old-ex) or to a sedentary control group (old-sed), and compared to young sedentary males (young-sed). After the intervention, animals underwent echocardiography, testing of exercise capacity (VO2max), and electrophysiology with AF induction before ex vivo electrophysiology. Fibrosis quantification, immunohistochemistry and western blotting of atrial tissue were performed.Results: Sustained AF was induced in vivo in 4 of 11 old-sed animals, but none of the old-ex or young-sed rats (p = 0.006). VO2max was lower in old-sed, while old-ex had comparable results to young-sed. Fibrosis was increased in old-sed (p = 0.006), with similar results in old-ex. There was a significantly slower atrial conduction in old-sed (p = 0.038), with an increase in old-ex (p = 0.027). Action potential duration was unaltered in old-sed, but prolonged in old-ex (p = 0.036). There were no differences in amount of atrial connexin 43 between groups, but a lateralization in atrial cardiomyocytes of old-sed, with similar findings in old-ex.Conclusion: AF vulnerability was higher in old-sed animals, associated with increased atrial fibrosis, lateralization of connexin-43, and reduced atrial conduction velocity. AIT reduced the age-associated susceptibility to AF, possibly through increased conduction velocity and prolongation of action potentials

Validation of self-reported and hospital-diagnosed atrial fibrillation: The HUNT study

Background: Self-reported atrial fibrillation (AF) and diagnoses from hospital registers are often used to identify persons with AF. The objective of this study was to validate self-reported AF and hospital discharge diagnoses of AF among participants in a population-based study. Materials and methods: Among 50,805 persons who participated in the third survey of the HUNT Study (HUNT3), 16,247 participants from three municipalities were included. Individuals who reported cardiovascular disease, renal disease, or hypertension in the main questionnaire received a cardiovascular-specific questionnaire. An affirmative answer to a question on physician-diagnosed AF in this second questionnaire defined self-reported AF diagnoses in the study. In addition, AF diagnoses were retrieved from hospital and primary care (PC) registers. All AF diagnoses were verified by review of hospital and PC medical records. Results: A total of 502 HUNT3 participants had a diagnosis of AF verified in hospital or PC records. Of these, 249 reported their AF diagnosis in the HUNT3 questionnaires and 370 had an AF diagnosis in hospital discharge registers before participation in HUNT3. The sensitivity of self-reported AF in HUNT3 was 49.6%, specificity 99.2%, positive predictive value (PPV) 66.2%, and negative predictive value (NPV) 98.4%. The sensitivity of a hospital discharge diagnosis of AF was 73.7%, specificity 99.7%, PPV 88.5%, and NPV 99.2%. Conclusion: Use of questionnaires alone to identify cases of AF has low sensitivity. Extraction of diagnoses from health care registers enhances the sensitivity substantially and should be applied when estimates of incidence and prevalence of AF are studied

Fast food increases postprandial cardiac workload in type 2 diabetes independent of pre-exercise: A pilot study

Background Type 2 diabetes aggravates the postprandial metabolic effects of food, which increase cardiovascular risk. We investigated the acute effects of fast food on postprandial left ventricular (LV) function and the potential effects of pre-exercise in type 2 diabetes individuals. Methods We used a cross-over study including 10 type 2 diabetes individuals (7 male and 3 females; 53.4 ± 8.1 years; 28.3 ± 3.8 kg/m2; type 2 diabetes duration 3.1 ± 1.8 years) and 10 controls (7 male and 3 females; 52.8 ± 10.1 years; 28.5 ± 4.2 kg/m2) performing high intensity interval exercise (HIIE; 40 min, 4 × 4min intervals, 90–95 % HRmax), moderate intensity exercise (MIE; 47 min, 70 % HRmax) and no exercise (NE) in a random order 16–18 hours prior to fast-food ingestion. Baseline echocardiography, blood pressure and biochemical measurements were recorded prior to and 16–18 hours after exercise, and 30 minutes, 2 hours and 4 hours after fast food ingestion. Results LV diastolic (peak early diastolic tissue velocity, peak early diastolic filling velocity), and systolic workload (global strain rate, peak systolic tissue velocity, rate pressure product) increased after consumption of fast food in both groups. In contrast to controls, the type 2 diabetes group had prolonged elevations in resting heart rate and indications of prolonged elevations in diastolic workload (peak early diastolic tissue velocity) as well as reduced systolic blood pressure after fast food consumption. No significant modifications due to exercise in the postprandial phase were seen in any group. Conclusions Our findings indicate that fast-food induces greater and sustained overall cardiac workload in type 2 diabetes individuals versus body mass index and age matched controls; exercise 16–18 hours pre-meal has no acute effects to the postprandial phase

Physical activity modifies the risk of atrial fibrillation in obese individuals: The HUNT3 study

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

Physical activity modifies the risk of atrial fibrillation in obese individuals: the HUNT3 study

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

Estimated cardiorespiratory fitness and risk of atrial fibrillation: the Nord-Trondelag Health Study

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

Physical activity, cardiorespiratory fitness, and cardiovascular outcomes in individuals with atrial fibrillation: The HUNT study

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

Aerobic interval training reduces the burden of Atrial fibrillation in the short term: a randomized trial

Background Exercise training is an effective treatment for important atrial fibrillation (AF) comorbidities. However, a high level of endurance exercise is associated with an increased AF prevalence. We assessed the effects of aerobic interval training (AIT) on time in AF, AF symptoms, cardiovascular health, and quality of life in AF patients.Methods and Results Fifty-one patients with nonpermanent AF were randomized to AIT (n=26) consisting of four 4-minute intervals at 85% to 95% of peak heart rate 3 times a week for 12 weeks or to a control group (n=25) continuing their regular exercise habits. An implanted loop recorder measured time in AF continuously from 4 weeks before to 4 weeks after the intervention period. Cardiac function, peak oxygen uptake , lipid status, quality of life, and AF symptoms were evaluated before and after the 12-week intervention period. Mean time in AF increased from 10.4% to 14.6% in the control group and was reduced from 8.1% to 4.8% in the exercise group (P=0.001 between groups). AF symptom frequency (P=0.006) and AF symptom severity (P=0.009) were reduced after AIT. AIT improved , left atrial and ventricular ejection fraction, quality-of-life measures of general health and vitality, and lipid values compared with the control group. There was a trend toward fewer cardioversions and hospital admissions after AIT.Conclusions AIT for 12 weeks reduces the time in AF in patients with nonpermanent AF. This is followed by a significant improvement in AF symptoms, o(2)peak, left atrial and ventricular function, lipid levels, and QoL.Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01325675

Aerobic interval training prevents age-dependent vulnerability to atrial fibrillation in rodents

Aims: Increasing age is the most important risk factor for atrial fibrillation (AF). Very high doses of exercise training might increase AF risk, while moderate levels seem to be protective. This study aimed to examine the effects of age on vulnerability to AF and whether long-term aerobic interval training (AIT) could modify these effects

Symptoms of anxiety and depression and risk of atrial fibrillation-the HUNT study

Background Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Anxiety and depression may activate the autonomic nervous system which is likely to play an important role in the etiology of AF. However, little is known about the association between symptoms of anxiety and depression and risk of AF. Objective This study aimed to assess the association between symptoms of anxiety and depression and risk of AF. Methods In a population-based study, 37,402 adult residents were followed for incident AF from 2006 to 2008 until 2015. Participants were classified according to data on anxiety and depression symptoms. Cox proportional regression models were used to adjust for common AF risk factors. Results During a median follow-up of 8.1 years, 1433 (3.8%) participants developed AF. In comparisons with no anxiety symptoms, the multivariable-adjusted hazard ratios (HRs) were 1.1 (95% CI: 0.9–1.5) for mild to moderate anxiety symptoms and 1.0 (95% CI: 0.8–1.4) for severe anxiety symptoms. In comparisons with no depression symptoms, the multivariable-adjusted HRs were 1.5 (95% CI: 1.2–1.8) for mild to moderate depression symptoms and 0.9 (95% CI: 0.6–1.3) for severe depression symptoms. Recurrent anxiety/depression symptoms were not associated with increased AF risk. Conclusions In this large, population-based study, we found no evidence of an association between symptoms of anxiety or severe depression and AF risk, even for recurrent anxiety or depression symptoms. An unexpected association of symptoms of mild to moderate depression with increased AF risk requires confirmation in other studies. Our findings add to the sparse literature on symptoms of anxiety and depression and risk of AF