Corresponding Author
Key Words: atrial fibrillation, cardiorespiratory fitness, exercise capacity, exercise treadmill test, ischemic stroke
Atrial fibrillation (AF) is the most common arrhythmia. In 2017, there were more than 3.04 million new cases of AF worldwide, with an estimated incidence rate of 403 per 100,000 people, which is 31% higher than the incidence rate in 1997.1 The global prevalence of AF is 37,574,000 cases, with a reported 33% increase over the past 20 years. It is predicted that the burden of AF will increase by more than 60% by 2050.1 While age and various risk factors contribute to the onset of AF, research on prevention is still insufficient, and new comprehensive strategies are needed.
Exercise capacity is a significant predictor of mortality. Myers et al2 reported that in men, those with peak metabolic equivalents (pMETs) of 8 METs or higher had higher mortality rates than those with lower pMETs, and those with pMETs lower than those predicted by age also had higher mortality rates. Additionally, Gulati et al3 reported that in women, having pMETs 85% lower than age-predicted pMETs was associated with a 2-fold increase in mortality risk.
Furthermore, there were reports that AF was associated with exercise capacity. A study of approximately 2,000 Finnish men indicated that higher pMETs were associated with a lower incidence of AF. However, after adjusting for confounding factors, the effect became unclear, and the risk of AF might increase once pMETs exceed a certain threshold.4 However, in a large-scale U.S. cohort study involving nearly 65,000 patients who underwent exercise stress tests, the risk of AF onset was reduced in those with higher pMETs, even after adjusting for confounding factors. Moreover, the association between pMETs and AF onset showed an interaction with obesity, with the association being particularly prominent in obese patients.5
Many studies have been conducted in Western countries, and although the U.S. report included multiple ethnic groups, it did not specifically address the results for Asians. Thus, there have been few studies investigating the association between exercise capacity and the onset of AF in Asian populations. Kim et al6 reported in a case-control study that pMETs were lower in the AF onset group than in the non-AF onset group.
In this issue of JACC: Asia, Lu et al7 report a retrospective analysis using large-scale data derived from the TARGET registry, a prospective administrative database of patients referred for noninvasive cardiac evaluation due to suspected coronary artery disease in Taiwan. Among consecutive patients who underwent exercise treadmill testing, those without a history of AF, severe valvular heart disease, high-grade atrioventricular block, implantable pacemaker, or acute coronary syndrome within the past 3 months were included. They linked the outcomes of 15,450 patients to the National Institute of Health Sciences Research Database. The clinical outcomes were onsets of AF and major adverse cardiac events (MACE), including stroke, myocardial infarction, and mortality, with a median follow-up period of 9.1 years. pMETs were independently associated with a reduced risk of AF after adjusting for confounding factors.7 This study demonstrated that in Asians, higher pMETs were associated with a lower incidence of AF and reduced risks of ischemic stroke and MACE, reaffirming the prognostic value of pMETs in AF prevention and cardiovascular risk reduction. Unlike reports from the United States, there was no interaction with body mass index. However, there was an interaction by age. No association between pMETs and AF or MACE existed in those aged 50 years or younger. Furthermore, although AF increases the risk of both ischemic stroke and MACE, even after adjusting for AF onset as a time-dependent variable, higher pMET levels were independently associated with a reduced risk of ischemic stroke and MACE. Higher pMET levels had an independent suppressive effect on MACE, independent of AF onset.
We perform exercise stress testing when ischemic heart disease is suspected; however, we may assess exercise tolerance, thereby enabling the evaluation of the risk of AF, ischemic stroke, and MACE. Additionally, a meta-analysis has reported that endurance training improves aerobic exercise capacity in older adults.8 They can improve their physical abilities by changing their lifestyle habits. The use of exercise stress testing for risk assessment and the development of preventive strategies may reduce the burden of atrial fibrillation.
Funding Support and Author Disclosures
The author has reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
The author attests they are in compliance with human studies committees and animal welfare regulations of the author’s institution and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
References
- 1.Lippi G., Sanchis-Gomar F., Cervellin G. Global epidemiology of atrial fibrillation: an increasing epidemic and public health challenge. Int J Stroke. 2021;16(2):217–221. doi: 10.1177/1747493019897870. [DOI] [PubMed] [Google Scholar]
- 2.Myers J., Prakash M., Froelicher V., et al. Exercise capacity and mortality among men referred for exercise testing. N Engl J Med. 2002;346(11):793–801. doi: 10.1056/NEJMoa011858. [DOI] [PubMed] [Google Scholar]
- 3.Gulati M., Black H.R., Shaw L.J., et al. The prognostic value of a nomogram for exercise capacity in women. N Engl J Med. 2005;353(5):468–475. doi: 10.1056/NEJMoa044154. [DOI] [PubMed] [Google Scholar]
- 4.Khan H., Kella D., Rauramaa R., et al. Cardiorespiratory fitness and atrial fibrillation: a population-based follow-up study. Heart Rhythm. 2015;12(7):1424–1430. doi: 10.1016/j.hrthm.2015.03.024. [DOI] [PubMed] [Google Scholar]
- 5.Qureshi W.T., Alirhayim Z., Blaha M.J., et al. Cardiorespiratory fitness and risk of incident atrial fibrillation: results from the Henry Ford Exercise Testing (FIT) project. Circulation. 2015;131(21):1827–1834. doi: 10.1161/CIRCULATIONAHA.114.014833. [DOI] [PubMed] [Google Scholar]
- 6.Kim J.Y., Cho S.J., Kim J., et al. Exercise capacity and risk of incident atrial fibrillation in healthy adults. Korean J Intern Med. 2023;38(6):872–878. doi: 10.3904/kjim.2023.075. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Lu C.-T., Lee C.-W., Huang W.-M., et al. Elevated exercise capacity mitigates atrial fibrillation incidence and major cardiovascular outcomes: a decade-long cohort study. JACC Asia. 2025;5(10):1346–1356. doi: 10.1016/j.jacasi.2025.06.009. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Huang G., Gibson C.A., Tran Z.V., et al. Controlled endurance exercise training and VO2max changes in older adults: a meta-analysis. Prev Cardiol. 2005;8(4):217–225. doi: 10.1111/j.0197-3118.2005.04324.x. [DOI] [PubMed] [Google Scholar]