The relationship between decreased pulmonary function and atrial fibrillation in general population: Findings from Ansung-Ansan cohort of the Korean Genome and Epidemiology Study

Association between Age of Onset of Hypertension and Incident Atrial Fibrillation

We investigated whether age at hypertension (HTN) onset was associated with the risk of atrial fibrillation (AF) in the general population. This prospective longitudinal community-based cohort study included 9892 participants without AF at baseline, who underwent biennial electrocardiography for a median duration of 11.5 years. The participants were divided into five groups, consisting of a normotensive group (Group-N) and four HTN groups based on HTN onset age: <45 years (Group-H1); 45−54 years (Group-H2); 55−64 years (Group-H3); and ≥65 years (Group-H4). A multivariate Cox proportional hazards model showed that the presence of HTN at baseline was associated with higher AF risk (hazard ratio [HR], 1.93; 95% confidence interval [CI] 1.32−2.80). The participants in Group-H1 had the highest risk of AF (HR 3.18; CI 1.74−5.82), and the risk of AF decreased as HTN onset age increased across the four HTN groups (p for trend = 0.014). The AF onset age was significantly younger in participants in Group-H1 than in Groups-H2−H4. Early-onset HTN was associated with an increased risk of AF, and younger onset of AF in the general population. Surveillance for AF should be considered at a younger age in individuals with HTN.

Association between lung function and the risk of atrial fibrillation in a nationwide population cohort study

We investigated the association between lung function and atrial fibrillation (AF) in 21,349 adults without AF aged ≥ 40 years who underwent spirometry. The study participants were enrolled from the Korean National Health and Nutritional Examination Survey between 2008 and 2016. The primary outcome was new-onset non-valvular AF identified from the National Health Insurance Service database. During the median follow-up of 6.5 years, 2.15% of participants developed new-onset AF. The incidence rate of AF per 1000 person-years was inversely related to the forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and FEV₁/FVC quartile. After adjustment for multiple variables, the AF risk in the lowest FEV₁ quartile was 1.64-fold higher than that in the highest quartile (hazard ratio (HR) 1.64 (95% confidence interval (CI) 1.26–2.12) for lowest FEV₁ quartile). The lowest quartile of FVC had 1.56-fold higher AF risk than the highest quartile (HR 1.56 (95% CI 1.18–2.08) for lowest FVC quartile). Although the lowest FEV₁/FVC quartile was associated with an increased risk of AF in the unadjusted model, this increased risk was not statistically significant in the multivariable analysis. Compared to those with normal lung function, participants with restrictive or obstructive lung function had 1.49 and 1.42-fold higher AF risks, respectively. In this large nationwide cohort study, both obstructive and restrictive patterns of reduced lung function were significantly associated with increased AF risk.

Causal Relationship Between Lung Function and Atrial Fibrillation: A Two Sample Univariable and Multivariable, Bidirectional Mendelian Randomization Study

Background: Observational studies have identified impaired lung function accessed by forced expiratory volume in one second (FEV1), forced vital capacity (FVC) or the ratio of FEV1 over FVC (FEV1/FVC) as an independent risk factor for atrial fibrillation (AF). However, the result may be affected by confounders or reverse causality.

Methods: We performed univariable MR (uvMR), multivariable MR (mvMR) and bidirectional two-sample MR to jointly estimate the causality of lung function with AF. Apart from the inverse variance weighted (IVW) approach as the main MR analysis, three complementary sensitive analyses approaches including MR-Egger regression, weighted median (WM) MR and Pleiotropy Residual Sum and Outlier (MR-PRESSO) in uvMR as well as mvMR-Egger and mvMR-PRESSO in mvMR were applied to control for pleiotropy. Linkage disequilibrium score (LDSC) regression was applied to estimate genetic correlation between lung function and AF.

Results: All forward and reverse uvMR analyses consistently suggested absent causal relations between lung function and AF risk [forward IVW: odds ratio (OR)_FEV1 = 1.031, 95% CI = 0.909–1.169, P = 0.630; OR_FVC = 1.002, 95% CI = 0.834–1.204, P = 0.982; OR_FEV1/FVC = 1.076, 95% CI = 0.966–1.199, P = 0.182; reverse IVW: OR_FEV1 = 0.986, 95% CI = 0.966–1.007, P = 0.187; OR_FVC = 0.985, 95% CI = 0.965–1.006, P = 0.158; OR_FEV1/FVC = 0.994, 95% CI = 0.973–1.015, P = 0.545]. The forward MR-Egger showed that each standard deviation (SD) increase in FEV1/FVC was related to a higher AF risk (OR = 1.502, 95% CI = 1.178–1.915, P = 0.006) without heterogeneity (Q_pval = 0.064), but pleiotropy effect exist (intercept = −0.017, P = 0.012). However, this significant effect disappeared after adjustment of FEV1 and FVC (OR = 1.523, 95% CI = 0.445–5.217, P = 0.503) in mvMR. No evidence was found for independent causal effects of FEV1 and FVC on AF in mvMR analysis by using mvIVW method (OR_FEV1 = 0.501, 95% CI = 0.056–4.457, P = 0.496; OR_FVC = 1.969, 95% CI = 0.288–13.474, P = 0.490). Notably, the association between lung function and AF were replicated using the FinnGen cohort data.

Conclusions: Our findings reported no coheritability between lung function and AF, and failed to find substantial causal relation between decreased lung function and risk of AF. However, lung function and AF were both associated with inflammation, which may be potential pathway, warranting further study.

The Relationship between Poor Pulmonary Function and Irregular Pulse in the Elderly: Findings from a Nationwide Cross-Sectional Survey in Korea

Arrhythmia may be caused by reduced pulmonary function, and pulse palpation is a useful screening method for the early detection of cardiac arrhythmia. The aim of this study was to investigate the association between reduced pulmonary function and abnormal findings on pulse palpation in 2347 subjects aged ≥65 years using data from a nationwide survey. Pulse palpation was initially performed for 15 s and, if felt to be abnormal, it was performed again for 60 s. The prevalence of irregular pulse (IP) determined by the 60-second palpation was 61 (2.6%). The mean age of subjects with an IP was 73.0 (95% CI 71.7–74.3) years, and 45.8% were male. After adjustment for covariates, forced vital capacity (FVC)/predicted FVC, forced expiratory volume in one second (FEV₁)/predicted FEV₁, and the lowest FEV₁ remained significant risk factors for IP. A restrictive or obstructive spirometry pattern was also an independent risk factor for IP. In summary, an IP is more prevalent when pulmonary function is reduced in the elderly, in whom careful pulse palpation may be necessary for the early detection of arrhythmia.