Objectives The purpose of this study was to assess the association between structural changes in human atria, age, and history of atrial fibrillation (AF). Background Development of fibrosis in ...atrial walls is associated with deterioration of atrial conduction and predisposes to AF in experiment. Human data, however, are scarce, and whether fibrosis is a cause or consequence of AF is not known. Methods Medical records for consecutive autopsies were checked for AF history and duration. Atrial specimens from 30 patients (ages 64 ± 12 years) were collected in 3 equal age-matched groups as patients without AF history, with paroxysmal AF, or with permanent AF. Tissue samples were obtained at the level of superior pulmonary veins, inferior pulmonary veins, center of posterior left atrial wall, terminal crest, and Bachmann's bundle. Histology sections were assessed for extent of fibrosis, fatty tissues, and inflammatory infiltration at each location. Results No correlation was observed between age and fibrosis at any location. Fibrosis extent and fatty infiltration were twofold to threefold higher at all locations in patients with history of AF and correlated with lymphomononuclear infiltration. Patients with permanent AF had greater fibrosis extent than did patients with paroxysmal AF. Conclusions In post-mortem material, structural changes in the atria were not associated with age, but were significantly correlated with presence of AF and its severity. Our findings suggest that age-related changes per se are unlikely to be the sole cause of advanced fibrosis underlying AF.
Objectives The purpose of this study was to assess the predictive accuracy of conventional cardiovascular risk factors for incident heart failure and atrial fibrillation, and the added benefit of ...multiple biomarkers reflecting diverse pathophysiological pathways. Background Heart failure and atrial fibrillation are interrelated cardiac diseases associated with substantial morbidity and mortality and increasing incidence. Data on prediction and prevention of these diseases in healthy individuals are limited. Methods In 5,187 individuals from the community-based MDCS (Malmö Diet and Cancer Study), we studied the performance of conventional risk factors and 6 biomarkers including midregional pro-atrial natriuretic peptide (MR-proANP), N-terminal pro–B-type natriuretic peptide (NT-proBNP), midregional pro-adrenomedullin, cystatin C, C-reactive protein (CRP), and copeptin. Results During a mean follow-up of 14 years, 112 individuals were diagnosed with heart failure and 284 individuals with atrial fibrillation. NT-proBNP (hazard ratio HR: 1.63 per SD, 95% confidence interval CI: 1.29 to 2.06, p < 0.001), CRP (HR: 1.57 per SD, 95% CI: 1.28 to 1.94, p < 0.001), and MR-proANP (HR: 1.26 per SD, 95% CI: 1.02 to 1.56, p = 0.03) predicted incident heart failure independently of conventional risk factors and other biomarkers. MR-proANP (HR: 1.62, 95% CI: 1.42 to 1.84, p < 0.001) and CRP (HR: 1.18, 95% CI: 1.03 to 1.34, p = 0.01) independently predicted atrial fibrillation. Addition of biomarkers to conventional risk factors improved c -statistics from 0.815 to 0.842 for heart failure and from 0.732 to 0.753 for atrial fibrillation and the integrated discrimination improvement for both diseases (p < 0.001). Net reclassification improvement (NRI) with biomarkers was observed in 22% of individuals for heart failure (NRI, p < 0.001) and in 7% for atrial fibrillation (NRI, p = 0.06), mainly due to up-classification of individuals who developed disease (heart failure: 29%, atrial fibrillation: 19%). Addition of CRP to natriuretic peptides did not improve discrimination or reclassification. Conclusions Conventional cardiovascular risk factors predict incident heart failure and atrial fibrillation with reasonable accuracy in middle-age individuals free from disease. Natriuretic peptides, but not other biomarkers, improve discrimination modestly for both diseases above and beyond conventional risk factors and substantially improve risk classification for heart failure.
The validity of atrial fibrillation (AF) diagnoses in national registers for use as endpoints in prospective studies has not been evaluated. We studied the validity of AF diagnoses in Swedish ...national hospital discharge and cause of death registers and the occurrence of and risk factors for AF in a middle-aged Swedish population using these registers. Our study included the 30,447 individuals (age 44-73) who attended baseline visits in 1991-1996 of the Malmö Diet and Cancer study. Individuals with a first AF diagnosis were identified by record linkage with national registers. A subset of cases was randomly selected for validation by examination of electrocardiograms and patient records. Electrocardiograms were available in 98% of the validation sample (95% definitive AF, 3% no AF). The 2% with ECGs unavailable had probable AF. Baseline AF prevalence was 1.3%, higher in men and increased with age. During 11.2 years of follow-up 1430 first AF diagnoses occurred. Risk factors were age, hypertension, BMI, diabetes, history of heart failure, history of myocardial infarction and, in men but not women, current smoking. The strongest risk factors were history of heart failure (hazard ratio men 4.5, women 8.7) and myocardial infarction (hazard ratio men 2.0, women 1.8). The largest population attributable risks were observed for hypertension (men 38%, women 34%) and obesity (men 11%, women 10%). In conclusion, case misclassification of AF in national registers is small, indicating feasibility of use in prospective studies. Hypertension and obesity account for large portions of population risk in middle-aged individuals with low prevalence of manifest cardiac disease.
Atrial fibrosis is common in atrial fibrillation （AF）. Experimental studies have provided convincing evidence that fibrotic transformation of atrial myocardium results in deterioration of atrial ...conduction, increasing anisotropy of impulse propagation and building of boundaries that promote re-entry in the atrial walls that maybe directly relevant for the mechanisms responsible for maintaining AF. Whether or not fibrosis is a result of structural remodelling caused by persistent AF or a manifestation of occult myocardial process that leads to development of arrhythmia is less clear. Human data indicate the presence of association between persistency of AF and the extent of structural changes in atrial myocardium. The role atrial fibrosis plays in the mechanisms of AF, however, may differ between patients with structurally normal hearts, such as lone AF, and those with advanced cardiovascular comorbidities.
Increasing awareness of atrial fibrillation (AF) and its impact on public health revives interest in identification of noninvasive markers of predisposition to AF and ECG‐based risk stratification. ...P‐wave duration is generally accepted as the most reliable noninvasive marker of atrial conduction, and its prolongation has been associated with history of AF. However, patients with paroxysmal AF without structural heart disease may not have any impressive P‐wave prolongation, thus suggesting that global conduction slowing is not an obligatory requirement for development of AF. P‐wave morphology is therefore drawing increasing attention as it reflects the three‐dimensional course of atrial depolarization propagation and detects local conduction disturbances. The factors that determine P‐wave appearance include (1) the origin of the sinus rhythm that defines right atrial depolarization vector, (2) localization of left atrial breakthrough that defines left atrial depolarization vector, and (3) the shape and size of atrial chambers. However, it is often difficult to distinguish whether P‐wave abnormalities are caused by atrial enlargement or interatrial conduction delay. Recent advances in endocardial mapping technologies have linked certain P‐wave morphologies with interatrial conduction patterns and the function of major interatrial conduction routes. The value of P‐wave morphology extends beyond cardiac arrhythmias associated with atrial conduction delay and can be used for prediction of clinical outcome of a wide range of cardiovascular disorders, including ischemic heart disease and congestive heart failure.
Objectives This study evaluated the role of pre-procedural clinical variables to predict procedural and clinical outcomes of catheter ablation in patients with long-lasting persistent atrial ...fibrillation (AF). Background Catheter ablation of persistent AF remains a challenging task. Methods Catheter ablation was performed in 90 patients (76 men, age 57 ± 11 years) with long-lasting persistent AF. The history of AF, echocardiographic parameters, presence of structural heart disease, and surface electrocardiogram (ECG) AF cycle length (CL) were assessed before ablation and analyzed with respect to procedural termination and clinical outcome. Mean follow-up was 28 ± 4 months. Results Persistent AF was terminated in 76 of 90 patients (84%) by ablation. The duration of continuous AF was shorter (p < 0.0001), the surface ECG AFCL was longer (p < 0.0001), and the left atrium was smaller (p < 0.01) in patients in whom AF was terminated by catheter ablation. The surface ECG AFCL was the only independent predictor of AF termination (p < 0.01). Maintenance of sinus rhythm was associated with a shorter duration of continuous AF (p < 0.0001), a longer surface ECG AFCL (p < 0.001), and a smaller left atrium (p < 0.05) compared with those with recurrent arrhythmia. In multivariate analysis, the surface ECG AFCL and the AF duration predicted clinical success of persistent AF ablation (p < 0.01 and p < 0.05, respectively). Conclusions The surface ECG AFCL is a clinically useful pre-ablation tool for predicting patients in whom sinus rhythm can be restored by catheter ablation. The duration of continuous AF and the surface ECG AFCL are predictive of maintenance of sinus rhythm.
Information about autonomic nervous system (ANS) activity may offer insights about atrial fibrillation (AF) progression and support personalized AF treatment but is not easily accessible from the ...ECG. In this study, we propose a new approach for ECG-based assessment of respiratory modulation in atrioventricular (AV) nodal refractory period and conduction delay.
A 1-dimensional convolutional neural network (1D-CNN) was trained to estimate respiratory modulation of AV nodal conduction properties from 1-minute segments of RR series, respiration signals, and atrial fibrillatory rates (AFR) using synthetic data that replicates clinical ECG-derived data. The synthetic data were generated using a network model of the AV node and 4 million unique model parameter sets. The 1D-CNN was then used to analyze respiratory modulation in clinical deep breathing test data of 28 patients in AF, where an ECG-derived respiration signal was extracted using a novel approach based on periodic component analysis.
We demonstrated using synthetic data that the 1D-CNN can estimate the respiratory modulation from RR series alone with a Pearson sample correlation of
= 0.805 and that the addition of either respiration signal (
= 0.830), AFR (
= 0.837), or both (
= 0.855) improves the estimation.
Initial results from analysis of ECG data suggest that our proposed estimate of respiration-induced autonomic modulation,
, is reproducible and sufficiently sensitive to monitor changes and detect individual differences. However, further studies are needed to verify the reproducibility, sensitivity, and clinical significance of
.
Aims
Exercise increases risk of ventricular arrhythmia in subjects with arrhythmogenic right ventricular cardiomyopathy (ARVC). We aimed to investigate the impact of exercise on myocardial function ...in ARVC subjects.
Methods and Results
We included 110 subjects (age 42 ± 17 years), 65 ARVC patients and 45 mutation‐positive family members. Athletes were defined as subjects with ≥4 h vigorous exercise/week ≥1440 metabolic equivalents (METs × minutes/week) during a minimum of 6 years. Athlete definition was fulfilled in 37/110 (34%) subjects. We assessed right ventricular (RV) and left ventricular (LV) myocardial function by echocardiography, and by magnetic resonance imaging (MRI). The RV function by RV fractional area change (FAC), RV global longitudinal strain (GLS) by echocardiography, and RV ejection fraction (EF) by MRI was reduced in athletes compared with non‐athletes (FAC 34 ± 9% vs. 40 ± 11%, RVGLS –18.3 ± 6.1% vs. –22.0 ± 4.8%, RVEF 32 ± 8% vs. 43 ± 10%, all P < 0.01). LV function by LVEF and LVGLS was reduced in athletes compared with non‐athletes (LVEF by echocardiography 50 ± 10% vs. 57 ± 5%, LVEF by MRI 46 ± 6% vs. 53 ± 8%, and LVGLS –16.7 ± 4.2% vs. –19.4 ± 2.9%, all P < 0.01). The METs × minutes/week correlated with reduced RV and LV function by echocardiography and MRI (all P < 0.01). The LVEF by MRI was also reduced in subgroups of athlete index patients (46 ± 7% vs. 54 ± 10%, P = 0.02) and in athlete family members (47 ± 3% vs. 52 ± 6%, P < 0.05).
Conclusion
Athletes showed reduced biventricular function compared with non‐athletes in ARVC patients and in mutation‐positive family members. The amount and intensity of exercise activity was associated with impaired LV and RV function. Exercise may aggravate and accelerate myocardial dysfunction in ARVC.
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