Left atrial structure and function among different subtypes of atrial fibrillation: an echocardiographic substudy of the AMIO-CAT trial

Left atrial size modify the association between uric acid and atrial fibrillation in patients with coronary artery disease

BACKGROUND AND AIMS

The potential influence of left atrial size on the relationship between uric acid and atrial fibrillation has not been fully investigated. This study aims to evaluate the interaction effect of left atrial size on the association between uric acid and atrial fibrillation in patients with coronary artery disease.

METHODS AND RESULTS

This retrospective cohort study, conducted from January 2018 to October 2022, included 2004 patients undergoing Drug-Eluting Stent implantation for coronary artery disease. Utilizing logistic regression models with the product of left atrial enlargement (LAE) and uric acid, interaction effects were assessed. Among the participants, 383 had LAE, and 159 experienced atrial fibrillation. After adjusting for covariates, continuous uric acid levels were associated with an increased risk of atrial fibrillation in patients without LAE (OR:1.631, 95% CI: 1.284-2.072), but not in those with LAE (OR:1.069, 95% CI: 0.848-1.348). A significant interaction of uric acid levels was observed between groups with and without LAE (p = 0.046). Restricted cubic spline curves indicated a J-shaped relationship between uric acid and atrial fibrillation in the absence of LAE. However, the association between uric acid levels and atrial fibrillation in the LAE group remained unchanged with increasing uric acid levels.

CONCLUSION

The study suggested that left atrial size modified the association between uric acid and atrial fibrillation in patients with coronary artery disease. Uric acid serves as a potential biomarker for atrial fibrillation risk, especially in individuals without LAE.

Association of Atrial Fibrillation Progression With Left Atrial Functional Reserve and Its Reversibility

BACKGROUND

Atrial fibrillation (AF) progression is closely related to heart failure occurrence, and catheter ablation carries a beneficial effect for heart failure prevention. Recently, particular attention has been given to left atrial (LA) function and functional reserve in the pathogenesis linking AF and heart failure, although its significance and reversibility is not well studied.

METHODS AND RESULTS

We prospectively investigated 164 patients with AF with normal left ventricular systolic function and free from heart failure who underwent first catheter ablation and pre-/postprocedural echocardiography. Conventional and speckle-tracking echocardiography were performed at rest and during passive leg lifting to assess LA size, LA reservoir strain (LARS), and functional reserve calculated as passive leg lifting-LARS - rest-LARS. Patients were categorized into 3 AF subtypes: paroxysmal AF (N=95), persistent AF (PeAF; N=50), and long-standing persistent AF (LS-PeAF; N=19). The PeAF and LS-PeAF groups had larger LA size and reduced LARS compared with the paroxysmal AF group (all P<0.05). LA functional reserve was significantly impaired in the LS-PeAF group (P=0.003). In multivariable analysis, LS-PeAF and advanced age were significantly associated with impaired LA functional reserve. Among 149 patients with sinus rhythm 1 to 2 days after catheter ablation, LARS was significantly improved in both PeAF and LS-PeAF groups but was still lower than that in the paroxysmal AF group. Sinus rhythm restoration also led to amelioration of LA functional reserve in patients with LS-PeAF.

CONCLUSIONS

AF progression was related to impaired LARS and LA functional reserve, and restoration of sinus rhythm might contribute to early LA reverse remodeling.

Influence of exercise training on the left atrium: implications for atrial fibrillation, heart failure, and stroke

The left atrium (LA) plays a critical role in receiving pulmonary venous return and modulating left ventricular (LV) filling. With the onset of exercise, LA function contributes to the augmentation in stroke volume. Due to the growing focus on atrial imaging, there is now evidence that structural remodeling and dysfunction of the LA is associated with adverse outcomes including incident cardiovascular disease. In patients with established disease, pathological changes in atrial structure and function are associated with exercise intolerance, increased hospital admissions and mortality, independent of left ventricular function. Exercise training is widely recommended in patients with cardiovascular disease to improve patient outcomes and maintain functional capacity. There are widely documented changes in LV function with exercise, yet less attention has been given to the LA. In this review, we first describe LA physiology at rest and during exercise, before exploring its association with cardiac disease outcomes including atrial fibrillation, heart failure, and stroke. The adaptation of the LA to short- and longer-term exercise training is evaluated through review of longitudinal studies of exercise training in healthy participants free of cardiovascular disease and athletes. We then consider the changes in LA structure and function among patients with established disease, where adverse atrial remodeling may be implicated in the disease process. Finally, we consider important future directions for assessment of atrial structure and function using novel imaging modalities, in response to acute and chronic exercise.

Interplay between natriuretic peptides and left atrial mechanics and the relation to recurrence of atrial fibrillation following catheter ablation

The relationship between natriuretic peptides and atrial distension is not fully understood. We sought to examine their interrelationship and how they relate to atrial fibrillation (AF) recurrence following catheter ablation. We analyzed patients enrolled in the AMIO-CAT trial (amiodarone vs. placebo for reducing AF recurrence). Echocardiography and natriuretic peptides were assessed at baseline. Natriuretic peptides included mid-regional proANP (MR-proANP) and N-terminal proBNP (NT-proBNP). Atrial distension was assessed by left atrial strain measured by echocardiography. The endpoint was AF recurrence within 6 months after a 3-month blanking period. Logistic regression was used to assess the association between log-transformed natriuretic peptides and AF. Multivariable adjustments were made for age, gender, randomization, and left ventricular ejection fraction. Of 99 patients, 44 developed AF recurrence. No differences in natriuretic peptides nor echocardiography were observed between the outcome groups. In unadjusted analyses, neither MR-proANP nor NT-proBNP were significantly associated with AF recurrence [MR-proANP: OR = 1.06 (0.99-1.14), per 10% increase; NT-proBNP: OR = 1.01 (0.98-1.05), per 10% increase]. These findings were consistent after multivariable adjustments. However, atrial strain significantly modified the association between MR-proANP and AF (p for interaction = 0.009) such that MR-proANP was associated with AF in patients with high atrial strain [OR = 1.24 (1.06-1.46), p = 0.008, per 10% increase] but not in patients with low atrial strain. In patients with high atrial strain, an MR-proANP > 116 pmol/L posed a fivefold higher risk of AF recurrence [HR = 5.38 (2.19-13.22)]. Atrial natriuretic peptide predicts AF recurrence in patients with preserved atrial distension. Assessing atrial strain may assist the interpretation of natriuretic peptides.

Evaluation of left atrial and ventricular remodeling in atrial fibrillation subtype by using speckle tracking echocardiography

Background

Atrial fibrillation (AF) is associated with cardiac structural and functional remodeling. We investigated the left atrial (LA) and left ventricular (LV) changes in AF subtypes by using two-dimensional echocardiography strain techniques.

Methods

The study population consisted of 102 subjects with sinus rhythm (control group) and 463 patients with AF, among which 284 patients had paroxysmal AF (PAF) and 179 patients had persistent AF (PerAF). A speckle tracking automatic functional imaging software was used to perform the strain analysis.

Results

Patients with AF had dilated LA maximum and minimum volume, decreased LA reservoir strain, lower LV ejection fraction (LVEF), and impaired global longitudinal strain (GLS) compared to those of the sinus rhythm control group. In patients with PerAF, the LA maximum and minimum volumes were larger, and the LA reservoir strain [PAF vs. PerAF, 28% (21,33) vs. 19% (14, 28), P < 0.05], LVEF, and absolute GLS value (PAF vs. PerAF, -16.9 ± 3.3 vs. -14.1 ± 3.5%) were lower than those in patients with PAF. Patients with AF regardless of LA enlargement had decreased LA reservoir strain and lower LVEF and absolute GLS value than those in the sinus rhythm control group.

Conclusion

Compared with those with normal sinus rhythm, patients with AF had dilated LA volume and impaired LA function, which were further worsened in patients with PerAF than those in patients with PAF. LA functional impairment occurred before LA enlargement. Left atrioventricular remodeling happened across different stages of AF development.

Influence of Sex-Based Differences in Cardiac Phenotype on Atrial Fibrillation Recurrence in Patients Undergoing Pulmonary Vein Isolation

Background

Pulmonary vein isolation (PVI) is a commonly engaged therapy for symptomatic atrial fibrillation (AF). Prior studies have documented elevated AF recurrence rates among females vs. males. Sex-specific mechanisms underlying this phenomenon are poorly understood. This prospective cohort study aimed to evaluate the sex-based differences in cardiac phenotype and their influence on (AF) recurrence following first-time PVI.

Methods

A total of 204 consecutive patients referred for first-time PVI and 101 healthy subjects were prospectively studied by cardiovascular magnetic resonance (CMR) imaging. Multi-chamber volumetric and functional measures were assessed by sex-corrected Z-score analyses vs. healthy subjects. Patients were followed for a median of 2.6 years for the primary outcome of clinical AF recurrence. Multivariable analyses adjusting for age and comorbidities were performed to identify independent predictors of AF recurrence.

Results

AF recurrence following first PVI occurred in 41% of males and 59% of females (p = 0.03). Females were older with higher prevalence of hypertension and thyroid disorders. Z-score-based analyses revealed significantly reduced ventricular volumes, greater left atrial (LA) volumes, and reduced LA contractility in females vs. males. Multivariable analysis revealed each of LA minimum and pre-systolic volumes and booster EF Z-scores to be independently associated with AF recurrence, providing respective hazard ratios of 1.10, 1.19, and 0.89 (p = 0.001, 0.03, and 0.01).

Conclusion

Among patients referred for first time PVI, females were older and demonstrated significantly poorer LA contractile health vs. males, the latter independently associated with AF recurrence. Assessment of LA contractile health may therefore be of value to identify female patients at elevated risk of AF recurrence. Factors influencing female patient referral for PVI at more advanced stages of atrial disease warrant focused investigation.