Echocardiographically Derived Pulse Wave Velocity and Diastolic Dysfunction Are Associated with an Increased Incidence of Atrial Fibrillation in Patients with Systolic Heart Failure

NADPH Oxidases and Oxidative Stress in the Pathogenesis of Atrial Fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and its prevalence increases with age. The irregular and rapid contraction of the atria can lead to ineffective blood pumping, local blood stasis, blood clots, ischemic stroke, and heart failure. NADPH oxidases (NOX) and mitochondria are the main sources of reactive oxygen species in the heart, and dysregulated activation of NOX and mitochondrial dysfunction are associated with AF pathogenesis. NOX- and mitochondria-derived oxidative stress contribute to the onset of paroxysmal AF by inducing electrophysiological changes in atrial myocytes and structural remodeling in the atria. Because high atrial activity causes cardiac myocytes to expend extremely high energy to maintain excitation-contraction coupling during persistent AF, mitochondria, the primary energy source, undergo metabolic stress, affecting their morphology, Ca2+ handling, and ATP generation. In this review, we discuss the role of oxidative stress in activating AF-triggered activities, regulating intracellular Ca2+ handling, and functional and anatomical reentry mechanisms, all of which are associated with AF initiation, perpetuation, and progression. Changes in the extracellular matrix, inflammation, ion channel expression and function, myofibril structure, and mitochondrial function occur during the early transitional stages of AF, opening a window of opportunity to target NOX and mitochondria-derived oxidative stress using isoform-specific NOX inhibitors and mitochondrial ROS scavengers, as well as drugs that improve mitochondrial dynamics and metabolism to treat persistent AF and its transition to permanent AF.

Prevalence and determinants of permanent atrial fibrillation in post-menopausal hypertensive women

Objective. We studied the prevalence and major predisposing factors of permanent atrial fibrillation (PAF) in a population of hypertensive post-menopausal (HPMW) women. Materials and Methods. We enrolled 125 consecutive HPMW with PAF, 125 HPMW in sinus rhythm were the control group (CG). Women with valvular heart disease, coronary artery disease, WPW syndrome, left ventricular (LV) ejection fraction <45% and thyroid disorders were excluded. The mean age was similar: 53±3 years for women on PAF and 51±6 for women with sinus rhythm (P<0.45). All women who underwent M-B mode echocardiography, LV mass, function, and left atrial (LA) volume were assessed according to American Society of Echocardiography guidelines. Diabetes was assessed according to American Diabetes Association guidelines. Results. In a population of 8945 consecutive women, 4497 were hypertensive (50.2%) and 125 were on PAF (0.3%). We observed a highly significant difference between the two groups in relation to obesity: 31 (24.8%) in the AF-group and 15 (12%) in CG, Chi-squared 10, P<0.0016, OR 2.8, 95%; to increased LA volume: 37 (29.6%) in AF-group and 13 (10.4%) in CG, Chi-squared 14.4, P<0.0001, OR 3.62, 95%. No difference in diabetes: 30 (24%) in AFgroup and 28 (22.4%) in CG, Chi-squared 0.09, P<0.76, OR 1.09, 95%, and LV diastolic dysfunction (LVDD): 24 (19.2%) in AF-group and 20 (16%) in CG, Chi-squared 0.44, P<0.5, OR 1.25, 95%. In contrast to what was expected LV hypertrophy had a lower incidence of 59 (47.2%) in AF-group than in CG 84 (67.2%), Chi-squared 10.21, P<0.0014, OR 0.44, 95%. Conclusions. The prevalence of PAF in HPMW is not elevated, obesity and increased LA volume are strong determinants of PAF, not depending on age. LVDD, LV hypertrophy, and diabetes status seem not to play a relevant role as PAF determinants.

Echocardiographic predictors of first onset of atrial fibrillation in dogs with myxomatous mitral valve disease

Background

Atrial fibrillation (AF) occurs in dogs with myxomatous mitral valve disease (MMVD) as a consequence of left atrial (LA) dilatation, and it affects survival and quality of life.

Objectives

To evaluate the usefulness of echocardiography in predicting the first occurrence of AF in dogs with MMVD.

Animals

Forty‐four client‐owned dogs with MMVD, 22 dogs that developed AF, and 22 dogs that maintained sinus rhythm.

Methods

Retrospective observational study. Medical databases were reviewed for dogs that developed AF during the year after diagnosis of MMVD (AF group). The last echocardiographic examination obtained while still in sinus rhythm was used to derive selected variables. For each dog with AF, a control dog matched for body weight, class of heart failure, and LA dimension was selected. Echocardiographic results including LA volumes and LA speckle tracking echocardiography (STE)‐derived variables were measured.

Results

Among the tested echocardiographic variables, only LA diameter (P = .03) and left ventricular internal diameter in diastole (P = .03) differed significantly between groups, whereas body weight‐indexed variables of cardiac dimension as well as LA volumes and volume‐derived functional variables were not different. Among the STE‐derived variables, peak atrial longitudinal strain (PALS) results differed significantly between the AF group (23.8% ± 8.6%) and the control group (30.5% ± 9.6%; P = .03). A value of PALS ≤28% predicted AF occurrence with sensitivity and specificity of 0.80 and 0.65, respectively.

Conclusions and Clinical Importance

Absolute cardiac diameters and LA STE (in particular, PALS) are useful echocardiographic predictors for the development of AF in dogs with MMVD.

The presence of fragmented QRS may predict the recurrence of nonvalvular atrial fibrillation after successful electrical cardioversion

OBJECTIVE

Atrial fibrillation (AF), the most common cardiac rhythm disorder, affects approximately 2% of the general population and is associated with increased risk of stroke and mortality as well as reduced exercise capacity and quality of life. After restoring normal sinus rhythm, a portion of these patients develops recurrent AF despite optimal medical treatment. In this study, we aimed to assess the relationship between the presence of fragmented QRS (fQRS) and AF recurrence following successful electrical cardioversion (ECV).

MATERIAL AND METHODS

A total of 306 patients with nonvalvular persistent AF achieving restoration of the sinus rhythm after successful ECV were included in this study. After ECV, patients were monitored at least 6 months for recurrence. The patients were divided into two groups according to the presence of fQRS and compared for AF recurrence during follow-up.

RESULTS

Patients were followed up for a mean time of 220 ± 113 days. AF recurred in 119 patients, corresponding to a recurrence rate of 38.8%. AF recurrence was found to be significantly increased in patients with fQRS as compared to those without fQRS (76.4% vs. 23.5%, p < .001). Furthermore, the presence of fQRS was higher in patients with recurrent AF as compared to others (57.1% vs. 11.2%, p < .001). In multiple regression analyses, the presence of fQRS was one of the independent predictors of AF recurrence (hazard ratio: 9.670, 95% CI: 4.714-19.837, p < .001).

CONCLUSION

The presence of fQRS may be associated with the recurrence of AF after successful ECV in persistent nonvalvular AF patients.

Imaging for Risk Stratification in Atrial Fibrillation with Heart Failure

Atrial fibrillation (AF) is the most common cardiac rhythm disorder and is associated with heart failure (HF). Cardiac imaging modalities play an important role in risk assessment and managing AF. This article reviews the use of cardiac imaging for risk assessment and to optimize treatment strategy in patients with AF and HF. First, the clinical role of echocardiography, computed tomography, and cardiac magnetic resonance for risk stratification is provided. Second, the value of imaging in catheter ablation is reviewed, including preoperative assessment, optimizing patient selection for ablation, use during the ablation procedure, and postoperative scar assessment.

A risk score for predicting atrial fibrillation in individuals with preclinical diastolic dysfunction: a retrospective study in a single large urban center in the United States

Background

Left ventricular diastolic dysfunction has been shown to associate with increased risk of atrial fibrillation (AF). We aimed to examine the predictors of AF in individuals with preclinical diastolic dysfunction (PDD) - diastolic dysfunction without clinical heart failure – and develop a risk score in this population.

Methods

Patients underwent echocardiogram from December 2009 to December 2015 showing left ventricular ejection fraction (LVEF) ≥ 50% and grade 1 diastolic dysfunction, without clinical heart failure, valvular heart disease or AF were included. Outcome was defined as new onset AF. Cumulative probabilities were estimated and multivariable adjusted competing-risks regression analysis was performed to examine predictors of incident AF. A predictive score model was constructed.

Results

A total of 9591 PDD patients (mean age 66, 41% men) of racial/ethnical diversity were included in the study. During a median follow-up of 54 months, 455 (4.7%) patients developed AF. Independent predictors of AF included advanced age, male sex, race, hypertension, diabetes, and peripheral artery disease. A risk score including these factors showed a Wolber’s concordance index of 0.65 (0.63–0.68, p <  0.001), suggesting a good discrimination.

Conclusions

Our study revealed a set of predictors of AF in PDD patients. A simple risk score predicting AF in PDD was developed and internally validated. The scoring system could help clinical risk stratification, which may lead to prevention and early treatment strategies.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1024-4) contains supplementary material, which is available to authorized users.

Is extensive atrial fibrosis in the setting of heart failure associated with a reduced atrial fibrillation burden?

Atrial fibrillation (AF) affects 10-50% of patients with chronic heart failure (HF) and is associated with poor long-term prognosis. AF is commonly associated with atrial structural remodeling (ASR), principally characterized by atrial dilatation and fibrosis. However, the occurrence of AF in the full spectrum of ASR encountered in patients with HF is poorly defined. Experimental studies have presented evidence that extensive ASR can be accompanied with a reduced burden of AF, secondary to a prominent depression of atrial excitability. This reduction in AF burden is associated with severe atrial fibrosis rather than with dilatation. Clinical studies of patients with HF point to the possibility that advanced ASR is associated with a less frequent AF occurrence than moderate ASR. Our goal in this review is to introduce the hypothesis that AF is less likely to occur in severe versus moderate atrial ASR in the setting of HF and that it is severe atrial fibrosis-associated depression of atrial excitability that reduces AF burden.

Evaluation of sex differences in the relationship between diastolic dysfunction and thromboembolism using propensity score analysis

BACKGROUND

Female sex is a risk factor for thromboembolism (TE) in atrial fibrillation (AF); however, the underlying mechanisms are unclear. We postulated that left ventricular (LV) diastolic dysfunction (LVDD) could be associated with increased thromboembolic risk in women.

METHODS

From a retrospective cohort, 158 patients (female : male = 79:79) with nonvalvular AF were propensity score-matched for age, presence of diabetes, hypertension, coronary artery disease, congestive heart failure, embolic history, AF type, and AF duration. Cardiac size and function and central aortic stiffness parameters were evaluated. Diastolic function was classified as normal, indeterminate, and LVDD according to recent guidelines. Surrogate markers for thromboembolism (dense spontaneous echo contrast and thrombus) were evaluated using transesophageal echocardiography.

RESULTS

Surrogate markers for TE showed a trend to be more frequent in women than in men (21.5% vs 11.4%, P = .086). LVDD was more prevalent in women than in men (22.8% vs 2.5%, P < .001); however, the prevalence of indeterminate diastolic function was not different between sexes (26.6% vs 20.3%, P = .453). Surrogate markers for TE were detected mostly in women with LVDD. LV diastolic parameters showed a restrictive pattern, and aortic stiffness parameters were worse in women than in men. Women with LVDD had increased aortic stiffness compared to women with indeterminate and normal function, whereas aortic stiffness did not differ among men in all groups. Significant relations between LV diastolic function and aortic stiffness parameters were observed only in women.

CONCLUSION

LVDD due to increased aortic stiffness could be related to a higher thromboembolic risk in women with AF.