Is there an anatomical substrate for idiopathic paroxysmal atrial fibrillation? A case–control echocardiographic study

The Predictive Value of the Left Atrial Kinetic Energy for Atrial Fibrillation Recurrence

Background and aim

Determining which patients will experience recurrence of atrial fibrillation (AF) is crucial for treatment modification. This study aimed to investigate the predictive value of left atrial kinetic energy (LAKE) in AF recurrence.

Materials and methods

A total of 120 consecutive patients who achieved sinus rhythm (SR) with electrical direct current cardioversion and met the inclusion criteria were included in the study. Transthoracic echocardiography (TTE) and LAKE values were calculated on the first day after cardioversion. Rhythm control was performed with 12-lead electrocardiography in the first-month follow-up.

Results

While 81 (67.5%) patients were in SR at one month, AF recurrence was detected in 39 (32.5%) patients. In the AF group, AF duration, cardioversion energy, number of diabetic patients, left atrium (LA) diameter, LA pre-mitral A wave volume, LA minimum volume, and pulmonary artery pressure values were significantly higher than in the SR group, while mitral A wave velocity and LAKE values were significantly lower. In multivariate regression analysis, AF duration (OR: 1.54; 95% CI: 1.22 - 1.93; p < 0.001), LA diameter (OR: 1.33; 95% CI: 1.10 - 1.61; p = 0.002), and LAKE (OR: 0.96; 95% CI: 0.94 - 0.99; p = 0.007) were determined to be independent predictors of AF recurrence at one month.

Conclusions

LA diameter, AF duration, and LAKE were found to be significant predictors of AF recurrence after cardioversion.

Comparison between real-time 3-dimensional and 2-dimensional biplane echocardiographic assessment of left atrial volumes in dogs with myxomatous mitral valve disease

BACKGROUND

Assessment of left atrial (LA) size is important in medical decision making and prognostication in dogs with myxomatous mitral valve disease (MMVD). Real-time 3-dimensional (RT3DE) and 2-dimensional echocardiographic (2DE) methods may be used to assess LA size.

OBJECTIVES

To compare measured LA volumes obtained by RT3DE with those calculated by biplane Simpson's modified method of discs (SMOD) and the area-length method (ALM) using the same RT3DE acquisition with the same timing.

ANIMALS

One hundred twenty-one privately owned dogs with naturally occurring MMVD.

METHODS

Prospective observational study comparing LA volumes indexed to body weight using RT3DE and 2DE-based biplane SMOD and ALM. Agreement between methods was evaluated using Bland-Altman plots and linear regression analyses.

RESULTS

Estimations of LA volume using SMOD or ALM did not show good agreement with RT3DE-derived measurements. Absolute differences between methods increased with increasing LA volume, but SMOD underestimated whereas ALM overestimated calculated volumes compared to RT3DE-derived measurements. The difference in LA volume between RT3DE and the biplane methods showed a systematic underestimation of 7% for SMOD and a systematic overestimation of 24% for ALM. Comparison of LA volumes obtained by SMOD and ALM did not show good agreement. The ALM yielded 30% larger LA volumes compared to SMOD.

CONCLUSION AND CLINICAL IMPORTANCE

In comparison with RT3DE, SMOD systematically underestimated whereas ALM systematically overestimated LA volumes in dogs with MMVD. Because the systematic difference between RT3DE and SMOD was only 7%, SMOD might be considered the method of choice.

Left atrial function in obese and non-obese patients undergoing percutaneous pulmonary vein isolation

Obesity constitutes a risk factor for atrial fibrillation (AF) and modifies the efficacy of invasive AF treatment. Left atrial (LA) global longitudinal strain (GLS), which is measured using speckle-tracking echocardiography (STE), is one of the new methods that are helpful in evaluating the function of LA. The aim of the study was to evaluate LA function in obese and non-obese patients that were undergoing percutaneous pulmonary vein isolation (PVI) before and 6 months after the procedure. 89 patients (F/M: 31/58; mean age: 55.8 ± 9.8 years) with paroxysmal or persistent symptomatic AF that had been qualified for percutaneous PVI were prospectively enrolled in the study. Body mass index (BMI) constituted as a discriminating factor for the study groups: obese group: BMI ≥ 30 kg/m² (29 patients, F/M: 13/16, mean age: 55.13 ± 10.1 years) and non-obese group BMI < 30 kg/m² (60 patients, F/M: 18/42, mean age: 57.17 ± 9.0 years). Transthoracic echocardiography (TTE) with LA GLS and segmental longitudinal strain were analysed 1 day before and 6 months after PVI. PVI efficacy was evaluated 6 months after PVI via a seven-day Holter monitoring. Baseline analysis revealed significantly lower two-chamber (2-Ch) LA GLS in the obese patients compared to the non-obese subjects (− 10.55 ± 3.7 vs − 13.11 ± 5.1, p = 0.004). Segmental strain analysis showed no significant differences between the groups. The data that was obtained 6 months after PVI showed a significantly lower 4-Ch LA GLS in the obese patients compared to the non-obese subjects (− 11.04 ± 5.0 vs − 13.91 ± 4.2, p = 0.02), which was accompanied by a significantly lower segmental 4-Ch LA function in the obese patients (med-sept: − 11.66 ± 11.2 vs − 15.97 ± 5.3, p = 0.04; api-sept: − 9.04 ± 6.3 vs − 13.62 ± 6.5, p < 0.001; api-lat: − 7.62 ± 4.0 vs − 13.62 ± 6.5, p < 0.001; med-lat: −9.31 + − 7.9 vs − 15.04 + −  6.3, p = 0.003, global: − 11.04 + − 5.0 vs − 13.91 + − 4.2, p = 0.02). PVI efficacy was confirmed in 52 (58.4%) patients and was similar in both groups. Comparison of the baseline and 6-month strain revealed no differences in LA GLS in either group. Differences in LA GLS before and after the procedure (delta LA GLS) were not obesity dependent. Apical-septal and apical-lateral strain in the obese group, which were measured in 4-Ch view, were significantly lower after the procedure compared to the baseline (p < 0.001). Obese patients with paroxysmal AF were characterised by impaired LA GLS, which is persistent and was accompanied by segmental dysfunction after PVI at the 6-month follow-up. PVI efficacy was comparable between the obese and non-obese patients.

Gender influence on the adaptation of atrial performance to training

BACKGROUND

High-intensity training has been associated with atrial remodelling and arrhythmias in men. Our purpose was to analyse atrial performance in female endurance athletes, compared to male athletes and controls.

METHODS

This was a cross-sectional study. We included four groups: female athletes, females controls, male athletes and male controls. Left (LA) and right atrial (RA) volumes and function were assessed using 2D and speckle-tracking echocardiography to determine peak atrial strain-rate at atrial (SRa) and ventricular contraction (SRs), as surrogates of atrial contractile and reservoir function, respectively. ANOVA and Bonferroni's statistical tests were used to compare variables among groups.

RESULTS

We included 82 subjects, 39 women (19 endurance athletes, 20 controls) and 43 men (22 endurance athletes, 21 controls). Mean age was similar between groups (36.6 ± 5.6 years). Athletes had larger bi-atrial volumes, compared to controls (women, LA 27.1 vs. 15.8 ml/m², p < 0.001; RA 22.31 vs. 14.2 ml/m², p = 0.009; men, LA: 25.0 vs. 18.5 ml/m², p = 0.003; RA 30.8 vs. 21.9 ml/m², p < 0.001) and lower strain-rate (women, LASRa -1.60 vs. -2.18 s^-1, p < 0.001; RASRa -1.89 vs. -2.38 s^-1, p = 0.009; men, LASRa -1.21 vs. -1.44 s^-1, p = 1; RASRa -1.44 vs. -1.60 s^-1, p = 1). However, RA indexed size was lower and bi-atrial deformation greater in female athletes, compared to male athletes.

CONCLUSIONS

The atria of both male and female athletes shows specific remodelling, compared to sedentary subjects, with larger size and less deformation at rest, particularly for the RA. Despite a similar extent of remodelling, the pattern in women had greater bi-atrial myocardial deformation and smaller RA size.

Cardiovascular Imaging in the Electrophysiology Laboratory

In recent years, rapid technological advances have allowed the development of new electrophysiological procedures that would not have been possible without the parallel development of imaging techniques used to plan and guide these procedures and monitor their outcomes. Ablation of atrial fibrillation is among the interventions with the greatest need for imaging support. Echocardiography allows the appropriate selection of patients and the detection of thrombi that would contraindicate the intervention; cardiac magnetic resonance imaging and computed tomography are also essential in planning this procedure, by allowing a detailed anatomical study of the pulmonary veins. In addition, in cardiac resynchronization therapy, echocardiography plays a central role in both patient selection and, later, in device adjustment and in assessing the effectiveness of the technique. More recently, ablation of ventricular tachycardias has been established as a treatment option; this would not be possible without planning using an imaging study such as cardiac magnetic resonance imaging of myocardial scarring.

Chronic adaptation of atrial structure and function in elite male athletes

AIMS

The aim of this study was to establish the degree of structural and functional adaptations in the left (LA) and right atria (RA) in elite male athletes engaged in 'high dynamic : high static' (HDHS) and 'low dynamic : high static' (LDHS) sporting disciplines compared with sedentary controls.

METHODS AND RESULTS

Eighteen male, elite HDHS athletes (13 boxers and 7 triathletes), 18 male, elite LDHS athletes (8 weightlifters and 10 Akido), and 20 male, age-matched sedentary controls were assessed using conventional 2D and myocardial speckle tracking (MST) echocardiography. Absolute LA and RA volumes [end systole (VOLes), pre A (VOLpreA), and end diastole (VOLed)] as well as the functional indices of reservoir (RESvol), conduit (CONvol), and booster volumes (BOOvol) were defined. MST allowed the assessment of atrial strain (ε) during the reservoir (RESε), conduit (CONε), and booster (BOOε) phases of the cardiac cycle. Both LA and RA sizes were significantly larger in HDHS compared with LDHS and controls (P < 0.05) across all structural and functional volume parameters with no significant difference between LDHS and controls (LAVOLes 35 ± 8, 26 ± 10, and 23 ± 5 mL/m(2); RAVOLes 37 ± 10, 26 ± 9, and 23 ± 5 mL/m(2), LARESvol 35 ± 9, 25 ± 11, and 23 ± 7 mL; RARESvol 41 ± 11, 34 ± 11, and 28 ± 7 mL for HDHS, LDHS, and controls, respectively). RA : LA ratios were >1 in all groups due to a comparatively larger RA volume (RAVOLes : LAVOLes 1.05 ± 0.26, 1.12 ± 0.55, and 1.04 ± 0.28 for HDHS, LDHS, and controls, respectively, P > 0.05). There was no significant between group differences for any ε parameter.

CONCLUSION

Bi-atrial hypertrophy is demonstrated in HDHS athletes and not in LDHS athletes, suggesting that the dynamic component to training is the primary driver for both LA and RA adaptation. Although functional data derived from volume shifts suggest augmented function in HDHS athletes, MST imaging demonstrated no difference in intrinsic atrial ε in any of the groups.

Assessment of left-atrial strain parameters in patients with frequent ventricular ectopic beats without structural heart disease

Ventricular ectopic beats (VEBs) are often encountered in daily clinical practice. Clinical significance of VEBs seen in patients without structural cardiovascular diseases is controversial. We aimed to investigate the effects of VEBs on left atrium (LA) function using speckle tracking echocardiography with LA strain parameters. Patients with frequent VEBs (more than 30 times in 1 h, according to the Lown classification) were identified. Identified patients were evaluated by speckle tracking methods. There were 40 patients with frequent VEBs and 40 controls in our study. The general characteristics were similar of the study population. The LA global longitudinal strain parameters were significantly different. Global Peak atrial longitudinal strain (PALS) (38.39 ± 7.93 vs. 44.15 ± 6.71, p = 0.001) and peak atrial contraction strain (PACS) (16.37 ± 4.58 vs. 20.49 ± 3.65, p = 0.000) were revealed significantly lower in the VEBs group. Time to peak longitudinal strain (TPLS) was found significantly longer in the VEBs group [485.5 (352-641) vs. 435 (339-516.5) p = 0.000]. Number of VEBS was correlated with TPLS (r = 0.499, p = 0.000). PALS and PACS were negatively correlated with number of VEBs (r = -0.348, p = 0.002 and r = -0.444, p = 0.000, respectively). We described that in this study, The LA functions are affected by VEBs adversely. This deterioration is increasing as the number of VEBs.

Slower heart rate and altered rate dependence of ventricular repolarization in patients with lone atrial fibrillation

BACKGROUND

Electrophysiological alterations in atrial fibrillation (AF) may be genetically based and may lead to changes in ventricular repolarization. Short QT syndrome is a rare channelopathy with abbreviated ventricular repolarization and a propensity for AF.

AIMS

To determine if minor unrecognized forms of short QT syndrome can explain some cases of lone AF.

METHODS

We prospectively compared QT intervals in 66 patients with idiopathic lone AF and 132 age- and sex-matched controls. QT intervals were measured during sinus rhythm in each of the 12 surface electrocardiogram leads and corrected using Bazett's formula (QTc). QT intervals were also corrected using other formulae. Uncorrected QT and heart rate regression lines were compared between AF patients and controls.

RESULTS

AF patients presented with a slower resting heart rate (64 ± 10 beats per minute [bpm] vs 69 ± 9 bpm; P=0.0006). QTc intervals were shorter in AF patients in 11/12 electrocardiogram leads (significant in 7/12, borderline in 2/12; mean QTc 381 ± 21 ms vs 388 ± 22 ms; P=0.02). QTc intervals were also shorter in AF patients, significantly or not, using other correction formulae. For similar heart rates, uncorrected QT intervals were shorter in patients when heart rates were greater than 70 bpm and longer when heart rates were less than 60 bpm. AF patients displayed steeper QT/heart rate regression line slopes than controls (P=0.009).

CONCLUSION

Heart rate is significantly slower and the rate dependence of ventricular repolarization is significantly altered in patients with lone AF compared with controls. Further study is warranted to determine if AF induces subsequent ventricular repolarization changes or if these modifications are caused by an underlying primary electrical disease.

Speckle echocardiographic left atrial strain and stiffness index as predictors of maintenance of sinus rhythm after cardioversion for atrial fibrillation: a prospective study

Background

Echocardiographic left atrial (LA) strain parameters have been associated with atrial fibrillation (AF) in prior studies. Our goal was to determine if strain measures [peak systolic longitudinal strain (LAS) and stiffness index (LASt)] changed after cardioversion (CV); and their relation to AF recurrence.

Methods and results

46 participants with persistent AF and 41 age-matched participants with no AF were recruited. LAS and LASt were measured before and immediately after CV using 2D speckle tracking imaging (2DSI). Maintenance of sinus rhythm was assessed over a 6-month follow up. Mean LAS was lower, and mean LASt higher, in participants with AF before CV as compared to control group (11.9 ± 1.0 vs 35.7 ± 1.7, p<0.01 and 1.31 ± 0.17 vs 0.23 ± 0.01, p<0.01, respectively). There was an increase in the mean LAS immediately after CV (11.9 ± 1.0 vs 15.9 ± 1.3, p<0.01), whereas mean LASt did not change significantly after CV (p=0.62). Although neither LAS nor LASt were independently associated with AF recurrence during the follow-up period, change in LAS after cardioversion (post-CV LAS – pre-CV LAS) was significantly higher among individuals who remained in sinus rhythm when compared to individuals with recurrent AF (3.6 ± 1.1 vs 0.4 ± 0.8, p=0.02).

Conclusions

LAS and LASt differed between participants with and without AF, irrespective of the rhythm at the time of echocardiographic assessment. Baseline LAS and LASt were not associated with AF recurrence. However, change in LAS after CV may be a useful predictor of recurrent arrhythmia.

Left atrial mechanical function and stiffness in patients with paroxysmal atrial fibrillation

Background

Abnormalities in the left atrial (LA) structure and function may develop in patients with paroxysmal atrial fibrillation (AF). We sought to determine the contribution of LA mechanical function, including LA stiffness, to AF by comparing patients with paroxysmal AF with normal control subjects, and to evaluate whether LA mechanical function and stiffness are related with the structural changes of LA.

Methods

Sixty-four paroxysmal AF patients (57 ± 13 years, 59% male) were studied, using a speckle tracking echocardiography, and were compared with 34 age-, gender-, and left ventricular (LV) mass-matched controls (53 ± 14 years, 61% male). LA volume indices, expansion index for reservoir function, active emptying fraction for contractile function, mitral annular velocities, and global longitudinal LA strain were measured. The ratio of E/e' to LA strain was used as an index of LA stiffness.

Results

Patients with paroxysmal AF had similar LV volume indices, ejection fraction, and diastolic function, when compared with that of the normal controls. However, paroxysmal AF patients showed increased LA volume indices and decreased LA reservoir function, but similar contractile function. LA stiffness was increased in patients with paroxysmal AF than in the control subjects (0.40 ± 0.25 vs. 0.29 ± 0.10, p = 0.002), and was related with LA volume indices and reservoir function.

Conclusion

Patients with paroxysmal AF have decreased LA reservoir function and increased stiffness, in comparison with that of the control subjects. LA stiffness was significantly related with LA volume indices and reservoir function. LA stiffness can be used for the assessment of LA function in patients with paroxysmal AF.

Lone atrial fibrillation: what is known and what is to come

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in adults, affecting >1% of general population. Atrial fibrillation is commonly associated with structural heart disease and is a major cause of significant cardiovascular morbidity and mortality. AF sometimes develops in a subset of young patients (e.g. aged ≤60 years), with no evidence of associated cardiopulmonary or other comorbid disease (including hypertension), and has been referred to as 'lone AF'. The latter generally has a favourable prognosis; the prognostic and therapeutic implications of an accurate identification of patients with truly lone AF (that is, truly at low risk of complications), if any, would be of the utmost importance. The true prevalence of lone AF is unknown, varying between 1.6% and 30%, depending on the particular study population. Nonetheless, novel risk factors for AF, including obesity, metabolic syndrome, sleep apnea, alcohol consumption, endurance sports, anger, hostility, subclinical atherosclerosis and others, have been increasingly recognised. Also, various underlying pathophysiological mechanisms predisposing to AF, including increased atrial stretch, structural and electrophysiological alterations, autonomic imbalance, systemic inflammation, oxidative stress and genetic predisposition, have been proposed. The growing evidence of these diverse (and numerous) pathogenic mechanisms and factors related to AF inevitably raises the question of whether 'lone AF' does exist at all. In this review article, we summarise the current knowledge of the epidemiology, pathophysiology, clinical course and treatment of patients with so-called 'lone AF' and outline emerging insights into its pathogenesis and the potential therapeutic implications of a diagnosis of lone AF.

'Lone' atrial fibrillation: hunting for the underlying causes and links

The presence of lone atrial fibrillation presupposes the absence of structural heart disease, hypertension, or other known predisposing factors. However, several recent clinical and experimental data provide novel insights into the pathogenesis of lone atrial fibrillation. In addition, modern diagnostic techniques often reveal some previously unappreciated abnormalities. Therefore, the increasing recognition of potential causes and links sets the base for a more complete elucidation of its etiology in the near future. This concise review article discusses the contemporary advances in the understanding of this form of atrial fibrillation.

Prevention of atrial fibrillation following cardiac surgery: basis for a novel therapeutic strategy based on non-hypoxic myocardial preconditioning

Atrial fibrillation is the most common complication of cardiac surgical procedures performed with cardiopulmonary bypass. It contributes to increased hospital length of stay and treatment costs. At present, preventive strategies offer only suboptimal benefits, despite improvements in anesthesia, surgical technique, and medical therapy. The pathogenesis of postoperative atrial fibrillation is considered to be multifactorial. However oxidative stress is a major contributory factor representing the unavoidable consequences of ischemia/reperfusion cycle occurring in this setting. Considerable evidence suggests the involvement of reactive oxygen species (ROS) in the pathogenic mechanism of this arrhythmia. Interestingly, the deleterious consequences of high ROS exposure, such as inflammation, cell death (apoptosis/necrosis) or fibrosis, may be abrogated by a myocardial preconditioning process caused by previous exposure to moderate ROS concentration known to trigger survival response mechanisms. The latter condition may be created by n-3 PUFA supplementation that could give rise to an adaptive response characterized by increased expression of myocardial antioxidant enzymes and/or anti-apoptotic pathways. In addition, a further reinforcement of myocardial antioxidant defenses could be obtained through vitamins C and E supplementation, an intervention also known to diminish enzymatic ROS production. Based on this paradigm, this review presents clinical and experimental evidence supporting the pathophysiological and molecular basis for a novel therapeutic approach aimed to diminish the incidence of postoperative atrial fibrillation through a non-hypoxic preconditioning plus a reinforcement of the antioxidant defense system in the myocardial tissue.