Left atrial volume and function in patients with atrial fibrillation

Study of P wave dispersion in patients with paroxysmal atrial fibrillation and its role in prediction of atrial fibrillation recurrence

BACKGROUND

It has been known that increased P wave duration and P wave dispersion reflect prolongation of intra-atrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. The objective of this study was assessment of P wave dispersion value in cases with paroxysmal atrial fibrillation and its role in predicting recurrence.

RESULTS

Forty-eight patients with documented paroxysmal AF were subjected to clinical evaluation, electrocardiogram and routine Doppler echocardiogram. We found that a statistically significant association was detected between P wave dispersion and older age, diabetic and hypertensive cases with positive correlation also detected with left atrial dimension (LAD), left ventricle size and diastolic dysfunction grade. Mean corrected P wave dispersion and corrected QT interval were higher among cases using sotalol, ca channel blockers, among cases using nitrates and among cases with Morris index > 0.04. Higher mean value of corrected QT was associated with biphasic P v1 shape. Old age, female sex, P wave dispersion and QT wave dispersion are statistically significant predictors of PAF recurrence.

CONCLUSION

P wave dispersion in patients with paroxysmal atrial fibrillation was strongly correlated to older age, diabetic and hypertensive patients and also with left atrial dimension (LAD), left ventricle size and diastolic dysfunction grade. Also, mean corrected P wave dispersion can predict atrial fibrillation recurrence in patients with Morris index > 0.04, old age, female sex, and QT wave dispersion.

Assessment of Left Atrial Structure and Function by Echocardiography in Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia with significant morbidity and mortality. Exacerbated by the aging population, the prevalence of AF is gradually increasing. Accurate evaluation of structure and function of left atrium (LA) has important prognostic significance in patients with AF. Echocardiography is the imaging technique of first choice to assess LA structure and function due to its better availability, accessibility and safety over cardiac computed tomography and cardiac magnetic resonance. Therefore, the aim of this review is to summarize the recent research progress of evaluating LA size by three-dimensional echocardiography and LA function by speckle tracking echocardiography (STE) in predicting the occurrence and recurrence of AF and determining the risk of stroke in AF. In addition, we summarized the role of traditional echocardiography in detecting AF patients that are at high risk of heart failure or cardiovascular death.

A lower left atrial appendage peak emptying velocity in the acute phase of cryptogenic stroke predicts atrial fibrillation occurrence during follow-up

BACKGROUND

Silent atrial fibrillation is a frequent etiology of cryptogenic stroke. Spontaneous conversion of atrial fibrillation to sinus rhythm results in atrial stunning.

OBJECTIVE

To evaluate if the presence of a lower left atrial appendage peak emptying velocity (LAAV) after a cryptogenic stroke is associated with the occurrence of atrial fibrillation (AF).

METHODS

We retrospectively selected consecutive patients with an acute ischemic stroke that had a transoesophageal echocardiogram (TEE) performed in the first 30 days of the acute event. Documented AF or potential cardioembolic sources in the TEE were considered exclusion criteria. We assessed the LAAV. During follow-up, we evaluated the occurrence of new-onset AF and the combined endpoint of death or new ischemic stroke.

RESULTS

We studied 73 consecutive patients, during a mean follow-up period of 54.9 ± 19.3 months. Seven developed AF, and 13 had the combined endpoint. LAAV was independently associated with AF occurrence (HR: 0.93, 95% CI: 0.88-0.99; P = .016). Patients with a LAAV ≤ 46.5 cm/s (AUC: 0.766, 95% CI: 0.579-0.954; P = .021) had a lower survival rate free from AF occurrence (Log-rank, P < .001) and free from the combined endpoint of death or ischemic stroke (Log-rank, P = .010).

CONCLUSION

A lower LAAV was associated with AF occurrence and the combined endpoint of death or ischemic stroke after an initial episode of cryptogenic stroke. Patients with this finding could eventually benefit from long-term cardiac rhythm monitoring.

Thromboembolic events around the time of cardioversion for atrial fibrillation in patients receiving antiplatelet treatment in the ACTIVE trials

Aims

It is unknown whether cardioversion of atrial fibrillation causes thromboembolic events or is a risk marker. To assess causality, we examined the temporal pattern of thromboembolism in patients having cardioversion.

Methods and results

We studied patients randomized to aspirin or aspirin plus clopidogrel in the ACTIVE trials, comparing the thromboembolic rate in the peri-cardioversion period (30 days before until 30 days after) to the rate during follow-up, remote from cardioversion. Among 962 patients, the 30-day thromboembolic rate remote from cardioversion was 0.16%; while it was 0.73% in the peri-cardioversion period [hazard ratio (HR) 4.1, 95% confidence interval (CI) 2.1–7.9]. The 30-day thromboembolic rates in the periods immediately before and after cardioversion were 0.47% and 0.96%, respectively (HR 2.2, 95% CI 0.7–7.1). Heart failure (HF) hospitalization increased in the peri-cardioversion period (HR 11.5, 95% CI 6.8–19.4). Compared to baseline, the thromboembolic rate in the 30 days following cardioversion was increased both in patients who received oral anticoagulation or a transoesophageal echocardiogram prior to cardioversion (HR 7.9, 95% CI 2.8–22.4) and in those who did not (HR 4.8, 95% CI 1.6–14.9) (interaction P = 0.2); the risk was also increased with successful (HR 4.5; 95% CI 2.0–10.5) and unsuccessful (HR 10.2; 95% CI 2.3–44.9) cardioversion.

Conclusions

Thromboembolic risk increased in the 30 days before cardioversion and persisted until 30 days post-cardioversion, in a pattern similar to HF hospitalization. These data suggest that the increased thromboembolic risk around the time of cardioversion may not be entirely causal, but confounded by the overall clinical deterioration of patients requiring cardioversion.

Does Left Ventricular Systolic Function Matter? Treating Atrial Fibrillation in HFrEF Versus HFpEF

Atrial fibrillation (AF) and heart failure (HF) pose international health care challenges that contribute significantly to hospitalizations, morbidity, mortality, and significant health care costs. Both AF and HF contribute to the development of each other and both are associated with a worsened prognosis when they occur together. Assessment of systolic function via transthoracic echocardiography is essential in the investigation of the AF patient. Clinical and echocardiographic assessment may classify AF patients with HF into HF with reduced ejection fraction (HF-rEF) and HF with preserved ejection fraction (HF-pEF). Such classification can assist in numerous important management decisions in AF.

Utility of P-Wave Dispersion in the Prediction of Atrial Fibrillation

Prevention is important in the case of the most common sustained arrhythmia-atrial fibrillation, with the intention of obtaining both medical and economic benefits. Electrocardiographic parameters have been tested as predictors of atrial fibrillation in different settings, and indices of P-wave have been assiduously studied.Increased P-wave dispersion has been described in different illnesses and correlated with several echocardiographic and clinical parameters. Several studies have demonstrated the relationship between P-wave dispersion with the first episode or paroxysmal atrial fibrillation, as well as with the recurrence of atrial fibrillation after conversion to sinus rhythm. Despite of some critics, the current evidencesentitleus to continue studying P-wave dispersion and use it for identifying patients with risk for atrial fibrillation.

The mitral annular displacement by two-dimensional speckle tracking: a new tool in evaluating the left atrial function

BACKGROUND

The methods used to characterize the volume change and the deformation of the left atrium are highly dependent on technical factors and difficult to use in a clinical environment. The aim of this study was to demonstrate that mitral annular displacement by speckle tracking can be an alternative method to studying the longitudinal left atrial function.

METHODS

Ninety study participants (54% men), with a mean age of 53(±15) years, underwent a complete echocardiographic examination, comprising two-dimensional, three-dimensional and tissue Doppler imaging (TDI). They were divided into normal individuals (35) and patients having an abnormal echocardiography (55).

RESULTS

There was a very strong correlation between three-dimensional volumetric function and mitral annular displacement, both for the reservoir (r = 0.78; P < 0.0001) and contractile (r = 0.76; P < 0.0001) functions. The correlation with the longitudinal strain displayed an r = 0.87, P > 0.0001 for the reservoir and r = 0.81, P < 0.0001 for the contractile function. The systolic speed in pulsed TDI and the systolic displacement had an r = 0.83, P < 0.0001. Mitral annular displacement was a very good discriminator for normal versus abnormal participants [area under the curve (AUC) for reservoir = 0.872 and for contractile = 0.843; P < 0.0001], performing less well than three-dimensional (AUC reservoir = 0.892 and contractile = 0.915; P < 0.0001) or deformation (AUC = 0.921 and 0.903 respectively; P < 0.0001), but better than pulsed TDI (AUC = 0.807; P < 0.0001). The percentage error was ±15% for interobserver and ±12% for intraobserver variability. The time taken for displacement analysis was 9 ± 3 s for an experienced cardiologist and 12 ± 4 s for a beginner.

CONCLUSION

Mitral annular displacement by speckle tracking is a reliable and fast method to evaluate left atrial function. Given the strength of the correlations with strain parameters, it could be used as a surrogate measure of the deformation of left atrium.

A MicroRNA-Transcription Factor Blueprint for Early Atrial Arrhythmogenic Remodeling

Spontaneous self-terminating atrial fibrillation (AF) is one of the most common heart rhythm disorders, yet the regulatory molecular mechanisms underlying this syndrome are rather unclear. MicroRNA (miRNA) transcriptome and expression of candidate transcription factors (TFs) with potential roles in arrhythmogenesis, such as Pitx2, Tbx5, and myocardin (Myocd), were analyzed by microarray, qRT-PCR, and Western blotting in left atrial (LA) samples from pigs with transitory AF established by right atrial tachypacing. Induced ectopic tachyarrhythmia caused rapid and substantial miRNA remodeling associated with a marked downregulation of Pitx2, Tbx5, and Myocd expression in atrial myocardium. The downregulation of Pitx2, Tbx5, and Myocd was inversely correlated with upregulation of the corresponding targeting miRNAs (miR-21, miR-10a/10b, and miR-1, resp.) in the LA of paced animals. Through in vitro transient transfections of HL-1 atrial myocytes, we further showed that upregulation of miR-21 did result in downregulation of Pitx2 in cardiomyocyte background. The results suggest that immediate-early miRNA remodeling coupled with deregulation of TF expression underlies the onset of AF.

Left atrial function in volume versus pressure overloaded left atrium

Left atrial (LA) pressure and volume overload both result in cavity enlargement and complications. LA volume has been shown to predict such complications, but it does not reflect myocardial function, which can be accurately assessed using myocardial deformation measurements. We hypothesized that volume overloaded LA have maintained myocardial function compared to pressure overloaded ones. We tested this hypothesis in 44 patient (mean age 62 ± 12 years) with LA volume overload (LAVOL) due to severe mitral regurgitation (MR) with no indirect signs of elevated left ventricular (LV) filling pressures based on Doppler measured isovolumic relaxation time >60 ms. We compared them with 24 (mean age 64 ± 12 years) patient with LA pressure overload (LAPOL) who proved to have PCWP >15 mmHg on right heart catheterization. Twenty-seven healthy controls (mean age 57 ± 10 years) constituted a control group. Patients with LAVOL had larger LA volumes, higher LV ejection fraction, global LV strain (LVGLS) and transmitral and pulmonary veins flow velocities (p < 0.05) and better LA atrial strain rate (LASR) function compared to LAPOL (p < 0.001). In LAVOL, the LASR during atrial contraction (LASRa) was lower than in controls (p < 0.05) indicating LA mechanical disturbances. LVGLS correlated with peak atrial longitudinal systolic strain in the whole group (r = -0.65, p < 0.001) and less so with LASRa (r = -0.43, p < 0.001) CONCLUSION: Irrespective of a smaller LA volume, LAVOL had less negative effect on LA myocardial function than LAPOL. Thus, monitoring atrial myocardial contraction might be useful in following patients with significant MR.