Predictors of Occurrence of Left Atrial Appendage Stunning After Electrical Cardioversion of Atrial Fibrillation to Sinus Rhythm

Objective To determine the predictors and risk factors of occurrence of atrial appendage stunning after electrical cardioversion of non-valvular atrial fibrillation.     

Does the E/e′ Index Predict the Maintenance of Sinus Rhythm after Catheter Ablation of Atrial Fibrillation?

Introduction: The role of left ventricular (LV) diastolic dysfunction in recurrent atrial fibrillation (AF) after catheter ablation remains unknown. We investigated LV diastolic function using the ratio of early transmitral flow velocity (E) to early diastolic mitral annular velocity (e′) and evaluated its predictive value for AF recurrence. Methods: One hundred three AF patients underwent transthoracic echocardiography before ablation and during 3 months of follow‐up. Clinical and echocardiographic parameters of patients with maintained sinus rhythm were compared with those with recurrent AF. Results: Of 103 patients, 26 had recurrent AF during follow‐up. The E/e′ index was the best independent predictor of AF recurrence in a multivariate logistic regression model. A cutoff value of 11.2 for the E/e′ measured before ablation was associated with a sensitivity of 80.8% and specificity of 81.8% (area under ROC curve, 0.840; 95% CI, 0.754–0.926) for AF recurrence. E/e′ measured in sinus rhythm after ablation had an even better predictive power (area under ROC curve, 0.917; 95% CI, 0.850–0.983). Conclusion: LV diastolic function was closely associated with AF recurrence after catheter ablation. The E/e′ index can be used as an incremental predictor for AF recurrence after catheter ablation. (Echocardiography 2010;27:630‐636)     

Stunning of the Left Atrium after Conversion of Atrial Fibrillation: Predictor for Maintenance of Sinus Rhythm?

Recurrence of atrial fibrillation (AF) after cardioversion (CV) to sinus rhythm (SR) is determined by various clinical and echocardiographic parameters. The aim of this study was to determine the value of mitral inflow A-wave velocity, performed at 24 hours after CV in estimation of AF recurrence. The study group consisted of 187 consecutive patients with nonvalvular atrial fibrillation, who had been cardioverted to SR from 1998 to 2000. Transthoracic echocardiography was performed in all cases recruited for the study 24 hours after CV. Left atrial (LA) diameter, left ventricular ejection fraction, and mitral inflow A-wave velocity were measured. The patients were evaluated in five groups according to their recurrence time (<30 days, 31-90 days, 91-180 days, 181-365 days, and >365 days). Maintenance of SR was determined to have a negative linear correlation with age (r =-0.97, P = 0.006), LA diameter (r =-0.93, P = 0.02), and AF duration (r =-0.93, P = 0.02), while having a positive linear correlation with mitral inflow A-wave velocity (r = 0.96, P = 0.008). In the maintenance of sinus rhythm, age, LA diameter, and AF duration were not affected from the method of CV, while mitral inflow A-wave velocity was found to be affected with the method of CV. No relationship was determined between mitral inflow A-wave velocity and the maintenance of sinus rhythm in those performed electrical cardioversion, while frequency of recurrence was found to be higher in those with slow mitral inflow A-wave velocity who were performed pharmacological cardioversion (r = 0.89, P = 0.004). In conclusion, age, duration of AF, LA diameter, and the mitral inflow A-wave velocity can be used to predict the maintenance of SR after CV.     

Sinus Pacemaker Function after Cardioversion of Chronic Atrial Fibrillation: Is Sinus Node Remodeling Related with Recurrence?

INTRODUCTION: The objective of this study was to investigate the temporal changes in sinus node function in postcardioversion chronic atrial fibrillation (AF) patients and their possible relation with the recurrence rates of AF. METHODS AND RESULTS: In 37 chronic AF patients, internally cardioverted to sinus rhythm, corrected sinus node recovery time (CSNRT), and the pattern of corrected return cycle lengths were assessed 5 to 20 minutes and 24 hours after conversion. The last 20 consecutive patients also were evaluated after autonomic blockade. Twenty subjects with normal atrial structure and no history of AF served as the control group. Patients were followed-up for 1 month for recurrence, and the density of supraventricular ectopic beats per hour was obtained during the first 24 hours after conversion. Fifteen patients (40.5%) relapsed during follow-up. CSNRT values at 600 msec (371 +/- 182 msec) and 500 ms (445 +/- 338 msec) were significantly higher than those of control subjects (278 +/- 157 msec, P = 0.050, and 279 +/- 130 msec, P = 0.037, respectively). Significant temporal changes in CSNRT also were observed during the first 24 hours after conversion (600 msec: 308 +/- 120 msec, P = 0.034; 500 msec: 340 +/- 208 msec, P = 0.017). No significant interaction and temporal effects were observed with regard to corrected return cycle length pattern. Similar data regarding CSNRT and corrected return cycle length pattern were obtained after autonomic blockade. Patients with abnormal CSNRT after cardioversion had higher recurrence rates (50%) than those with normal function (37%; P = NS). Patients who relapsed had a higher density of supraventricular ectopic beats per hour (159 +/- 120) compared with those who did not (35 +/- 37; P = 0.001). CONCLUSION: Depressed sinus node function is observed after conversion of chronic AF. Recovery from this abnormality and its independence from autonomic function suggest that AF remodels the sinus node. Our data do not support a causative role of sinus node function in AF recurrence, but they do indicate such a role for the density of atrial ectopic beats.     

What Is the Role of Left Atrial Appendage Closure in the Rhythm Control of Atrial Fibrillation?

Interventional catheter ablation approaches to the rhythm control of atrial fibrillation (AF) have advanced significantly in the past decade. The foundation of the catheter ablation in AF is electrical isolation of the pulmonary veins (PVI). However, PVI only in more advanced stages of AF (persistent AF) has only modest to poor success rates prompting a search for alternative and adjunctive procedures to improve the outcomes of ablation in persistent AF. The left atrial appendage (LAA) is well understood to be a primary source of emboli in AF but less well known be a trigger or driver for AF. Therefore, LAA exclusion is an attractive target to potentially improve AF ablation outcomes in more advanced stages of AF and possibly as an alternative to chronic oral anticoagulation in the prevention of stroke and systemic embolism in AF. However, the precise role of LAA closure in the interventional approach to AF is still to be elucidated with ongoing clinical investigations.     

Does Left Atrial Volume and Pulmonary Venous Anatomy Predict the Outcome of Catheter Ablation of Atrial Fibrillation?

Introduction: Preprocedural factors may be helpful in selecting patients with atrial fibrillation (AF) for treatment with catheter ablation and in making an assumption regarding their prognosis. The aims of this study were to investigate whether left atrial (LA) volume and pulmonary venous (PV) anatomy, evaluated by computed tomography (CT) prior to ablation, will predict AF recurrence following catheter ablation.
Methods and Results: We included 146 patients (mean age 57 ± 11 years, 83% male) with symptomatic AF (55% paroxysmal, 18% persistent, 27% long-standing persistent). All patients underwent CT scanning prior to catheter ablation to evaluate LA volume and PV anatomy. Circumferential PV isolation was performed guided by Cartomerge electroanatomical mapping. The outcome was defined as complete success, improvement, or failure.
After a mean follow-up of 19 ±7 months, complete success was achieved in 59 patients (40%), and 38 patients (26%) demonstrated improvement. LA volume was found to be an independent predictor of AF recurrence with an adjusted OR of 1.14 for every 10-mL increase in volume (95% CI 1.00–1.29, P = 0.047). PV variations were equally distributed among the different outcomes of the ablation procedure, and therefore univariate analysis did not identify PV anatomy as a predictor of outcome.
Conclusion: LA volume is an independent predictor of AF recurrence after catheter ablation. Additionally, PV anatomy did not have any effect on the outcome. These findings suggest that an assessment of LA volume may be incorporated into the preprocedural evaluation of patients being considered for AF ablation.     

Ionic Remodeling and Direct Effects of Valsartan on Ionic Currentsin Human Atrial Myocytes with Atrial Fibrillation

Objectives Previous studies demonstrated that angiotensin receptor antagonists had effects on some potassium channels in guinea pig myocytes and cloned channels that expressed in human cardiac myocytes. This study determined the direct effects of Valsartan on I caL, INa, IKur, IK1 and Ito1 in isolated human atrial myocytes. Methods and Results Specimens of right atrial appendage tissue were obtained from 39 patients with coronary artery and valvular heart diseases during cardiopulmonary bypass procedure. Pre- operation cardiac rhythm was sinus (SR)in 19 patients and was atrial fibrillation (AF) in the others. Single atrial myocyte was isolated by enzymatic dissociation with the chunk method. The ionic currents were recorded using the whole cell coffiguration of the voltage clamp technique. ICaL and Ito1 densities in AF patients were significantly lower than those in SR patients by 74% and 60%, respectively, while IK1density was significantly higher by 34% at command potential of - 120 mV. With 10 μmol/L Valsartan, INa density was significantly decreased by 59% in SR patients and by 66% in AF patients. IKur and IKl density were significantly decreased in only AF patients by 31% and23%, respectively. Conclusions Conclusions Decreased IcaL and Itol and increased IKl at hyperpolarizing potentials in AF patients‘ atrial myocytes may result from the electrophysiological remodeling by AF. Valsartan significantly decreases INa, IK1 and IKur current densities in AF patients‘ myocyte, but decreases only INa in SR patients‘ myocyte, suggesting that Valsartan may be beneficial to the recovering of remolded atria.     

The Relation of Atrial Fibrillation and Inflammation Do Inflammation Imply the Pathogenesis of Atrial Fibrillation？

Atrial fibrillation （AF）, the most commonly encountered arrhythmia in clinical practice, is associated with a 2-fold increase in total cardiovascular mortality, as well as the potential for substantial morbidity, including stroke, congestive heart failure, and cardiomyopathy. Its incidence and prevalence are increasing, and it represents a growing clinical and economic burden. Owing to relative inefficacy and side effects of current pharmacological and non-pharmacological therapy for AF, it remains a great challenge to improve primary and secondary AF prevention strategies to reduce this potentially enormous health burden.     

Early Recurrences of Atrial Fibrillation After Electrical Cardioversion: A Result of Fibrillation-Induced Electrical Remodeling of the Atria?

Objectives. We sought to investigate whether, in humans, the timing and incidence of a relapse of atrial fibrillation (AF) during the first month after cardioversion indicates the presence of electrical remodeling and whether this could be influenced by prevention of intracellular calcium overload during AF.Background. Animal experiments have shown that AF induces shortening of the atrial refractory period, resulting in an increased vulnerability for reinduction of AF. This electrical remodeling was completely reversible within 1 week after cardioversion of AF and was presumably related to intracellular calcium overload.Methods. Using transtelephonic monitoring in 61 patients cardioverted for chronic AF, we evaluated the daily incidence of recurrence of AF and determined, by Cox regression analysis, the influence of patient characteristics and medication on relapse of AF.Results. During 1 month of follow-up, 35 patients (57%) had a relapse of AF, with a peak incidence during the first 5 days after cardioversion. Furthermore, in patients with a recurrence of AF, there was a positive correlation between the duration of the shortest coupling interval of the premature atrial beats after cardioversion and the timing of the recurrence of AF (p = 0.0013). Multivariate analysis revealed that the use of intracellular calcium-lowering drugs duringAF was the only significant variable related to maintenance of sinus rhythm after cardioversion (p = 0.03).Conclusions. The daily distribution of recurrences of AF suggests a temporary vulnerable electrophysiologic state of the atria. Use of intracellular calcium-lowering medications during AF appeared to reduce recurrences, possibly due to a reduction of electrical remodeling during AF.     

Does Rapid Atrial Pacing Terminate Atrial Fibrillation? A Comparison of Laboratory and Device Termination Studies

Atrial fibrillation is understood to be a re-entrant arrhythmia and for many years electrophysiologists have attempted to pace-terminate the rhythm. Several studies have demonstrated that an excitable gap is present during atrial fibrillation and that the capture of small amounts of atrial tissue is possible. Early attempts to terminate atrial fibrillation however were unsuccessful. The rapid development of pacemaker and defibrillator technology has provided an exciting new direction for the treatment of recurrent symptomatic atrial fibrillation. Results from studies of the effectiveness of atrial anti-tachycardia pacing algorithms have suggested that 50% of atrial arrhythmias (including atrial fibrillation) can be pace-terminated. These findings conflict with data from the electrophysiology laboratory where atrial fibrillation has yet to be convincingly terminated. In this review, the current literature is discussed and possible reasons for this discrepancy are proposed.     

Does Minimal-Access Aortic Valve Replacement Reduce the Incidence of Postoperative Atrial Fibrillation?

As the most common sequela of cardiac valvular surgery, atrial fibrillation (AF) has an important impact on postoperative morbidity. Minimal-access aortic valve replacement (AVR), with purported benefits on operative outcomes, has emerged as an alternative to conventional AVR. We used meta-analysis to determine whether minimal access influences the incidence of postoperative AF after AVR. Further, we sought first to evaluate via sensitivity analysis the impact of any differences and to identify the sources of possible heterogeneity between studies; second, we sought to evaluate any indirect effect of minimal-access AVR on other surrogate outcomes related to postoperative AF. We identified 10 studies from 26 comparative randomized and nonrandomized reports that documented the primary outcome of interest: new-onset AF. Overall meta-analysis showed no significant difference between minimal-access and conventional AVR in the incidence of postoperative AF (odds ratio, 0.85; 2,262 patients; P=0.24; 95% confidence interval, 0.66–1.11). Nor were there any apparent differences in surrogate outcome measures of intensive care unit stay, total length of stay, or stroke among studies that displayed a notable difference in AF incidence between groups. Sensitivity analysis that included only high-quality studies similarly showed no significant difference in the incidence of AF and further showed several intraoperative variables as potential sources of heterogeneity between studies. Therefore, minimal access may not have a significant effect on postoperative AF. Future randomized studies must take into account the potential sources of heterogeneity identified here to better demonstrate any differences between the 2 approaches in the onset of AF.Key words: Aortic valve/surgery, aortic valve stenosis/surgery, atrial fibrillation/etiology/prevention & control, postoperative complications, surgical procedures, minimally invasiveAtrial fibrillation (AF) is an important complication of valvular heart surgery: the reported incidence is as high as 60%.^1–3 Postoperative AF can result in hemodynamic compromise, thromboembolic phenomena, and anxiety. Other sequelae include prolonged length of stay (LoS) and increased cost. Controversy exists concerning the benefits of a minimal-access approach for aortic valve replacement (AVR); it is important, therefore, to evaluate whether the minimal-access approach carries a different incidence of AF than does the conventional approach.Preoperative, intraoperative, and postoperative variables all affect the incidence of postoperative AF.^1,3–7 Therefore, the array of contributory pathophysiologic factors implicated in postoperative AF is diverse. It includes age- and hypertension-related structural changes in the atria, the effects of surgical manipulation of the heart or pericardium, the duration of myocardial ischemia, and the effects of systemic influences such as electrolyte imbalance, drug administration, and cardiopulmonary bypass (CPB)-related inflammatory effects.^8,9Minimal-access AVR (mAVR) offers apparent benefits in terms of postoperative morbidity, such as fewer respiratory complications and fewer patients transfused.^10–16 On the other hand, mAVR has been associated with longer CPB and aortic cross-clamp (CC) times and with a greater propensity for pleural and pericardial effusions.^14,15,17 We hypothesized that the incidence of AF after mAVR would relate to factors other than the technique of surgical access itself. To investigate this, we analyzed all studies in the surgical literature published in English that compared mAVR and conventional AVR (cAVR) with regard to the incidence of postoperative AF. We used a meta-analytical synthesis of data to examine the effects of minimal access on the incidence of AF, and we focused on the variables associated with AF, including the established preoperative predictors of postoperative AF and predictors that are related to intraoperative manipulation of the heart.     

Assessment and Impact of Cardiac Fibrosis on Atrial Fibrillation

Real-time magnetic resonance imaging (MRI) combines the advantages of excellent soft-tissue characterization in a true 3D anatomical and functional model with the possibility of lesion and gap visualization without the need of any radiation. Therefore, real-time MRI presents a particularly attractive imaging technology to guide electrophysiology studies and catheter ablation procedures. This article aims to provide an overview on current routine clinical application of MRI in the setting of interventional electrophysiology. Furthermore, development of real-time MRI guided electrophysiology studies and first experiences with MRI guided catheter ablation procedures are depicted. In this context advantages, challenges and limitations of real-time MRI guided catheter ablation as well as future perspectives are discussed.