Left atrial posterior wall and pulmonary vein refractory periods are associated with atrial fibrillation inducibility in a swine model

INTRODUCTION AND OBJECTIVES: Ectopic activity originating inside the pulmonary veins has been associated with paroxysmal atrial fibrillation in some patients. However, the roles played by the pulmonary veins and the posterior wall of the left atrium in maintaining atrial fibrillation are not well understood. METHODS: Our aim was to determine whether there is a correlation between the refractory period of either the lateral wall of the right atrium, the lateral wall of the left atrium, the posterior wall of the left atrium, or the pulmonary veins, and the inducibility of atrial fibrillation in an experimental swine model. We assessed atrial fibrillation inducibility using programmed atrial stimulation before and after intravenous administration of a high dose of methacholine in 20 pigs. RESULTS: Atrial fibrillation was induced in 17 out of the 20 pigs. Univariate analysis showed that there were negative correlations between all refractory periods and atrial fibrillation inducibility. A short refractory period was associated with greater inducibility. In the multivariate analysis, only the refractory periods of the posterior wall of the left atrium and the pulmonary veins were associated with inducibility. We also investigated the relationship between the local atrial fibrillation cycle length and refractory period; the only significant correlation was with the refractory period of the lateral wall of the right atrium (Pearson correlation coefficient 0.97). CONCLUSIONS: In an experimental swine model, the inducibility of atrial fibrillation was found to be associated with the refractory periods of both the pulmonary veins and the posterior wall of the left atrium.     

应用舒适护理在射频消融治疗心房颤动的临床疗效观察

目的：探讨射频消融治疗心房颤动患者采用舒适护理干预的临床效果。方法：选择2013年1月至2014年1月在我院就诊的80例射频消融治疗心房颤动患者为观察对象，随机将其分为对照组和实验组，实验组在对照组常规护理的基础上接受舒适护理干预，对比分析两组患者穿刺部位出血或血肿、恶心呕吐、下肢麻木、腰酸背痛等并发症和不良反应发生情况，术后用药时间及护理满意度。结果：实验组术后并发症和不良反应为5.00％，对照组为70.00％，两组比较，P<0.05， 差异有统计学意义；同时实验组观察对象术后用药时间明显短于对照组用药时间，两组比较有统计学意义（P<0.05）。对照组护理满意程度明显低于实验组，差异显著，具有统计学意义（Χ2=7.440，p<0.01)。结论：对射频消融治疗心房颤动者施行舒适护理，比普通常规护理更能提高临床疗效。     

Echocardiographic assessment of atrial function in patients with hypertrophic cardiomyopathy with and without paroxysmal atrial fibrillation

Introduction and objectivesHypertrophic cardiomyopathy (HCM) is accompanied by pathophysiological changes that predispose to the development of atrial fibrillation (AF). This arrhythmia impacts negatively on the morbidity, mortality and quality of life of these patients. Our objective was to evaluate the behavior of left atrial function, by means of atrial strain (derived from speckle tracking) and volumetric analysis by three-dimensional echocardiography, in patients with HCM with paroxysmal AF.MethodWe analysed left atrial function in 53 patients with HCM, 25 of whom were paroxysmal AF carriers (mean age 61.7±9.9 years; 56% female) compared with 28 members of the control group (mean age 60.5±10 years; 53.6% female) who were matched especially for sex, age and other demographic data.ResultsIt was observed that patients with HCM and a history of paroxysmal AF had lower left atrial emptying fractions than individuals in the control group; and the active atrial emptying fraction was a factor independently associated with the presence of this arrhythmia (p=0.018; odds ratio=0.93). Moreover, we found a significant reduction of the left atrial strain in all its components in the total sample of patients, with no difference between the groups.ConclusionsMeasurements of atrial emptying fractions by three-dimensional echocardiography allowed differentiating patients with HCM with and without paroxysmal AF.     

Therapeutic success of a prospective cardioversion protocol for persistent atrial fibrillation

INTRODUCTION AND OBJECTIVES. The best therapeutic approach for persistent atrial fibrillation has yet to be defined. Our aim was to investigate the effects of cardioversion in unselected patients with persistent atrial fibrillation who were treated according to a strict protocol involving pretreatment, cardioversion, and follow-up. METHODS. Consecutive patients with persistent atrial fibrillation of at least 1 months' duration were included prospectively in a cardioversion protocol that involved standard antiarrhythmic pretreatment, with amiodarone being offered first, and follow-up. RESULTS. The study included 295 patients, 87.5% of whom were taking the antiarrhythmic drug amiodarone. Sinus rhythm was restored in 92.5%, with pharmacologic cardioversion occurring in 9.5%. The recurrence rate was 33.5% in the first month and 54.9% by month 12. Antiarrhythmic treatment had to be modified in 10.8% of patients. Independent risk factors for recurrence during the first year after cardioversion were an atrial fibrillation duration greater than one year, previous cardioversion, and left ventricular dilatation. A simple risk scoring system was able to differentiate between subgroups of patients with a low, intermediate or high risk of recurrence in the first year after cardioversion. CONCLUSIONS. Sinus rhythm was maintained for 1 year after effective cardioversion in 45.1% of patients who received homogeneous antiarrhythmic pretreatment. There were few side effects. Recurrence can be predicted using clinical variables such as left ventricular dilatation, arrhythmia duration, and previous cardioversion.     

The superior vena cava as a site of ectopic foci in atrial fibrillation

Radiofrequency catheter ablation of ectopic foci that trigger atrial fibrillation has been established as a curative method for patients with symptomatic paroxysmal atrial fibrillation. Although the majority of these foci are located in and around the pulmonary veins, other less common locations have been identified. Recognition that foci can lie outside the pulmonary veins is important for ensuring therapeutic success. The most frequently reported foci of ectopic activity outside the pulmonary veins are in the superior vena cava and the posterior wall of the left atrium. Here we report our experience with the ablation of ectopic foci located in the superior vena cava in patients with symptomatic paroxysmal atrial fibrillation.     

Benefits of cardiac resynchronization therapy in patients with atrial fibrillation who have not undergone atrioventricular node ablation

The aim of this study was to compare the effects of cardiac resynchronization therapy on left ventricular function and reverse remodeling in patients in sinus rhythm with the effects in patients with atrial fibrillation who have not undergone atrioventricular node ablation. Echocardiographic and clinical parameters were evaluated at baseline and after 6 months of cardiac resynchronization therapy in 55 patients: 15 had atrial fibrillation and 40 were in sinus rhythm. Device programming was similar in the 2 groups, as were the reductions in QRS interval and echocardiographic measures of asynchrony observed after implantation. However, although significant improvements in end-systolic volume and ejection fraction were seen in both groups, reverse remodeling was greater in patients in sinus rhythm (reduction in end-systolic volume 30.9%+/-24.6% vs 12.5%+/-18.6%; P=.024), as was the relative increase in ejection fraction (15.4%+/-12.6% vs 5.0%+/-7.2%; P=.010). Cardiac resynchronization therapy in patients with atrial fibrillation who had not undergone atrioventricular node ablation resulted in significant improvements in ejection fraction and reverse remodeling, but these were less than those observed in patients in sinus rhythm.     

Sex differences in the treatment of patients with atrial fibrillation: population-based study in a local health district

Differences in the treatment of atrial fibrillation between men and women were investigated by using patients in a local health district as a reference population. The study included 688 patients (359 female) who presented with atrial fibrillation. Women were older, more frequently had heart failure, and were more often functionally dependent than men. With regards to the management of atrial fibrillation, women were prescribed digoxin more frequently than men, but underwent electrical cardioversion less often, were less frequently seen by a cardiologist, and understood less about their treatment. After stratifying the findings by age and adjusting for heart failure and the degree of functional dependence, it was observed that women aged over 85 years were prescribed digoxin more often than men, while women aged under 65 years underwent cardioversion less often than men. In conclusion, gender differences observed in the treatment of atrial fibrillation cannot be fully explained by differences in clinical characteristics between men and women in the population.Full English text available from: www.revespcardiol.org     

Pheochromocytoma diagnosed after anticoagulation for atrial fibrillation ablation procedure: A giant in disguise

Pheochromocytoma is a rare catecholamine-producing tumor, discovered incidentally in 50% of cases. We present the case of a 44-year-old male with a history of paroxysmal palpitations. Baseline ECG, transthoracic echocardiogram and ECG stress test showed no relevant alterations. Paroxysmal atrial fibrillation was detected on 24-hour Holter ECG. After antiarrhythmic therapy, the patient remained symptomatic, and was accordingly referred for electrophysiological study and atrial fibrillation ablation. Anticoagulation was initiated before the procedure. After ablation and still anticoagulated, he complained of hematospermia. The abdominal and pelvic imaging study showed a 10-cm left adrenal mass, predominantly cystic, compatible with pheochromocytoma, which was confirmed after biochemical tests (increased urine metanephrines and plasma catecholamines). Metaiodobenzylguanidine scintigraphy scanning confirmed localized disease in the adrenal gland, excluding other uptake foci. Following appropriate preoperative management, surgical resection of the giant mass was performed successfully and without complications.     

Relationship between C-reactive protein level and early recurrence of atrial fibrillation after electrical cardioversion

INTRODUCTION AND OBJECTIVES: Atrial remodeling is responsible for the early recurrence of atrial fibrillation (AF) after cardioversion. Recently, it has been shown that the C-reactive protein (CRP) level is elevated in patients with AF, indicating that inflammation may play a role in the pathogenesis of this arrhythmia. We postulated that a high CRP level would predict early recurrence of AF after electrical cardioversion. PATIENTS AND METHOD: Forty-two patients with persistent AF, but without known heart disease, who underwent elective electrical cardioversion were investigated. The CRP level was measured immediately before cardioversion. The study population comprised the 37 patients in whom sinus rhythm was restored. RESULTS: After a follow-up period of 30 days, 16 patients (43%) had recurrence of AF; the other 21 (57%) remained in sinus rhythm. The mean CRP level was significantly higher in patients with AF recurrence (6.3 [3.3] mg/L vs 2.4 [2.1] mg/L, P=.0001). On dividing patients according to whether their CRP level was < or =3 mg/L or >3 mg/L, it was observed that only 33% of those in sinus rhythm had a level >3 mg/L compared with 81% of those with AF recurrence (P=.004). Patients with a CRP level >3 mg/L had a significant increase in the 1-month risk of AF recurrence (RR=3.7; 95% CI, 1.3-10.8). There was no association between CRP level and left atrial diameter (P =.50) or AF duration (P=.458). CONCLUSIONS: A high CRP level is associated with early recurrence of AF after electrical cardioversion, suggesting that inflammation could play a role in atrial remodeling.     

Atrial flutter: an update

Invasive electrophysiologic studies have changed the clinical outlook for patients with atrial flutter. Recognition of the reentrant circuit responsible for typical atrial flutter has led to the development of catheter ablation techniques that can prevent recurrence in >90% of cases. In addition, general understanding of atrial tachycardias has changed radically, such that ECG-based classifications are now obsolete. Atypical reentrant circuits associated with surgical scars or fibrotic areas in either atrium, which are indistinguishable from focal tachycardias on ECG, have been identified. These circuits also seem amenable to treatment by ablation. Recently, a new type of reentrant tachycardia that could be problematic in the future has emerged in patients who have undergone extensive left atrial ablation for the treatment of atrial fibrillation. These atypical circuits can be characterized using the mapping and entrainment techniques initially developed for typical flutter. In these cases, electroanatomical mapping, involving the construction of a virtual anatomical model of the atria, is extremely helpful. Despite the success of ablation, long-term prognosis is frequently overshadowed by the appearance of atrial fibrillation, which suggests that flutter and fibrillation share a common arrhythmogenic origin that is not modified by cavotricuspid isthmus ablation. In contrast with our clear electrophysiologic understanding of atrial flutter, little is known about the natural history of the condition because the literature has traditionally grouped patients with flutter and fibrillation together. Consequently, the complex relationship between the two arrhythmias has still to be clearly delineated. Primary prevention and preventing the development of atrial fibrillation after ablation remain outstanding clinical challenges.     

Optimizing prognosis in atrial fibrillation: A call to action in Portugal

Atrial fibrillation (AF), the most common arrhythmia in the adult population worldwide, represents a significant burden in terms of cardiovascular mortality and morbidity and has repercussions on health economics. Oral anticoagulation (OAC) is key to stroke prevention in AF and, in recent years, results from landmark clinical trials of non-vitamin K oral anticoagulants (NOAC) have triggered a paradigm shift in thrombocardiology. Despite these advances, there is still a significant residual vascular risk associated with silent AF, bleeding, premature sudden death and heart failure.The authors review AF epidemiologic data, the importance of new tools for early AF detection, the current role of catheter ablation for rhythm control in AF, the state-of-the-art in periprocedural OAC, the optimal management of major bleeding, the causes of residual premature death and future strategies for improvements in AF prognosis.     

Left atrial deformation analysis by speckle tracking echocardiography to predict exercise capacity after myocardial infarction

Introduction

Left atrial (LA) size and function are associated with outcome after myocardial infarction (MI). In this study we aimed to assess the impact of LA function as a predictor of exercise capacity through speckle tracking echocardiography.

Clinical value of the combined use of P-wave dispersion and troponin values to predict atrial fibrillation recurrence in patients with paroxysmal atrial fibrillation

IntroductionP-wave dispersion (PWD) and cardiac troponin levels are independently associated with the recurrence of atrial fibrillation (AF) in patients with paroxysmal AF (PAF). We investigated the clinical usefulness of combining PWD and cardiac troponin I to predict AF recurrence in patients presenting to the emergency department with PAF.MethodsThis study included 65 patients with PAF who were divided into three groups according to baseline troponin I and PWD values (group 1, troponin I<0.11 ng/dl and PWD<44.5 ms; group II, troponin I<0.11 ng/dl and PWD≥44.5 ms, or troponin I≥0.11 ng/dl and PWD<44.5 ms; group III, troponin I≥0.11 ng/dl and PWD≥44.5 ms).ResultsThe AF recurrence rate was significantly higher in group III than in groups I and II. Multivariate analysis revealed that the troponin I and PWD values in group III (odds ratio: 7.236, 95% confidence interval: 1.879-27.861, p=0.004) were independent predictors of AF recurrence.ConclusionsThe combined use of PWD and basal troponin I levels is a better predictor of AF recurrence than either value alone.     

Impact of new criteria for anticoagulant treatment in atrial fibrillation

Introduction and objectives

The guidelines for the management of atrial fibrillation (AF) incorporate new risk factors for thromboembolism, trying to de-emphasize the use of the ‘low’, ‘moderate’, and ‘high’ risk categories. The objective of this study was to determine the impact of the new scheme CHA₂DS₂-VASc and of the new recommendations for oral anticoagulation (OAC) in a contemporary sample of patients with AF seen by primary physicians and cardiologists.

Methods

Multicenter, observational, cross-sectional study on the epidemiology of hypertension and its control, designed by the arterial hypertension department. Each researcher enrolled the first 6 consenting patients who came for examination during a 5-day period.

Results

Of 25 137 individuals recruited, 1544 were diagnosed with AF. The vast majority of the sample had a CHADS₂ score ≥2 (77.3%). Individuals with a risk score lower than 2 were categorized according to the CHA₂DS₂-VASc score: 14.4% were aged 75 years or older (CHA₂DS₂-VASc = 2). Of those younger than 75, 42.3% had a CHA₂DS₂-VASc = 2; 23.7% CHA₂DS₂-VASc = 3, and 1.1% CHA₂DS₂-VASc = 4. This means that the 85.1% of the patients with a CHADS₂ score <2 and no contraindications are indicated for OAC.

Conclusions

The new recommendations will result in a significant increase in patients with indications for OAC, at the expense of those previously characterized as low-to-moderate risk. Therefore, patients at risk of thromboembolic events must be identified, although an evaluation of bleeding risk should be part of the patient assessment before starting anticoagulation.Full English text available from: www.revespcardiol.org