Clinical significance of atrial fibrillation after myocardial infarction

Atrial fibrillation (AF) is a common complication of acute myocardial infarction (AMI) and has been associated with increased risk of mortality, heart failure and stroke. In this article, we evaluate a recent publication investigating the relationship between new-onset AF and clinical outcome after AMI in a community-based cohort. This study shows that the occurrence of AF portends increased risk for mortality after AMI. The findings are discussed in the context of current knowledge on the clinical implications and treatment strategies of AF in the setting of acute coronary syndromes.     

急性心肌梗死并发心房颤动33例临床分析

目的 探讨急性心肌梗死并发心房颤动的临床特点及治疗。方法 对３３例急性心肌梗死并发心房颤动的临床资料进行了回顾性分析。结果 急性心肌梗死并发心房颤动的发生率为１４．４％,梗死部位以广泛前壁乡见。结论 急性心肌梗死并发心房颤动多见于梗死后左心功能不全或窦房结功能低下所致,当。心室率＞１２０／分时应给予紧急措施控制心室率．若心房颤动持续不能转复则预后不良。     

The significance of new onset atrial fibrillation complicating acute myocardial infarction

Background  

Atrial fibrillation (AF) in the setting of acute myocardial infarction (AMI) independently predicts in-hospital and long-term morbidity and mortality. Very little data exist regarding the prognostic significance and management of new-onset AF in this setting in the era of dual anti-platelet therapy.     

Slow pathway ablation decreases vulnerability to pacing-induced atrial fibrillation: Possible role of vagal denervation

BACKGROUND: Studies indicate that success of radiofrequency (RF) ablation of atrial fibrillation (AF) may be in part due to vagal denervation. RFAof supraventricular tachycardia (SVT) has been associated with vagal denervation. The effects of slow pathway (SP) ablation on AF inducibility have not been studied. OBJECTIVE: To test the hypothesis that SP ablation renders AF less inducible. Methods: Consecutive patients referred for SVT were studied. After atrioventricular nodal reentrant tachycardia (AVNRT) was confirmed they underwent induction of AF. After SP ablation AF induction was reattempted. Vulnerability to AF was reassessed. RESULTS: Twenty-four patients were enrolled; eight were not inducible for AF in the preablative state. Mean CLof the AVNRT was 340 +/- 16 ms. The average RF ablation time was 131 +/- 42 seconds. Presence of junctional rhythm was required. Of the 16 with inducible AF two patients had AF induced during routine invasive electrophysiology study. None of these had inducible AF after SP ablation. Fourteen of 16 patients required specific AF induction. Ten of these were noninducible after SP ablation; two were inducible after SP ablation but with a more aggressive pacing protocol (P < 0.03 compared to preablation) and two had no change in AF vulnerability. Seven of the eight noninducible patients remained noninducible for AF post SP ablation. In the 12 patients who were inducible prior but noninducible after ablation the mean atrial effective refractory period (AERP) increased for both BCL at 400 and 600 ms (400/216 +/- 8 ms preablation vs 400/248 +/- 12 ms postablation, P < 0.03; 600/228 +/- 8 ms preablation vs 600/259 +/- 6 ms postablation, P < 0.04). There were no significant changes in AERP of patients who remained inducible or who were noninducible before ablation. The average ablation time for patients who became noninducible after ablation was significantly higher than those who had no change in inducibility or remained inducible but at a more aggressive pacing threshold (157 +/- 24 seconds vs 35 +/- 5 seconds; P < 0.005). CONCLUSION: SP ablation acutely decreases vulnerability to pacing-induced AF in patients with AVNRT. This may reflect the effect of ablation on atrial vagal tone.     

急性心肌梗死并发心房颤动病人的预后评估

[目的]探讨急性心肌梗死(AMI)并发心房颤动(AF)的危险因素、近期预后及护理对策。[方法]对137例急性心肌梗死合并心房颤动11例病人发生心力衰竭、心室颤动及行气管插管、主动脉内球囊反搏(IABP)事件发生情况进行相关因素研究。[结果]AMI并发AF的病人年龄大、气管插管率高、病死率高,与非AF组比较具有统计学意义(P<0.05)。[结论]高龄AMI并发AF病人气管插管率高、病死率高,预后不良,应做好预见性护理。     

Postoperative atrial fibrillation

Atrial fibrillation is a common arrhythmia after cardiac surgery. It is associated with an increase in morbidity, length of hospital stay, and mortality. Patients who are at higher risk of postoperative atrial fibrillation should receive prophylactic treatment. Atrial fibrillation usually resolves spontaneously after heart rate is controlled; however, if patients are highly symptomatic or hemodynamically unstable, sinus rhythm should be restored by electrical or pharmacologic cardioversion. Patients with atrial fibrillation of more than 48 hours should receive antithrombotic therapy for thromboembolism prevention.     

Effects of intravenous nifekalant, a class III antiarrhythmic drug, on atrial vulnerability parameters in patients with paroxysmal atrial fibrillation

Nifekalant, a class III antiarrhythmic drug, has been shown to suppress ventricular tachyarrhythmias, but its effects on AF are unclear. The aim of this study was to clarify the effects of nifekalant on the atrial vulnerability parameters in patients with paroxysmal AF. The study included 18 patients with paroxysmal AF who underwent electrophysiological study before and after intravenous infusion of nifekalant. The atrial electrophysiological parameters including the atrial effective refractory period (AERP), maximum intraatrial conduction delay, and wavelength index, calculated as the ratio of AERP to the maximum conduction delay, were quantitatively measured at baseline and during nifekalant infusion. The mean AERP was significantly prolonged from 214 +/- 27 ms at baseline to 242 +/- 39 ms after nifekalant (P < 0.001). Although earlier studies have shown that nifekalant does not affect the atrial conduction time, the mean maximum conduction delay of the study patients was significantly prolonged from 59 +/- 19 ms at baseline to 72 +/- 28 ms after nifekalant (P = 0.015). There was no significant difference in the wavelength index at baseline (4.1 +/- 1.7) and after nifekalant (4.1 +/- 2.5). However, when the differences of AERP and wavelength index were defined as each parameter during nifekalant infusion minus that at baseline, the difference of AERP showed a direct positive correlation with that of the wavelength index (P = 0.013). In conclusion, nifekalant may be effective in the prevention of AF due to prolongation of the AERP. However, in those patients who have a lesser degree of prolongation of the AERP by nifekalant, the wavelength index tended to be decreased, suggesting that the drug might augment the propensity for AF.     

应变率成像评价高血压合并阵发性心房颤动患者左心房心肌功能

目的：应用实时三平面应变率成像检测高血压合并阵发性心房颤动患者左心房心肌功能的变化,探讨其临床意义。方法：选取单纯高血压患者35例、高血压合并阵发性心房颤动患者32例、正常人33例,应用实时三平面应变率成像检测左心房心肌收缩期平均峰值应变率（MSRs）、舒张早期平均峰值应变率（MSRe）和心房收缩期平均峰值应变率（MSRa）。结果：MSRs在正常人、单纯高血压患者和高血压合并阵发性心房颤动患者中呈逐渐减低的变化（P<0.0001）;MSRe在单纯高血压患者中显著减低（P<0.01）,在高血压合并阵发性心房颤动患者中无显著性变化（P>0.05）;MSRa在单纯高血压患者中显著增高（P<0.01）,在高血压合并阵发性心房颤动患者中显著减低（P<0.05）。结论：高血压患者左心房心肌功能受损,合并阵发性心房颤动时受损程度加重,实时三平面应变率成像对高血压患者左心房心肌功能的全面评估具有重要应用价值。     

Management of atrial fibrillation

Atrial fibrillation (AF) is one of the most common arrhythmias encountered in the adult population. It can be an isolated event or a chronic lifelong rhythm disturbance. The common causes of AF and the presenting electrocardiogram characteristics are outlined. The risks to the patient in AF, the role of the nurse, and treatment options are also discussed.     

心房颤动的药物治疗

药物治疗对绝大多数房颤患者来说，仍然是基本或首选的治疗方式，其内容包括基础疾病的治疗，抗血栓治疗，控制心室率的治疗以及维持窦性心律的药物治疗。     

Genetics of atrial fibrillation

Recent studies of atrial fibrillation (AF) have identified mutations in a series of ion mutations; however, these channels appear to be relatively rare causes of AF. Recent genome-wide association studies for AF have identified novel variants associated with the disease, although the mechanism of action for these variants remains unknown. Ultimately, a greater understanding of the genetics of AF should yield insights into novel pathways, therapeutic targets, and diagnostic testing for this common arrhythmia.     

Persistent atrial fibrillation vs paroxysmal atrial fibrillation: differences in management

Introduction: Atrial fibrillation (AF) is the most common human arrhythmia. AF is a progressive disease, initially being nonsustained and induced by trigger activity, and progressing towards persistent AF through alteration of the atrial myocardial substrate. Treatment of AF aims to decrease the risk of stroke and improve the quality of life, by preventing recurrences (rhythm control) or controlling the heart rate during AF (rate control). In the last 20 years, catheter-based and, less frequently, surgical and hybrid ablation techniques have proven more successful compared with drug therapy in achieving rhythm control in patients with AF. However, the efficiency of ablation techniques varies greatly, being highest in paroxysmal and lowest in long-term persistent AF.

Areas covered: In this review, we discuss the fundamental differences between paroxysmal and persistent AF and the potential impact of those differences on patient management, emphasizing the available therapeutic strategies to achieve rhythm control.

Expert commentary: Treatment to prevent AF recurrences is suboptimal, particularly in patients with persistent AF. Emerging technologies, such as documentation of atrial fibrosis using magnetic resonance imaging and documentation of electrical substrate using advanced electrocardiographic imaging techniques are likely to provide valuable insights about patient-specific tailoring of treatments.     

经食管超声心动描记术评价非风湿性房颤患者左心耳功能

目的应用多平面经食管超声心动图技术（ＴＥＥ）评价排风湿性房颤患者左心耳功能。方法对３０名健康人和３０例非风湿性房颤（ＮＲＡＦ）患者分别在心底短轴观测量了左心耳最大直径,同一心动周期内左心耳最大、最小面积及左心耳最大排空速度,并将ＮＲＡＦ患者按照左房自发显影及血栓的有无分为２组。结果ＮＲＡＦ组左心耳增大,收缩力及血流速度均减低,且这种变化在有血栓和（或）有血栓形成倾向的患者中更为明显。结论应用ＴＥＥ技术评价左心耳功能可为判断ＮＲＡＦ患者血栓栓塞危险程度提供新的依据。     

心房颤动致心动过速心房心肌病临床探讨

目的探讨心房颤动（AF）引起心房心肌病（TACMP）临床特征及心功能关系。方法对12例AF合房室结病变伴双心房扩大者进行临床心功能分析。结果本组年龄65～79岁（平均72.3岁），平均心率〈85次／分，12例中，左心房内径4．5-6.4cm（平均5.4cm），右心房内径4．6～6．5cm（平均5.6cm），左室内径35．8-48．3cm（平均42．3cm），左室射血分数EF45％～65．4％（平均56．5％），左室舒张功能E／A1．20～0．90（平均0．92）。临床心功能NYHA分级：Ⅱ级2例、Ⅲ级8例、Ⅳ级2例（平均3，16级）。结论持续性AF引起双心房扩大形成（快速心律失常）心房心肌病（TACMP），心房从解剖重构、代谢重构、电重构、直至收缩舒张重构是否与临床心功能改变的因素值得探讨。     

Diagnostic implications of atrial vulnerability.

Extrastimulation in the atrial vulnerable zone may result in atrial fibrillation or flutter (AFF), especially with stimulation of multiple atrial sites. However, the clinical relevance of such vulnerability to AFF is unknown. Therefore, single twice-threshold extrastimuli were applied at three disparate right atrial sites in 45 consecutive unmedicated patients without overt heart failure. Group I consisted of 12 patients with documented spontaneous paroxysms of AFF. AFF was duplicated in 9 to 12 patients using extrastimulation in the vulnerable zone (5 in sinus rhythm, 4 requiring atrial pacing at 120 beats/min). Group II consisted of 33 patients without documented AFF dispite monitoring. Vulnerability to AFF was found in 12 of 33 patients (4 in sinus rhythm, 8 requiring atrial pacing). The duration of induced AFF did not discriminate between the two groups. Among the 12 Group II patients vulnerable to AFF, 3 had rapid palpitations, 2 had undiagnosed rapid tachycardias, 1 had atrial tachycardias and 1 junctional tachycardias. In vulnerable patients, the pause after AFF correlated with the pause after atrial pacing, but only 1 of 11 Group II patients with sick sinus syndrome was vulnerable. Thus, paroxysmal AFF may be duplicated with the extrastimulus technique if sufficient arial sites are stimulated, providing a model for evaluation of these arrhythmias. But atrial vulnerability, even to extrastimulation at normal heart rates, may be seen in patients suspected of atrial tachyarrhythmia in the absence of documented AFF, and does not contribute to the diagnosis of sinoatrial dysfunction.     

The atrial electrical remodeling in atrial fibrillation

The electrical remodeling in atrial fibrillation is defined as the shortening of the atrial effective refractoriness, the loss of its late dependency and the slowing of conduction velocity caused by rapid excitation of the atrial muscle. Although, this phenomenon may play an important role in promoting the appearance of the reentrant atrial fibrillation by shortening the wavelength, the clinical aim and importance of controlling the electrical remodeling are still unclear. Ca channel or Na channel blockers may reduce the electrical remodeling in relatively short-term by preventing the elevation of intracellular Ca concentration, though, the long-term effect is unknown.     

Deglutition induced atrial tachycardia and atrial fibrillation

Deglutition induced supraventricular tachycardia is an uncommon condition postulated to be a vagally mediated phenomenon due to mechanical stimulation. Patients usually present with mild symptoms or may have severe debilitating symptoms. Treatment with Class I agents, beta blockers, calcium channel blockers, amiodarone and radiofrquency catheter ablation has shown to be successful in the majority of reported cases. We report the case of a 46-year-old healthy woman presenting with palpitations on swallowing that was documented to be transient atrial tachycardia with aberrant ventricular conduction as well as transient atrial fibrillation. She was successfully treated with propafenone with no induction of swallowing-induced tachycardia after treatment. This is also the first case to show swallowing-induced atrial tachycardia and atrial fibrillation in the same patient.