Variation of inflammatory indexes after electrical cardioversion of persistent atrial fibrillation. Is there an association with early recurrence rates?

Inflammation has been recently implicated in the pathophysiology of atrial fibrillation (AF). The aim of this study was to examine the variation of inflammatory indexes during the first week after successful electrical cardioversion of persistent AF. Successive measurements of white blood cell (WBC) count, C-reactive protein (CRP) and fibrinogen levels were performed in 30 cardioverted patients. At the end of the 7-day follow-up period, AF had recurred in 30% of patients. A significant variance was found in serial measurements of fibrinogen levels in the two groups (non-relapse and relapse, p = 0.005). Fibrinogen levels increased significantly in patients who relapsed into AF, but remained stable in patients who remained in sinus rhythm. In the latter patients, CRP values tended to decrease post-cardioversion, but WBC count was significantly lower (p < 0.001) on the 7th day (6083 +/- 1335), compared with baseline values (6648 +/- 1395). The variation of inflammatory indices post-cardioversion might have prognostic implications with regard to sinus rhythm maintenance.     

Classification of atrial fibrillation as a model of decisional analysis for the treatment of patients with current atrial fibrillation observed in the emergency department.

Atrial fibrillation (AF) is the most common cardiac arrhythmia observed in the emergency room (ER). We propose a new classification of AF which is useful for the standardization of terms to be used for future clinical trials and for clinical management of this arrhythmia in the ER. We recognized three categories: (1) atrial fibrillation lasting less than 72 hours (AF < 72 h); (2) persistent atrial fibrillation and (3) permanent atrial fibrillation. Atrial fibrillation lasting less than 72 hours can be reconverted to sinus rhythm spontaneously or with pharmacological or electrical cardioversion. If AF < 72 h is not treated and the arrhythmia persists for more than 72 hours we recognize persistent AF. In persistent AF the systemic thrombo-embolism is a significant risk and therapeutic anticoagulation must be associated to pharmacological or electrical cardioversion even though transoesophageal echocardiography does not visualize thrombi or spontaneous echocontrast in the cardiac chambers. These treatments can reconvert the persistent AF to sinus rhythm, but, in the absence of treatment, or if treatment fails, the arrhythmia goes into the permanent category. In permanent AF ventricular rate control and anticoagulation, if suitable, are the first choice for stroke prevention.     

血清C反应蛋白水平与孤立性心房颤动复律后复发的关系

目的 探讨C反应蛋白(CRP)水平对孤立性心房颤动患者转复窦性心律后复发的预测作用.方法 选取孤立性持续性房颤经药物复律或电复律患者,按其1个月内复发情况分为复发组(15例)和窦律组(18例),复律前抽取静脉血检测其CRP水平,并取18名正常人作对照.结果 两组房颤患者年龄、性别、房颤持续时间、电复律的比例及左室射血分数差异均无统计学意义,但复发组左房内径明显大于窦性心律者(P＜0.05).复发组CRP水平较窦性组明显升高(P＜0.05),两组CRP均比正常组显著升高(P＜0.01).结论 孤立性房颤患者复律前CRP水平可作为复律后复发的预测指标.     

Cardioversion of pre-excited atrial fibrillation leading to ventricular fibrillation- case report and review of literature

Pre-excited, fast conducting atrial fibrillation (AF) is a serious life-threatening arrhythmia that requires urgent pharmacological or electrical cardioversion. When anti-arrhythmic medications fail to restore sinus rhythm, biphasic, direct current (DC) cardioversion is required. Appropriate synchronization of the DC shock with the QRS is crucial, however not easily achieved. Since the QRS-T complexes in pre-excited AF are severely distorted, the diagnosis of inaccurate synchronization may be overlooked. Here, we report a unique case where during electrical cardioversion of pre-excited AF with inappropriate synchronization on the T wave inadvertently resulted in ventricular fibrillation (VF), and review the literature.     

Electrical cardioversion for persistent atrial fibrillation or atrial flutter in clinical practice: predictors of long-term outcome

Despite the results of Atrial Fibrillation Follow-up Investigation of Rhythm Management and Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation trials, which favour a general shift in atrial fibrillation (AF) therapeutic approach towards control of ventricular rate, a strategy based on restoration of sinus rhythm could still play a role in selected patients at lower risk of AF recurrence. We explored possible predictors of relapses after external electrical cardioversion among patients with persistent AF or atrial flutter (AFL). We analysed the clinical characteristics and conventional echocardiographic parameters of patients with persistent AF/AFL enrolled in an institutional electrical cardioversion programme. Among 242 patients (AF/AFL, 195/47; mean age 62+/-13 years), sinus rhythm was restored in 215 (89%) and maintained in 73 (34%) at a follow-up of 930 days (median). No baseline clinical/echocardiographic variables predicted acute efficacy of cardioversion at logistic regression analysis. However, two variables predicted long-term AF/AFL recurrence among patients with successful cardioversion at multivariate Cox's proportional hazards analysis: (i) duration of arrhythmia>or=1 year (HR, 2.07; 95% CI, 1.29-3.33) and (ii) presence of previous cardioversion (HR, 1.67; 95% CI, 1.17-2.38). These variables also presented high-positive predictive values (72% and 80% respectively). Whereas the high acute efficacy of electrical cardioversion (approximately 90%) does not appear to be predictable, two simple clinical variables could help identify patients at higher risk of long-term AF/AFL recurrence after successful electrical cardioversion. We think there could be a case for initially attempting external electrical cardioversion to patients who have had AF/AFL for <1 year. In such patients, the chance of long-term success appears to be relatively high.     

预激综合征合并房颤20例急诊治疗临床分析

目的 分析预激综合征合并房颤的急诊治疗效果.方法 回顾性分析20例预激综合征合并房颤病例的电复律、药物复律疗效.结果 盐酸普罗帕酮使用11例次,转复7例,好转4例;利多卡因使用5例次,转复3例;急诊血流动力学障碍3例和药物复律无效2例,经直流电复律一次性转复为窦性心律.结论 普罗帕酮和利多卡因是急诊治疗预激综合征合并房颤常规使用的有效复律药物,血流动力学障碍或药物复律无效者宜采取电复律.     

Factors Influencing Long Term Persistence of Sinus Rhythm After a First Electrical Cardioversion for Atrial Fibrillation

It is conventionally thought that electrical cardioversion in patients with atrial fibrillation (AF) of longstanding duration or with a large lefi atrial diameter, only seldom results in long term success. Recurrence is common, although antiarrhythmic drugs often effectively decrease the number and duration of recurrent AF episodes. We analysed clinical, functional and pharmacological variables which could possibly infiuence the long term outcome after a first electrical cardioversion for AF in a retrospective study on 85 patients. Univariate and multivariate analysis was used to identify factors predicting maintenance of sinus rhythm at 100 days, and absence of recurrence during the entire follow-up. In univariate analysis, the only significant predictor for maintenance of sinus rhythm at 100 days was the duration of the preceding AF episode. Multivariate analysis with persistence of sinus rhythm at 100 days as endpoint confirmed this as a prognostic factor (p <0.03), but sotalol treatment also contributed to maintenance of sinus rhythm (p <0.05). When considering ihe entire observation period, class III antiarrhythmic drugs, i.e. sotalol ami amiodarone, were useful in preventing recurrence (p <0.01 and < 0.02). High age (above 75 years) was a predictor of recurrence. In conclusion, class III antiarrhythmic drugs, the duration of atrial fibrillation and high age were the most important determirumts of long term outcome, while echocardiographic parameters and the presence of heart disease played no role.     

The prognostic significance of atrial arrhythmias recorded early after cardioversion for atrial fibrillation

In a substantial number of patients, AF recurs after successful electrical cardioversion. The purpose of this study was to investigate if the atrial arrhythmias recorded immediately after cardioversion are associated with the risk of recurrence of the arrhythmia and to compare the prognostic significance of this parameter with that of other established risk factors. In a series of 71 patients, the risk factors for recurrence of AF during the first year after successful electrical cardioversion were analyzed. A new parameter that was investigated was the frequency of atrial premature beats and the presence of runs of supraventricular tachycardia in the Holter recording started immediately after the cardioversion. Age, left atrial size, left ventricular systolic function, duration of the arrhythmia before cardioversion, underlying cardiac disease, or medication taken were not found to be predictive of recurrence of the arrhythmia. However, the natural logarithm of the number of atrial premature complexes per hour of the Holter recording in the 37 patients in whom AF recurred was higher compared to that of the 34 patients who maintained sinus rhythm (P < 0.0005). The same was true if only the first 6 hours of the recording were analyzed (P < 0.0005). There was a trend for more frequent arrhythmia recurrence if runs of supraventricular tachycardia were present. The finding of > 10 atrial premature complexes per hour in the recording had a relative risk of 2.57 (1.51-4.37), a positive predictive accuracy of 76.5%, and a negative predictive accuracy of 70.3% for subsequent arrhythmia recurrence. We can conclude that frequent (> 10/hour) atrial premature complexes in the Holter recording after electrical cardioversion for AF is a significant risk factor for recurrence of the arrhythmia.     

Effects of pretreatment with intravenous flecainide on efficacy of external cardioversion of persistent atrial fibrillation

Electrical cardioversion is the most effective and safe method to restore sinus rhythm in patients with persistent AF. However, at least 25% of electrical cardioversions are unsuccessful. The aim of the present study was to evaluate, in a prospective, randomized and double-blind study, the efficacy of a pretreatment with intravenous flecainide in patients who underwent electrical cardioversion. Fifty-four consecutive patients with persistent AF, mean arrhythmia duration 8 (mean 3-18) weeks, were randomized in two groups. In the first group (n = 26), patients received flecainide (2 mg/kg as a 30-minute IV infusion) before electrical cardioversion. In the second group (n = 28), 100 mL IV infusion of 5% glucose was administered 30 minutes before electrical cardioversion. The study evaluated the (1). acute efficacy of electrical cardioversion, (2). mean and maximal energy required, (3). mean number of shocks needed, and (4). incidence of complications. The two groups were similar in terms of age, sex, mean AF duration, left ventricular systolic function, atrial dimension, and cardiovascular risk factors. Seventy-seven percent of patients recovered sinus rhythm with electrical cardioversion. No statistical difference was noted between the two groups: flecainide 19/26 (73%) versus placebo 23/28 (82%). No significant differences were found concerning mean or maximal energy and number of shocks required. No major complications were observed. After a 30-day follow-up, 54% of patients maintained sinus rhythm with no difference between the two groups. Pretreatment with intravenous flecainide before electrical cardioversion is not useful in reducing technical failure of cardioversion, however, flecainide does not diminish the effectiveness of electrical cardioversion.     

Prediction of Maintenance of Sinus Rhythm after Cardioversion of Atrial Fibrillation by Analysis of Serial Signal-Averaged P Waves

After cardioversion from atrial fibrillation (AF) many patients develop early recurrence of the arrhythmia. While these patients may be appropriate for immediate prophylaxis against AF recurrence their identification at the time of cardioversion is not possible. Since the signal-averaged P wave (SAPW) is abnormal in individuals with atrial arrhythmia, we assessed its utility for predicting early AF recurrence after cardioversion. Seventy-five cardioversions in 31 patients were evaluated. The mean age was 59 (range 28–79) years; 26 were male. Fifty-eight cardioversions were internal using low energy biphasic DC shocks delivered via electrodes placed in the right atrial appendage and coronary sinus. P wave specific signal averaging was performed at 3 and 24 hours after each cardioversion to estimate filtered P wave duration and energy from 20, 40, and 60 to 150 Hz. Follow-up was by regular clinic visits and transtelephonic ECG monitoring. Early recurrence of AF (prospectively defined as sinus rhythm duration < 1 week) occurred after 30 cardioversions. No differences were found in any P wave variable measured at 3 hours between these cardioversions and those that resulted in a longer duration of sinus rhythm. Paired 3- and 24-hour signal-averaged data were available in 47 cardioversions. There were significant falls in P wave energy from 3 to 24 hours after 31 cardioversions that resulted in sinus rhythm for > 1 week, (P40: 3 hours 11.2 [±1.5] μV²· s, 24 hours 8.6 [±1.2] μV²· s, P < 0.001), but not following the 16 after which AF returned within 1 week (P40: 3 hours 9.0 [±1.2] μV²· s, 24 hours 8.5 [±1.2] μV²· s, P = NS). A fall in P40 of > 25% had a positive predictive accuracy for maintenance of sinus rhythm of 87%; negative predictive accuracy was only 37%. Similar falls in P wave energy occurred after cardioversions that resulted in longer term (> 4 weeks) sinus rhythm, but not in those that did not. However, the predictive accuracy of a fall in P40 was less (positive predictive accuracy 38%, negative predictive accuracy 62%). Patients with relapsing permanent AF who remain in sinus rhythm for at least 1 week after cardioversion show a fall in P wave energy within the first 24 hours. However, in these patients the technique does not predict recurrent AF within 1 week nor sinus rhythm > 4 weeks. These observations suggest persistent disordered atrial activation as a mechanism for early recurrence of AF after cardioversion.     

Cardioversion of Atrial Fibrillation and Subsequent Maintenance of Sinus Rbythm

This article gives an overview of electrical cardioversion of AF and includes the discussion of newer strategies. DC external cardioversion is highly effective and carries a low risk of complications. Other approaches, like transesophageal cardioversion and high energy internal cardioversion, may improve the acute success rate but do not enhance long-term maintenance of sinus rhythm compared to external cardioversion. An atrial defibrillator may have important advantages which relate to the fact that the duration and possibly also the number of AF episodes become reduced. Supposedly, shortening the attacks of AF may exert an antiarrhythmic effect by limiting electrical, anatomical, and neurohumoral remodeling. So far. low energy biatrial defibrillation using an atrial defibrillator seems to be effective and safe (i.e., does not induce ventricular arrhythmias). However, discomfort limits its tolerability in clinical practice. Future improvement of leads and light sedation that is easy to administer may overcome this problem. In the second part of this overview, the probability of AF recurrence using a serial cardioversion approach is discussed. In middle-aged patients with a fair exercise tolerance and an arrhythmia duration < than 36 months this approach may be worthwhile. Young patients (age < 57 years) with an arrhythmia duration < 3 months and without hypertension may be cured from the arrhythmia with a single shock and without the institution of antiarrhythmic drugs. However, the serial electrical cardioversion approach is unlikely to succeed in elderly patients with a duration of AF exceeding 36 months and a poor exercise tolerance (NYHA Functional Class III or IV).     

Management of atrial fibrillation in the emergency department

Although atrial fibrillation remains the most common cardiac arrhythmia, the treatment and disposition remain varied. An accept-able standard of practice requires an evidence-based approach.This approach has revealed that half of the patients who present with acute atrial fibrillation will convert to sinus rhythm without intervention. In the hemodynamically stable subset, ascertaining the on-set of atrial fibrillation within 48 hours is critical because this period dictates when and if anticoagulation should be instituted and if and where electrical or chemical cardioversion needs be performed.The hemodynamically unstable patient, however, requires emergent cardioversion, irrespective of the chronicity of atrial fibrillation. An evidence-based approach may serve to optimize treatment and obviate the need for unnecessary hospital admissions.     

Does Sinus Rhythm Beget Sinus Rhythm?

The aim of this study was to determine the effect of early patient activated cardioversion of atrial fibrillation (AF) using the atrial defibrillator on recurrence of AF. Fifteen patients, mean age 63 +/- 14 years, 80% men, with drug-resistant persistent AF were implanted with the Jewel AF atrial defibrillator. All patients performed self-administered cardioversion for AF recurrences. Over a 2 year follow-up, 238 patient-activated cardioversions were performed in 14 patients. Sinus rhythm was restored on every occasion with 96% of episodes terminating with a single shock. The median time from AF onset to patient awareness of symptoms was 2.5 hours. The median time from onset of symptoms to cardioversion was 3.5 hours. Comparison of the first and second six month period following implant showed a nonsignificant increase in mean total AF duration (75.7 +/- 107.8 hours vs 146.6 +/- 194.1 hours, P = 0.28). Two patients (13%) had a decreasing frequency of AF recurrences. The majority continued to have regular recurrences of AF. The atrial defibrillator is an extremely effective method of restoring sinus rhythm in patients with persistent AF. Regular early use of the atrial defibrillator, increased the duration of sinus rhythm in a minority of patients during long-term follow-up. Most patients had regular recurrences of AF requiring patient-activated cardioversion.     

Early recurrence of atrial fibrillation after external cardioversion

Early recurrence of atrial fibrillation (AF) has been reported to occur in a significant number of patients after internal cardioversion. However, information about early recurrence of AF after external cardioversion has never been reported. The present study was conducted to investigate the clinical and electrophysiological characteristics of early recurrence of AF and its role in failure of cardioversion in patients with chronic AF. METHODS AND RESULTS: The study included 50 consecutive patients, age 69+/-9, with a history of chronic AF for more than 3 months duration and electrical cardioversion. They were divided into two groups according to the presence (group 1) or absence (group 2) of early recurrence of AF. There were 13 (26%) patients in group 1 and 37 (74%) patients in group 2. The age, gender, duration of AF, left ventricular function, left atrial dimension, and underlying heart disease were similar between group 1 and 2. Forty-five patients were successfully converted to sinus rhythm with a mean energy of 158+/-57 . Among those who failed to be converted to sinus rhythm, 4 (80%) belonged to group 1 and 1 (20%) belonged to group 2. The early recurrences of AF were initiated with consecutive APDs; but the numbers of APD in the first 30 seconds after cardioversion were similar between group 1 and 2. However, the coupling interval of the second APD was shorter in group 1 than group 2 (188+/-22 vs 324+/-59 ms, P = 0.003). Nine of the 13 early recurrences were prevented by an increase of shock energy (n = 3) or intravenous amiodarone infusion (n = 6). There were no differences in duration of follow-up, recurrence rate, and time interval to recurrence between group 1 and group 2. Early recurrence of AF occurred in 26% of chronic AF patients who underwent external electrical cardioversion and was a major cause of failure in cardioversion. Early recurrence of AF was initiated by APDs with decreasing coupling intervals and could be prevented with an increase of shock energy or amiodarone.     

房颤电复律相关影响因素分析

目的探讨影响房颤电复律成功的因素。方法试验组房颤患者62例，对照组门诊查体窦性心律者60例。将试验组分为复律成功组（A组）和复律失败组（B组），比较试验组、对照组以及试验组各组间左心房内径、左心室舒张末期内径、左心室射血分数、c反应蛋白（CRP）水平的差异。所有患者于入院后或入组后第2天常规空腹抽血，采用免疫比浊法测定高敏感CRP（hs—CRP）。结果①A、B组与对照组相比，左心房内径大于对照组（P〈0．05），CRP高于对照组（P〈0．05）；②B组左心房内径更大（P〈0．05），多合并瓣膜性病变（P〈0．05），房颤持续时间长于复律成功组（P〈0．05），CRP更高（P〈0．05）。经多因素分析，CRP水平OR为2．1（95％CI 1．4～3．2，P=0．004），左房直径OR为1．8（95％CI 1．2～2．2，P=0．006），房颤持续时间OR为2．8（95％CI 1．6～4．0，P=0.007）。结论高敏感CRP、左房直径及房颤持续时间是影响房颤电复律成功的独立预测因素。     

特发性心房颤动患者的血浆心钠素水平的变化

目的：探讨特发性阵发性与持续性心房颤动患者的血浆心钠素（ANP）水平的变化及其原因。方法：采用放射免疫分析法检测21例特发性阵发性房颤患者房颤发作时（A1组）和房颤终止后7天（A2组）及28例特发性持续性房颤患者（B组）的血浆ANP水平，同时测定各组红细胞压积及血小板数，并与健康对照组（C组）进行比较。结果：特发性阵发性房颤患者房颤发作时及特发性持续性房颤患者的血浆心钠素水平及红细胞压积均显著高于正常对照组（P＜0．01），而A1组的血浆心钠素水平和红细胞压积显著高于A2组（P＜0．01），但血小板各组间差异无显著性（P＞0．05）。结论：特发性阵发性及特发性持续性心房颤动患者均存在血液浓缩，且与心钠素释放增加有关。     

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.     

Exercise‐Induced Natriuretic Peptide Secretion Predicts Cardioversion Outcome in Patients with Persistent Atrial Fibrillation: Discordant ANP and B‐Type Natriuretic Peptide Response to Exercise Testing

Background: Measurement of natriuretic peptide's (NP) release in response to hemodynamic stress may be complementary to its baseline assessment in individuals. Atrial natriuretic peptide (ANP) and B‐type natriuretic peptide (BNP) increase in patients with atrial fibrillation (AF) and decrease after successful cardioversion, suggesting that AF may stimulate secretion of NPs. However, there are conflicting data on the predictive value of NPs on the cardioversion outcome. Objectives: The purpose of this study was to investigate whether baseline and exercise‐induced NP plasma levels can be useful in predicting successful cardioversion of persistent AF and maintenance of sinus rhythm during 6‐month follow‐up. Methods: A prospective study enrolled 77 consecutive subjects with persistent AF with normal left ventricular function, referred for elective cardioversion. Patients underwent a modified Bruce protocol treadmill exercise test 24 hours before cardioversion. Blood samples for ANP and BNP analyses were obtained at rest and 5 minutes after exercise peak. Results: The group of successful cardioversion and stable sinus rhythm presented higher exercise ANP (110.6 ± 41.2 pg/mL vs 43.8 ± 36.1; pg/mL, P < 0.0001) and lower BNP increase (5.2 ± 5.2 pg/mL vs 40.5 ± 34.2 pg/mL, P < 0.0001) than the group of unsuccessful cardioversion or AF recurrence. Using an optimized cutoff level of ≤12% of relative exercise‐induced increase in BNP concentration, and of >50 pg/mL of ANP increase, successful cardioversion can be predicted with high accuracy. Conclusions: An increase in ANP and stability of BNP plasma concentration during exercise testing are independently associated with successful cardioversion and maintenance of sinus rhythm during 6‐month follow‐up. (PACE 2010; 33:1203–1209)     

Reverse electrical remodeling of the atria post cardioversion in patients who remain in sinus rhythm assessed by signal averaging of the P-wave

OBJECTIVES: This study was designed to determine whether the signal-averaged electrocardiogram of the P-wave (SAPW) is an independent predictor of recurrence of atrial fibrillation (AF) post cardioversion (CV), and to assess atrial remodeling using SAPW. BACKGROUND: There are limited electrophysiologic data to predict the recurrence of AF post-CV. The electrical remodeling that occurs post-CV is poorly understood. METHODS: Sixty-four patients with persistent AF undergoing CV were prospectively enrolled. SAPW parameters were measured the day of CV and repeated at 1 month. These SAPW parameters were compared to other baseline indices for the recurrence of AF. RESULTS: Sixty patients (94%) had successful CV. At 1 month, 22 (37%) maintained sinus rhythm (SR). The SAPW total duration decreased significantly in those who remained in SR (159 ms +/- 19 to 146 ms +/- 17; P < 0.0001). Only the duration of AF (46 +/- 50 days vs 147 +/- 227 days, P = 0.03) and the presence of left ventricular hypertrophy (LVH, 12% vs 65%, P = 0.0006) were significantly associated with recurrence of AF. Atrial size strongly correlated with the SAPW duration in patients who remained in SR (R(2)= 0.67, P = 0.003) but not in those who returned to AF (R(2)= 0.11, P = 0.65). CONCLUSIONS: Atrial electrical reverse remodeling occurs in patients with AF who maintain SR post-CV. This remodeling is likely inversely related to the duration of AF and LVH. SAPW duration does not predict recurrence of AF post-CV.     

Atrial fibrillation: current therapeutic approaches.

Atrial fibrillation is associated with potentially life-threatening strokes. Anticoagulation with warfarin or aspirin reduces the risk of embolic events in patients with chronic atrial fibrillation and mitral valve stenosis or other underlying heart disease. In patients with acute onset of atrial fibrillation, anticoagulation is not necessary before cardioversion. However, in patients with chronic atrial fibrillation, anticoagulation should be started three weeks before cardioversion and continued for four weeks after the return of normal sinus rhythm. Quinidine remains the agent most commonly used for medical cardioversion in patients who are hemodynamically stable. If a patient is hemodynamically unstable or the atrial fibrillation is not corrected with drug therapy, direct-current electrical cardioversion has a high success rate. Antiarrhythmic (quinidine) therapy is often continued indefinitely to help maintain sinus rhythm.