Flecainide versus ibutilide for immediate cardioversion of atrial fibrillation of recent onset.

AIMS: This study compared the efficacy and safety of intravenous flecainide and ibutilide for immediate cardioversion of atrial fibrillation (AF). METHODS AND RESULTS: We conducted a prospective, randomised trial, including 207 patients with AF of recent onset (< or = 48 h). Flecainide was given over 20 min at a dose of 2 mg/kg body weight (maximum 200 mg), ibutilide was infused at a dose of 1 mg (or 0.01 mg/kg if less than 60 kg) over 10 min, followed by a 10 min observation period and an identical second dose if AF did not convert to sinus rhythm (SR). Treatment was considered successful if SR occurred within 90 min of starting medication. The conversion rates were 56.4% in patients given flecainide and 50.0% in patients given ibutilide (P=0.34). Multivariate analysis revealed that a lower age for women independently increased the probability of conversion. None of the other variables, including left atrial size, left ventricular systolic function, presence of left ventricular hypertrophy, plasma levels of potassium or magnesium at baseline, or concomitant use of digoxin, beta-blocker, diltiazem or verapamil were predictors of conversion. The frequency of adverse events was comparable in the two treatment groups. CONCLUSIONS: There was no significant difference in the cardioversion efficacy or in the risk of adverse events between flecainide and ibutilide in patients with AF of recent onset. In patients without contraindications to both medications, the physician's choice has to be governed by other factors.     

Novel rectangular biphasic and monophasic waveforms delivered by a radiofrequency-powered defibrillator compared with conventional capacitor-based waveforms in transvenous cardioversion of atrial fibrillation.

AIMS: To investigate the feasibility and efficacy of novel low-tilt biphasic waveforms in transvenous cardioversion of atrial fibrillation (AF), delivered by a radiofrequency-powered defibrillator. METHODS AND RESULTS: The investigation was performed in three phases in an animal model of AF: a feasibility and efficacy study (in 10 adult Large White Landrace swine), comparison with low-tilt monophasic and standard capacitor-based waveforms, and an assessment of sequential shocks delivered over several pathways (in 15 adult Suffolk sheep). Defibrillation electrodes were positioned transvenously under fluoroscopic control in the high lateral right atrium and distal coronary sinus. When multiple defibrillation pathways were tested, a third electrode was also attached to the lower interatrial septum. The electrodes were then connected to a radiofrequency (RF)-powered defibrillator or a standard defibrillator. After confirmation of successful induction of sustained AF, defibrillation was attempted. Percentage success was calculated from the effects of all shocks delivered to all the animals within each set of experiments. Of the low-tilt (RF) biphasic waveforms delivered during internal atrial cardioversion, 100% success was achieved with a 6/6 ms 100/-50 V waveform (1.45+/-0.01 J). This waveform was similar in efficacy to low-tilt (RF) monophasic waveforms (88 vs. 92% success, 1.58+/-0.01 vs. 2.67+/-0.03 J; P=NS; delivered energy 41% lower) and superior to equivalent voltage standard monophasic (50% success, 0.67+/-0.00 J; P<0.001) and biphasic waveforms (72% success, 0.69+/-0.00 J; P=0.03). Sequential shocks delivered over dual pathways did not improve the efficacy of low-tilt biphasic waveforms. CONCLUSION: A low-tilt biphasic waveform from a RF-powered defibrillator (6/6 ms 100/-50 V) is more efficacious than standard monophasic or biphasic waveforms (equivalent voltage) and is similar in efficacy to low-tilt monophasic waveforms.     

Maintenance of sinus rhythm with metoprolol CR initiated before cardioversion and repeated cardioversion of atrial fibrillation: a randomized double-blind placebo-controlled study.

AIMS: To assess the effect of metoprolol in combination with repeated cardioversion on maintenance of sinus rhythm (SR). METHODS AND RESULTS: Consecutive outpatients with persistent atrial fibrillation (AF) were randomized to treatment with metoprolol CR or placebo in a double-blind fashion. Study treatment was started at least one week before direct current (DC) cardioversion. Patients were followed once a week during the first 6 weeks after cardioversion. In case of relapse during this period, a second cardioversion was performed. Total treatment time was 6 months. A total of 168 patients were randomized to metoprolol (n = 83) or placebo (n = 85). The dose of study treatment at cardioversion was 169 +/- 47 mg in the metoprolol group and 180 +/- 40 mg in the placebo group (P = 0.12). In an intention-to-treat analysis, 46 patients (55%) in the metoprolol group and 34 patients (40%) in the placebo group (P = 0.04) had SR 1 week after cardioversion, and 38 patients (46%) in the metoprolol group compared with 22 patients (26%) in the placebo group had SR after 6 months (P < 0.01). CONCLUSION: A treatment strategy of metoprolol CR started before cardioversion in combination with prompt second cardioversion in case of early relapse (1-6 weeks) significantly increases the proportion of patients in SR during six months of follow-up.     

依布利特与普罗帕酮转复心房颤动的临床研究

目的　研究和比较新型Ⅲ类抗心律失常药物依布利特与普罗帕酮转复心房颤动 (房颤 )的有效性及安全性。方法　采用随机、单盲对照研究。共入选房颤持续 1 5h~89d的患者 69例,其中男性 28例,女性 41例,随机进入依布利特组(n=34)、普罗帕酮组(n=35)。前者于 10min内静脉注射依布利特 1mg,后者于 10min内静脉注射普罗帕酮 70mg,如给药结束 10min后仍未转复为窦性心律,各组重复前述治疗 1次。观察开始给药后 1 5h内房颤的转复率及 4h内的不良反应。结果　(1)依布利特转复房颤的成功率明显高于普罗帕酮(70 .59% vs42 .86%,P<0. 05); (2)房颤的转复率与房颤的持续时间有关,持续时间低于 24h的房颤转复率 ( 71 05%, 27 /38 )明显高于持续时间超过 24h者(38 71%, 12 /31,P<0. 01),其中依布利特对持续 24h之内的房颤转复率高达 83 .33% (15 /18); (3)房颤的转复率与左心房直径呈负相关,左心房直径 <4 0cm患者的转复率 ( 75 68%, 28 /37 )明显高于左心房直径≥4 0cm患者的转复率(34. 38%, 11 /32,P<0 01); (4)依布利特最严重的不良反应为非持续性单形室性心动过速,发生率为 8 .82% (3 /34);普罗帕酮最严重的不良反应为低血压 (2. 86%, 1 /35)及长间歇(RR间期>2 .0s, 11 .43%, 4 /35)。结论　依布利特是一种快速转复     

Increased P-wave dispersion predicts recurrent atrial fibrillation after cardioversion

Atrial fibrillation (AF) will recur in a number of patients treated with cardioversion. Being able to identify reliable risk factors would be useful for making management decisions. P-wave dispersion (PWD) is an electrocardiographic measurement, which reflects a disparity in atrial conduction. P-wave dispersion has been shown to be increased in patients with paroxysmal AF. This pilot study aims to determine the role of PWD in predicting AF recurrence in patients who underwent elective cardioversion. Forty-five patients who were successfully cardioverted for persistent AF were included for study. Eighteen patients had a PWD greater than 80 ms; of these 13 had AF recurrence. Of the 25 patients with PWD less than 80 milliseconds, 12 had recurrent AF. P-wave dispersion values greater than 80 milliseconds were found more frequently in patients with AF recurrence (P = .05), supporting the use of this parameter in predicting return of AF. Larger studies are needed for further evaluation.     

心房颤动复律后维持窦性心律影响因素的临床分析

目的探讨心房颤动（Af）复律后维持窦性心律的影响因素。方法选择2006年～2008年首次诊断Af（发病时间〈3个月）经药物或直流电成功转复窦性心律的住院患者98例。随访6个月后Af未复发者为维持窦性心律组（A组）52例,Af复发者（B组）46例。回顾性对比分析两组的临床特征、心电图指标、超声心动图（UCG）参数及相互关系,探讨A组的独立预测因子及诊断价值。结果 6个月随访后,52例（占53%）仍维持窦性心律,46例Af复发,半数以上复发在复律后2周内。两组间在性别、年龄、基础心脏病、β受体阻断剂使用、复律方式、左心室射血分数（LVEF）等差异无统计学意义。B组与A组相比,复律前Af持续时间（28.7±26.3d对1.3±1.4d,P〈0.01）、P波最大时间（Pmax）（P〈0.01）和P波离散度（Pd）（52±12ms对40±10ms,P〈0.01）、左心房直径（LAD）（47±4mm对41±3mm,P〈0.01）和左房自发性声学显影（P〈0.01）差异有统计学意义;但是两组间P波最小时间（Pmin）差异无显著性。多元回归分析显示：Af持续时间〈7d（OR=2.61）、LAD〈45mm（OR=2.10）和Pd〈47ms（OR=3.72）是复律后维持窦性心律的独立预测因子,准确性分别为82%、83%和86%。Pmax和左房无自发性声学显影仅是单因素影响因子。结论复律前Af持续时间、左房大小和Pd是预测Af复律后维持窦性心律的重要因素。     

26例心房颤动患者心律转复前后心肺运动试验分析

目的探讨心房颤动对心脏功能的影响及心房颤动患者转复心律前后摄氧量等运动参数的改变。方法采用美国MedGraphics公司心肺运动仪和活动平板,在Bruce改良方案的基础上,对26例心房颤动患者分别进行心律转复前后心肺运动试验。结果26例心房颤动患者心律转复后,静息心率(HRrest)平均由109次min减慢到83次min(P<0001),最大运动时心率(HRmax)平均由182次min减慢到141次min(P<0001);最大每搏摄氧量(VO2maxHR)平均由788mL提高到109mL(P<0001);运动总时间(TET)平均由81min增加到88min(P<0001);最大运动速度(Speed)平均由30mph增加到33mph(P<001);斜度(Elevation)由1315%提高到1385%(P<001),试验过程中无并发症发生。结论心房颤动患者转复窦性心律后,心率明显减慢,最大每搏摄氧量增加,运动时间延长,运动耐力提高,心功能得到改善。     

Contemporary real life cardioversion of atrial fibrillation: Results from the multinational RHYTHM-AF study

Aims

Electrical and pharmacological cardioversion (ECV, PCV) are important treatment options for symptomatic patients with recent onset atrial fibrillation (AF). RHYTHM-AF is an international registry of present-day cardioversion providing information that is not currently available on country differences and acute and long-term arrhythmia outcomes of ECV and PCV.

Methods and results

3940 patients were enrolled, of whom 75% underwent CV. All patients were followed for 2 months. There were large variations concerning mode of CV used, ECV being heterogeneous. A choice of PCV drug depended on the clinical patient profile. Sinus rhythm was restored in 89.7% of patients by ECV and in 69.1% after PCV. Among patients not undergoing CV during admission, 34% spontaneously converted to sinus rhythm within 24 h. ECV was most successful in patients pretreated with antiarrhythmic drugs (mostly amiodarone). PCV was enhanced by class Ic antiarrhythmic drugs; conversion rate on amiodarone was similar to that seen with rate control drugs. Female patients and those with paroxysmal and first detected AF as well as those without previous ECV responded well to PCV. The median duration of hospital stay was 16.2 and 24.0 h for ECV and PCV patients, respectively. There were very few CV-related complications regardless of mode of CV. Chronic maintenance of sinus rhythm was enhanced in patients on chronic antiarrhythmic drugs, beta-blockers or inhibitors of the renin–angiotensin system.

Conclusions

Mode of CV varied significantly, but both PCV and ECV were safe and effective. Class Ic drugs were most effective conversion drugs, but amiodarone is used most frequently despite providing merely rate control rather than shorten time to conversion.     

Supraventricular ectopy and recurrence of atrial fibrillation after electrical cardioversion.

AIMS: Paroxysmal atrial fibrillation (AF) is usually preceded by a premature atrial complex (PAC). We hypothesized that patients with a high frequency of atrial ectopic activity after restoration of sinus rhythm following direct current cardioversion would be more likely to experience recurrence of AF. METHODS AND RESULTS: Forty-four patients with documented persistent AF were studied. A 24 h Holter recording was performed from the day of external direct current cardioversion. Patients were reviewed at 1 week, 1 month, and 6 months. After 6 months, 59% of patients had experienced a recurrence of AF. Neither the frequency of PACs nor the frequency or duration of supraventricular tachycardia (SVT) episodes predicted AF recurrence (P=0.60, 0.30, and 0.42, respectively). There was a trend towards maximum rate of SVT predicting recurrence of AF (P=0.08). CONCLUSION: Frequency of supraventricular ectopy or the number and length of SVT runs in the 24 h after restoration of sinus rhythm are not strong predictors of recurrence of AF after electrical cardioversion. A larger study would be required to detect a small predictive effect.     

Atrial stunning as predictor of early relapse into atrial fibrillation after cardioversion

Although the high rate of success after cardioversion, less than 50% of patients maintain sinus rhythm for the first year. In view for the high percentage of relapse into atrial fibrillation, it is interesting to analyze the relationship between atrial stunning after cardioversion and relapse into atrial fibrillation. Thus, we evaluated 101 patients with atrial fibrillation and successful cardioversion. Atrial mechanical function was assessed by measures of transmitral peak A wave velocity, determined before and weekly after cardioversion during 1 month. Fifty-five percent of patient relapse into atrial fibrillation during follow-up. No significant differences were found in clinical and echocardiographic variables between the group with and without relapse. However, the group of patients who relapsed into atrial fibrillation showed a lower peak A wave velocity immediately after cardioversion than patients who maintain in sinus rhythm at month (0.44 ± 0.27 vs. 0.60 ± 0.38 m/s p < 0.01). Impaired atrial function improves during the first 14 days after cardioversion.     

Factors related to the early and late success of direct current cardioversion of chronic nonrheumatic atrial fibrillation: An echocardiographic study

OBJECTIVES:

To assess factors related to the success of restoration and one-year maintenance of sinus rhythm in chronic (more than 48 h) nonrheumatic atrial fibrillation (AF).

METHODS AND RESULTS:

One hundred and fifty consecutive patients aged 62±9 years with AF lasting 123±254 days were evaluated clinically with transthoracic and transesophageal echocardiography before elective direct current cardioversion. Heart chamber dimensions and left ventricular ejection fraction were measured. The presence of left atrial thrombi and spontaneous echocardiographic contrast as well as flow velocities in the left atrial appendage were assessed. The first cardioversion was followed by standardized two-step antiarrhythmic treatment including a second cardioversion, if necessary. Twenty patients (13%) spontaneously reverted to sinus rhythm (S) during anticoagulation preceding cardioversion, 81 (54%) were successfully cardioverted (Y), and in 49 (33%) cardioversion failed initially (N). No differences were noted between the two latter groups. However, S patients had smaller left atria measured in the short and long axes (42±4 mm, P=0.05, and 53±7 mm, P=0.005, respectively) than both the Y (45±4 and 61±8 mm) and the N patients (46±4 and 61±8 mm). One-year follow-up was obtained in 95 patients: 64 (67%) were in sinus rhythm while 31 (33%) had AF. Again, no initial differences predicting the maintenance of sinus rhythm were found.

CONCLUSIONS:

Spontaneous reversion of AF seems more likely with smaller left atria. Echocardiography, including trans-esophageal echocardiography, is unlikely to identify patients in whom attempts to restore and maintain sinus rhythm will fail or succeed.     

心房颤动及复律药物的研究新进展

心房颤动（atrial fibrillation,AF）是一种心房快速紊乱的心律失常,是一种以心房不协调活动而导致心房机械功能恶化为特征的室上性心律失常,也是目前临床上最常见及危害最严重的心律失常之一,可引起血流动力学发生改变和脑栓塞等严重并发症,因此,房颤已成为心律失常领域的研究热点.世界范围内有3％～5％的人群发生房颤。普通人群发病率为0．7％～1．0％,65岁以上人群发病率约5％,80岁以上老年人发病率高达8％～9％。     

Effects of atrial fibrillation substrate and spatiotemporal organization on atrial defibrillation thresholds

BACKGROUND: We previously showed that canine models of atrial fibrillation (AF) have different substrates (either structural or electrical) that lead to differences in AF characteristics. OBJECTIVE: The purpose of this study was to determine whether the differences in AF characteristics also would lead to differences in atrial defibrillation thresholds (ADFTs). METHODS: Dogs were divided into five groups: control; MR-mitral regurgitation for 5 weeks; CHF-congestive heart failure for 4 weeks; RAP-rapid atrial pacing for 6 weeks; and METH-acetyl-beta-methylcholine acutely administered. A cross-sectional area of the left atrium was calculated, and AF was induced with rapid atrial pacing. Biphasic shocks with a pulse width of 3/3 ms were delivered through specially constructed shocking catheters with a surface area of 3.7 cm(2) that were placed in the right and left atria. An up-down-up protocol was used to determine the 50% ADFT threshold (ADFT(50)). A wide-bipole AF signal was digitally filtered, and a fast Fourier transform was calculated over a 2-second window every 1 second. The dominant frequency was determined, and the organization index was calculated as the ratio of the area under the dominant peak and its harmonics to the total area of the spectrum. RESULTS: For left atrial size, the CHF and MR groups had a significantly larger atria than did control. ADFT(50) for control, MR, CHF, RAP, and METH groups were 160 +/- 30 V, 120 +/- 50 V, 132 +/- 20 V, 668 +/- 205 V, and 593 +/- 128 V, respectively (analysis of variance, P <.0001). Dominant frequencies were significantly higher and organization indexes significantly lower in the RAP and METH models compared with the other models. CONCLUSION: RAP and METH canine models had a significantly higher ADFT(50) compared with the other AF models. The increase in ADFT(50) in these models corresponded with higher global dominant frequencies and lower measured organization indexes.     

A randomized placebo-controlled trial of pre-treatment and short- or long-term maintenance therapy with amiodarone supporting DC cardioversion for persistent atrial fibrillation.

AIMS: The efficacy of cardioversion (DCCV) for restoration of sinus rhythm (SR) in persistent atrial fibrillation (AF) is limited by a high relapse rate. Relapse may be reduced by amiodarone but no placebo-controlled trials of efficacy have been performed and the appropriate duration of therapy is unknown. METHODS AND RESULTS: In this double-blind study, 161 subjects with persistent AF were randomized to one of three groups-placebo (n=38); amiodarone 400mg BD for 2 weeks prior to DCCV and 200mg daily for 8 weeks followed by placebo for 44 weeks (n=62, short-term amiodarone); amiodarone 400mg BD for 2 weeks then 200mg daily for 52 weeks (n=61, long-term amiodarone). Spontaneous reversion to SR occurred before DCCV in 21% (26/123) patients on amiodarone and none of the 38 patients on placebo (absolute difference 21%, 95% confidence interval (CI): 10 to 29%, P=0.002). At 8 weeks following DCCV, 51% (63/123) patients on amiodarone remained in SR compared to 16% (6/38) taking placebo (difference-35% 95% CI: -48 to -18%, P<0.001). At 1 year, 49% (30/61) patients on long-term amiodarone were in SR compared to 33% (21/62) taking short-term amiodarone (difference-15%, 95% CI: -31 to 2%, P=0.085). There was no difference in adverse event rate or quality of life scores between groups. CONCLUSIONS: Amiodarone pre-treatment before electrical DCCV for persistent AF allows chemical conversion in one-fifth of patients without altering the efficacy of subsequent DC conversion. Amiodarone is more effective than placebo in the maintenance of SR when continued for 8 weeks following successful DCCV. More patients taking long-term amiodarone remained in SR at 52 weeks, but more had serious adverse effects requiring discontinuation of therapy. Eight weeks of adjuvant therapy with amiodarone following successful DCCV may be the preferred option.     

Dronedarone for prevention of atrial fibrillation: a dose-ranging study.

AIMS: Dronedarone, a benzofurane derivative without iodine substituents, shares the electrophysiologic properties of amiodarone. This study was designed to determine the most appropriate dose of dronedarone for prevention of atrial fibrillation (AF) after cardioversion. METHODS AND RESULTS: Patients with persistent AF were randomly allocated to 800, 1200, 1600 mg daily doses of dronedarone or placebo. The main analysis was conducted on 199/270 patients, who entered the maintenance phase following pharmacological cardioversion or, if unsuccessful, DC cardioversion. Within 6-month follow-up, the time to AF relapse increased on dronedarone 800 mg, with a median of 60 days vs 5.3 days in the placebo group (relative risk reduction 55% [95% CI, 28 to 72%] P=0.001). No significant effect was seen at higher doses. Spontaneous conversion to sinus rhythm on dronedarone occurred in 5.8 to 14.8% of patients (P=0.026). There were no proarrhythmic reactions. Drug-induced QT prolongation was only noticed in the 1600 mg group. Premature drug discontinuations affected 22.6% of subjects given 1600 mg dronedarone versus 3.9% on 800 mg and were mainly due to gastrointestinal side effects. No evidence of thyroid, ocular or pulmonary toxicity was found. CONCLUSION: Dronedarone, at a 800 mg daily dose, appears to be effective and safe for the prevention of AF relapses after cardioversion. The absence of thyroid side effects and of proarrhythmia are important features of the drug. Further studies are needed to better delineate the antiarrhythmic profile of the drug.     

伊布利特与胺碘酮转复持续性心房颤动的疗效和安全性对比研究

目的 比较伊布利特和胺碘酮转复持续性心房颤动（PAF）的疗效和安全性.方法 2012年3月至2014年5月选取郑州市第十人民医院心内科住院的72例PAF患者,随机分为2组.伊布利特组（33例）采用伊布利特静脉注射转复窦性心律,用量：体质量≥60kg的患者,首次剂量1 mg,体质量＜60kg的患者,首次剂量0.01 mg/kg.胺碘酮组（39例）采用胺碘酮静脉注射转复窦性心律,用量：体质量≥60 kg的患者,首次剂量300 mg,体质量＜60 kg的患者,首次剂量5 mg/kg.比较两组患者用药后30 min内、3h内、12 h内、24h内的转复率,并记录两组患者用药过程中的不良反应.结果 伊布利特组患者用药后30 min内、3h内、12h内、24h内转复率均明显高于胺碘酮组（x2=10.7330,10.6500,8.4538,5.1932,P＜0.01或P＜0.05）;伊布利特组患者的平均转复时间明显短于胺碘酮组（t=7.9009,P＜0.01）;伊布利特QTc平均恢复时间短于胺碘酮（t=15.783,P＜0.01）;两组患者不良反应发生率比较差异无统计学意义（x2=0.4690,P＞0.05）,但伊布利特组的不良反应持续时间较胺碘酮组更短[（0.38±0.10）h比（16.75±8.39）h,t=11.195,P＜0.01].结论 与胺碘酮相比,伊布利特对持续性房颤的转复率高,转复时间短,不良反应消失快.     

Relapse and mortality following cardioversion of new-onset vs. recurrent atrial fibrillation and atrial flutter in the elderly.

AIMS: Trials of rate control vs. rhythm control for atrial fibrillation or flutter included few patients with new-onset arrhythmia. Our objective was to assess the relapse rate and the effect of the relapse of new-onset atrial arrhythmias on mortality after direct-current cardioversion (DCCV). METHODS AND RESULTS: A cohort of 351 patients with atrial fibrillation (new onset in 179) and 126 patients with atrial flutter (new onset in 78) was followed-up after DCCV. Cox proportional hazard models were used. Median age was 74.6 years. Mean follow-up for relapse was 7.7 months; for death, 29.4 months. Patients with new-onset atrial flutter [adjusted hazard ratio (HR) = 1] were more likely to maintain sinus rhythm than the patients with recurrent atrial flutter (adjusted HR = 2.5, P < 0.01), new-onset atrial fibrillation (adjusted HR = 2.4, P < 0.01), or recurrent atrial fibrillation (adjusted HR = 2.7, P < 0.01). Patients with new-onset atrial fibrillation were as likely to have relapses as patients with recurrent atrial fibrillation or flutter. Relapse of atrial arrhythmia after DCCV was associated with increased mortality (adjusted HR= 3.1, P < 0.01). CONCLUSION: DCCV is more successful in maintaining sinus rhythm in patients with new-onset atrial flutter than in patients with new-onset atrial fibrillation. Relapse of atrial arrhythmia after cardioversion is associated with increased mortality.     

Success of serial external electrical cardioversion of persistent atrial fibrillation in maintaining sinus rhythm; a randomized study.

AIMS: The aim of this prospective, randomized study was to determine the efficacy of a serial external electrical cardioversion strategy in maintaining sinus rhythm after 12 months in patients with recurrent persistent atrial fibrillation. METHODS AND RESULTS: Ninety patients with persistent atrial fibrillation lasting more than 72 h but less than 1 year were randomized in a one to one fashion to repetition of up to two electrical cardioversions in the event of relapse of atrial fibrillation detected within 1 month of the previous electrical cardioversion (Group AGG), or to non-treatment of atrial fibrillation relapse (Group CTL). ECGs were scheduled at 6 h, 7 days, and 1 month. Clinical examination and ECGs were repeated during the 6-month and 12-month follow-up examinations. Echocardiography was repeated during the 6-month follow-up examination. Clinical and echocardiographic characteristics were similar in the two groups. All patients were treated with antiarrhythmic drugs before electrical cardioversion and throughout follow-up. After 12 months, sinus rhythm was maintained in 53% of Group AGG patients and in 29% of Group CTL patients (P<0.03). After 6 months, left ventricular ejection fraction had recovered significantly only in Group AGG (56.8 +/- 9.0% at enrollment vs 60.4 +/- 9.4% at 6 months,P <0.001). CONCLUSION: These results demonstrate that an aggressive policy towards persistent atrial fibrillation by means of repetition of electrical cardioversion after early atrial fibrillation recurrence is useful in maintaining sinus rhythm after 12 months.     

Association between transthoracic impedance and electrical cardioversion success with biphasic defibrillators: An analysis of 1055 shocks for atrial fibrillation and flutter

Background

The relevance of transthoracic impedance (TTI) to electrical cardioversion (ECV) success for atrial tachyarrhythmias when using biphasic waveform defibrillators is unknown.

Hypothesis

TTI is predictive of ECV success with contemporary defibrillators.

Methods

De‐identified data stored in biphasic defibrillator memory cards from ECV attempts for atrial fibrillation (AF) or atrial flutter (AFL) over a 2‐year period at our center were evaluated. ECV success, defined as arrhythmia termination and ≥ 1 sinus beat, was adjudicated by 2 blinded cardiac electrophysiologists. The association between TTI and ECV success was assessed via Cochrane‐Armitage trend and Spearman rank correlation tests, as well as simple and multivariable logistic regression. The influence of TTI on the number of shocks and on cumulative energy delivered per patient was also examined.

Results

703 patients (593 with AF, 110 with AFL) receiving 1055 shocks were included. Last shock success was achieved in 88.0% and 98.2% of patients with AF and AFL, respectively. In patients with AF, TTI was positively associated with last shock failure (P_trend =0.019), the need for multiple shocks (P_trend <0.001), and cumulative energy delivered (ρ = 0.348; P < 0.001). After adjusting for first shock energy, 10‐Ω increments in TTI were associated with odds ratios of 1.36 (95% CI: 1.24–1.49) and 1.22 (95% CI: 1.09–1.37) for first and last shock failure, respectively (P < 0.001 for both).

Conclusions

Although contemporary defibrillators are designed to compensate for TTI, this variable continues to be associated with ECV failure in patients with AF. Strategies to lower TTI during ECV for AF may improve procedural success.