External cardioversion of atrial fibrillation in patients with implanted pacemaker or cardioverter-defibrillator systems: a randomized comparison of monophasic and biphasic shock energy application.

AIMS: External cardioversion (ECV) of atrial fibrillation (AF) may damage implanted pacemaker and cardioverter-defibrillator (ICD) systems. This prospective study evaluated the safety and efficacy of ECV comparing mono- to biphasic shock waveforms in patients with implanted rhythm devices. METHODS AND RESULTS: Patients with pacemaker or ICD systems and an indication for ECV were randomized to receive mono- or biphasic shocks. Systems were tested immediately before and after ECV, 1 h and 1 week later with respect to device and lead integrity. Forty-four patients (71 +/- 10 years, 31 male; 29 pacemakers, 12 ICDs, three cardiac resynchronization systems) underwent ECV with antero-posterior paddle orientation (monophasic in 21 and biphasic in 23 patients). Pacing impedances were reduced immediately after ECV (atrial 402-392 ohm, P < 0.001; ventricular 517-496 ohm, P = 0.001) and returned to baseline values within 1 week. Ventricular sensing was reduced immediately after ECV (12.4-11.6 mV, P = 0.004). There was no device or lead dysfunction in any patient. ECV was successful in 42/44 patients (95%), cumulative energy was significantly lower for biphasic compared with monophasic shocks (P = 0.001). CONCLUSION: ECV for AF seems to be safe and effective in patients with implanted rhythm devices.     

External cardioversion of atrial fibrillation: comparison of biphasic vs monophasic waveform shocks.

AIMS: It is well established in transthoracic ventricular defibrillation that biphasic truncated waveform shocks are associated with superior defibrillation efficacy when compared with damped sine wave monophasic waveform shocks. The aim of this study was to explore whether biphasic waveform shocks were superior to monophasic waveform shocks for external cardioversion of atrial fibrillation (AF). METHODS AND RESULTS: Fifty-seven patients in whom cardioversion of AF was indicated were randomized in this prospective study, to transthoracic cardioversion with either monophasic damped sine waveform shocks or biphasic impedance compensating waveform shocks. In the group randomized to monophasic waveform shocks (27 patients), a first shock of 150 J was delivered, followed (if necessary) by a 360 J shock. In the biphasic waveform group (30 patients), the first shock had an energy of 150 J and (if necessary) a second 150 J was delivered. All shocks were delivered in the anterolateral chest pad position. Sinus rhythm was restored in 16 patients (51%) with the first monophasic shock and in 27 patients (86%) with the first biphasic shock. The difference was statistically significant (P=0.02). After the second shock, sinus rhythm was obtained in a total of 24 patients (88%) with monophasic shocks and in 28 patients (93%) with biphasic shocks. No complication was observed in either group and cardiac enzymes (CK, CKmb, troponin I, myoglobin) did not show any significant changes. CONCLUSION: This study suggests that at the same energy level of 150 J, biphasic impedance compensating waveform shocks are superior to monophasic damped sine waveform shocks cardioversion of atrial fibrillation.     

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.     

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。     

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.     

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.     

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。     

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.     

心房颤动患者复律前后左心房功能变化的超声研究

目的　探讨心房颤动 ( AF )复律后左心房功能变化的特点。方法　选择 AF病人 96例 ,按心脏节律转复的方式分为自发性复律 ( A)组 2 4例 ,药物复律 ( B)组 40例及直流电复律 ( C)组 3 2例 ;分别应用超声心动图测定其左心房内径和容积 ,计算左心房主动和被动排空容积 ,并评价左心房功能。结果　AF时所有病人的左心房扩大 ,而恢复窦性心律后 A、B及 C组左心房内径降低者分别为 10 0 %、74%及 5 2 %。 62例左心房机械功能正常患者与 3 4例左心房功能降低患者比较有更强的左心房射血力 ( LAEF ) ,这与复律后左心房内径降低有关。左心房功能异常( L AEF<7达因 )患者左心房内径和容积分别与左心房射血力呈负相关 ( r=-0 .72和 -0 .76,P<0 .0 0 1)。左心房主动排空分数降低而管道容积却增加。结论　心房颤动复律后 ,左心房机械功能的延迟恢复与持续存在的的左心房扩大有关     

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％。     

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.     

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.     

Clinical practicality and predictive value of transoesophageal echocardiography in early cardioversion of atrial fibrillation.

AIMS: The objective of this study is to evaluate the feasibility of transoesophageal echocardiography (TOE)-guided cardioversion (CV) of atrial fibrillation (AF) in daily clinical practice. METHODS AND RESULTS: Transthoracic echocardiography and TOE were performed in 346 consecutive patients with AF lasting longer than 48 h or of unknown duration. If no intracavitary thrombus was found, CV was performed within 24 h of the TOE examination. Anticoagulation with subcutaneous low-molecular-weight heparin and warfarin was always started before CV. Warfarin was continued for at least 1 month after CV. The predictive value of several echocardiographic parameters including peak left atrial appendage emptying velocity (PLAAEV), left ventricular ejection fraction, left atrial diameter, and spontaneous echo contrast for the initial and long-term success of CV were evaluated. Transoesophageal echocardiography revealed no thrombus or other contraindications to CV in 274/346 (79%) patients. Early CV restored normal sinus rhythm or pacemaker rhythm in 90% (246/274) of the patients. One patient (0.3%) had a stroke within 30 days after CV. Peak left atrial appendage emptying velocity was significantly lower in patients with contraindications to early CV (P<0.001). However, neither PLAAEV nor any other echocardiographic parameter predicted the initial success of CV and the maintenance of sinus rhythm during long-term follow-up. CONCLUSION: Early TOE-guided CV with short-term anticoagulation is a safe and clinically effective alternative in treatment of AF lasting longer than 48 h or of unknown duration. The initial and long-term success of CV cannot be reliably predicted by echocardiographic parameters.     

Prospective, randomized comparison of two biphasic waveforms for the efficacy and safety of transthoracic biphasic cardioversion of atrial fibrillation

OBJECTIVES: The purpose of this study was to determine if there is a difference in commercially available biphasic waveforms. BACKGROUND: Although the superiority of biphasic over monophasic waveforms for external cardioversion of atrial fibrillation (AF) is established, the relative efficacy of available biphasic waveforms is less clear. METHODS: We compared the effectiveness of a biphasic truncated exponential (BTE) waveform and a biphasic rectilinear (BR) waveform for external cardioversion of AF. Patients (N = 188) with AF were randomized to receive transthoracic BR shocks (50, 75, 100, 120, 150, 200 J) or BTE shocks (50, 70, 100, 125, 150, 200, 300, 360 J). Shock strength was escalated until success or maximum energy dose was achieved. If maximum shock strength failed, patients received the maximum shock of the opposite waveform. Analysis included 141 patients (71 BR, 70 BTE; mean age 66.5 +/- 13.7. Forty-seven randomized patients were excluded because of flutter on precardioversion ECG upon blinded review (n = 25), presence of intracardiac thrombus (n = 7), or protocol deviation (n = 15). Groups were similar with regard to clinical and echocardiographic characteristics. RESULTS: The success rate was similar for the two waveforms (93% BR vs 97 BTE, P = .44), although cumulative selected and delivered energy was less in the BTE group. Only AF duration was significantly different between successful and unsuccessful patients. No significant complications occurred. CONCLUSIONS: Biphasic waveforms were very effective in transthoracic cardioversion of AF, and complication rates were low. No significant difference in efficacy was observed between BR and BTE waveforms. Impedance was not an important determinant of success for either biphasic waveform.     

Impedance compensated biphasic waveforms for transthoracic cardioversion of atrial fibrillation: a multi-centre comparison of antero-apical and antero-posterior pad positions.

AIMS: To compare the success rate for transthoracic direct current cardioversion (DCC) of atrial fibrillation (AF) with antero-posterior (AP) and antero-apical (AA) electrode positions using an impedance compensated biphasic (ICB) waveform. METHODS AND RESULTS: Three-hundred and seven patients [mean age 66 (SD+/-13), 195 male] with AF were recruited in three centres. Patients were randomized to an AA (n=150) or AP (n=144) pad position. Thirteen patients with implanted pacemakers were defaulted to the AP pad position. Cardioversion was performed using an ICB waveform with a 70, 100, 150, and 200 J energy selection protocol. If the fourth shock was unsuccessful, the pads were crossed over to the alternative position for a final 200 J shock. Shock 1 was successful in 54/150 (36%) AA and 45/144 (31%) AP patients, whereas success was achieved by shock 2 in 99/150 (66%) AA and 74/144 (51%) AP, by shock 3 in 123/150 (82%) AA and 109/144 (76%) AP, and by shock 4 in 143/150 (95%) AA and 127/144 (88%) AP and after cross-over in 144/150 (96%) AA and 135/144 (94%) AP. Overall success rate was higher than expected at 95%. Pad position was not associated significantly with success. There was a trend towards an improved outcome with the AA configuration (P=0.05). CONCLUSION: The influence of pad position for DCC of AF may be less pertinent with ICB waveforms than with monophasic waveforms.     

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